JPH04268178A - Coolant recovery device - Google Patents

Abstract

PURPOSE: To provide a refrigerant recovery device for a refrigeration system which discharges less fluorine carbide into the air, that is, causes less pollution of the environment. CONSTITUTION: A method of recovering a refrigerant comprises steps of extracting the refrigerant from a refrigeration system 12 to be maintained, and compressing the refrigerant extracted by a compressor 44 to form a high- pressure gaseous refrigerant. The high-pressure gaseous refrigerant is delivered to a compressor 60 to be condensed into a liquid refrigerant therein. The liquid refrigerant condensed in the compressor 60 is delivered to refrigerant storage means 26. In addition, the refrigeration system is provided with means for determining a compression ratio of a recovery compressor and means for monitoring whether or not the recovery compressor is operated with the determined compression ratio. When the monitored compression ratio exceeds a set value, above which the compressor may be adversely affected in operation, a recovery system 10 is stopped and the extraction of refrigerant from the refrigeration system 12 to be maintained is terminated. The recovery system 10 extracts refrigerant stored in the storage means 26.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to refrigerant recovery devices used in mechanical refrigeration systems.

[0002] Mechanical refrigeration systems are currently widely used across a variety of applications. These fields span many fields, including private refrigeration, commercial refrigeration, air conditioning, dehumidification, food freezing, refrigeration, and manufacturing processes.

0003

[Prior Art] As prior art documents, U.S. Patent No. 4,
No. 441,330 Lower et al., Refrigerant Recovery and Re-Entry System, U.S. Pat. No. 4,476,688 God
"Refrigerant Recovery and Purification System" by dard, U.S. Pat. No. 4,766,733; "Refrigerant Regeneration and Charge Unit" by Scuderi, U.S. Pat. No. 4,809,52
"Refrigerant recovery and purification system" by No. 0 Manz et al.
U.S. Pat. No. 4,862,699 by Lounis
``Refrigerant Recovery, Purification, and Separation Method and Apparatus from Lubricants'' by Merritt, U.S. Pat. No. 4,903,499.
Refrigerant Recovery System” and U.S. Patent No. 4,942,74
There is a "refrigerant recovery device" by No. 1 Hancock et al.

0004

The majority of mechanical refrigeration systems use closed loop channels for the flow of refrigerant.
The same well-known method is used. Various saturated fluoride carbide compounds and azeotropic compounds are widely used as refrigerants in refrigeration systems. A typical refrigerant is R-12.
, R-22, R-500 and R-502.

Those who have been familiar with these mechanical refrigeration systems must always be aware that such systems require periodic inspection and maintenance. Inspection and maintenance includes the removal, replacement, and repair of refrigeration system components. Furthermore, even according to normal system operation, the refrigerant can become contaminated by foreign objects in the refrigerant loop or excessive moisture in the system. Excessive moisture can cause ice formation in diffusion valves and capillaries, corrosion of metals, and chemical damage to gas-tight compression pump packings. Oxides are also generated due to motor burnout and cause refrigerant overheating phenomena. Such burnout is accidental and local in nature, as is the case with friction-generating particles that cause localized hot spots in the refrigerant, causing overheating phenomena. The acidic substance mainly involved here is hydrogen chloride (HCl),
Other acids and pollutants are produced as decomposition products of oils, insulating materials, varnishes, gaskets, adhesives, and the like. Accumulation of contaminants in the refrigerant as described above can lead to failure of system components, and it may be determined that it is advisable to replace the refrigerant in order to maintain and improve the operating efficiency of the system. .

When maintaining refrigeration systems, it has been customary to release the refrigerant to the atmosphere prior to inspecting or repairing the equipment. At this time, the refrigerant loop is suctioned by a suction pump, the remaining refrigerant in the loop is sucked out into the atmosphere, and new refrigerant is sucked into the loop. Such a method is currently not permissible from the perspective of environmental protection, and in particular, it is known that the above-mentioned release of fluorine carbide into the atmosphere reduces the ozone concentration in the atmosphere. ing. Depletion of the ozone layer in the atmosphere has come to be recognized as having a negative impact on the global environment and the human body. Furthermore, the cost of refrigerants has come to occupy an important position from the viewpoint of maintenance costs for refrigeration systems, and after recovery, refining and
It is also possible to dispose of refrigerant that can be reused as described above.
This is no longer acceptable.

[0007] In order to prevent the release of fluorine carbide into the atmosphere,
Several devices are considered and designed for recovering refrigerant from refrigeration systems. These devices are often equipped with refrigerant processing equipment so that the refrigerant can be recovered in reusable form. Examples of such devices include U.S. Pat.
No. 76,688 Goddard, “Refrigerant Recovery and Purification System,” U.S. Pat. No. 4,766,733 Scu.
"Refrigerant Recovery and Purification Unit" by Deri, U.S. Pat. No. 4,809,520; "Refrigerant Recovery and Purification System" by Manz et al., U.S. Pat. No. 4,862,699; , "Separation Method and Apparatus", U.S. Patent No. 4,903,499M
Examples include "Refrigerant Recovery System" by Scott Erritt and "Refrigerant Recovery Apparatus" by Hancock et al. in US Pat. No. 4,942,741.

[0008] When using the conventional apparatus described above, a recovery compressor is used to discharge refrigerant from the refrigeration system to be maintained. As the pressure in the refrigerant recovery system decreases, the pressure differential between the input and output of the recovery compressor increases. This is because while the pressure on the discharge side of the recovery compressor is constant, the pressure on the suction side of the recovery compressor gradually decreases. If this pressure difference becomes excessively large, the heat generated inside the compressor due to the pressure difference and the stress acting on the bearing surface of the compressor exceed a permissible range, and there is a risk of damaging internal components of the compressor. Based on the above, it is necessary to limit the pressure difference and pressure ratio of the recovery compressor, but this limit also limits the amount of refrigerant discharged per unit operating time from the refrigeration system being maintained. This leads to things.

When servicing large capacity refrigeration systems using a refrigerant recovery device such as that described above, it is particularly advantageous to be able to recover the refrigerant from the system in liquid form and direct it to a recovery vessel. . In other words, recovery efficiency is clearly higher when the refrigerant is recovered in a liquid state with higher refrigerant density than when it is recovered in a vaporized state.

[0010] A preferable feature of the above refrigerant recovery apparatus is that the refrigerant recovery apparatus itself is provided with a quality inspection function for the recovered refrigerant.

[0011]

SUMMARY OF THE INVENTION In accordance with the present invention, recovery compressor protection is accomplished by a device and apparatus for recovering compressible refrigerant from a refrigeration system and directing the recovered refrigerant to a refrigerant storage means. The recovery method consists of recovering refrigerant from a refrigeration system undergoing maintenance and compressing the recovered refrigerant by a compressor to form a high pressure gaseous refrigerant. The high pressure gaseous refrigerant is sent to a condenser where it is condensed into liquid refrigerant. The liquid refrigerant condensed in the condenser is sent to the refrigerant storage means. Further, means for determining the pressure ratio of the recovery compressor;
Means are provided for monitoring that the recovery compressor is operating at the determined pressure ratio. The monitored pressure ratio is
If the set value exceeds the set value above which operating the compressor would have an adverse effect, the recovery system is shut down and recovery of refrigerant from the refrigeration system being maintained is stopped.

[0012] Here, the recovery system recovers the refrigerant stored in the storage means. The refrigerant recovered from the storage means is further condensed by the same condenser used to condense the refrigerant recovered from the refrigeration system. The refrigerant thus condensed is further condensed into liquid refrigerant, passed through an appropriate expansion device, and returned to the storage means, and the cooled refrigerant is stored in the storage means. This refrigerant cooling cycle is repeated for a predetermined period of time until the temperature of the storage means drops to a preset temperature. Additionally, the recovery system continues to recover refrigerant from the refrigeration system undergoing maintenance. When the suction pressure of the recovery compressor falls below a predetermined value, the refrigerant recovery operation is terminated.

Another feature of the present invention is that when operating a refrigerant recovery system for recovering compressible refrigerant from a refrigeration system, the liquid refrigerant is first removed from the refrigeration system to be maintained via appropriate piping. , the extracted refrigerant is sent to the refrigerant storage means. In the refrigerant storage means, at least a portion of the refrigerant taken out as described above contains a gaseous refrigerant. This gaseous refrigerant portion is recovered from the storage means, compressed and
It becomes a high-pressure gaseous refrigerant. Furthermore, this high pressure gaseous refrigerant is condensed and becomes a high pressure liquid refrigerant. This high pressure liquid refrigerant is sent to a diffusion device where, after undergoing a pressure drop, at least a portion of the refrigerant is vaporized. The refrigerant, which is a mixture of liquid and gas, is further sent to the storage means, where it evaporates by absorbing heat from the stored refrigerant while cooling the storage means and maintaining a low pressure. Due to the action,
Facilitates recovery of liquid refrigerant from the refrigeration system via piping.

A control system monitors the rate of change in the liquid refrigerant level in the storage means. When the rate of change approaches a set value that indicates the end of recovery of the refrigerant in the liquid state, the control system outputs a control command so that the recovery system automatically shifts to the operation of recovering the gaseous state.

Still another function of the control system means is that when the state of the refrigerant being recovered from the refrigeration system changes in response to the time of transition from liquid to gas, the change is detectable as a value. There is a function to detect parameters as system control parameters. This parameter is
It is used to switch the operation mode of the recovery system from liquid refrigerant recovery mode to gaseous refrigerant recovery mode.

The purity of the recovered refrigerant is determined using a method and apparatus for measuring the purity of refrigerant flowing within a refrigeration system. The refrigeration system has an inlet pipe that is a fluid introduction section, and includes a compressor that forms part of the low-pressure side of the refrigeration system. Furthermore, this compressor has a fluid outlet, an outlet pipe, and forms part of the high pressure side of the refrigeration system. The refrigerant measuring container is attached in parallel to the input and output pipes of the compressor so that the refrigerant bypasses the compressor. As the compressor operates, a flow of refrigerant in the refrigeration system is created, with the refrigerant flowing from the high pressure side to the low pressure side of the system. Therefore, the refrigerant is recovered from the high pressure side,
The refrigerant is introduced into the refrigerant measurement container and after the measurement is completed, it is returned to the flow path on the low pressure side.

[0017]

[Operation] Means for determining the pressure ratio of the recovery compressor and means for monitoring whether the recovery compressor is being operated at the determined pressure ratio are provided. If the monitored pressure ratio is
If the set value exceeds the set value above which operating the compressor would have an adverse effect, the recovery system is shut down and recovery of refrigerant from the refrigeration system being maintained is stopped.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A refrigerant recovery and purification apparatus included in a refrigeration system is indicated at 10 in FIG. The refrigeration system from which the refrigerant is recovered is indicated at 12 and may be any practical mechanical refrigeration system.

As shown, the interconnections or taps between the recovery and purification system 10 and the refrigeration system 12 used are standard gauge and service manifolds 14. The manifold 14 has one pipe 16 connected to the system 1.
2 and the other piping is connected to the high pressure side of the refrigeration system 12 used. High pressure refrigerant piping 20 is interconnected between a service connection 22 of the service manifold and a T-connection 11 for coupling piping 20 to recovery system 10 .

[0020] A filter dryer 13, which is external to the recovery system, is arranged in interconnecting piping 20. As will be appreciated, this device is normally installed in the piping 20 only when the system is first to be operated in the liquid recovery mode of operation.

Collection system 10 includes two parts, as shown in FIG. The components and controls of the retrieval system are contained within a compact housing schematically represented by dashed line 24. The refrigerant storage portion of the system is contained within the section of dashed line 26. Details of each of these parts and their interconnections and interactions will be described in detail below.

As will be understood from the subsequent description of the operation of the system, there are two refrigerant passages extending from the T-junction 11 at the end of the interconnecting piping 20. The first or liquid path extends to the left of T-11 towards electrically actuable solenoid valve SV7. The valve selectively allows the passage of refrigerant when driven to the open position or prevents the passage of refrigerant when electrically driven to the closed position. Additional electrically actuated solenoid valves included in the system operate in a similar conventional manner. From SV7, liquid refrigerant piping 15 extends to the refrigerant storage portion of system 26. There, it communicates via a valve 90 with a refrigerant storage cylinder 86 . In the system's liquid recovery mode of operation, liquid refrigerant passes directly from the refrigeration system 12 to the storage cylinder 86 via line 15 .

When the system is operated in vapor recovery mode, the gaseous refrigerant flowing through interconnecting piping 20 is T
-11 and to the right with respect to the electrically actuatable solenoid valve SV3. From SV3, refrigerant passes through drive 28 via check valve 98 to second electrically drivable SV2. From SV2, a suitable conduit 30 leads the refrigerant to the inlet of a combined accumulator/oil trap 32 with a drain valve 34. The refrigerant gas is then routed from the oil trap via conduit 36 to acid purification filter dryer 38.
I'm drawn to it. In the dryer, impurities such as acids, moisture, foreign matter, etc. are removed before the gas is passed through conduit 40 to suction 42 of compressor 44. A suction accumulator 46 is positioned in the conduit 42 to prevent liquid refrigerant from passing to the compressor suction. The compressor 44 is preferably of a rotary type. it is,
It is readily available from many compressor manufacturers. However, it may also be of a reciprocating type, a scroll type, or a screw type.

Gaseous refrigerant flows from the compressor outlet 48 to the conduit 5.
0 to a conventional floating oil separator 52. In the separator, oil from the recovery system compressor 44 is separated from the gaseous refrigerant and directed via a float control return line 54 to a conduit 40 that communicates with the compressor suction. From the outlet of oil separator 52, gaseous refrigerant passes via conduit 56 to the inlet of heat exchanger/condenser coil 60. An electrically driven condenser fan 62 is associated with coil 60 and passes outside air through the coil as described in connection with the operation of the system.

From the outlet 64 of the condenser coil 60, a suitable conduit 66 leads the refrigerant to a T-junction 68. T6
8, one conduit 70 passes to another electrically driven solenoid valve SV4, while the other branch 72 of T
is passed through a suitable refrigerant expansion device 74. In the illustrated embodiment, the expansion device 74 is a capillary tube, and a strainer 76 is placed in the refrigerant line 72 to remove particles that may clog the capillary tube. The expansion device may be comprised of any number of other well-known refrigerant expansion devices that are widely used commercially. Conduit 72 containing expansion device 74 and conduit 70 containing valve SV4 are recombined at a second T-junction 78 downstream of both devices. Solenoid valve S
V4 and expansion device 74 are in parallel fluid flow relationship. As a result, if solenoid valve SV4 is open,
Refrigerant flow passes through the solenoid valve in a substantially unrestricted manner due to the high resistance of the expansion device. On the other hand, when valve SV4 is closed, the refrigerant flow passes through the high resistance path provided by the expansion device. Coupling devices such as electrically driven expansion valves that couple the functions of valve SV4 and capillary tube 74 are known. However, by configuring as described above, desired functions can be obtained at minimum cost.

From the second T-78, the conduit 80 connects to the pipe 24
The flexible refrigerant piping 8 passes through a suitable coupling (not shown) for connection of the system, such as formed by a restriction of the
2 to the liquid inlet 84 of what was previously referred to as a refillable refrigerant storage container 86 . Vessel 86 is of conventional construction and includes a second inlet 88 adapted to a steam outlet.
has. Additionally, storage cylinder 86 includes a liquid level indicator 92 . The liquid level indicator consists of a small continuous liquid level sensor, for example from the Imo Delaval company. Such an indicator may provide an electrical signal representative of the level of liquid contained within storage cylinder 86.

The refrigerant pipe 94 is connected to the steam outlet 8 of the cylinder 86.
8 is interconnected with a T-connection 96 in conduit 28 extending between solenoid valve SV3 and solenoid valve SV2. An additional electrically driven solenoid valve SV1 is located within the line 94. A check valve is also located in conduit 28 downstream of T-96 to provide flow in the SV3 to SV2 direction and to prevent flow in the SV2 to SV3 direction.

Next, reference is made to FIG. A refrigerant gas contamination detection circuit 100 is included in the system in parallel fluid arrangement with the compressor 44. Contamination detection circuit 100 includes an inlet conduit 102 in fluid communication with conduit 56 extending from oil separator 52 to condenser inlet 58 . The inlet conduit 10
2 has an electrically driven solenoid valve SV6 arranged along it, leading from there to the inlet of the sampling tube holder 104. Sampling tube holder 10
4 is connected via conduit 106 to the compressor suction port 42.
It is interconnected with a conduit 40 communicating with.

Solenoid valves SV5 and SV6, when closed, isolate sampling tube holder 104 from the system and facilitate replacement of the sampling tube ring contained therein. The sampling tube holder is
It may be of the type described in US Pat. No. 4,389,372 entitled Portable Holder Apparatus for Gas Detection Tubes. Additionally, the refrigerant contamination testing system is preferably as detailed in US Pat. No. 4,923,806, entitled Method and Apparatus for Testing Refrigerants in Closed Systems, assigned to the assignee of the present invention.

Automatic control of all components of the refrigerant recovery system 10 is formed by a microprocessor with memory and controls all operations of the solenoid valves SV1 to SV7, along with the compressor motor and condenser fan motor. This is implemented by an electrical controller 108 which is microprogrammable. Inputs to controller 108 include a number of measured or sensed system control parameters. In the disclosed embodiment, these control parameters include the temperature of the storage cylinder Tstor, which is comprised of a temperature transducer capable of accurately providing a signal representative of the temperature of the refrigerant within the storage cylinder 86. The outside air temperature is measured by a temperature transducer placed at the inlet of the condenser coil or condenser fan 62 and
Referenced as. The temperature of the refrigerant passing through the compressor discharge pipe 50 is sensed by a temperature transducer placed in the compressor discharge pipe 50.

The most important control structure of the system is:
The compressor suction pressure is designated as P2 and the compressor discharge pressure is designated as P3. As shown in Figure 1, P2
A pressure transducer labeled , is in fluid communication with the suction line 40 to the compressor. The second pressure transducer P3, on the other hand, is in fluid communication with the high pressure refrigerant line 56 going to the condenser. The pressure ratio across compressor 44 is defined as the ratio P3/P2. An additional input to controller 108 is liquid level indicator 9
This is the signal from 2.

Now, refer to FIG. 10. Note that the operating modes of the system are specified and the states of the electrically driveable elements of the system are indicated in different modes. In the ready mode, the system is activated and all electrically driveable mechanical systems are de-energized and ready for operation. In service mode, all electrically driven solenoid valves SV1 to SV4 are opened and
This equalizes the pressure within the system so that the system can be operated without the risk of encountering high pressure refrigerant.

Recovery and purification system 10 can operate in both liquid recovery and vapor recovery modes. The steam recovery cycle is
We start under two different sets of circumstances. That is, 1) 5
For systems containing pounds or more of refrigerant, follow the previously performed liquid recovery cycle. and 2) for refrigerant systems containing less than 5 pounds of refrigerant;
The vapor recovery cycle represents the beginning of the recovery sequence.

Additionally, the transition from liquid recovery to vapor recovery is initiated by several different control structures.

To facilitate a thorough understanding of the system in its various operational modes of operation, first, in conjunction with FIGS. Explain the system. continue,
A combined liquid and vapor cycle for liquid level control will be described in conjunction with FIGS. 1, 4, 5, 6 and 12. Finally, we will discuss the combined liquid-vapor cycle in terms of control using parameters that correlate with the state changes of the withdrawn refrigerant in Figures 1, 7, 8, and 9 to 12.
Explain using.

The recovery and cylinder cooling modes will be explained in detail using the flowchart of FIG. Recovery mode is a mode in which apparatus 10 is coupled to air conditioning system 12 to remove refrigerant from the system. is,
See FIG. 2. The first step performed by the controller 108 when a recovery cycle is selected is that if the compressor discharge pressure (P3-P2) is greater than 30 psi, the controller 108 equalizes the pressure in the system. To do this, valves SV1 to SV4 are opened. The difference between P3 and P2 is 1
Once less than 0 psi, the system then enters recovery mode. Initial comparison of P3 and P2 is 30psi
If the difference is less than or equal to , the system immediately goes into retrieval mode. The reason for this comparison is that the pressure difference is 3
When it is less than or equal to 0 psi, the compressor starts quickly; when the pressure difference is greater than 30 psi, it is difficult to start the compressor and indicates a reduction in the pressure difference thereon.

To begin the recovery mode, controller 108 opens valves SV2, SV3, and SV4, and valve SV1 remains closed. As noted in FIG. 4, valves SV5 and SV
6 operate together as a single output from the microprocessor (controller) and only when these valves are open;
This is when the contamination testing process is being performed. These valves are not described in connection with other modes of operation of the system. Compressor 44 and condenser fan 62 are also activated at the beginning of recovery mode.

Let's take a look at the operation of the system in retrieval mode. Please refer to FIG. When SV3 opens, refrigerant from the system 12 being operated is directed by the refrigerant pressure of that system and by the suction created by the operation of compressor 44 through conduit 20 to valve SV3, check valve 98, and valve SV2. and via conduit 30 to accumulator/oil trap 32. In the accumulator/oil trap, the oil contained in the refrigerant removed from the operating system falls to the bottom of the trap along with the liquid refrigerant withdrawn from the system. The gaseous refrigerant is passed through the accumulator/dryer 38 where moisture, acids and particles are removed from the refrigerant.
Oil is drawn from trap 32 and thence via conduit 40 to suction accumulator 46 to compressor 44 .

Compressor 44 compresses the low pressure gaseous refrigerant entering the compressor into high pressure gaseous refrigerant. The high pressure gaseous refrigerant is delivered to an oil separator 52 via conduit 50. The oil separated from the high pressure gaseous refrigerant in separator 52 is from the recovery compressor 44, and this oil is routed via conduit 54 to the compressor suction line 40 to keep the compressor lubricated. will be returned to. From the oil separator 52, the high pressure gaseous refrigerant is transferred to the conduit 5
6 to the condenser coil 60. There, the hot compressed gas is condensed into a liquid. The liquefied refrigerant exits condenser coil 60 via conduit 66 and passes through T68 via open solenoid valve SV4 to liquid line 8.
0 and 82 to a refrigerant storage cylinder 86 via a liquid inlet 84.

While refrigerant recovery continues, controller 108
receives the signals from pressure transducers P3 and P2, calculates the pressure ratio P3/P2, and compares the calculated ratio with a predetermined value. Compressor suction pressure P2 is also viewed alone and compared to a predetermined return end suction pressure. As shown in FIG. 2, the predetermined collection end suction pressure is 4 psia. If P2 becomes less than this value, the recovery mode is terminated and the controller 108 begins a refrigerant test cycle identified as a comprehensive test. This cycle will be described below, followed by a complete description of the other modes of operation. The Total test is
is a registered trademark of Carrier Corporation for "Tester for Contamination in Refrigerants."

The selection of the predetermined collection end suction pressure of 4 psia results from collection system operation. There, 4psi
A compressor suction pressure P2 of a or less recovers 98 to 99% of the refrigerant from the operated system. Achieving this pressure during the first recovery mode cycle is unusual, but it is achievable. As an example, P2 may be brought to a final value of 4 psia in cold outside temperature conditions. There, the condenser coil temperature (which is the cooled outside air) is low enough to cause P3 to remain sufficiently low relative to P2 to reach 4 psia before pressure ratio limiting occurs.

Returning to the compressor pressure ratio in the illustrated embodiment, as shown in FIG. If the pressure ratio is equal to or greater than 16, the microprocessor within controller 108 performs what is called a recovery cycle test. If the recovery cycle now executed is the first recovery cycle executed and the compressor suction pressure P2 is greater than or equal to 10 psia, the controller considers refrigerant recovery complete and performs a refrigerant contamination test. Cycle (Total tes
t).

The latter condition, P2 being less than 10 psia in the second recovery cycle, is a condition that has been found to exist at high ambient temperatures. For example, such conditions exist when recovering R-22 from an air conditioning system at an outside temperature of 105 degrees Fahrenheit or higher. Under such conditions, the compressor suction pressure P2 should be reduced to 10p.
Attempts to reduce sia to values less than sia produce undesirable effects in that a substantial amount of run time is required to obtain a very small additional drop in suction pressure. Furthermore, under these conditions, the transition to the cylinder cooling mode described below also does not substantially increase the amount of refrigerant ultimately withdrawn from the system. Therefore,
The end of recovery mode and the beginning of the refrigerant contamination test cycle is indicated.

Assuming that the recovery cycle test indicates either a first recovery cycle or that the compressor suction pressure P2 is greater than or equal to 10 psia, the controller 108 initiates a cylinder cooling mode of operation. .

As shown in FIG. 12, in the cylinder cooling mode, solenoid valves SV1 and SV2 are energized, thereby opening them. Solenoid valve SV3 and SV
4 is closed and the compressor motor and condenser fan motor remain energized. The cylinder cooling mode of operation necessarily turns the system into a closed cycle refrigeration system. There, the refrigerant storage cylinder 86 functions as a charge evaporator. By closing solenoid valve SV3, refrigerant recovery and purification system 10 is isolated from operating refrigeration system 12. Opening of solenoid valve SV1 establishes a flow path between vapor outlet 88 of storage cylinder 86 and conduit 28 communicating with the low pressure side of compressor 44. Closing solenoid valve SV4 creates a path for refrigerant to flow from condenser 60 to refrigerant expansion device 74.

With respect to the control solenoid valve set described above, in the cylinder cooling mode, the compressor 44 compresses the low pressure gaseous refrigerant entering the compressor and delivers the high pressure gaseous refrigerant via conduit 50 to the oil separator 52. Ru. From the oil separator 52,
High pressure gaseous separation passes via conduit 56 to condenser coil 60 where the hot compressed gas is condensed to a liquid. The liquefied refrigerant is transferred to condenser coil 60 via conduit 66.
, through strainer 76 , through T-junction 68 , and via conduit 72 to refrigerant expansion device 74 . The high pressure condensed refrigerant thus passes through expansion 74 where it undergoes a pressure drop and is at least partially vaporized. The liquid vapor mixture is then transferred to conduits 78 and 8.
2 to the refrigerant storage cylinder 86 where it vaporizes and absorbs heat from the refrigerant within the cylinder 86, thereby cooling the refrigerant.

The low pressure refrigerant vapor is then transferred to the storage cylinder 8
6 via steam outlet 88 to T-connection 96 via conduit 94 and solenoid valve SV1. From there, the refrigerant is transferred to the check valve 98 solenoid valve SV2, oil separator/
Accumulator 32, filter dryer 38 and conduit 4
0 and returns to compressor 44, completing the circuit.

As the cylinder cooling mode of operation continues, the cylinder temperature, as measured by the temperature transducer Tstor, continues to drop as the refrigerant is continuously circulated through the closed cooling circuit. Also, during this time, the refrigerant passes through the refrigerant purification element,
That is, the refrigerant passes through the oil separator 32 and the filter dryer 38 multiple times, thereby purifying the refrigerant.

Referring again to FIG. The cylinder cooling mode of operation ends when one of three conditions of the globe occurs.

1) The cylinder temperature measured by Tstor is at a level of 70° lower than the outside air temperature (Tamb).
2) When the cylinder cooling operation mode continues for 15 minutes, or 3) When the cylinder temperature Ts
This is when the tor drops to 0°F. And although three conditions triggered the end of the cylinder cooling mode, the results were substantially the same. That is, the temperature of the refrigerant stored in the cylinder 86 (Tstor) is now well below the outside temperature. As a result, the pressure within the cylinder is substantially lower than elsewhere in the system in response to the lower temperature.

When any one of the cylinder cooling mode termination events occurs, controller 108 transitions the system to a second recovery mode of operation. In the second recovery mode, the solenoid valves and compressor and condenser motors are energized as described above in connection with the first recovery mode. Because of the low temperature Tstor created within the refrigerant storage cylinder, the system's ability to withdraw refrigerant from the operating unit is greatly increased without subjecting the recovery compressor to high pressure differentials.

This phenomenon can be understood by referring to FIG. It is illustrated by sensing the recovery cycle at the point where the refrigerant withdrawn from the operating system is discharged to the compressor 44 and goes to the condenser 60 via conduit 56. At this point, it extends from the compressor outlet 48 and includes a storage cylinder 86 . The pressure within the system is determined by the temperature and pressure conditions within the storage cylinder 86. As a result, the storage cylinder 86 is now connected to the condenser sensor, with the recovered refrigerant passing through the condenser coil as superheated vapor and going via solenoid valve SV4 and conduits 80, 82 to the storage cylinder 86 where it is condensed to liquid form. work effectively as

The second or next collection mode (ie,
The suddenly low compressor discharge pressure P3 experienced during the cylinder cooling mode followed by the recovery mode causes the recovery compressor 44 to cause the system 12 in operation to still maintain an acceptable pressure ratio across the recovery compressor. Pull to a lower pressure than what was previously obtained.

In the second recovery mode, the pressure ratio P3/P2 exceeds a predetermined value (16 in the given example) and, depending on other system conditions, additional This causes cylinder cooling operation mode or termination.

Next, reference will be made to FIG. Thereafter, the system operates as described above until a condition exists that causes the controller 108 to switch to the refrigerant total test mode of operation. Before starting the collection cycle, the operator should ensure that the sampling tube is placed in the sampling tube holder. Comprehensive exam (To
tal test) At the start of the operating mode, solenoid valves SV1, SV2, SV4 and SV5/SV6 are all energized to the open position. Solenoid valve SV3 is not energized and is therefore closed. With respect to the flow control valve in the conditions described above, the flow of refrigerant through the recovery system is similar to that described above with respect to the cylinder cooling mode, except that solenoid valve SV4 is opened and therefore no refrigerant passes through expansion device 74. ing. With respect to the refrigerant flowing through the circuit in this way and with the solenoid valves SV5 and S opened
With respect to V6, the pressure differential that exists between the high and low pressure sides of the system causes refrigerant flow through conduit 102, solenoid valve SV6, sampling tube holder 104 (and the tubes contained therein), solenoid valve SV5, and conduit 106. guide,
Thereby, the refrigerant to be tested is returned to the suction side of the compressor 44.

[0056] In order to ensure the reliability of the test of the passing refrigerant, a
The refrigerant flow through the test tube is
Appropriate orifices are provided in the conduit 102, so as to provide the necessary pressure drop to ensure that the flow is at a velocity to ensure adequate refrigerant flow through the conduit 102 during operating hours.
Or provided within the sampling tube holder 104. When referring to FIG. 2, note that the operating time for the refrigerant test is shown as X minutes. Typical operating time for a Total test system that can be used commercially is:
It is approximately 10 minutes and the controller is programmed to run the test for different times for different refrigerants. However, if the refrigerant being tested contains a large amount of acid and the test tube indicator changes color for less than the programmed run time, the quality test is terminated and an additional refrigerant purification cycle is initiated.

[0057] Addition purification cycles are identified as recycle modes. A flowchart showing the theory of system operation is shown in FIG. See FIG. 4. The conditions for the electrically driveable element are such that it is not recyclable, except that solenoid valve SV4 is opened so that refrigerant does not flow through expansion device 74, but through open solenoid valve SV4. Note that it is the same as for cylinder cooling mode. This increases the volumetric flow of refrigerant through the system during recycle mode. The function of this mode is to better purify the refrigerant by passing it through the oil truck 32 and filter dryer 38 multiple times.

Refer to FIG. 3. The amount of time the system is operated in recycle mode is determined by the operator as X minutes, which varies as a function of refrigerant type and quality and outside temperature. The type of refrigerant is known and the outside temperature can be measured. Quality is also determined by the operator by evaluating the test tubes used in the refrigerant test cycle. Next, refer to FIG. 3. At the end of the selected recycle time, if the system so selected by the operator performs another refrigerant test and the results of this test indicate so, the above procedure is followed by another recycle test. The period begins.

The purpose of the system and control structure described above is to provide a system that ensures that, under any given external or system conditions, the compressor of the recovery system is not subject to adverse operating conditions. The goal is to constantly monitor control parameters and remove as much refrigerant as possible from the operated system. As mentioned above, the system control parameter is the pressure ratio P3/P2 across the recovery compressor 44. In the example above, P which is 16
The value of 3/P2 was used as the upper pressure ratio at which the compressor was counter-affected. Note that for different compressors the value of this parameter is different.

The ultimate goal of controlling this system is to keep compressor operation within predetermined limits to ensure long and reliable compressor life. As mentioned above, in the context of the present invention, internal compressor temperature is considered by compressor experts to be a control factor in preventing internal compressor damage during operation. In the preferred embodiments disclosed herein, pressure ratio has been found to be a very reliable and effective control parameter that can be related to internal compressor temperature. Therefore, in the preferred embodiments described above, pressure ratio was selected as the preferred control parameter. Pressure differential (ie, P3-P2) can also be practically used to control the system. However, other system control parameters such as the discharge temperature, as measured by the temperature transducer 110 in the compressor discharge pipe 50, or the compressor suction pressure P2, are also the conditions at which the compressor is not adversely affected. It can be used to control the operation of the system, only to limit the operation of the system.

With respect to temperature, it is generally accepted that the internal compressor temperature at which the lubricating oil begins to break down is about 325°F. Above this temperature, reverse compressor operation and damage may occur. In the present system, controller 108 is programmed to shut down the system in the event that the compressor discharge temperature, as measured by temperature transducer 110, exceeds a maximum of 225°F regardless of pressure ratio conditions. There is.

[0062] If the compressor discharge temperature measured at transducer 10 is used as the primary system control parameter:
To ensure that the compressor is not adversely affected during system operation, temperatures near 200° F. are used to switch the recovery system from recovery mode to cylinder cooling mode of operation.

According to another embodiment of the invention, the system control parameter detected for compressor protection is compressor suction pressure P2. In this case, the microprocessor of the controller 108 is programmed with respect to the considered compressor suction pressure P2, representing the reverse compressor operation, for the outside temperature range and for the different refrigerants that can be processed by the system. . As an example, when processing refrigerant R-22 at an outside temperature of 90°F, 13 psia to 15 psi
A suction pressure P2 in the range a is programmed to switch the system from recovery mode to cylinder cooling mode of operation.

The refrigerant recovery capabilities of the present invention are reflected in the following example. The recovery device was connected to a refrigerant system with 4.5 pounds of refrigerant R-12 charged to the system at an outside temperature of 70°F. Such systems are typically used in automotive air conditioning systems.

At the beginning of the recovery, before the system reaches the limiting pressure ratio P2/P3, which is 16, the system has 8.
The first collection cycle was run for 67 minutes. In that respect, 3.
Seventy-three pounds were recovered from the system. This is 82.9% of the total system charge. A typical prior art system would shut down at this point, leaving .77 pounds. That is more than 17% of the system fill. This ,77 pounds would eventually be released into the atmosphere.

At this point, the system was transitioned to cylinder cooling mode of operation. The cylinder cooling cycle was run for 15 minutes to reduce the cylinder temperature (Tstor) to 10°F. At this point, the second retrieval cycle operated for 3.8 minutes, at which point retrieval ended when the suction pressure P2 dropped to 4.0 psia.

At this point, the total system operating time is 27.
5 minutes and a total of 4.42 pounds of refrigerant was recovered from the system. This is 98 for a total fill of 4.5 lbs.
．． 2% in the system. Only 0.08 pounds remained.

After completion of recovery and purification, the storage cylinder 86
Contains clean refrigerant that is returned to the refrigerant system. Refer to FIG. 12. The refill mode results in the simultaneous opening of valves SV1 and SV3, which removes the storage cylinder 86 from the refrigeration system 1.
Establish a direct refrigerant path to 2. All other valves as well as the compressor and condenser are deenergized in this mode. The amount of refrigerant delivered to the system is selected by the operator and controller 108, and input from the liquid level sensor 92 ensures accurate refilling of the system with the selected quality of refrigerant.

Next, in relation to the flowchart of FIG.
The liquid recovery mode will be described in detail. The liquid recovery mode is
For example, it should be understood that it is designed for use in large systems having refrigerant flow charges greater than 5 pounds. For systems containing less than 5 pounds of refrigerant, the liquid recovery mode of operation is eliminated and the operator directs directly to the vapor recovery mode previously described. The mode will be explained next.

At this point, a system containing more than 5 pounds of refrigerant is about to be operated, and equipment 10
is coupled to it to remove refrigerant from the system. and now refer to FIGS. 5 and 12. At the beginning of the liquid recovery mode, controller 108 activates valves SV1,
It is understood to open SV2 and SV7. Valve SV3,
SV4, SV5 and SV6 remain closed. Figure 12
As noted above, valves SV5 and SV6 operate together as a single output from the microprocessor (controller 108), and the contamination test process is performed only during the time these valves are open. These valves will not be further discussed in connection with other modes of operation of the system. Compressor 4
4 and condenser fan 62 motors are also energized upon initiation of liquid recovery mode.

Now, with reference to FIG. 1, the operation of the system in the liquid recovery mode will be considered. With valve SV3 closed and valve SV7 open, refrigerant from system 12 being operated is directed by refrigerant pressure within the system through conduit 20, through T-11, through SV7, and Via the liquid refrigerant line 15, it is forced into the valve 90 of the refrigerant storage cylinder 86 and directly into the refrigerant storage cylinder.

Upon entering storage cylinder 86 in external conditions, a portion of the liquid refrigerant is in gaseous form. At this time, solenoid valve SV1 is open, so storage cylinder 8
A flow path is established directly between vapor outlet 88 of 6 and a conduit 94 communicating with the low pressure side of compressor 44 . With solenoid valve SV4 closed, refrigerant from condenser 60 passes through refrigerant expansion device 74.

Thus, during liquid recovery, with the control solenoid valve set as described above, the compressor 44 operates to draw low pressure gaseous refrigerant directly from the storage cylinder 86. This refrigerant passes through conduit 94 and T-96.
Oil separator 3 via check valve 98, valve SV2 and conduit 30
Flows to 2. From the oil separator, it flows via conduit 36 to filter dryer 38 and then via conduit 40 and accumulator 46 to compressor 44. The compressor 44 delivers high pressure gaseous refrigerant to an oil separator 52 via conduit 54 . From the oil separator 52, the high pressure gaseous refrigerant flows via conduit 56 to a condenser coil 60 where the hot compressed gas is condensed to a liquid.

The liquefied refrigerant leaves condenser coil 60 via conduit 66 , passes through strainer 76 via T-junction 68 , and flows via conduit 72 to refrigerant expansion device 74 . Therefore, the high pressure condensed refrigerant flows through the expansion device 74;
There, the refrigerant undergoes a pressure drop and is at least partially vaporized. The liquid vapor mixture is then returned to the refrigerant storage cylinder 86 via conduits 78 and 82. There, the refrigerant evaporates and absorbs heat from the refrigerant within the cylinder 86, thereby reducing the pressure and temperature within the storage cylinder 86. As a result of the decrease in pressure and temperature within the storage cylinder 86, the pressure differential between the operating refrigeration system 12 at ambient temperature and the storage tank 86 is substantially increased;
As a result, the flow of liquid refrigerant through the liquid refrigerant line 15 to the storage cylinder is substantially increased.

During this mode of operation, refrigerant continues to be recirculated through the refrigeration purification circuit described above.

Refer to FIG. 4. It is understood that the liquid recovery mode is operated in accordance with the illustrated embodiment for two minutes when the system is transitioned to the cylinder cooling cycle. Next, refer to FIG. The only difference between the operation of the system in the cylinder cooling cycle and the liquid recovery cycle is that solenoid valve SV7 is closed and the system operates in a closed circuit, as described with no connections to the system being operated. . As the cylinder cooling mode of operation continues, the cylinder temperature continues to drop as the refrigerant is continuously circulated through the closed refrigerant circuit. Also, during this time, the refrigerant is passed through the refrigerant purification elements, oil separator 32 and filter dryer 38 multiple times, thereby
Purify the refrigerant even further. To ensure that the temperature and pressure within the storage cylinder is reduced so that it is substantially below ambient temperature, the system is run on a cylinder cooling cycle for 5 minutes.

Next, refer to FIG. 4. At this point, the system returns to liquid recovery operation. As the second liquid recovery cycle continues, controller 108 continues to receive the signal generated by liquid level sensor 92 representative of the liquid level within storage cylinder 86. A processor receives these successive signals and determines the rate of increase in liquid level within the storage cylinder 86. The processor then generates a signal representative of the rate of increase in liquid level. The processor is further programmed to monitor a signal representative of the rate of increase in liquid level and determine whether the rate is the same as the withdrawal of liquid refrigerant from the system.

FIG. 6 illustrates the reduction in refrigerant recovery. Accordingly, the figure shows the decrease in the rate of increase in liquid level within cylinder 86 that occurs as refrigerant recovery transitions from liquid to vapor state. The straight line in the graph represents a linear increase in the amount of refrigerant recovered over time when the recovery is in the liquid state. At the top of the graph, where the slope changes rapidly, the fraction of refrigerant recovered is in the vapor state. When the microprocessor detects an abrupt change in the rate at which refrigerant is being recovered, the liquid recovery mode of operation is automatically terminated.

The accuracy of the information provided by liquid level sensors varies over a wide range. The above liquid recovery system operation is
Effective recovery can be achieved using level sensors where the system provides less accurate readings. In systems using highly accurate level sensors, the liquid recovery mode of operation outlined in FIG. 5 is implemented by eliminating the first cylinder cooling cycle and the return to the liquid recovery cycle.

Refer to FIG. 5. It will be appreciated that at this point the system transitions into a cylinder cooling cycle to reduce the temperature and pressure in the storage cylinder 86 prior to the start of the vapor recovery cycle. Continuing to refer to FIG. This cylinder cooling operation mode ends when any one of the following three conditions occurs. That is, 1) Ts
The cylinder temperature measured by tor is equal to the outside air temperature (Ta
mb) or 2)
3) When the cylinder cooling operation mode has been in the cylinder cooling mode for 15 minutes, or 3) When the cylinder temperature Tstor drops to 0°F. Regardless of which of the three conditions triggers termination of the cylinder cooling mode, the results are substantially the same. That is, the temperature of the refrigerant stored in the cylinder 86 is significantly below the outside temperature. At this point, the system enters vapor recovery mode of operation, completely withdrawing refrigerant from the operating system.

[0081] The steam recovery and cylinder cooling operation mode is
This is illustrated in the flowchart of FIG. The operation of the system at this time is the same as the steam recovery and cylinder control cycle described previously, and it is not repeated.

FIGS. 7 and 8 illustrate the operation of the system in liquid recovery mode. There, the transition from liquid recovery to vapor recovery is controlled by parameters that are correlated to the change in state of the withdrawn refrigerant. The operation of the system is the same as described in connection with FIGS. 4 and 5, except for the control signal source.

As the second liquid recovery cycle continues, controller 1
08 continues to receive signals regarding many conditions within the system. In particular, the temperature transducer Tstor is connected to the storage cylinder 8
6 provides a signal representative of the refrigerant temperature within the 6. Pressure transducers P2 and P3 provide information regarding the pressure of what enters and leaves compressor 44, respectively. These three parameters are referred to as system control parameters.

FIGS. 9, 10, and 11 represent the values of the system control parameters Tstor, P3 and P2, respectively, as a function of the length of time that the liquid recovery cycle was traveled. For each of these graphical representations, the respective parameter increases at the 7 minute mark, then stabilizes, and then begins to fall. The start of the increase in each parameter, ie, the 7 minute time point, represents the beginning of the second liquid collection cycle. It has been found that the point at which each of these parameters begins to fall is correlated to when the state of the refrigerant withdrawn from the refrigerant system 12 changes from a liquid state to a vapor state. The microprocessor of controller 108 is programmed to automatically terminate the recovery mode of operation when one of these selected system control parameters falls below its maximum value by a predetermined amount. As noted in FIG. 7, Tstor is a preferred controlled parameter, and in a preferred embodiment, liquid recovery
ends when the temperature drops 5°F from its maximum value. If the control parameter is P2 or P3, 5p from the maximum value
It has been found that the drop in si causes the transition from liquid recovery to vapor recovery to occur at the appropriate time.

Refer to FIG. 7. It can be seen that the system transitions to a cylinder cooling cycle at this point in order to reduce the temperature and pressure in the storage cylinder 86 prior to the start of the vapor recovery cycle. Continuing to refer to FIG. This cylinder cooling operation mode is set to one of the following three conditions.
Terminates when occurs. That is, 1) Tsto
The cylinder temperature measured by r is the outside air temperature (Tamb
) or 2) when the cylinder cooling mode of operation has been in operation for 15 minutes, or
3) When the cylinder temperature Tstor drops to 0°F. Regardless of which of the three conditions triggers termination of the cylinder cooling mode, the results are substantially the same. That is, the temperature of the refrigerant accumulated in the cylinder 86 is
It is considerably lower than the outside temperature. At this point, the system enters vapor recovery mode of operation, completely withdrawing refrigerant from the operating system.

[0086]

Effects of the Invention By using the refrigerant recovery and purification apparatus of the present invention, a refrigeration system that releases less fluorine carbide into the atmosphere, that is, causes less environmental pollution, can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a refrigerant recovery and purification system embodying the principles of the present invention.

FIG. 2 is a flowchart of an exemplary program for controlling an element of the present invention in a vapor recovery cycle.

FIG. 3 is a flowchart of an exemplary program for controlling an element of the present invention in a recycle mode of operation.

FIG. 4 is a flowchart of a program for controlling the system in a liquid recovery mode of operation using liquid recovery rate as a control parameter.

FIG. 5 is a continuation of the flowchart of FIG. 4 showing a program for controlling the system in vapor recovery mode of operation.

FIG. 6 is a graph showing the amount of recovered refrigerant versus time in the liquid recovery operation mode.

FIG. 7 is a flowchart of a program for controlling the system in a liquid recovery mode of operation using control parameters that are correlated to changes in the state of the withdrawn refrigerant.

FIG. 8 is a continuation of the flowchart of FIG. 7 showing a program for controlling the system in vapor recovery mode of operation.

FIG. 9 is a graph showing storage cylinder temperature versus time in a liquid recovery mode of operation.

FIG. 10 is a graph showing pressure exiting the compressor versus time in a liquid recovery mode of operation.

FIG. 11 is a graph showing pressure entering the compressor versus time in a liquid recovery mode of operation.

FIG. 12 illustrates the operation of various elements of the system during different modes of operation.

[Explanation of symbols]

10 Collection system 12 Refrigeration system 44 Compressor 52 Oil separator 60 Condenser coil 74 Expansion device 86 Refrigerant storage cylinder 108 Controller

Claims (6)

[Claims] 1. Compressor means having an inlet and an outlet for compressing an incoming gaseous refrigerant, and a first compressor means for connecting the refrigerant to the inlet of the compressor means. conduit means; condenser means having an inlet and an outlet for passing refrigerant through the means; and a second conduit for connecting the outlet of the compressor means with the inlet of the condenser means. means and means for storing refrigerant;
third conduit means for connecting said outlet of said condenser means with said refrigerant storage means, in an apparatus for recovering compressible refrigerant from a refrigeration system. a fourth conduit means for connecting to the first conduit means; and a fourth conduit means disposed within the first conduit means upstream of a connecting portion between the fourth conduit means and the first conduit means and operable to open and close. a second valve means disposed in the third conduit means and operable between an open state and a refrigerant expansion state; and a third valve disposed in the fourth conduit means operable between an open and closed state. means for sensing a system control parameter related to protection of the compressor and providing a signal having a value representative of the sensed system control parameter; receiving the signal provided by the sensing means; In response to said signal having a value within a predetermined range when the compressor is not reversely operated, said first valve means is opened, said second valve means is opened, and said third valve means is opened. in response to the signal having a value within a predetermined range when the compressor is not reversely operated, the first valve means is closed and the second valve means is operated to expand the refrigerant. and processing means for operating said third valve means in an open state. 2. The apparatus of claim 1, wherein said means for sensing a system control parameter is for sensing a pressure of refrigerant entering said compressor and providing a first pressure signal representative of said pressure. a first pressure converting means; a second pressure converting means for sensing the pressure of the refrigerant exiting the compressor and providing a second pressure signal representative of this pressure; and the first pressure signal and the second pressure. processing means for processing a signal, determining a pressure ratio across the compressor, and providing the signal having a value representative of the sensed control parameter, which is the compressor pressure ratio. Refrigerant recovery equipment. 3. The apparatus of claim 1, further comprising means for purifying refrigerant passing from a refrigerant system to said compressor means via said first conduit means, and a quantity of refrigerant from an end thereof. fifth conduit means having one end in fluid communication with said second conduit means for withdrawing said second conduit means;
A refrigerant fluid downstream from said refining means and in sealed fluid flow connection with said sixth conduit means having one end in fluid communication with said first conduit means and with other ends of said fifth and sixth conduit means. means for operatively supporting the purification sampling tube and establishing a fluid flow interconnection therebetween; second valve means disposed on said fifth conduit means and operable between open and closed conditions; a third valve means disposed in the sixth conduit means and operable between the open and closed states; a fourth valve means disposed in the fourth conduit means and operable between the open and closed states; , said first valve means in an open condition, and said second valve means in an open condition;
means for actuating the third and fourth valve means closed, thereby operating the system in a refrigerant recovery mode; and energizing the compressor and the first valve in the closed position; means for forming a closed refrigerant circuit for operating a valve in a closed position, said third valve in a closed position, and said fourth valve in an open position, thereby establishing a refrigerant purification mode of operation; energizes the machine and operates the first valve to the closed position, the fourth valve to the open position, the second valve to the open position, and the third valve to the open position, thereby causing the refrigerant to flow. A refrigerant recovery device comprising: means for forming a refrigerant circuit such that refrigerant is passed through the refrigerant sampling tube in a test run mode. 4. The apparatus of claim 1, further comprising: a fifth conduit means for connecting a refrigerant system to the refrigerant storage means; a fourth valve means, said fifth conduit means forming a refrigerant path from said refrigerant system directly to said refrigerant storage means, said first valve means being closed, and said fourth valve means and said fifth conduit means forming a refrigerant path from said refrigerant system directly to said refrigerant storage means; when the valve means is open, from said refrigerant storage means, through said compressor means, through said second conduit means, through said condenser means, to said third conduit means, and said third conduit means disposed therein; The refrigerant returned to said refrigerant storage means via said expansion means forms a cooling circuit which reduces the temperature and pressure within said storage, thereby causing said refrigerant from the refrigerant system to enter said refrigerant storage via said first conduit. When the flowing refrigerant flow is activated, the first valve means and the fourth valve means are closed and the third valve means is opened, the recovery device is isolated from the refrigerant system and A refrigerant recovery device characterized in that the cooling circuit operates in a closed circuit to reduce the temperature and pressure within the recovery device. 5. The apparatus of claim 4, further comprising means for sensing a liquid level within said refrigerant storage means and generating a signal representative of said liquid level within said refrigerant storage means; receiving said successive signals representative of said refrigerant storage means and determining a rate of increase in liquid level within said refrigerant storage means;
means for generating a signal indicative of a rate of increase in the liquid level, and receiving the signal indicative of the rate of increase in the liquid level and exceeding a predetermined value of the rate of increase in liquid level indicative of liquid refrigerant recovery from the refrigerant system; operating said first valve means in an open condition and said second valve means in a closed condition in response to said rate of liquid level increase; processing means for operating said first valve means in a closed condition and said second valve means in an open condition in response to said signal indicative of a rate of increase in liquid level falling below said predetermined value; A refrigerant recovery device characterized by: 6. The apparatus of claim 4, further comprising: a system control having a detectable value change occurring at a time that is correlated to a time at which the state of the refrigerant withdrawn from the refrigerant system changes from liquid to vapor; means for sensing a parameter and providing a signal indicating that a detectable change has occurred; and when the apparatus is operative to draw liquid refrigerant from the refrigerant system via the first conduit, the first valve means; means for actuating the second valve to an open position and the second valve to a closed position; and in response to the signal indicating that a detectable change has occurred, gaseous refrigerant is removed from the refrigerant system by the fifth valve. A refrigerant recovery apparatus comprising means for operating said first valve means in a closed position and said second valve means in an open position for withdrawal through a conduit.