JPH03112421A - Depressurizing system of pipeline - Google Patents

Abstract

PURPOSE:To obtain the subject depressurizing system capable of providing complete depressurizing effects even in rapid fluctuation of pressure by branching a water draining pipe on the down stream side of a pressure reducing valve arranged in the course of a water supply pipe having the upstream side thereof connected to a high pressure water supply source, installing a safety valve and simultaneously providing air bags in a pipeline on the downstream side of the pressure reducing valve. CONSTITUTION:High pressure water is supplied from the upstream side of a water supply pipe 1 and the first and second gate valves 2 and 5 are opened to remove solid substances with strainers 3. The resultant water is subsequently depressurized to the set pressure with a pressure reducing valve 4. The depressurized supply water under reduced pressure is then distributed into branch pipes 12, passed through respective air bags 13, made to flow into branch pipes 14 and then scattered from irrigation apparatuses attached to the tip parts thereof on a field. In the process, fluctuation, such as a sudden rise in water pressure on the upstream side, due to rapid opening or closing of water supply plugs 15, etc., is absorbed and dampened with the air bags 13 without normally affecting the pressure reducing valve 4, etc., on the upstream side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a system that can reduce the pressure of a pipeline in, for example, an irrigation water supply system for fields such as fields.

[Prior art 1] Conventional water supply systems for field strata include a water supply tap at the end of the line, and a sprinkler further beyond that.
We have rinsing equipment such as:

Rapid fluctuations in water pressure occur in pipelines by opening and closing water taps or operating sprinklers.

For this reason, high-pressure pipes such as iron pipes are currently used in this type of pipeline.

Generally, the above-mentioned high-pressure pipes are expensive, and therefore, the installation of pipelines not only imposes a considerable burden on farmers and the like, but also tends to cause a rise in the prices of field crops.

In order to solve these problems, it is conceivable to install a pressure reducing valve in the middle of the pipeline to reduce the pressure in the downstream pipe, thereby installing an inexpensive synthetic resin pipe.

[Problem to be Solved by the Invention 1] However, simply arranging only a pressure reducing valve in the middle of a water supply pipe still leaves the following problems.

(1) The pressure reducing valve has a delay in its operation in response to sudden pressure fluctuations that occur due to the closing of a water tap or the action of a sprinkler, etc., and there is a risk that the secondary pressure will greatly exceed the set secondary pressure.

(2) Depending on conditions such as pipeline length and pipe materials,
A resonance phenomenon with the pipeline pressure vibration was observed, and there is a concern that the set secondary pressure may be greatly exceeded.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to ensure that the pressure reducing valve has a complete pressure reducing effect even if rapid pressure fluctuations are repeated every few hours. As a result, our objective is to provide a pipeline pressure reduction system that uses low-cost plastic pipes and can minimize capital investment.

[Means for Solving the Problems] The pipeline pressure reduction system of the present invention provides a pressure reducing valve in the middle of a water supply pipe whose upstream side is connected to a high-pressure water source, and branches a drain pipe downstream of the pressure reducing valve. At least a safety valve is arranged, and an air batter is arranged at an appropriate position in the pipeline on the downstream side of the pressure reducing valve to buffer pressure fluctuations on the downstream side. This system is characterized in that the pipeline on the downstream side of the pressure reducing valve is constructed of a synthetic resin pipe.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a water supply pipe, the upstream side of which is connected to a high-pressure water source. On the downstream side of the water supply pipe 1, there is a first
Gate valve 2, strainer 3, pressure reducing valve 4 and second gate valve 5
are being deployed sequentially.

A drain pipe 6 is branched from the water supply pipe 1 between the pressure reducing valve 4 and the second gate valve 5. A safety valve 7 and a third
A gate valve 8 and a drainage bit 9 are arranged. The kinetic energy of the water flow flowing rapidly and at high speed through the drain pipe 6 is once reduced by the drain cut 9.

Reference numeral 10 denotes a bypass pipe, which is opened and closed by a fourth gate valve 11. The above strainer 3 and pressure reducing valve 4
During maintenance inspection or in the event of a failure, the first gate valve 2. Although the second gate valve 5 is closed, the fourth gate valve 11 can be opened at this time to allow water to be fed through the bypass pipe 11.

A plurality of branch pipes 12 are branched and arranged at the downstream end of the water supply pipe 1. An air bag 13 is attached to the middle of the branch W12.

The air bag 13 has a structure in which air is sealed in a rubber bag, and is designed to absorb and buffer sudden pressure fluctuations within the branch pipe 12. The capacity and installation location of the air bag 13 are determined by the value of the water hammer W12.
It is preferable to determine the pressure within a range that does not exceed the maximum allowable pressure within the range.

A large number of branches W14 are arranged in the branch pipe 12! has been,
A rinsing device (not shown) such as a sprinkler is disposed at its tip. 15 is a water tap.

All or most of the pipelines downstream of the pressure reducing valve 4 are constructed of pipes made of inexpensive synthetic resin such as vinyl chloride.

Next, the water supply function of the above embodiment system will be explained.

First, high-pressure water is supplied from the upstream side of the water supply pipe 1 by a water supply pump (not shown) or by gravity, and
When the gate valve 2 and the second gate valve 5 are opened, solid matter is removed by the strainer 3, and then the pressure is reduced to a set pressure (for example, about 5 kg/cm2) by the pressure reducing valve 4.

The supply water whose pressure has been reduced is distributed to each branch pipe 12, passes through an air bag 13, flows to a branch pipe 14, and is connected to the branch pipe W1.
Water is sprinkled onto the field by a rinsing device (not shown) such as a sprinkler attached to the tip of the field.

At this time, if the water supply faucet 15 is suddenly opened or closed or an intermittent water supply device such as a sprinkler is operated, the water pressure on the upstream side thereof will suddenly increase or fluctuate.

In addition, secondary pressure can also increase due to clogging or malfunction of pipelines or equipment.

These increases and fluctuations in water pressure are absorbed and buffered by the air bag 13, and normally do not affect the pressure reducing valve 4 and the like on the upstream side.

When not using water at all, the safety valve 8
In such cases, the safety valve 7 operates and the high-pressure water in the pipeline is discharged from the drain pipe 6 without affecting the pressure reducing valve 4.

FIG. 2 is a graph showing water pressure fluctuations at various positions in the pipeline when only a pressure reducing valve is used, and it can be seen that the water pressure fluctuates violently in any dark place.

On the other hand, in the system of the present invention shown in diagram #tJ3,
There are almost no fluctuations in water pressure, indicating that it is stable.

Next, the theoretical background of this system will be explained.

a) Absorption of pressure vibrations The gas sealed in the air bag expands and contracts in accordance with Boyle's law in response to pressure changes occurring within the pipe. As a result of this action, water flows into the air bag in response to a temporal increase in the internal pressure of the pipe, and water is replenished from within the air bag when the pipe descends.

Due to this effect, most of the pressure vibrations generated within the pipe are absorbed and converted into a gentle waveform (a waveform with a long wavelength).

l]) Effect of reducing water hammer pressure (by installing an air bag) Conversion to a gentle waveform means that the pressure propagation velocity α in the pipe becomes slower. The magnitude of water gamma pressure is
Since it is expressed by the following formula and is in a proportional relationship with a, the value of water hammer pressure also becomes small.

In the experimental examples shown in FIGS. 2 and 3, it can be seen that by installing the air bag, a is reduced to approximately 1/4, that is, the value of water hammer pressure/4.

HIIlax=a1■/g where H+++ax: Value of water hammer pressure (+6) a: Propagation velocity (m/s) ■: Flow velocity in pipe (+a/s) g: Weight acceleration (9,8/52) C) Effect of promoting the operation of pressure reducing valves and safety valves by installing air bags A pressure reducing valve is a valve that operates to keep the secondary pressure constant, and when the secondary pressure becomes higher than the set secondary pressure, the valve body moves in the direction of the leap and lowers. Sometimes it operates in the open direction. However, if a sudden pressure rise (fall) occurs, the operation of the valve body cannot keep up with the pressure fluctuation speed, and the secondary pressure will greatly exceed (below) the set secondary pressure.

Here, by installing the air bank, as described in a), since pressure fluctuations are gently converted, the delay in actuation of the valve body is eliminated.

While the pressure reducing valve is a pulp with a constant secondary pressure, the safety valve has a constant primary pressure (safety valve upstream pressure, in other words, pressure reducing valve secondary pressure)
Although it is a fixed type, its structure and operating principle are exactly the same as a pressure reducing valve. Therefore, the problem of valve element activation delay is also the same, and can be solved by installing an air bag.

[Effects of the invention] 1) Air bags are installed at appropriate positions in the pipeline downstream of the pressure reducing valve to buffer pressure fluctuations on the downstream side, ensuring reliable and stable operation of the pressure reducing valve. be done.

2) Even if the safety valve is delayed in response to sudden pressure fluctuations,
Since the air bag absorbs this sudden pressure fluctuation, the safety valve can be operated reliably.

3) Since the pressure is maintained and managed using an air bag, it has the advantage of being easy to manage and being cheap.

4) Since the pipeline on the downstream side of the pressure reducing valve is constructed using a synthetic resin pipe, the equipment cost for the pipeline becomes extremely low, and the efficiency of the pipeline can be promoted.

[Brief explanation of drawings]

Figure 1 is a 70-diagram of the system of the present invention, Figure 2 is a graph showing water pressure fluctuations at each position in the case of only a pressure reducing valve, PttJ
FIG. 3 is a graph showing similar water pressure fluctuations according to the system of the present invention. 1... Water supply pipe, 2... ml gate valve, 3... Strainer, 4... Pressure reducing valve, 5... Second gate valve, 6...
Drain pipe, 7...Safety valve, 8...Third gate valve, 9...
・Drainage pinto, 10... bypass pipe, 11... 4th
Gate valve, 12... branch pipe, 13... air bag,
14... Branch pipe, 15... Water tap.

Claims (1)

[Claims] 1. A pressure reducing valve is provided in the middle of a water supply pipe whose upstream side is connected to a high-pressure water source, and a safety valve is provided by branching a drain pipe downstream of the pressure reducing valve. 1. A pipeline pressure reduction system, characterized in that an air bag is provided at an appropriate position on the downstream side of the pipeline to buffer pressure fluctuations on the downstream side. 2. The pipeline pressure reduction system according to claim 1, wherein the pipeline downstream of the pressure reducing valve is constructed of a synthetic resin pipe.