JPH0835874A - Flowmeter - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a flow meter capable of maintaining the fluid pressure constant and eliminating the fluctuation of the flow rate to improve the measurement accuracy. [Structure] Fluid vibration type flow meter 1 and thermal flow meter 2
By arranging the pressure adjusting means 4 on the upstream side of the two flowmeters and adjusting the pressure of the fluid 3 at a constant level, even if a pressure fluctuation occurs, the flow rate of the flow into the flowmeter that is proportional to the inflow pressure is It is possible to eliminate fluctuations and measure the flow rate in a constant state, which improves the measurement accuracy of the flow rate from the low flow rate region to the large flow rate region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter for measuring the flow rate of city gas or LP gas.

[0002]

2. Description of the Related Art In recent years, for example, as the consumption of city gas has increased, it has become necessary to make the shape of a gas meter (flowmeter) larger and larger, and the ratio of the installation place becomes a problem. From this, a flow meter using fluid vibration,
For example, attempts have been made to use a fluidic flow meter (see FIG. 2 described later) as a gas meter for city gas.
In such a flow meter using fluid vibration, the amount of gas used per fixed time is represented by the frequency of fluid vibration, so the frequency of fluid vibration increases even if the consumption of gas increases. It is not necessary to increase the size of the fluid element itself, and is promising as a next-generation gas meter. However, in a flow meter utilizing such vibration of fluid, the detection sensitivity of fluid vibration in a low flow rate region of about 200 L / H or less is poor, and an accurate flow rate of fluid cannot be measured. As a flow meter in the low flow rate region, a thermal flow meter, for example, a microbridge type flow sensor provided on a silicon substrate (see FIG. 3 described later) is used from the viewpoint of detection sensitivity and durability. Therefore, in order to uniformly detect the flow rate from the low flow rate range to the high flow rate range, a microbridge type flow sensor is used for measuring the low flow rate range, and a fluidic flow meter is used for measuring the high flow rate range. There is a combination of these (Japanese Patent Laid-Open No. 2-161313).
JP-A-3-264821 and JP-A-3-96817.
No. 4-47225, etc.).

An example of such a combined flowmeter is disclosed as a "fluid vibration type gas meter" in Japanese Patent Application Laid-Open No. 5-313604 (first conventional example). This flow meter is a composite sensor consisting of a differential pressure sensor that detects fluid vibration and a thermal flow sensor that detects flow velocity, and outputs signals from a pressure sensor and a temperature sensor that are integrated into this composite sensor. Based on the flow rate measurement calculation,
It is provided with each calculation function of pressure correction calculation and calculation for determining flow rate abnormality, and a function of displaying the calculation result. Also,
There is one disclosed as a "flowmeter" in Japanese Patent Application Laid-Open No. 4-64020 (second conventional example). This flow meter
The Karman vortex flowmeter is used as a flowmeter for correcting the output of the thermal flow sensor type flowmeter, and it is designed to perform highly accurate and stable measurement from a low flow rate range to a high flow rate range.

[0004]

In a flowmeter (fluidic flowmeter, etc.) utilizing fluid vibration as described above, the fluid vibration frequency per unit time is proportional to the fluid velocity passing through the nozzle of the fluid element. Therefore, the volume of the fluid passing through the nozzle per unit time can be measured by measuring the frequency per unit time by some means. On the other hand, in a thermosensitive flow meter (such as a microbridge type flow sensor), the output value is the number of molecules of the fluid that exchanges heat with the element in a given time because the heated element detects the amount of heat taken by the fluid. That is, it is proportional to the number of moles.

However, even if a constant volume of fluid is flowing per unit time and the output value of the fluid vibration type flow meter is constant, if the pressure or temperature of the fluid is different, the output value of the thermal type flow meter will be They will be different, which makes it impossible to make an accurate measurement of the flow rate. In this case, when obtaining the flow rate from the output value of each flow meter, there is a method of correcting the measured value using a calibration curve of output value-flow rate. However, a flow meter that incorporates a fluid vibration type flow meter and a thermal type flow meter in one is not designed with due consideration of environmental temperature fluctuations and pressure fluctuations. There is a problem that you cannot do it.

A first conventional example (Japanese Patent Laid-Open No. 5-313604)
In the case of No.), the calibration curve of output value-flow rate should be obtained in the standard state in advance, and at the time of measurement, the pressure and temperature of the fluid should be measured using the pressure sensor and the temperature sensor and converted to the standard state for comparison. By this, the fluctuation of the environmental temperature and the fluctuation of the pressure are corrected. However, in such a measurement method, for example,
When the environmental temperature is constant and the inlet pressure of the fluid flowing into the flowmeter is Pin and the outlet pressure is Pout, the flow rate value is (Pin-
In order to satisfy the accuracy of ± 1.5% as the flow rate error required by the current membrane gas meter in proportion to Pout), a flowmeter with an extremely high measurement accuracy of about 1% of (Pin-Pout) is required. Will be needed. As an example, for LP gas (P
in-Pout) is about 300 mmH ₂ O at maximum,
3 mmH ₂ O is required as the resolution of the pressure gauge. Since Pout may be atmospheric pressure, the dynamic range value required for the pressure gauge of this system is 10,000.
It becomes about / 3 to 3300. As a result, in atmospheric pressure measurement with this method, the dynamic range with a resolution of several mmH ₂ O is 3000 or more (accuracy: 0.03% F
An extremely high-precision pressure gauge that indicates the value of S) is required. Therefore, it is difficult to manufacture such an extremely high-precision flowmeter, and the cost is high. In addition, in the case of this conventional method, since the pressure sensor itself to be mounted has a temperature characteristic, if the temperature fluctuation is taken into consideration, the output value of the pressure sensor must also be temperature-corrected. However, it has an extremely complicated structure. Furthermore, in the case of this conventional method, the measured flow rate is displayed in a standard state, but the concept of this standard state is difficult for general users to target general households such as city gas or LP gas flow meters. Is not suitable for the flow meter.

Second conventional example (Japanese Patent Laid-Open No. 4-64020)
In the case of, the object can be achieved by satisfying the condition that the fluid pressure is constant, and even if the volumetric flow rate of the thermal type flow sensor type flow meter is constant, the error due to the fluid pressure fluctuation of the flow rate obtained from the Karman vortex flow meter is Since it is not taken into consideration, the output value of the thermal type flow sensor type flow meter changes due to the pressure change of the fluid, and as a result, the output of the thermal type flow rate sensor type flow meter cannot be sufficiently corrected. In city gas, the gas pressure may fluctuate depending on the area or the time of day, and it is almost impossible to use the conventional method for such an application.

[0008]

According to a first aspect of the present invention, there is provided a fluid vibration type flow meter for measuring the flow rate by converting the vibration of the fluid by the fluid element into an electric signal, and the flow velocity of the fluid is converted into an electric signal. In a flow meter that measures the flow rate from a low flow rate range to a large flow rate range by arranging a heat-sensitive flow meter that measures the flow rate with a flow path through which a fluid flows,
A pressure adjusting means for adjusting the pressure of the fluid to a constant value is disposed upstream of the two flow meters.

According to a second aspect of the invention, in the first aspect of the invention, there is provided a fluid volume calculating means for calculating the volume of the fluid flowing for a certain time from the output value of the fluid vibration type flow meter utilizing the fluid vibration, A particle information calculation means for calculating the number of moles or mass number of the fluid flowing for a fixed time from the output value of the heat-sensitive flow meter using the flow velocity of the fluid is provided, and the fluid vibration type flow meter obtained from the fluid volume calculation means Particle information conversion means for converting the volume of the fluid per unit time into the number of moles or the number of masses based on the fluid temperature measured by the temperature measuring element was provided.

According to a third aspect of the present invention, in the second aspect of the invention, the flow rate determined by the heat-sensitive flow meter is calibrated by using the number of moles or mass of the fluid flowing within a fixed time in the fluid vibration type flow meter. A means for calibrating the flow rate is provided.

According to a fourth aspect of the invention, in the third aspect of the invention, a particle information display means for displaying the number of moles or the number of masses of the fluid passing in a fixed time is provided.

[0012]

According to the first aspect of the present invention, by adjusting the pressure of the fluid to a constant value by the pressure adjusting means, even if the pressure of the fluid fluctuates, the fluctuation of the flow rate flowing into the flow meter that is proportional to the pressure. You can lose minutes, this
It is possible to measure the flow rate while keeping the flow rate constant without including the fluctuation component.

According to the second aspect of the invention, the output value of the heat-sensitive flow meter is converted into the number of moles or the mass number by the particle information calculating means, and the output value of the fluid vibration type flow meter is converted into the fluid volume calculating means and the particles. By converting to the number of moles or the number of masses by the information conversion means, the output value of the flow rate is displayed only by the number of moles or the mass number, which does not include factors such as environmental temperature and fluid pressure, and the uniqueness of the output is maintained. Be done.

According to the third aspect of the invention, the number of moles or the number of masses of the fluid flowing per unit time of the fluid vibration type flow meter is obtained by using the flow rate calibrating means, and the obtained number of moles or the number of masses is corresponded. By setting the output value to be the output value of the thermal type flow meter, the drift amount of the output value of the thermal type flow meter can be calculated, and this drift amount can be calculated from the calibration curve (the number of moles is determined from the output value). By subtracting at each point, it becomes possible to obtain the correct calibration curve for the thermal flow meter.

According to the present invention, the weight can be easily calculated and displayed from the calibrated number of moles or mass of the fluid by using the particle information display means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention according to claim 1 is shown in FIGS.
It will be described based on. The flowmeter in this embodiment is shown in FIG.
As shown in, a fluidic flow meter 1 as a fluid vibration type flow meter that converts the vibration of a fluid into an electric signal to measure the flow rate, and a heat-sensitive flow rate that converts the flow velocity of the fluid into an electric signal to measure the flow rate. Micro (μ) bridge type flow sensor 2 as a meter (hereinafter referred to as thermal flow sensor) 2
The flow rate from the low flow rate range to the large flow rate range can be measured by these two flow meters. In this case, the fluid (here, LP
The LP gas 3 is provided on the upstream side of the flow path into which the gas 3) flows.
A pressure adjuster 4 is arranged as a pressure adjusting means for adjusting the pressure of the constant pressure. The pressure regulator 4 has a pressure of 300 Kg / cm ^{2 for} the inlet pressure.
The one having an outlet pressure of mmH ₂ O is used, and the one having an atmospheric pressure as a reference pressure is used so that the difference from the atmospheric pressure is always 300 mmH ₂ O.

FIG. 2 shows the structure of a fluidic flow element 5 as a flow element constituting the fluidic flow meter 1 used for measuring the flow rate in the high flow rate region. After being guided into the element, the LP gas 3 is jetted from the nozzle 6 and guided into the flow channel expanding portion 7, collides with the exciter 8, and the flow channel direction is switched. A partition wall 9 for stabilizing the path of the LP gas 3 is arranged behind the exciter 8. As a result, the LP gas 3 flows along the direction indicated by the arrow according to the direction of the exciter 8, and vibrates between the two curved portions of the partition wall 9 according to the flow rate. The vibration due to the LP gas 3 is detected by a sensor (not shown) and converted into an electric signal to measure the flow rate.

FIG. 3 shows the structure of the heat-sensitive flow sensor 2 used for measuring the flow rate in the low flow rate region.
The silicon substrate 10 is etched to form trenches 11a and 11b at two locations along the flow direction of the LP gas 3. A bridge 12 made of an insulating film is provided between the moat 11a and the moat 11b. A temperature measuring element Rs for measuring the temperature of the bridge 12 made of a platinum thin film resistor and a heating element Rh for setting the temperature of the bridge 12 are wired on the bridge 12. The resistors Rf and Rr for fluid temperature measurement are wired around the moats 11a and 11b. FIG. 4 shows the configuration of the drive circuit of the thermal flow sensor 2, and R1 and R2 are reference resistors of the Wheatstone bridge. When a difference occurs between the temperature on the bridge 12 and the temperature around the moats 11a and 11b by this drive circuit, the output value from the amplifier 13 due to the difference is applied to the base of the transistor 14, As a result, the transistor 1
4 is turned on and a current flows through the heating element Rh to generate heat. The output voltage Eo from the heating element Rh is proportional to the amount of heat that the silicon substrate 10 is deprived of by the LP gas 3, that is, proportional to the number of moles (number of molecules) of the fluid that exchanges heat with the element for a certain period of time. The flow rate can be measured from the output voltage Eo.

A pressure regulator 4 for maintaining a constant pressure of the LP gas 3 arranged on the upstream side of the fluidic flow meter 1 and the thermal flow sensor 2 in such a configuration will be described. LP gas 3 has a normal supply pressure of 30
Since it is 0 mmH ₂ O, the pressure regulator 4 has several K
An outlet pressure of 300 mmH ₂ O with respect to an inlet pressure of g / cm ² is used, and an atmospheric pressure is used as a reference pressure so that the difference from the atmospheric pressure is always 300 mmH ₂ O. Such a pressure regulator 4 may be arranged anywhere as long as it is on the upstream side. However, there is almost no pressure loss between the pressure regulator 4 and the flow meter, or it may fluctuate even if there is some. It is necessary to design it in consideration of piping so that it will not occur. As for the adjustment accuracy of the pressure adjuster 4, since the flow rate is proportional to the inflow pressure to the flow meter, the flow rate error required by the current membrane gas meter must meet the accuracy of ± 1.5%. , The source pressure of LP gas 3 is 300 mm
When H ₂ O is used, the allowable fluctuation pressure of the pressure regulator 4 is 3 m
It must be mH ₂ O or less. Further, since such pressure adjustment is essentially due to the force of the spring, the temperature characteristic can be ignored.

As described above, by disposing the pressure regulator 4 on the upstream side of the fluidic flow meter 1 and the heat-sensitive flow sensor 2, the pressure regulator 4 can be used even when pressure fluctuations occur in the LP gas 3. Since the inflow pressure of the LP gas 3 at the time of passing through the flow rate is adjusted to a constant value, there is no fluctuation in the flow rate flowing into the flowmeter that is proportional to the inflow pressure. It can be measured in a constant state without receiving it. Therefore,
Due to this, it is possible to provide a flow meter that eliminates the effects of pressure fluctuations and temperature fluctuations and that can perform highly accurate flow rate measurement from a low flow rate range to a large flow rate range.

In this embodiment, the LP gas 3 is used as the fluid and the fluidic flow meter 1 is used as the fluid vibration type flow meter. However, the present invention is not limited to this. For example, city gas or air may be used as the fluid. Such a gas may be used, or a Karman vortex may be used as the fluid vibration type flow meter.

Next, an embodiment of the invention described in claim 2 will be described with reference to FIG. In addition, the above-described embodiment (FIGS.
The description of the same parts as those in FIG. 4) is omitted, and the same reference numerals are used for the same parts.

Also in this embodiment, the fluidic flowmeter 1 is used as the fluid vibration type flowmeter for measuring the high flow rate range, and the heat sensitive flow sensor 2 is used as the heat sensitive flowmeter for measuring the low flow rate range. Has been. Further, a pressure regulator 4 for adjusting the pressure P from the fluid (LP gas 3) to a constant value is arranged on the upstream side of these flow meters.
Then, here, as shown in FIG. 5, L flowing from the output value (frequency f) of the fluidic flow meter 1 at a constant time
A fluid volume calculating means 15 for calculating the volume V of the P gas 3 is provided. In addition, the output value of the thermal flow sensor 2 (voltage E
The particle information calculating means 16 for calculating the number of moles n ₂ (or the number of masses) of the fluid flowing from o) in a certain time is provided. Furthermore, the volume V of the LP gas 3 per unit time of the fluidic flow meter 1 obtained from the fluid volume calculation means 15 is calculated based on the fluid temperature T measured by the temperature measuring element 17 and the number of moles n ₁
The particle information conversion means 18 for converting (or mass number) is provided.

In such a structure, the fluid volume calculation means 15, the particle information calculation means 16, and the particle information conversion means 18
Each operation will be mainly described. Now, the pressure P of the LP gas 3 flowing through the two flow meters is adjusted to be constant by the pressure adjuster 4. Then, as the high flow rate range, for example, 200 L /
In the case of H or more, f-V constituting the fluid volume calculating means 15 from the frequency f detected by the fluidic flow meter 1
The flow rate (volume V) is determined by the calibration curve. When the volume V is obtained in this way, the pressure P of the LP gas 3 is constant,
Since the fluid temperature T measured by the temperature measuring element 17 is known, if the number of moles passing through the fluidic flow meter 1 in a certain period of time is n ₁ and the gas constant is R, the particle information conversion means 18 is configured. The number of moles n ₁ can be calculated from the general formula of PV = nRT. On the other hand, the voltage Eo is detected from the heat-sensitive flow sensor 2 of 200 L / H or less, and En that constitutes the particle information calculation means 16 is formed from this voltage Eo.
The number of moles n ₂ is directly obtained by the calibration curve. Then, by displaying the number of moles n ₁ and n ₂ thus obtained using the particle information display means 19 (detailed description will be given later) or the like, the flow rate from the low flow rate range to the high flow rate range can be displayed by the user. Can be recognized immediately.

As described above, by displaying the flow rate per unit time from the low flow rate range to the high flow rate range in terms of the number of moles n ₁ and n ₂ (or the number of mass), it is possible to change the ambient temperature or the fluid pressure. Since there is no difference in the flow rate display, the uniqueness of the output as a flow meter can be maintained. This ensures that the flow meter can be checked accurately in the inspection process.
Here, in order to measure the fluid temperature T, the temperature measuring element 17 is provided in the thermal flow sensor 2, but the temperature measuring element 17 is not limited to this. For example, a thermocouple is attached inside or outside the flow meter to measure the temperature. May be measured. Further, even if the mass number is obtained instead of the number of moles, the uniqueness of the output can be maintained and the same effect can be obtained.

Next, an embodiment of the invention described in claim 3 will be described with reference to FIGS. 6 and 7. The description of the same parts as those in the above-described embodiment (FIGS. 1 to 5) is omitted, and the same reference numerals are used for the same parts.

In the present embodiment, the fluid vibration type flow meter (fluidic flow meter 1) uses the number of moles n ₁ (or the mass number) of the fluid (LP gas 3) flowing within a fixed time, and the heat type flow meter. A flow rate calibrating means for calibrating the flow rate obtained by the (heat-sensitive flow sensor 2) is provided.

In such a structure, the operation of the flow rate calibration means will be mainly described. As the thin-film resistance of the heat-sensitive flow sensor 2, a platinum film is generally used, which does not easily react with various gases and has a relatively large resistance change with temperature of 3000 ppm. However, if the ambient temperature changes,
If the resistance value of the thin film resistor changes over time for a long time, the sensor output value drifts. In this case, the E-n calibration curve 20 (see FIG. 5) showing the relationship between the output voltage Eo and the number of moles n _{2 of the} fluid flowing per unit time changes as shown in FIG. Since the drift amount δ of the sensor output value Eo due to this change is unknown in actual use, it is necessary to correct the E-n calibration curve 20 with a known flow rate.

Therefore, in the present embodiment, both the fluidic flow meter 1 and the thermal flow sensor 2 have sensitivity as shown in FIG.
In the hatched region, as shown in FIG. 7, the number of moles n ₁ obtained from the fluidic flow meter ₁
By using the E-n calibration curve 20 of the thermal flow sensor 2
Correction processing is performed. That is, first, the output value Eo ′ of the thermal flow sensor 2 is obtained, and the frequency f, which is the output value of the fluidic flow meter 1, is calculated as f−
Using the V calibration curve and the equation of PV = nRT (see FIG. 5), the number of moles n _{1 of the} fluid flowing for a certain period of time is determined. Next, the number of moles n ₁ of the fluidic flow meter 1 is set as a known flow rate for correcting the E-n calibration curve 20 of the thermal flow sensor 2, and the output value Eo ′ of the thermal flow sensor 2 is set to the number of moles n. ₁
Is set as the output value when is flowing (S1). On the other hand, according to the conventional E-n calibration curve 20, the output value of the thermal flow sensor 2 corresponding to the number of moles n ₁ should be Eo.
Therefore, since the drift amount δ of the output value of the thermal flow sensor 2 at the time of measurement is obtained from Eo-Eo ′ (S2−
S3), the drift amount δ is subtracted at each point of the E-n calibration curve 20 to correct the curve to obtain an accurate E'-n 'calibration curve (S4). However, this newly obtained E′-n ′ calibration curve is used until the flow rate enters the hatching region again and a new drift amount δ ′ is calculated.

As described above, the fluidic flow meter 1
The number of moles n ₁ or mass of the fluid flowing per unit time is calculated, and the drift value δ is calculated using the output value corresponding to this number of moles n ₁ or mass as the output value of the thermal flow sensor 2 to obtain a correct calibration curve. Therefore, the calibration curve of the heat-sensitive flow sensor 2 can be corrected without performing a special conversion process, and the calculation process can be shortened.

Next, an embodiment of the invention described in claim 4 will be described. The description of the same parts as those of the above-described embodiment (FIGS. 1 to 7) is omitted, and the same reference numerals are used for the same parts.

When the LP gas 3 is used as the fluid, since the LP gas 3 is based on the cylinder, the amount used is generally managed by weight. From this fact, in the gas meter of each household. However, it is also necessary to display the flow rate in order to eliminate discomfort with the conventional gas meter, but it is convenient and convenient for the dealer and the user to display the weight as the integrated consumption amount, because it is easy to accept. In addition, the concept of displaying the flow rate in a standard state in a flow meter for general households using city gas is not familiar to general users and is difficult to understand, and it is desirable to use an accurate and easy-to-understand weight display. .

Therefore, in this embodiment, the particle information display means 19 for displaying the number of moles (or the number of masses) of the fluid passing through in a fixed time is provided. As a result, for example, as shown in FIG. 5, by calculating the number of moles of the fluid used, it can be easily converted into the weight used, and thus the weight used can be displayed. It is convenient not only for the vendor but also for the user to understand the usage situation immediately. In this case, in order to eliminate discomfort with the conventional gas meter, volume display may be used together if necessary.

[0034]

According to the first aspect of the present invention, the pressure of the fluid is adjusted to a constant level by using the pressure adjusting means arranged on the upstream side of the two flowmeters. Even in this case, it is possible to eliminate the fluctuation of the flow rate flowing into the flow meter that is proportional to the pressure and keep the flow rate constant for measurement, which allows measurement of the flow rate from the low flow range to the large flow range. The accuracy can be increased.

According to a second aspect of the invention, in the first aspect of the invention, the output value of the heat-sensitive flow meter is calculated by the particle information calculating means, and the output value of the fluid vibration type flow meter is calculated by the fluid volume calculating means and the particles. Since the information converting means converts the values into the number of moles or the number of masses, respectively, the output value of the flow rate can be displayed only by the number of moles or the mass, which does not include factors such as environmental temperature and fluid pressure. Since the uniqueness can be maintained, the handling of the product whose flow rate is measured is not confused in the inspection process, and strict measurement accuracy is not required, so that the production cost can be reduced.

According to a third aspect of the present invention, in the second aspect of the invention, the number of moles or mass of the fluid flowing per unit time of the fluid vibration type flow meter is obtained by the flow rate calibrating means, and the number of moles at this time is obtained. Or, the drift value was calculated using the output value corresponding to the mass number as the output value of the thermal flow meter, and the drift value was subtracted from the calibration curve of the thermal flow meter to obtain the correct calibration curve. The calibration curve of the meter can be corrected without performing a special conversion process, whereby the flow rate measurement time can be shortened and labor can be saved.

According to the invention of claim 4, in the invention of claim 3, the particle information display means can easily convert the number of moles or masses of the calibrated fluid into a weight, and display it. When a cylinder such as LP gas is used as a reference, the condition of the flow rate can be immediately understood by the operator or the user, and the handling becomes convenient.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the invention described in claim 1.

FIG. 2 is a sectional view showing a structure of a fluidic flow meter.

FIG. 3 is a plan view showing a surface shape of a thermal flow sensor.

FIG. 4 is a circuit diagram showing a drive circuit of a thermal flow sensor.

FIG. 5 is a block diagram showing an embodiment of the invention described in claim 2.

FIG. 6 is a characteristic diagram showing correction processing of a calibration curve of the heat-sensitive flow sensor according to the third embodiment of the invention.

FIG. 7 is a flowchart showing a flow of flow rate correction processing of the thermal flow sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluid vibration type flow meter 2 Thermal type flow meter 3 Fluid 4 Pressure adjusting means 5 Fluid element 15 Fluid volume calculating means 16 Particle information calculating means 17 Temperature measuring element 18 Particle information converting means 19 Particle information displaying means T Fluid temperature

Claims (4)

[Claims] 1. A fluid vibration type flow meter for converting vibration of a fluid by a fluid element into an electric signal to measure a flow rate, and a heat sensitive flow meter for converting a flow velocity of the fluid into an electric signal to measure the flow rate. In a flow meter which is disposed in a flow path of a flow meter and which measures the flow rate from a low flow rate range to a large flow rate range by these two flow meters, the pressure of the fluid is adjusted to a constant level upstream of the two flow meters. A flowmeter characterized in that it is provided with a pressure adjusting means. 2. A fluid volume calculating means for calculating a volume of a fluid flowing in a certain time from an output value of a fluid vibration type flow meter using fluid vibration is provided, and an output value of a heat sensitive type flow meter utilizing a flow velocity of the fluid is used. A particle information calculating means for calculating the number of moles or the number of mass of the fluid flowing for a fixed time is provided, and the volume of the fluid per unit time of the fluid vibration type flow meter obtained from the fluid volume calculating means is measured by a temperature measuring element. The flowmeter according to claim 1, further comprising particle information conversion means for converting the number of moles or the number of masses based on the fluid temperature. 3. The fluid vibration type flow meter is provided with a flow rate calibrating means for calibrating the flow rate obtained by the thermal type flow meter by using the number of moles or the mass number of the fluid flowing within a fixed time. The flowmeter according to 2. 4. The flowmeter according to claim 3, further comprising particle information display means for displaying the number of moles or the number of masses of the fluid passing through for a certain period of time.