JPS6122772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flowmeter verification device, in which a container is provided between a flowmeter to be verified and a reference flowmeter, and the pulsations generated in the reference flowmeter are detected along with fluctuations in the liquid level within the container. By absorbing the structure, the pulsations (pressure fluctuations) generated in the reference flowmeter are prevented from having an adverse effect on the flowmeter being tested, thereby ensuring that the flow rate measurement accuracy of the flowmeter being tested is always accurately verified. The purpose of the present invention is to provide a flow meter verification device that can perform the following steps.

Various types of flow meter verification devices are generally known. For example, by connecting a flowmeter to be verified to a reference volume pipe whose volume has been accurately measured in advance, and comparing the volume of fluid supplied to the reference volume pipe with the volume of fluid that has passed through the flowmeter to be verified, There is a known verification device that verifies the instrumental error of a flow meter, but this device requires a long time to finish supplying the required volume of fluid into the reference volume pipe, so the verification work can be carried out in a short time. This method has disadvantages such as being bulky and not being able to be carried out efficiently.

There is also a known testing device that sends an elastic ball into the pipe connected to the flowmeter to be tested and verifies the flow rate measurement accuracy of the flowmeter to be tested based on the volume of fluid displaced by the elastic ball. This device had drawbacks such as a complicated device configuration and high cost.

Furthermore, the flow rate measurement accuracy of the flowmeter to be tested is verified by comparing the flow rate measurement value measured by the flowmeter to be tested with the accurate flow measurement value of a calibrated reference flowmeter connected in series with the flowmeter to be tested. Verification devices are also known, but with these devices, the flowmeter to be verified is adversely affected by pressure fluctuations, flow rate fluctuations, etc. that occur in the reference flowmeter or the flowmeter to be verified. As a result, the flow meter to be verified must be tested under conditions completely different from the actual usage conditions, resulting in drawbacks such as the inability to perform accurate flow verification.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings. The figure shows a schematic configuration diagram of an embodiment of a flow meter verification device according to the present invention.

In the figure, the verification device 1 is located in the middle of a pipe 3 that extends from a liquid storage tank 2 that stores liquid and returns to the liquid storage tank 2.
A pump 4, a flowmeter to be verified 5, and a reference flowmeter 6 are provided, and a flowmeter to be verified 5 and a reference flowmeter 6 are provided.
A tank 7 serving as a container is connected in communication between the two. Here, the pump 4 is a centrifugal pump, and the reference flowmeter 6 is a two-lobed Roots flowmeter.
The flow rate measured in is indicated to the flow rate indicating device 6a. Furthermore, in this embodiment, the flowmeter to be verified 5 is constructed using, for example, a turbine type flowmeter, and the flow rate measured by the flowmeter to be verified 5 is passed through a pickup coil 5b that verifies the rotation of the turbine. This is instructed by the flow rate indicating device 5a.

A valve 8 is provided in a bypass pipe 9 that communicates and connects the discharge side of the pump 4 and the discharge side of the reference flowmeter 6, and is used to open and close the valve 10 provided between the flowmeter 5 to be verified and the tank 7. Related opening and closing.

The tank 7 is a sealed container having a predetermined volume, and the pipe 3a from the flowmeter to be verified 5 is connected to the bottom of the tank 7, and the pipe 3b to the reference flowmeter 6 is connected to the tank 7.
are connected to the sides of each. The liquid flowing into the tank 7 from the pipe 3a forms a liquid level at a constant level in the tank 7 and flows out into the pipe 3b, so that an air chamber 11 is defined between the liquid level and the inside of the tank 7.

Reference numeral 12 denotes a liquid level control mechanism which constitutes a main part of the present invention together with the tank 7, and supplies air at a predetermined pressure into the air chamber 11 to control the liquid level in the tank to be constant. The liquid level control mechanism 12 includes a spherical float 13 floating on the liquid level in the tank 7, a valve body 15 attached to a shaft 14 of the float 13, and a valve seat 16a on which the valve body 15 is seated. and a partition wall 1 that divides the air chamber 11 into a pair of chambers 11a and 11b.
6, and a pressure air supply mechanism 17 that supplies pressurized air at a constant pressure to one chamber 11a. The pressure air supply mechanism 17 is configured by connecting the chamber 11a and the pressure air source 18 through a pipe 19, and providing a pressure reducing valve 20 in the middle of the pipe 19. A throttle valve 21 is attached to the other chamber 11b, and the chamber 11b communicates with the outside via the throttle valve 21.

Here, the pressure air acting on the chamber 11a is higher than the discharge pressure of the pump 4, and the pressure air acting on the chamber 11a is higher than the discharge pressure of the pump 4.
The pressurized air applied to 1b is constantly blown out of the tank 7 through the throttle 21.

When the pump 4 is started with the valve 8 open and the valve 10 closed, the liquid in the liquid storage tank 2 is pumped 4,
The liquid is refluxed into the liquid storage tank 2 via the piping 3 and the piping 9.

At the time of verification, when the valve 10 is opened and the valve 8 is closed, the liquid in the liquid storage tank 2 is supplied into the tank 7 via the flowmeter 5 to be verified and the valve 10, and passes through the tank 7. The liquid is supplied to the reference flowmeter 6 and returned to the liquid storage tank 2 again.

Here, when the liquid passes through the reference flowmeter 6, pressure pulsations occur due to the non-uniform rotation of the rotor.
This pressure pulsation propagates around the reference flowmeter 6 to the upstream and downstream sides thereof.

For example, when the hydraulic pressure of the liquid passing through the reference flowmeter 6 increases with the rotation of the rotor, this increase in hydraulic pressure is propagated to the liquid remaining in the tank 7 via the pipe 3b. As a result, the liquid level in the tank 7 rises, and the float 13 is displaced upward as the liquid level rises.

When the float 13 moves upward, the valve body 15 moves away from the valve seat 16a, and the opening of the valve seat 16a opens wide. As a result, a large amount of the pressurized air that has been supplied into one chamber 11a through the piping 19 flows into the other chamber 11b through the opening of the valve seat 16a. As a result, the pressure of the air in the chamber 11b increases, the liquid level in the tank 7 is pushed from above and is prevented from rising, and the liquid level is displaced downward by the pressurized air in the chamber 11b, and accordingly Valve seat 16a
As the opening area of the opening becomes smaller, the liquid level stabilizes at a certain level. At this time, pressurized air is constantly blown out from the throttle 21 to the outside.

Further, contrary to the above, when the liquid level in the tank 7 decreases due to a decrease in the hydraulic pressure at the reference flowmeter 6 portion, the valve body 15 is displaced in the seating direction with respect to the valve seat 16a,
The opening area of the opening of the valve seat 16a is made small, and as a result, the air pressure in the chamber 11b is reduced, and a drop in the liquid level is prevented.

As mentioned above, the liquid level in the tank 7 is kept almost constant by the pressure air supplied from the outside, but there are control operations to counteract fluctuations in the liquid level.
That is, since the pressure within the chamber 11b changes with a slight delay, the liquid level within the tank 7 slightly fluctuates up and down.

The above fluctuation in the liquid level is caused by the pressure pulsations generated when the liquid passes through the reference flowmeter 6 propagating into the tank 7. It will be absorbed as a change in the liquid level within the tank. Therefore, pressure pulsations generated in the reference flowmeter 6 or accompanying flow rate fluctuations are not propagated to the flowmeter 5 to be verified.

For this reason, the fluid pressure before and after the flow meter 5 to be verified is kept approximately constant during the verification process, and therefore the flow meter 5 to be verified can always measure flow rate under the same conditions as in actual use. .

After a certain period of time has passed since the start of the test, valve 1
At the same time as the valve 0 is closed, the valve 8 is opened and the drive of the pump 4 is stopped.

Here, since the flow rate of the liquid that has passed through the flowmeter 5 to be verified is measured with a predetermined accuracy by the reference flowmeter 6, the measured flow rate value indicated by the flow rate indicator 5a of the flowmeter 5 to be verified is By comparing the measured flow rate value indicated by the flow rate indicator 6a of the reference flowmeter 6, the flow rate measurement accuracy, instrumental error, etc. of the flowmeter to be verified 5 can be accurately verified. In that case, since the flowmeter 5 to be verified always measures the flow rate under the same conditions as the normal usage conditions, the measured value measured by the flowmeter 5 to be verified is useful for determining flow rate measurement accuracy, instrumental error, etc. It can be treated as sufficiently reliable and accurate information.

In the above embodiment, the pump 4 is connected to the liquid storage tank 2.
The reference flowmeter 6 may be connected between the flowmeter 6 and the reference flowmeter 6, and the liquid in the storage tank 2 may be sent from the reference flowmeter 6 to the flowmeter 5 to be verified.

Further, the flowmeter 5 to be verified is not limited to a turbine type flowmeter, but may be a roots type flowmeter, for example.

Further, the reference flowmeter 6 is not limited to a Roots type flowmeter, and may be, for example, an oval gear type flowmeter.

As mentioned above, the flow meter verification device according to the present invention has the following features:
A container is installed between the flowmeter to be verified and the reference flowmeter,
Since the structure is designed to absorb the pulsations generated in the reference flowmeter along with fluctuations in the liquid level in the container, fluctuations in flow rate, pressure, etc. that occur as the liquid for flowmeter verification passes through the reference flowmeter are absorbed by the fluctuations in the liquid level in the container. Therefore, the flowmeter under test is never adversely affected by the reference flowmeter and is always subjected to the same conditions as applied in normal piping. It has the advantage of being able to supply a verification liquid to the verification flowmeter, thereby enabling accurate verification at all times.

[Brief explanation of the drawing]

The figure is a schematic configuration diagram of an embodiment of a flow meter verification device according to the present invention. DESCRIPTION OF SYMBOLS 1...Verification device, 2...Liquid storage tank, 3...Piping, 4...Pump, 5...Flowmeter to be verified, 6...Reference flowmeter, 7...
Tank, 11...Air chamber, 12...Liquid level control mechanism, 1
7... Pressure air supply mechanism.

Claims (1)

[Claims] 1. In a flow meter verification device configured by installing a pump and a reference flow meter in the middle of the piping extending from the liquid storage tank and returning to the liquid storage tank, and connecting the flow meter to be verified between the pump and the reference flow meter. A container is connected between the flowmeter to be verified and the reference flowmeter, and a liquid level control mechanism is provided for supplying pressure gas to the container and controlling the liquid level in the container to a constant level using the pressure gas. A flow meter verification device characterized by: