JPH0143248B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the instrumental error of a flowmeter.

After a flowmeter is manufactured or repaired, it is necessary to perform adjustment so that the error in the indicated amount is always within a predetermined range.

In the standard tank method, the measurement of instrumental error, which is a prerequisite for this adjustment work, usually involves passing the fluid through the flowmeter to be tested, guiding the fluid to the reference tank, and accurately measuring the flow rate. This is also done by measuring how much the indicated amount of the flow meter deviates due to the passage of this fluid.

Current instrumental error measurement devices are capable of performing almost all of these tasks automatically.

For example, in the case of a water meter, first, a rotating disk or polygonal pyramid with radial stripes at regular intervals is used as the pilot pointer of the water meter, and a light emitting element is placed above the pointer. A pick-up consisting of a light-receiving element and a light-receiving element is set up, and the rotational speed of the pilot pointer is extracted from the pick-up as a pulse signal.

On the other hand, in the reference tank, electrodes that emit a signal by touching the water surface rising inside the tank are installed at predetermined intervals. Arrange it so that it can be accommodated.

Then, water is supplied to the water meter, and the signal emitted when the water surface of the reference tank touches the first electrode is used as a gate signal to start counting pulses from the pick-up. Count the number of pulses until water is applied, that is, until the second electrode emits a signal, and based this value on the reference number of pulses that should originally occur with water of 1,
This automatically calculates the instrumental error of the water meter.

In addition, in the pipe prover method, the reference device consists of a circular tube with a uniform inner diameter, an elastic ball (hereinafter referred to as a sphere) housed with a predetermined tension against the inner wall of the circular tube, and a uniform circular tube. It is composed of two detectors installed at an appropriate distance apart from each other in the tube, and the internal volume of the circular tube between these two detectors is taken as the reference volume.

Both ends of the pipe prover are inclined for sphere operation, and these inclined parts are connected to a flow path switching valve to enable reciprocating movement of the sphere.

The inspection flowmeter is equipped with a pulse transmitter, which emits pulses according to the flow rate.
The pulse is configured to be integrated by a proving count, and the signal transmitted by the detector switch is used as the start and stop command signal for this pulse integration, and the flowmeter integrated value I corresponding to the volume between the detector switches, that is, the reference volume Q. is obtained, and the instrumental error E% is calculated using the formula: E=I-Q/I×100%.

Therefore, in the standard tank system of the conventional instrumental error measuring device, fluctuations in the liquid level may occur in the reference tank,
Further, there are problems in that measurement accuracy is poor due to adhesion of water droplets, and the need for frequent cleaning is required due to the adhesion of dirt.

In addition, the pipe prover method solves the problems of the reference tank method mentioned above, but the device is complex and large, making it expensive to manufacture and making it difficult to test inexpensive flowmeters such as water meters. In addition, because the amount of liquid required for inspection is constant, it takes a long time to test small flow rates, and if the output pulses of the flowmeter are not large enough, the necessary accuracy cannot be obtained. There are also problems.

In addition, when conventionally known pipe provers are used for a long period of time, internal leaks occur, a certain degree of error is inevitable, and it is not easy to inspect the presence or absence of internal leaks and the amount thereof.

The present invention was made in order to solve the above-mentioned problems, and its purpose is to provide a simple mechanism, low manufacturing cost, less failure, maintenance-free, and high-flow test and small-flow test. Both can be easily done within a short period of time, and even if an internal leak occurs due to long-term use, the occurrence and amount of leak can be easily known, making it possible to perform highly accurate measurements. The purpose is to provide testing equipment.

Therefore, the gist of the present invention is to automatically measure the indicated value I of the flowmeter to be tested and the true volume Q of the fluid that has passed through the flowmeter to be tested, and to satisfy the following equation: E =I-Q/I×100% A reference device for a flow meter difference test device is used to calculate the instrumental error E% of the flow meter using an electronic computer, and a fluid inflow hole and a fluid outflow hole are provided at each end. The cylinder is equipped with a pair of O-rings on its side surfaces, and has a liquid leakage passage inside thereof leading from the side wall surface between the pair of O-rings to the center of one end surface, a piston slidably inserted into the piston; a cross-sectional area with an outer diameter d that is one-half or more of the cross-sectional area of the outer diameter D of the piston; and a leakage conduction path provided along the central axis of the piston. which passes through one end wall of the cylinder in an airtight and slidable manner, and is arranged coaxially with the piston so that the leakage passageway communicates with the leakage passageway of the piston. The invention consists in using a reference cylinder consisting of a piston rod connected at one end to the piston and a position detector which emits an output pulse corresponding to the movement or position of the piston rod.

Hereinafter, the details of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of the flow meter difference testing device according to the present invention, and FIG. 2 is a sectional view of a reference cylinder for performing instrumental difference measurement in FIG. 1.

In Figures 1 and 2, 1 is a water tank, 2 is a pump that pumps water from water tank 1, 3 is a motor that drives pump 2, 4 is a water meter to be tested, 5 is a reference cylinder, and 6 is for an O-ring. Grooves 6a, 6b and 6
c and a piston having a leak hole 6d; 7 a piston rod having a leak hole 7a and a limit switch dog 7b; 8 a cylinder tube whose cylindrical inner surface is honed and internal threads provided on both end surfaces; 9 an O-ring groove. A cylinder head 10 has an O-ring groove 10a, a water supply hole 10b, and an escape hole 10c. The cylinder heads 11 and 12 screwed into the cylinder tube 8 are the water supply pipes 1 and 1 attached to the cylinder heads 10 and 9, respectively.
3 and 14 are drain pipes attached to the cylinder tube 8, and 15 and 16 are cylinder heads 9 and 1, respectively.
O-rings provided in O-ring grooves 9a and 10a of 0,
17 is an O-ring provided in the O-ring groove 9b of the cylinder head 9; 18 and 19 are O-rings provided in the O-ring grooves 6a and 6b of the piston 6; 20 is an O-ring provided in the O-ring groove 6c of the piston 6; 21 is a nut for attaching the piston 6 and piston rod 7, 22 and 23 are water supply solenoid valves attached to the water supply pipes 11 and 12, respectively, 24 and 25 are drain solenoid valves attached to the drain pipes 13 and 14, respectively, and 26 is for large flow. Flow rate control valve, 27 is a flow rate control valve for small flow rate,
28 and 29 are limit switches, 30 is a linear scale, 31 is a counter, 32 is a start button 33,
Air flow button 34, small flow test start button 35, large flow test start button 36, input keyboard 37, flow rate indicator 3
8. An electronic control device having an instrumental error (%) display 39 and a printer 40; 41 is a relief valve;

Thus, the water meter 4 to be tested is set so as to be easily attachable and detachable between joints (not shown).

The end faces of each machined part of the standard cylinder 5 are chamfered appropriately to facilitate assembly and operation, and the thread diameter of the female threads at both ends of the cylinder tube 8 is set to be smaller than the inner diameter of the cylinder tube 8. By increasing the size, the O-rings 18 and 19 provided on the piston 6 are prevented from being damaged when the piston 6 is assembled to the cylinder tube 8.

Water supply pipes 11 and 12 attached to the reference cylinder 5
The threaded portions of the drain pipes 13 and 14 shall be sealed using seal tape or the like to prevent water from leaking.

The leak hole 6d of the piston 6 is an O-ring groove 6.
A and 6b are provided with a plurality of holes penetrating toward the center hole, and a groove is provided in the center hole so that it communicates with the leak hole 7a of the piston rod 7 without alignment. These leak holes 6d and 7a are formed by the O-ring 6 due to long-term use of the reference cylinder 5.
If wear or scratches occur on a or 6b, water leaks and an instrumental measurement error occurs, so this is to quickly detect the occurrence of this leak in such cases.

The drain pipes 13 and 14 are provided at the positions shown in FIG. 2, and by appropriately determining the relative positions of the limit switches 28 and 29 and the dog 7b, the movement stop position of the piston 6 can be adjusted to the opening of the drain pipes 13 and 14. It shall be set closer to the center of the cylinder.

In such a case, even if the piston 6 overruns due to malfunction, the openings of the drain pipes 13 and 14 are blocked by the piston 6, thereby preventing the piston 6 from colliding with the cylinder heads 9 and 10. be.

After setting the water meter 4 to be tested between joints (not shown), first push the start button 33 and the air button 34 of the electronic control device 32, and move the reference cylinder 5 back and forth several times to Air is removed from the piping, and data such as the test date, meter diameter, and meter number are entered from the input keyboard 37.

Next, in the case of a large current test, press the large current test start button 3.
When 6 is pressed, the water supply solenoid valve 22, drain solenoid valve 24, and large flow rate control valve 26 are opened, and the water in the water tank 1 is pumped by the pump 2 through the water meter 4 to the reference cylinder 5 on the left side of the piston 6. The piston 6 and the piston rod 7 are moved to the right in the figure. After the piston 6 has completed its run-up and the flow rate has reached a predetermined value, the counter 31 is started at the rising edge of one pulse of the water meter 4, and the linear scale 30 attached to the piston rod 7 protruding from the reference cylinder 5 sends a signal. Make the pulses count.

The reference pulse number of the water meter 4 is set in the electronic control device 32 in advance, and when the emitted pulse of the water meter 4 reaches that value, the counter 31 is stopped, and the counted pulse number is sent to the electronic control device 32. The instrument error E% and the flow rate at which the test was actually conducted are calculated using the above calculation formula, and the values are displayed on the instrument error (%) display 39 and the flow rate display 38, respectively, and the printer 40 Print with .

When the piston 6 reaches the end of its movement on the right side in the figure, the dog 7b operates the limit switch 29, and in response to this signal, the water supply solenoid valve 22, the drain solenoid valve 24, and the large flow rate control valve 26 are closed.

In the case of a small stream test, similarly press the small stream test start button 3.
5 is pressed to open the water supply solenoid valve 23, drain solenoid valve 25, and small flow rate control valve 27, and conduct the test in the same manner as the large flow test described above.

As described above, instrumental error calculation can be performed by causing the piston 6 and piston rod 7 to reciprocate and performing the following calculations using the electronic control device 32.

For example, if the reference pulse of a water meter is set to N
pulse/, the outer diameter of the piston 6 is D, the outer diameter of the piston rod is d, and the piston displacement corresponding to n pulses of the water meter is L. During the large flow test, Q = π (D/2) ² ×L=v During the small flow test, Q'=π [(D/2) ² - (d/2) ² ]×L/N I=n/N, and from this, the formula, E=I-Q/I× If we now set (d/D) ² = 1/2 based on 100%, it is possible to measure the instrumental error during a small flow test using 1/2 the passing volume during a large flow test.

Since the present invention is constructed as described above, the present invention is a simple device that can perform large flow tests and small flow tests in a short time by reciprocating the piston of the reference cylinder and the piston rod. Because it is a mechanism, manufacturing costs are low, it is difficult to break down, and it is maintenance-free. Internal leaks are immediately discovered, so there is no risk of unexpected errors, and we can provide a flowmeter difference testing device with extremely high measurement accuracy. It is something.

In the embodiments of the present invention, the instrumental error measurement of water meters was particularly described, but it is not limited to water meters.
Instrumental measurement of gasoline meters, oil meters for high viscosity fluids, etc. can also be carried out safely and reliably.

Note that the configuration of the present invention is not limited to the above-mentioned embodiments; for example, the shape of the reference cylinder is a single-rod cylinder head that is screwed into the internal thread of the cylinder tube; It is also possible to fit the cylinder head into the cylinder tube and install it using four tie rods and nuts without installing it. It is also recommended that the O-ring provided on the piston be used in conjunction with the back-up seal. It is also possible to use rotary encoders and other various known position detectors, and furthermore, the configuration of each element can be freely changed within the scope of the purpose of the present invention, and the present invention encompasses all of them. It is something.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the flow meter difference testing device according to the present invention, and FIG. 2 is a sectional view of a reference cylinder for performing instrumental difference measurement in FIG. 1. 1...Aquarium, 2...Pump, 3...Motor, 4
...Water meter, 5...Reference cylinder, 6...Piston, 6a, 6b, 6c...O-ring groove, 6
d...Leak hole, 7...Piston rod, 7a...
...Leak hole, 7b...Dog, 8...Cylinder tube, 9, 10...Cylinder head, 9a, 9
b, 10a... O-ring groove, 9c, 10b... Water supply hole, 10c... Relief hole, 11, 12... Water supply pipe, 13, 14... Drain pipe, 15-20... O-ring, 21... Nut, 22, 23...Water supply solenoid valve, 24, 25...Drainage solenoid valve, 26...Flow rate control valve for large flow rate, 27...Flow rate control valve for small flow rate, 2
8, 29...Limit switch, 30...Linear scale, 31...Counter, 32...Electronic control device, 33...Start button, 34...Air button, 3
5... Small flow test start button, 36... Large flow test start button, 37... Input keyboard, 38... Flow rate indicator, 39... Instrument difference indicator, 40... Printer,
41...Relief valve.

Claims (1)

[Claims] 1. Automatically measuring the indicated value I of the flowmeter to be tested and the true volume Q of the fluid passing through the flowmeter to be tested, and using the formula: E=I-Q/I In a flow meter difference testing device that uses an electronic computer to calculate the instrumental error E% of the flow meter, which is determined by ×100%,
The above-mentioned flow meter difference testing device, characterized in that a reference cylinder made of the components described in the following items (a) to (d) is used as a reference device. (a) A cylinder having a fluid inlet and an outlet at each end. (b) A pair of O-rings is provided on the side surface thereof, and a leakage passageway is provided inside thereof leading from the side wall surface between the pair of O-rings to the center of one end surface, and a liquid leakage passage is provided inside the cylinder. A slidably inserted piston. (c) has a cross-sectional area of an outer diameter d that is one half or more of the cross-sectional area of the outer diameter D of the piston, and a leakage passage provided along the central axis of the piston; penetrating the end wall in an airtight and slidable manner so that the liquid leakage passage communicates with the liquid leakage passage of the piston, and coaxially with the piston;
A piston rod, one end of which is connected to the piston. (d) A position detector that emits an output pulse corresponding to the movement or position of the piston rod. 2 (d/D) ² = 1/2 in claim 1
Flow rate meter difference test device as described in section.