JP3366075B2 - Gas meter test equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter test apparatus, and more particularly, to air sucked in a test apparatus for performing a flow test of air with a gas meter based on a sonic nozzle. The present invention relates to a gas meter test device in which a temperature stabilizing device is attached to an air intake side in order to maintain a constant temperature. 2. Description of the Related Art Various tests are performed on a film type gas meter used at home or the like when it is shipped from a factory, and a gas meter that passes the test is shipped. The main test items include a flow rate test, a differential pressure test between the gas meter inlet and outlet at the maximum flow rate, and a leak test. The flow test is a comparison test with the reference flow meter in the atmosphere, and the leak test is
For example, a change in pressure from the reference pressure when compressed air at a reference pressure of 10 kpa (kilopascal) is applied, for example, for 3 minutes is observed. [0003] A standard device for a reference flow rate is a sonic nozzle (SV nozzle; Sonic Venturi Nozzle) calibrated by a specific standard device such as the primary national flow standard constant volume tank of the National Institute of Metrology.
And wet flow meters. However, the latter wet type flow meter has a problem that it has a movable part and is large and difficult to handle. Therefore, recently, a sonic nozzle is often used as a standard flow rate. In a sonic nozzle, when the pressure before and after the throat drops below a critical pressure when a compressible fluid flows, the velocity of the gas flowing in the throat becomes the sonic velocity in that state, and a constant gas mass flow rate is obtained. Has features. However, this mass flow is conditional on the temperature, pressure and humidity upstream of the throat being constant. In a flow test of a gas meter, a sonic nozzle is used alone, or a plurality of sonic nozzles having a throat section partitioned and fixed by the partition in a chamber whose upper and lower parts are separated by a partition are selectable. The set SV meter unit is used. [0006] A gas meter line in which test gas meters are connected in series is connected to the upstream side of the SV meter unit.
A vacuum pump is connected to the downstream side, and at the time of the test, air sucked by the vacuum pump from the upstream side of the gas meter line flows to each gas meter and is compared with the reference flow rate of the selected sonic nozzle. [0007] As described above, since the reference mass flow rate of the sonic nozzle changes depending on the temperature, pressure, humidity, and the like of the air upstream of the sonic nozzle, the gas meter test apparatus has It is usually installed in a test room controlled to keep the room temperature constant. However, for example, even if the temperature in the test chamber is controlled with an accuracy of about 0.5 class in the standard state temperature of the test place, there is a temperature difference of 1.0 ° C., and the reference flow rate of the sonic nozzle is A deviation of about 0.2% occurs. This value is a value that cannot be ignored for an instrument error of ± 1.5% in the acceptable range of the gas meter. For this reason,
In order to obtain a more accurate and constant temperature test room, a huge amount of equipment was required. [0008] The present invention SUMMARY OF], in order to solve the above problems, a gas meter line connected in series a plurality of the gas meter having a flow inlet-outlet, before and after the throat is defined by the diaphragm An SV meter unit in which a plurality of sonic nozzles are selectably disposed and a vacuum pump are sequentially connected, and the gas meter line obtains an air flow reading obtained by vacuum suctioning the atmosphere, and the selection value. a test apparatus for performing a flow rate test gas meter and a flow value of sonic nozzle, disposed the temperature stabilizing device to the atmosphere suction side of the gas meter line, the gas meter line via a temperature stabilizing device A gas meter that sucks air
In the temperature test device , the temperature stabilizing device is disposed coaxially at a predetermined interval in a cylindrical casing having a connection portion where an air intake side is open and a discharge side is connected to the meter line. A honeycomb formed of a plurality of thermal conductors and a punching plate disposed between the honeycombs arranged at a predetermined interval and spaced apart from the honeycomb in a direction perpendicular to the flow. Things. A temperature stabilizing device is mounted on the upstream side of the gas meter line of the test gas meters connected in series, and the atmosphere in the test chamber sucked into the gas meter line is introduced through the temperature stabilizing device, thereby reducing the cost. The purpose of the present invention is to provide a highly accurate gas meter test device. FIG. 1 is a block diagram for explaining a gas meter test apparatus according to the present invention. In the figure, 1 is a test chamber, 2 is a temperature stabilizing apparatus, 3 is a casing, 4 is an outlet, 5 is an atmosphere line, 6 is an on-off valve, 7 is a pressurized air line, 8 is a filter, 9 is a gas meter line, 10 is a gas meter, 11
Is an SV meter unit, 12 is a sonic nozzle, 13 is a straightening tube, 14 is an inlet, 15 is an outlet, 17 is a valve, 18 is a strainer, 19 is a vacuum pump, 19, 22, 27 are conduits, and 26 is absolute pressure. 27 is a thermometer, 28 is a hygrometer. Each of the gas meters 10-1,..., 10-n to be tested has an inlet 10a and an outlet 10b, and is connected to the gas meter line 9 in series. In addition, the inlet 10a of each gas meter 10-1, ..., 10-n of the gas meter line 9
On / off valves 6-3 to 6-n are attached to the outlet 10b. On the upstream side of the gas meter line 9, an atmosphere line 5 for a gas meter flow rate test according to the present invention is connected to a pressurized air line 7 for supplying a high-pressure reference pressure for a gas meter leak test, and is connected to the gas meter line 9. The connection of the pressurized air line 7 communicating with the atmosphere line 5 or the pressurized air source 7a is performed by switching between the on-off valves 6-1 and 6-2. The atmosphere line 5 communicates with an outlet 4 of a temperature stabilizing device 2, which will be described later, having an atmosphere inlet 3 a opened at one end of the casing 3. An inflow port 14 of the SV meter unit 11 is connected to a downstream side of the gas meter line 9 via a filter 8, and an outflow side 15 of the SV meter unit 11 is
It is connected to a vacuum pump 19 via a valve 17 and a strainer 18. When the upstream side of the gas meter line 9 is connected to the pressurized air source 7a, the pressurized air source stabilizing device 7b is connected to the outflow side of the pressurized air source 7a. The SV meter unit 11 is divided into a throat upstream side and a downstream side of the sonic nozzle 12 by a partition plate 11a. The sonic nozzles 12 have the same standard flow rate or different standard flow rates calibrated in the primary national flow standard constant volume tank of the National Institute for Metrology. In order to make the standard flow rate of air flow more stably, Rectifier tube 13 with rectifier grid inserted
The SV meter unit 11 is closed with the cover 11b. The sonic nozzle 12 is selected by sealing the outlet of the sonic nozzle 12 in the SV meter unit 11 on the outlet 15 side. The pressure, temperature and humidity on the upstream side of the sonic nozzle 12 are detected by detecting ends 11c, 11d and 11e attached to the chamber on the inlet 14 side of the SV meter unit 11, and the absolute pressure gauge 26 and Total 27
And the hygrometer 28. When it is necessary to detect the differential pressure, the amount of leakage, etc. of the gas meter 10, the detection is performed by connecting a differential pressure transmitter (not shown) to the conduits 21, 22, 27. FIGS. 2A, 2B and 2C are views for explaining an example of the temperature stabilizing device according to the present invention.
2A is a sectional view taken along line BB of FIG.
FIG. 2B is a cross-sectional view taken along line AA of FIG.
(C) is a plan view of the punching plate.
30 is a honeycomb, 31 is a punching plate, 32, 3
5 is a temperature detector boss, and 33 and 34 are humidity detector bosses. The temperature stabilizing device 2 shown in FIG.
a is opened, the other end is narrowed, and a honeycomb 30 made of a heat conductive material such as aluminum having a length L coaxial with the casing 3 is provided at a predetermined interval M in a cylindrical casing 3 having a discharge port 4.
And a large number of through holes 31a are provided within a predetermined interval M.
Is provided. The honeycomb 30 and the punching plate 31 form a pair, and a plurality of pairs are sequentially arranged toward the downstream side, and an empty room 3b is provided at a downstream portion. Detection bosses 32, 33 and 3 for inserting detectors for temperature, humidity and the like are provided on the outer wall of the casing of the empty room 3b.
4 is attached. The operation of the gas meter test apparatus according to the present invention having the above-described structure will be described with reference to FIGS.
First, the on-off valve 6-1 of the pressurized air line 7 is closed, and the on-off valve 6-2 on the atmosphere line side and the on-off valves 6-3, 6-4,-, 6-n and the valve 17 on the gas meter line 9 are closed. The valve is opened, the temperature stabilizing device 2, the gas meters 10-1, ..., 10-n and SV
The meter unit 11 and the vacuum pump 19 are connected in series. The sonic nozzle 12 in the SV meter unit 11 determined according to the test flow rate of the gas meter 10 is selected, and the atmosphere in the test chamber 1 passes through the temperature stabilizing device 2 by the operation of the vacuum pump 19. Gas meter line 9, S
The air is released to the atmosphere through the V meter unit 11 and the vacuum pump 19. At this time, for example, the flow rate of the air flowing through the gas meter 10-1 is detected by the flow rate detection device 10c.
The detected flow rate of the gas meter 10-1 is corrected by the pressure value of the absolute pressure gauge 26, the temperature value of the thermometer 27, and the humidity value of the hygrometer 28 with respect to the flow rate of the selected sonic nozzle 12 of the SV meter unit 11. Are added and compared. Such a comparison is performed for each gas meter 10-n. At this time, the atmosphere pulsating in temperature flowing into the gas meter line 9 is kept at a constant temperature through the temperature stabilizing device 2. That is, the air in the test chamber flowing from the air suction port 3a first flows into the honeycomb 30. When passing through the honeycomb 30 and the punching plate 37, the temperature is equalized. The air passing through the honeycomb 30 is rectified and flows along the honeycomb, but the downstream side is provided with a punching plate 31 that faces at right angles to the flow. The air flow is generated along the surface of the punching plate 31 on the low speed side, and the air flow passing through the punching plate 31 is turbulently diffused and mixed. As a result, the air temperature is more effectively equalized. Such a honeycomb 30 and a punching plate 3
By combining 1 in a plurality of stages, the inflow air is further equalized in temperature and introduced into the SV nozzle unit 11. As described above, by using the temperature stabilizing device 2 having a high temperature equalizing effect, the temperature change was ± 0.5 ° C. before the temperature stabilizing device 2 was not attached.
± 0.05 ° C by attaching temperature stabilizing device 2
And the temperature fluctuation range was reduced to about 1/10. As a result,
The accuracy of the reference flow rate was ± 0.07%, and the accuracy of 1/150 could be maintained for the acceptable range of the gas meter of ± 1.5%. The aperture ratio of the honeycomb 30 and the punching plate 31 used in the temperature stabilizing device 2 according to the present invention is appropriately selected. Further, instead of the combination of the honeycomb 30 and the punching plate 31, only the punching plate made of a good heat conductor, only the honeycomb, or a combination of these may be used. As is apparent from the above description, according to the present invention, in a gas meter test apparatus for performing a flow test of a gas meter based on a sonic nozzle, even if the gas meter test apparatus is provided in a test chamber. whereas instrumental error influence of sonic nozzle by the temperature control accuracy of the test chamber can not be ignored with respect to acceptance criteria range of the gas meter, the honeycomb
By installing a temperature stabilization device consisting of a combination with a punching plate , the inflow air is more evenly heated,
Sonic nozzle accuracy that can ignore temperature effects is obtained,
The reliability of the gas meter test equipment could be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram for explaining a gas meter test device according to the present invention. FIG. 2 is a diagram for explaining an example of a temperature stabilizing device according to the present invention. [Explanation of Signs] 1 ... Test room, 2 ... Temperature stabilizing device, 3 ... Casing, 4
... Exhaust port, 5 ... Atmosphere line, 6 ... On-off valve, 7 ... Pressurized air line, 8 ... Filter, 9 ... Gas meter line, 10 ...
Gas meter, 11 SV meter unit, 12 sonic nozzle, 13 rectifier tube, 14 inlet, 15 outlet, 1
7 ... Valve, 18 ... Strainer, 19 ... Vacuum pump, 21
22, 27: conduit, 25: open pipe, 26: absolute pressure gauge, 27: thermometer, 28: hygrometer, 30: honeycomb, 3
1: punching plate, 32, 35: temperature detector boss, 33, 34: humidity detector boss.

Continued on the front page (72) Inventor Yuyasu Yamashita 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo Inside Oval Co., Ltd. (72) Inventor Sakujiro Otsuki 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo Oval Co., Ltd. (56) References JP-A-60-39936 (JP, U) Utility model registration 2502072 (JP, Y2) JP-B 7-122587 (JP, B2) JP-B-59-42806 (JP, B2) Hei 4-22269 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01F 25/00

Claims (1)

(57) [Claims] [Claim 1] A plurality of gas meters having an inflow / outflow port
Are connected in series with the gas meter line
Multiple sonic nozzles divided by a plate are arranged to be selectable
Connect the SV meter unit and the vacuum pump sequentially,
The gas meter line was obtained by vacuum suction of the atmosphere.
The gas flow rate reading of the gas meter and the selected sound velocity
Test to perform gas meter flow test from nozzle flow value
A gas temperature line on the gas suction side of the gas meter line.
Temperature stabilizing device, and the temperature stabilizing device
A gas meter that sucks air into the gas meter line
In the temperature test device, the temperature stabilizing device is provided coaxially at a predetermined interval in a cylindrical casing having a connection portion in which an air intake side is open and a discharge side is connected to the meter line. A honeycomb formed of a plurality of thermal conductors, and a punching plate arranged at a distance from the honeycomb in a direction perpendicular to the flow between the honeycombs arranged at the predetermined interval. br /> be Ruga Sumeta test equipment.