JPH07110257A - Gas meter testing device - Google Patents

Abstract

PURPOSE:To improve the accuracy of the flow rate test of a gas meter performed by using acoustic velocity nozzles. CONSTITUTION:The temperature fluctuation on the upstream side of acoustic velocity nozzles 12 is reduced and the reference flow rates of the nozzles 12 are stabilized by providing a temperature stabilizing device 2 constituted by arranging in series a honeycomb 30 and punching plate 31 at a prescribed interval in a cylindrical casing on the upstream side of a flow rate testing line constituted by connecting an SV meter unit 11 in which gas meters 10-1 to 10-n and the nozzles 12 are selectably arranged and a vacuum pump 19 after closing the opening/closing valve 6-1 of a high-pressure air line 7 and through which the air in a laboratory 1 is sucked for tests and stabilizing the temperature of sucked air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas meter test apparatus, and more particularly to a gas meter in a test apparatus for carrying out a flow rate test by air with a sonic nozzle as a reference in order to keep the temperature of the air taken in constant. The present invention relates to a gas meter test device equipped with a temperature stabilizer.

[0002]

2. Description of the Related Art A membrane gas meter used at home is subjected to various tests when shipped from a factory, and gas meters that pass the tests are 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 rate test is a comparison test with the reference flow meter in the atmosphere, and the leak test is
For example, the pressure change from the reference pressure when compressed air having a reference pressure of 10 kpa (kilopascal) is applied for, eg, 3 minutes is observed.

The standard device for the flow rate to be the reference flow rate is a sonic nozzle (SV nozzle; Sonic Venturi Nozzle) calibrated by a specific standard instrument such as the primary national flow rate standard constant volume tank of the Metrology Institute.
There is also a wet flowmeter. However, the latter wet flowmeter has a moving part and is large in size and difficult to handle. Therefore, recently, many sonic nozzles have been used as a standard flow rate.

In the sonic nozzle, when the pressure before and after the throat becomes less than the critical pressure when a compressive fluid is flown, the velocity of the gas flowing in the throat becomes the sonic velocity in that state, and a constant mass flow rate of gas is obtained. It has features. However, this mass flow rate is subject to the constant temperature, pressure, and humidity on the upstream side of the throat.

In the flow rate test of the gas meter, the sonic nozzles are used alone, or a plurality of sonic nozzles having the throat section partitioned and fixed by the partition plate are arranged in a chamber whose upstream and downstream are separated by the partition plate. The installed SV meter unit is used.

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 during the test, the 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, the reference mass flow rate of the sonic nozzle varies depending on the temperature, pressure and humidity of the air on the upstream side of the sonic nozzle. It is installed in a test chamber controlled to be constant. However, for example, even if the temperature in the test chamber is controlled with an accuracy of the standard state temperature of the test site of about 0.5 class, the temperature difference is 1.0 ° C., and due to this temperature difference, 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 with respect to the instrumental error ± 1.5% of the acceptable range of the gas meter. For this reason,
Obtaining a more accurate and constant temperature test chamber requires a huge cost for the device.

[0008]

In order to solve the above-mentioned problems, the present invention provides (1) a gas meter line in which a plurality of gas meters having inflow / outflow ports are connected in series and a throat front and rear are partitioned by a partition plate. An SV meter unit having a plurality of selectable sonic nozzles and a vacuum pump are sequentially connected to each other, and the gas meter line obtains a reading value of the air flow rate of the gas meter obtained by vacuum suction of the atmosphere and the selected value. In a test device for performing a gas meter flow rate test from the flow rate value of the sonic nozzle, a temperature stabilizing device is provided on the atmosphere suction side of the gas meter line, and the atmosphere is fed to the gas meter line via the temperature stabilizing device. Sucking, and (2) in (1), the temperature stabilizing device has a connecting portion for opening the air intake side and connecting the discharge side to the meter line. A tubular casing, a honeycomb made of a plurality of good thermal conductors coaxially arranged in the casing at a predetermined interval, and the honeycomb at a right angle to the flow between the honeycombs arranged at the predetermined interval. It is characterized in that it is composed of a honeycomb and a punching plate arranged at a distance.

[0009]

[Function] A temperature stabilizer is installed upstream of the gas meter line of the test gas meter connected in series, and the atmosphere in the test chamber sucked into the gas meter line is introduced through the temperature stabilizer to reduce the cost and increase the cost. The purpose of the invention is to provide an accurate gas meter test device.

[0010]

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 device, 3 is a casing, 4 is a discharge port, and 5 is atmospheric air. Line, 6 open / close valve, 7 pressurized air line, 8 filter, 9 gas meter line, 10 gas meter, 11
Is an SV meter unit, 12 is a sonic nozzle, 13 is a rectifying pipe, 14 is an inlet, 15 is an outlet, 17 is a valve, 18 is a strainer, 19 is a vacuum pump, 21, 22 and 27 are conduits, and 26 is an absolute pressure. Reference numeral 27 is a thermometer and 28 is a hygrometer.

The gas meters 10-1, ..., 10-n to be tested each have an inlet 10a and an outlet 10b and are connected in series to the gas meter line 9. In addition, the inlets 10a of the respective gas meters 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 atmospheric line 5 for flow rate test of the gas meter according to the present invention is connected to a pressurized air line 7 which supplies a high pressure reference pressure for leak test of the gas meter, and is connected to the gas meter line 9. The joining of the pressurized air line 7 communicating with the atmosphere line 5 or the pressurized air source 7a is performed by switching the on-off valves 6-1 and 6-2. Further, the atmosphere line 5 communicates with an outlet 4 of a temperature stabilizing device 2 which will be described later and has an atmosphere inlet 3a opened at one end of the casing 3.

An inflow port 14 of the SV meter unit 11 is connected to the downstream side of the gas meter line 9 through a filter 8, and an outflow side 15 of the SV meter unit 11 is connected to the outflow side 15.
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 rate standard constant volume tank of the Metrology Institute. Rectifier tube 13 with rectifier grid inserted
The SV meter unit 11 is closed by the mounting lid 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 the detection 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 the temperature are detected. 27 in total
And the hygrometer 28 is instructed.

When it is necessary to detect the differential pressure, leak amount, etc. of the gas meter 10, a differential pressure transmitter (not shown) is connected to the conduits 21, 22 and 27.

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 in FIG.
2B is a sectional view taken along the line AA of FIG.
(C) is a plan view of the punching plate.
30 is a honeycomb, 31 is a punching plate, 32, 3
Reference numeral 5 is a temperature detector boss, and 33 and 34 are humidity detector bosses.

The temperature stabilizing device 2 shown in FIG.
In a cylindrical casing 3 having an opening a and the other end narrowed and having a discharge port 4, a honeycomb 30 made of a heat conductive material such as aluminum having a length L coaxial with the casing 3 is arranged at a predetermined interval M.
And a plurality of through holes 31a are provided within a predetermined space M.
A punching plate 31 having a is arranged. The honeycomb 30 and the punching plate 31 form a pair, and a plurality of pairs are sequentially arranged toward the downstream side, and the vacant chamber 3b is arranged in the downstream portion. Detection bosses 32, 33 and 3 into which detectors for temperature, humidity, etc. are inserted on the outer wall of the casing of the vacant chamber 3b.
4 is attached.

The operation of the gas meter test apparatus according to the present invention constructed as above will be described with reference to FIGS.
First, the opening / closing valve 6-1 of the pressurized air line 7 is closed, and the opening / closing valve 6-2 on the atmosphere line side and the opening / closing valves 6-3, 6-4, ..., 6-n and the valve 17 of the gas meter line 9 are closed. The valve is opened, the temperature stabilizer 2 and 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 which is 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
It is released into the atmosphere through the V meter unit 11 and the vacuum pump 19. At this time, for example, the flow rate of 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 in which the temperature flowing into the gas meter line 9 pulsates is kept constant through the temperature stabilizing device 2. That is, the air in the test chamber that has flowed in through the air inlet 3a first flows into the honeycomb 30. When passing through the honeycomb 30 and the punching plate 37, the temperature is soaked.

The air that has passed through the honeycomb 30 is rectified and flows along the honeycomb. However, since a punching plate 31 that faces the flow at a right angle is arranged on the downstream side, when there is a non-uniform flow. The air flow is generated on the low speed side along the surface of the punching plate 31, and the air flow passing through the punching plate 31 is turbulently diffused and mixed. As a result, the air temperature is equalized more effectively. Such a honeycomb 30 and punching plate 3
By combining 1 in a plurality of stages, the temperature of the inflowing air is further equalized 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 of ± 0.5 ° C. before the temperature stabilizing device 2 is not attached,
± 0.05 ° C by attaching the temperature stabilizer 2
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 was able to be maintained against the gas meter passing range of ± 1.5%.

The hole ratios of the honeycomb 30 and punching plate 31 used in the temperature stabilizing device 2 according to the present invention are appropriately selected. Further, instead of using 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.

[0024]

As is apparent from the above description, according to the present invention, in the gas meter test apparatus for performing the flow rate test of the gas meter with the sonic nozzle as a reference, even when the gas meter test apparatus is installed in the test chamber, Although the influence of the sonic nozzle due to the temperature control accuracy on the sonic nozzle was not negligible with respect to the pass standard range of the gas meter, by installing the temperature stabilizer, the sonic nozzle accuracy was low enough to ignore the temperature effect. As a result, the reliability of the gas meter test device could be improved.

[Brief description of 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 symbols]

1 ... Test room, 2 ... Temperature stabilization device, 3 ... Casing, 4
... Exhaust port, 5 ... Atmosphere line, 6 ... Open / close 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 ... Atmosphere 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.

Front page continuation (72) Inventor Yasuyasu Yamashita 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo Within Oval Co., Ltd. (72) Inventor Sakujiro Otsuki 3-10-8 Kamiochiai, Shinjuku-ku, Tokyo Within Oval Co., Ltd.

Claims (2)

[Claims] 1. A gas meter line in which a plurality of gas meters having inflow / outflow ports are connected in series, an SV meter unit in which a plurality of sonic nozzles having front and rear throats partitioned by partition plates are selectably arranged, and a vacuum pump. Sequentially connected, the gas meter line, the reading of the air flow rate of the gas meter obtained by vacuum suction of the atmosphere, and the flow rate value of the selected sonic nozzle, the test device for performing a gas meter flow rate test, A gas meter test device, wherein a temperature stabilizing device is disposed on the atmosphere suction side of the gas meter line, and the atmosphere is sucked into the gas meter line via the temperature stabilizing device. 2. The temperature stabilizing device, wherein a cylindrical casing having a connecting portion whose air intake side is open and whose exhaust side is connected to the meter line, and which are coaxially arranged in the casing at a predetermined interval. It is characterized in that it is composed of a honeycomb made of a plurality of good thermal conductors, and a punching plate arranged at intervals with the honeycomb in a direction perpendicular to the flow between the honeycombs arranged at the predetermined intervals. The gas meter test apparatus according to claim 1.