RU2476830C2 - Test setup for gas flowmeters/counters - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: setup includes pipeline, shutoff valves, compressor for injection of consumed medium (1), flexible bag (3), inlet test line (4), test manifold (5), outlet test line (7), filter (8), reference flowmeter (9), flow rate setting device (10), absolute pressure sensor (11), temperature sensor (12) and differential pressure sensor (13). Flexible bag (3) is covered with a plate intended for weights loaded onto it with certain mass. Compressor outlet (1) is connected to flexible bag (3) loaded with the specified mass. Outlet of flexible bag (3) is connected to inlet test line (4) that is connected to test manifold (5). Test manifold (5) includes test sections (6) intended for installation of tested gas flowmeters/counters. Test manifold (5) is connected to outlet test line (7) that is connected through filter (8) to reference flowmeter (9). Outlet of reference flowmeter (9) is connected to flow rate setting device (10).

EFFECT: providing strict pressure constancy of consumed medium at complete elimination of its pulsations occurring at operation of compressor; possibility of setting a big number of flow metre points at tests and calibration of flowmeters/counters; automation of calibration process and drawing up a calibration record; simplifying the design of the setup and improving its operating reliability; providing the filtration of consumed medium.

2 cl, 1 dwg

Description

The invention relates to measuring equipment and may find application in the testing and calibration of gas flow meters.

A device for calibrating meters is known, comprising a measuring bell immersed in a reservoir with liquid, equipped with an orientation system in a vertical position, connected through a cable, an envelope wheel, with balancing weights and a pipeline with shut-off and control valves (patent RU No. 2175116, publ. 20.10.2001 g.).

Such a device allows you to check the gas meters by comparing their readings with a known volumetric value of the displaced air from under the measuring bell at a given pressure.

The main disadvantages of such a device are insufficient accuracy, since there are technological difficulties in the manufacture of measuring devices with a constant internal cross section, the visual reading of the volume of the consumed medium on the scale of the measuring ruler and pointer makes it difficult to carry out a dynamic calibration mode, which leads to additional errors and the need to increase the averaging time of the flow rate. To increase the dynamic range of costs, there is a need to use several measuring devices, which further complicates the design.

Closest to the technical nature of the present invention is the installation for calibration of gas meters (patent RU No. 2239795, publ. 10.11.2004,). The installation includes a blower, piping, temperature and pressure sensors, a device for setting costs, an assembly table with a base plate for a reference gas meter and verifiable meters, on which racks with movable guide gas ducts are fixed and a fixing device equipped with a movement drive. The device for setting costs is made in the form of vertical lines, on each of which are mounted valves and valves and a device for visual control of flow stability (rotameter).

The disadvantages of this design include pulsations of air pressure during the operation of the blower.

The technical problems to which the invention is directed are ensuring strict constancy of the pressure of the flowing medium with the complete elimination of its pulsations arising from the operation of the blower, the possibility of setting a large number of flow points during testing and calibration of flow meters, counters, automating the verification process and compiling a verification protocol , simplifying the design of the installation and improving the reliability of its operation, ensuring filtering of the flowing medium.

These tasks are solved by using an elastic tank as a device for setting the pressure and storing the expendable medium; Install a fluid filter the use of a device for setting the flow rate in the form of a cylinder with calibrated holes in the side wall, inside which the piston moves, thereby changing the total cross section of the output ports involved; the use of equipment with the ability to transfer data to a personal computer about the characteristics of the flow medium and the costs of the reference and verified flow meters.

Since the proposed installation is designed for work with pressures up to 5 kPa (only 5% of atmospheric), corresponding to the pressure of natural gas at the end user, an elastic reservoir is used as a pressure setting device. The use of an elastic tank makes it possible to obtain a highly stable and precisely set pressure in the system due to loads loaded with a certain mass on it, which positively affects the accuracy of pressure measurement and the operation of the reference flow meter. To obtain the required pressure, a flat plate is laid on the elastic tank, on which loads of a given mass are placed. Consequently, the error in setting the pressure will depend on the error of the scales on which the load was weighed, and the pressure will be maintained until the contact of the upper and lower surfaces of the tank is reached.

The flow setting device, in contrast to the system of the input throttle and the output throttles of the prototype, is a cylinder with calibrated holes in the side wall and a piston moving inside. The number and diameter of holes can vary by the developer, so you can specify arbitrary values and the number of points at which the flowmeter should be rotated. A single flow setting device can serve multiple flow meters with different measuring limits. The piston moves with the help of a stepper motor, which allows to obtain high positioning accuracy, and therefore to minimize errors in the flow rate. This design is optimal both when testing new models of flowmeters, when the standard procedure for checking household flowmeters-counters, carried out at points 5, 10, 50 and 100% of Q _max (maximum flow rate), and directly when calibrating household meters in accordance with the standard, is insufficient .

Use in the design of devices with the possibility of exchanging data and control signals with a computer allows you to automate the process of verification and the formation of the output document. Therefore, the operator of the calibration installation is required only to install and disassemble the calibrated flow meters, and to monitor alarm messages.

The invention is illustrated by drawings, where figure 1 shows the structural diagram of the installation.

Installation for testing flowmeters, gas meters contains a compressor 1, the output of which through valve 2 is connected to an elastic tank 3 loaded with a given mass. The output of the elastic reservoir 3 is connected to the input test line 4. The test collector 5 is connected between the input 4 and output 7 of the test lines and contains test sections 6, in which the tested gas flow meters are mounted. The output test line through the filter 8 is connected to a reference flowmeter 9, and the output of the latter is connected to a flow setting device 10. The pressure at the input of the reference flowmeter is controlled by an absolute pressure sensor 11, and the pressure difference between the input and output of the flow setting device (atmospheric pressure) is controlled by a differential sensor gauge pressure 13. The temperature of the fluid is measured by a temperature sensor 12.

Consumable medium is air. It is pumped by the compressor 1 into the elastic tank 3 through the valve 2, which is closed when the tank 3 is sufficiently filled. The outlet of the tank is connected via a pipeline to the inlet test line 4 and then to the test manifold 5, consisting of four vertically calibrated pipes with different nominal diameters, corresponding to the diameters of the nominal passage of the gas meters to be verified. At the inlets and outlets of each of the pipes of the test manifold 5, valves are installed. At a height of about 1 m from the lower test line, test sections 6 are located for mounting the test flow meters with coupling couplings. Above, at a distance of at least 1 meter from the test sections, the upper test line 7 passes, the end of which is connected through a confuser to a pipe that is bent vertically downward with a radius of at least 150 mm and at a height of about 1 m from the floor to it through a filter 8 the reference flowmeter 9 is connected. The pressure and air temperature at the inlet of the reference flowmeter 9 are controlled by a high-precision absolute pressure sensor 11 and the temperature sensor 12. The output of the reference flowmeter 9 is connected to the flow setting device 10. At the input of the device To set the flow rate 10, a high-precision differential pressure sensor 13 is installed.

Installation works as follows. The air is pumped by compressor 1 into the elastic tank 3 in an amount that does not allow strong stretching of the material, with the valves closed on the inlet test line 4. After filling the elastic tank 3, the valve 2 is shut off leading to the compressor 1. A flat plate is placed on the elastic tank 3, not exceeding its size elastic tank. On this plate loads of a given mass are set to obtain the required pressure value. In the test manifold 5, a verifiable flowmeter is installed in the corresponding section for mounting 6, and valves leading to this section open on highways 4 and 7. After the output test line 7, the air passes through the filter 8, the reference flow meter 9 and exits through the device for setting the flow rate 10 into the atmosphere.

Claims (2)

1. Installation for testing gas flow meters, comprising a pipeline, shutoff valves, a temperature sensor, an absolute pressure sensor and a differential pressure sensor, characterized in that a compressor is introduced for pumping a flowing medium, a reference flow meter, an elastic tank, covered with a flat plate, designed for loads of a certain mass loaded onto it, a flow rate setting device, the compressor output being connected to an elastic reservoir loaded with a given mass, its output being connected to a test line connected to a test collector containing test sections for installing test gas flow meters, in turn, the test collector is connected to an output test line, which is connected to a reference flowmeter through a filter, and its output is connected to a reference device expense. 2. Installation according to claim 1, characterized in that the device for setting the flow rate is made in the form of a cylinder with calibrated holes in the side wall and a piston located inside the cylinder with the possibility of movement.