Operation, use and maintenance of v-cone flowmeter

　　V-cone flowmeter operation and use

　　①V-cone flowmeter must be used with a differential pressure transmitter to know the flow rate. In order to facilitate the zero point adjustment on site, a "three-valve group" must be installed at the pressure guiding pipe of the differential pressure transmitter. For usage instructions, see the transmitter manual.

　　②In order to measure the differential pressure value of the real flow rate, in addition to laying the pressure pipe correctly, it is also necessary to keep the pressure medium (the static pressure value of the transmitted fluid) in the pressure pipe in a single phase (liquid phase or gas phase). When measuring the flow rate of a liquid medium, the pressure pipe must be filled with liquid and must not be mixed with gas; when measuring the flow rate of a gas medium, the pipe must be filled with gas and liquid must not condense. For this purpose, a gas collector or settler can be added to collect the gas in the liquid (regular discharge) or the liquid in the gas (regular removal).

　　③ For new meters or built-in throttling devices that have been reactivated after being out of service for a period of time, the pressure piping should be checked for blockage or leakage before being put into use. For liquid media, the pressure piping should be filled with clean water or other For pressure-conducting liquids, pay attention to the gas mixed in the discharge pipeline. For gas media, pay attention to the liquid accumulation in the discharge pipeline.

　　④ Before putting into operation, open the balance valve in the "three-valve group", close the valves on the positive and negative pressure pipelines, check and correct the zero point of the differential pressure transmitter, be sure to note that the "zero point" is completely equal pressure in the positive and negative pressure chambers (That is, when the differential pressure is equal to 0), check and adjust the differential pressure transmitter.

　　Even if the "balance valve" is fully opened under fluid flow, the zero point cannot be checked as long as the pressure valve on the positive negative pressure pipeline is not closed. Because the balance valve itself has resistance, it cannot completely balance the pressures in the positive and negative pressure chambers, that is, it cannot achieve a "zero differential pressure" state.

　　⑤ When measuring the flow rate of fluids containing suspended solids or dust, a settler or isolator must be configured. Pay attention to how to reasonably select the positions of the inlet, outlet and sewage outlet of the pressure-guiding fluid to achieve the purpose of sewage discharge. To measure dirty fluids, it is recommended to choose a "differential pressure transmitter with a remote transmission capsule".

　　⑥ When measuring the flow rate of corrosive fluid, be sure to select a suitable isolator, select a suitable isolator fluid according to the specific gravity of the medium, and pay attention to the reasonable selection of the isolation fluid and the fluid to be measured.

　　⑦Whether the design parameters of the V-cone flowmeter are consistent with the actual parameters is directly related to the measurement accuracy. When the V-cone flowmeter is put into use, if the measured parameters are within the design parameter range, the measurement accuracy will generally not exceed the design calculation accuracy; but if the measured parameters are far from the design parameter range (assuming orifice plate and differential pressure transmitter If the selection, manufacturing, and installation all meet the requirements), it is possible that the design parameters provided are incorrect. The design parameters should be changed and the throttling device should be redesigned and calculated.

　　⑧ If changes in process conditions during use lead to changes in fluid parameters, automatic tracking and compensation of temperature and pressure should be used, otherwise measurement errors will occur. At present, there are many types of intelligent flow indicators on the market, which can input medium temperature, pressure, medium density under standard conditions, compression coefficient, flow coefficient (outflow coefficient), etc., to ensure accurate measurement of orifice plates.

　　Maintenance of v-cone flowmeter

　　When installed and applied on site, it can adapt to the measurement of a large number of media. The application is relatively simple, the stability is high, and the installation is relatively simple. But for the site, in order to ensure the stability of on-site operation, the V-cone flowmeter maintenance instructions are as follows:

　　1. When put into use, the air must be eliminated from the exhaust valve at the highest point of the signal pipeline.

　　2. Clean the signal pipeline and differential pressure flow meter regularly to remove all debris.

　　3. Before installation, it must undergo metrological verification. Only after confirming that all technical indicators are met, the signal pipeline and differential pressure gauge can be installed in strict accordance with the installation requirements. For different media, we must refer to relevant standards for different installation and identification to achieve a one-to-one correspondence.

　　4. Before putting it into use, the zero position should be checked. When checking the zero position, close the two pressure pilot valves on the instrument valve and open the balancing valve. If zero offset is found, the cause should be identified and adjusted.

　　5. If it is found that the indication value of the differential pressure flow meter is significantly different from the measured value, a comprehensive inspection and repair should be carried out, and the measurement verification should be carried out again.