Installation and Maintenance Instructions for Orifice Flow Meters

Abstract: The installation and maintenance instructions of the orifice flow meter are provided by the excellent flow meter and flow meter manufacturers. Instructions for installation and use of standard orifice plate 1. Principle and structure: When fluids filled with pipelines flow through the standard orifice plate in the pipeline, the flow rate will form a local contraction at the throttling of the standard orifice plate, thereby increasing the flow rate and decreasing the static pressure , so in a standard orifice plate. More flowmeter manufacturers choose models and price quotations. You are welcome to inquire. The following is the details of the installation and maintenance instructions of the orifice flowmeter. Installation and use instructions of standard orifice plate 1. Principle and structure: When fluids filled with pipelines flow through the standard orifice plate in the pipeline, the flow rate will form a local contraction at the throttling of the standard orifice plate, thereby increasing the flow rate and reducing the static pressure , so there is a pressure drop or pressure difference before and after the standard orifice. The greater the flow rate of the medium flow, the greater the pressure difference generated before and after the standard orifice, so the fluid flow can be measured by measuring the pressure difference. . This measurement method is based on the law of conservation of energy and the law of flow continuity. 2. Installation 2.1 Basic requirements: 2.1.1 For the newly installed pipeline system, the standard orifice plate must be installed after line sweeping to prevent debris in the pipe from clogging or damaging the standard orifice plate. 2.1.2 Before installation, carefully check whether the number, position number, and specification of the standard orifice plate are consistent with the pipeline conditions, flow range and other parameters. Marked near the pressure tap“+”One end should be connected to the fluid upstream section, marked with“—”One end should be connected to the downstream pipe section of the fluid. 2.1.3 The centerline of the standard orifice plate shall be coaxial with the centerline of the pipe. 2.2 Requirements for pipelines: 2.2.1 The throttling piece (standard orifice plate) should be equipped with a section of measuring pipe, at least the same diameter straight pipe section of the first 10DN and the rear 5DN should be maintained to improve the measurement accuracy. 2.2.2 If a valve needs to be installed before and after the throttling part, it is best to choose a gate valve and fully open it during operation; the regulating valve should be in the pipeline after 5DN downstream. 3. Requirements for the differential pressure lead-out pipeline: 3.1 The inner diameter of the pressure-inducing pipeline is related to the length of the pipeline and the degree of contamination of the medium. Usually, a pipe with an inner diameter of 8-12mm is used within 45 meters. 3.2 When measuring the liquid flow, the horizontal section of the impulse pipe should be in the same horizontal plane. If the throttling piece is installed on the vertical pipeline, the short pressure pipes are separated by a certain distance (the direction of the vertical line), which will affect the zero point of the differential pressure transmitter and should be passed through.“Zero migration”to correct. 3.3 The pressure pipe should be supported by a firm bracket. The two pressure pipes should be as close to each other as possible and away from the heat source or vibration source. When measuring the flow of water vapor, they should be wrapped with thermal insulation materials. The following) add heat tracing pipes to prevent icing. When measuring dirty flow, an isolator or settler should be attached. 3.4 The single-phase fluid state must always be maintained in the impulse piping. When the measured fluid is gas, all the pressure piping (including the pressure chamber of the differential pressure gauge) is gas phase; when the measured fluid is liquid, all the pressure piping is liquid, and there must be no air bubbles. For this reason, a drain valve should be installed at the lowest point of the pressure-inducing pipeline or an exhaust valve should be installed at the highest point, and special attention should be paid when the differential pressure instrument is newly installed or repaired. 4. Use and maintenance 4.1 Precautions for use 4.1.1 A new meter or a standard orifice plate that is reactivated after being out of use for a period of time should check whether the pressure-inducing pipeline is blocked or leaked before putting it into use. The road is filled with clean water or other pressure guiding liquid, pay attention to the gas mixed in the discharge pipeline, and pay attention to the accumulation of liquid in the discharge pipeline for the gas medium. 4.1.2 Open before putting into operation“Three valve block”The balance valve in the middle, close the valve on the positive and negative pressure pipeline, check and correct the zero point of the differential pressure transmitter, be sure to pay attention“zero”It is to check and adjust the differential pressure transmitter when the positive and negative pressure chambers are completely equal pressure (that is, the differential pressure is equal to 0). 4.1.3 Even fully open when the fluid is flowing“Balance valve”, as long as the pressure-taking valve on the positive and negative pressure-taking pipeline is not closed, the zero point cannot be checked. Because the balance valve itself has resistance, it cannot completely balance the pressure of the positive and negative pressure chambers, that is, it cannot reach the“zero differential pressure”state. 4.1.4 When measuring the flow of dirty fluid, be sure to configure a settler or isolator. Pay attention to how to reasonably select the position of the inlet, outlet and sewage outlet of the pressure guiding fluid to achieve the purpose of sewage discharge. 4.1.5 When measuring the flow rate of corrosive fluid, it is necessary to select a suitable isolator, select a suitable isolation liquid according to the specific gravity of the medium, and pay attention to the reasonable selection of the isolation liquid and the inlet of the fluid to be measured. 4.1.6 Whether the design parameters of the standard orifice plate are consistent with the actual parameters is directly related to the measurement accuracy. When the standard orifice plate is put into use, if the measured parameters are within the range of the design parameters, the measurement accuracy will generally not exceed the design calculation accuracy; but if the measured parameters are far from the design parameter range (assuming the standard orifice plate and the differential pressure transmitter) Selection, manufacture, and installation all meet the requirements), it may be that the provided design parameters are wrong, and the design parameters should be changed, and the standard orifice plate should be redesigned and calculated. 4.2 Maintenance precautions: 4.2.1 The daily maintenance work is mainly to remove the scale in the settler or isolator, and regularly discharge it from the sewage outlet. When the measured medium is high temperature and high pressure corrosive or toxic fluid, pay attention to safety when removing it. . 4.2.2 The zero point of the differential pressure transmitter sometimes drifts, which affects the measurement accuracy (especially when the flow rate is small and the differential pressure is close to the lower limit value). The zero point should be checked frequently. A good quality differential pressure transmitter can extend the zero calibration cycle to 1 year according to experience, while a poor quality differential pressure transmitter may calibrate the zero point every few days, so we recommend using a good quality differential pressure transmitter to reduce the workload of daily maintenance . The above is the whole content of this article. You are welcome to inquire about the flowmeter selection and quotation of our factory. 'Installation and Maintenance Instructions for Orifice Flow Meters'

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