Feedwater pump recirculation multi - stage throttle device installation standard

Throttle device is used to measure the flow, its working principle is as follows: in the pipeline with a cross-section changes in the orifice or nozzle and other throttle, when the fluid flow through the throttle due to shrinkage, Resulting in static pressure difference, the use of pressure and the relationship between the flow rate can be further measured flow. For non-calibrated throttle devices, as long as it is geometrically similar and kinetic to the throttle device that has been fully experimentally calibrated, the static pressure difference between the front and rear of the throttle can be considered under the known parameters There is a definite numerical relationship between the flow of the fluid flowing through the fluid. So you can measure the flow through the pressure difference.
   The correctness and reliability of the flowmeter installation is important for ensuring that the differential pressure signal output from the throttle device is accurately transmitted to the differential or differential pressure transmitter. Therefore, the installation of the flowmeter must meet the requirements.
Feed water pumps recirculation multi-stage throttle device installation requirements:
        1) When installing, it is necessary to ensure that the openings and pipes of the throttle are concentric and the end of the throttling device is perpendicular to the axis of the pipe. In the upstream and downstream of the throttle, must be equipped with a certain length of straight pipe.
        2) the pressure tube as far as possible by the shortest distance laying in the 3 ~ 50m. In order not to accumulate gas and moisture in this pipe, the pressure pipe should be installed vertically. Horizontal installation, the slope should not be less than 1:10, the pressure tube for the diameter of 10-12mm copper, aluminum or copper.
        3) When measuring liquid flow, the differential pressure gauge should be installed below the throttling device. If it must be installed at the top. Install the valve with the valve at the highest point of the connecting line and install the settler with the valve at the lowest point to drain the gas and sediment in the pilot pipe.
        4) to measure the gas flow, it is best to install the differential pressure gauge higher than the device. If it is necessary to install it below, install the settler at the lowest point of the connection duct to remove condensate and dirt.
        5) When measuring the flow of viscous, corrosive or flammable fluids, install the isolator. The purpose of the isolator is to protect the differential pressure gauge from corrosion and contamination of the fluid under test. The isolator is two identical metal containers, the inside of the container is filled with liquid that is chemically stable and does not interact and melt with the measured flow. The differential pressure gauge is filled with the isolation fluid.
        6) When measuring the steam flow, the relative configuration between the differential and throttle devices is the same as the measured flow rate. To ensure that the condensate in the two pilot tubes is on the same level, install the condenser near the throttling device. The condenser is designed so that the differential pressure gauge is not affected by high temperature fluid above 70 ° C and the condensate of the steam can be on the same level to ensure measurement accuracy.More about farm irrigation pumps
        There are many forms of throttle, perforated plate, nozzle, venturi tube, quarter arc plate, eccentric orifice and round plate. Some can even use pipelines on the components such as elbows generated by the pressure difference to measure the flow, but because it produces a smaller pressure difference, the impact of many factors, it is difficult to measure accurately. The most widely used is the standard throttle device for orifice, nozzle and venturi.
        The standard throttle device is composed of the first resistance element, the second resistance element, the downstream first resistance element and the straight pipe section between them. The standard throttle device also specifies the type of fluid to which it is adapted, the fluid flow conditions, and the requirements for pipe conditions, installation conditions, and fluid parameters.