The difference of Differential pressure transmitter 3 valve manifold & 5 valve manifold
Two valve group: it is a shut-off valve (switch or conduction), which is generally used for pressure transmitters. It connects the process pressure with the pressure guide port of the transmitter, where A is connected to the process conduit, and B is connected to the pressure changer. The pressure guide port of the feeder, C is used for blowdown or purging, and D is the check port.
Three-valve group: It is 2 globe valves plus a balance valve in the middle (also a globe valve), and the 2 globe valves are the globe valves on the high pressure side and the low pressure side (open, the pressure on the high pressure side or the low pressure side is transmitted. past), if the balance valve is opened, the high-pressure side and the low-pressure side are connected, usually with the differential pressure transmitter to connect the pressure guide pipe.
The integrated three-valve manifold is more compact and easier to install than the separate three-valve. The inlet A of the three-valve group is directly connected to the terminal joint. The impulse conduit is welded to the nozzle of the terminal joint. Outlet B is fixed to the pilot pressure port of the transmitter with 4 screws and washers. The two outlets B of the three-valve group, that is, the distance between the two pressure guiding ports of the transmitter, are generally 54mm.
When the high and low pressure valves of the three-valve group are closed and the balance valve is opened, the pressures of the high and low pressure measurement chambers of the transmitter are balanced, and the differential pressure is 0. When the high and low pressure valves are opened at the same time, and the balance valve is closed, the pressures at the two output ends are the high pressure and low pressure of the throttling device respectively; when the balance valve is opened, one valve of the high and low pressure valves is closed, and the other valve is open, then the pressures at the two output ends are equal. high or low pressure.
There are also two pressure check ports D on some three-valve groups, which are blocked with plugs during normal operation. When calibrating, first cut off the high and low pressure valve and balance valve, and then pass the calibrated pressure from the test port, so that the transmitter can be calibrated without disassembling other joints.
⑵ five valve group. The five-valve group is based on the three-valve group with the addition of two blowdown valves 3 (empty). Its working principle is shown in Figure 7-12(b). During normal operation, close the two sets of blowdown valves and balance valves; when the instrument is at zero position, cut off the high and low pressure valves and open the balance valve. Some five-valve groups also have two pressure calibration ports D. To calibrate the instrument, just open the test port and connect the calibrated pressure. Therefore, inspection, verification, sewage discharge and flushing can be carried out on these five valve groups, which is more flexible and much easier to install.
During normal operation, close the two sets of blowdown valves and balance valves; when the instrument is at zero position, cut off the high and low pressure valves and open the balance valve. Some five-valve groups also have two pressure calibration ports D. To calibrate the instrument, just open the test port and connect the calibrated pressure. Therefore, inspection, verification, sewage discharge and flushing can be carried out on these five valve groups, which is more flexible and much easier to install.
