Orifice plate flowmeter installation:
Pressure sensing hole - through the induction tube (also known as the pulse tube) to connect the orifice plate upstream and downstream pressure and differential pressure transmitter. The most commonly used pressure sensing hole locations are:
From the flange (or orifice plate) take pressure. This is the most common way to take pressure, but take special care when the pressure port is at the bottom of the pipe, as there may be clogging at the bottom. Orifice 1 times before the diameter, after 0.5 times the diameter of pressure. This method is relatively difficult, but more accurate, because the maximum differential pressure in the fluid at the contraction section, that is 0.5 times the diameter. Corner take pressure - in the smaller diameter of the orifice plate is usually used this method. Because of space constraints, it is difficult to process pressure holes on the flange. Angle to take pressure method is generally used for pipe diameter is less than or equal to DN50 the occasion. The signals generated by the differential pressure transmitter can be output to the flow indicator or input to the flow computer along with the temperature and pressure signals to compensate for the density of the fluid. Piping - The minimum straight pipe downstream of the orifice plate is required to be 5 times the pipe diameter to reduce the variation in the velocity distribution due to the pipe effect