Pressure Measurement.    

We also need to measure Pressure in any line to get a constant flow. But how will we measure?   Recently I have discussed about flow measurement of instrumentation in various industries. Here I want to discuss about pressure measurement. The pressure may be gas or water or air in the line or in a vessel or drum.

1. One  pressure Transmitter

2. One Digital Indicator

3. One power supply unit (24V )

4. Two coiled wire (as per requirement)

5. Mild steel ½” impulse line ( as per requirement)

First look carefully here one line is connected with the line and the other side of transmitter kept open to atmosphere. It is done as the pressure differential is created on the respect of atmospheric pressure. The pressure is normally denoted by mmwc(millimeter water column).

Thus differential pressure is created and the transmitter responds. Suppose differential range is 0-100 mmwc and the Transmitter range is 4-20 mA, then

In 0 pressures the transmitter will give an output 4 mA i.e. now no pressure in line.

Similarly In 100 mmwc pressure the transmitter will give 20mA i.e. maximum pressure and maximum output. This current will vary according to pressure of that line. We can receive the output in voltage also. This output goes to a digital indicator which shows the visual reading.

The pressure measurement is an important parameter in calculating Raft calculation in heavy industries. we should also maintain the pressure to get a constant flow in line.

We should keep in mind also that no leakage should be in impulse line to get the accuracy in pressure measurement. The impulse line is a closed line so may be some dirt may fill the line. So we should purge the lines in a time interval. we should also calibrate the instruments timely.

This is an electronics measurement but one simple system also we can do. We can use a simple gauge to measure any pressure as shown in picture.