Question

List the operating procedure to put the differential pressure transmitter into service and put it out of service with suitable diagram.   

Answer 1

Answer:

Valve manifold is a very important accesory for any diffrential pressure transmitter. Most of the diffrential pressure transmitter either comes with 3 valve manifold or comes with 5 valve manifold and it is also available with single block and bleed valve manifold . We will discuss the diffrential pressure transmitter putting in service and putting out of service one by one.

3 valve manifold differential pressure transmitter:

Isolation and equilization of pressure from the process to the transmitter for the maintenance and calibration pupose is done by the manual valves. High and low pressure block valves are also available in this system.

DPT shown in figure is diffrential pressure transmitter

Procedure of putting 3 valve manifold diffrential pressure transmitter in to service:

• Equalizing valve should be closed and all high pressure and low pressure valve to be chacked
• After that equalizing valve should be opened. By this same pressure is applied at the both sides of the transmitter and it creates zero diffrential pressure
• After this high pressure block to be opened very slowly and checking to be done for leakage from both high and low pressure side of the transmitter
• After this equalizing valve is closed. This is used to lock the pressure at both sides of transmitter
• After this low process block valve is made open so that the process pressure is applied at low pressure side of the transmitter and it leads to create the working diffrential pressure.
• After doing all thiese steps, transmitter will come under serice or operation.

Removing the 3 valve manifold diffrential pressure transmitter from the service:

• Very first, low pressure block valve need to be closed.
• After this equalizing valve is made open
• High pressure block valve is closed.
• Transmitter is out of sevice after this but still pressure will be inside that should be bleeded

5 valve manifold differential pressure transmitter:

Procedure of putting 5 valve manifold diffrential pressure transmitter in to service:

• Bleeding valve and Equalizing valve should be closed and all high pressure and low pressure valve to be chacked
• After that equalizing valve should be opened. By this same pressure is applied at the both sides of the transmitter and it creates zero diffrential pressure.
• After this high pressure block to be opened very slowly and checking to be done for leakage from both high and low pressure sides of the transmitter
• After this equalizing valve is closed. This is used to lock the pressure at both sides of transmitter
• After this low process block valve is made open so that the process pressure is applied at low pressure side of the transmitter and it leads to create the working diffrential pressure.
• After doing all thiese steps, transmitter will come under serice or operation.

Removing the 5 valve manifold diffrential pressure transmitter from the service:

• Very first, low pressure block valve need to be closed.
• After this equalizing valve is made open
• Opening of the beeding valve for venting process pressure in to the atmosphere
• Transmitter is out of sevice after this but still pressure will be inside that should be bleeded

Sinlgle block and bleed valve manifold:

This is used for guage pressure applications. In this process, the low pressure port of the tranmitter is always vented to the atmosphere. Impulse lines are used to connect the high pressure port to the process medium For putting it in service one should ensure that initially both bleed and block valves are in closed condition and than block valve is slowly opened for taking the unit in to service

Removing single block and bleed valve manifold diffrential pressure transmitter from the service:

It is very easy to remove it from servive and it is done by just closing the block valve and opening of the bleed valve for venting the process pressure to the atmosphere.