Differential pressure transmitters are used in level measurement and flow measurement. For ensuring the protection of pressure transmitter or for isolating the transmitter from the process loop, manifolds are used.
A three-valve manifold system consists of an equalising valve and two blocking valves. One blocking valve at the high-pressure side other at the low-pressure side. The two block valves are opened and the equalizing valve is closed during normal operation.
When the transmitter is removed from the system, the manifold must be operated such that the high pressure is never applied to the single side of the transmitter.