2.1. ISOLATING VALVES
Manifold
The manifold is quite simply an assembly of isolating valves on a same block. Its main job is to isolate a pressure transmitter so that its zero can be calibrated.
2-way manifolds
The 2-way manifold is used for “conventional” pressure transmitters. It has a transmitter
HP isolating valve and a drain valve. This type of manifold is very rarely used.
3- and 5-way manifolds
The 3- and 5-way manifolds are much used in the instrumentation field, they connect
directly to the differential pressure transmitters. The 3-way manifold combines the isolating and bypass functions.
Using two valves (right and left), we isolate the HP and the LP sides of the transmitter, and
we balance the two chambers (HP and LP) using the bypass valve (middle): this facilitates
the transmitter zero check when the two measurement chambers are well balanced.
The 5-way manifold 5 is identical to the 3-way manifold except that we have added two
drain valves. These allow each of the transmitter’s measurement chambers to be drained.
The manifold and its associated transmitter
In this example, the manifold is mounted directly on the transmitter by
means of screws supplied with the manifold.
3-way manifold associated with a transmitter
