Using the 3-valve manifold
In normal operation the "isolate" valves are open while the "equalize" valve is closed.
This provides a differential pressure reading to the pressure gauge or transmitter. To zero the instrument, first close the downstream "isolate" valve then open the "equalize" valve and adjust the zero setting on the instrument.

Note: The body & trim parts on all 316/316L Valves & Manifolds comply to NACE MR-01-75 & NORSOK M-650 as standard.