Technical explainer
Instrumentation Manifold Types and Functions
An instrumentation manifold combines valves in one compact body to isolate, equalize, vent or drain a pressure instrument. The number of valves does not by itself define the correct choice; the instrument, hook-up drawing and operating procedure determine the required arrangement.
By SNG Services · Updated 1 Oct 2026
Core manifold functions
Isolation valves separate the instrument from the process. Equalizing valves connect pressure paths when the procedure calls for balanced pressure, while vent or drain paths provide controlled access for commissioning, calibration or maintenance. Operators must follow the approved sequence for the installation.
Common two, three and five valve arrangements
Two-valve manifolds are commonly associated with isolation plus venting for a single pressure instrument. Three-valve manifolds commonly provide two isolation paths and one equalizing path for differential pressure service. Five-valve arrangements add venting or test access. Exact porting should always be checked on the drawing.
- Two-valve arrangements for isolation and vent functions
- Three-valve arrangements for differential pressure isolation and equalizing
- Five-valve arrangements where additional vent or test paths are required
- Application-specific layouts that may not follow a generic pattern
Direct-mount and remote-mount manifolds
A direct-mount manifold connects closely to the instrument and must match its interface and dimensions. A remote-mount manifold connects through impulse lines and needs suitable process and instrument ports. Access, support, vibration and maintenance space influence the layout.
Information needed before selection
Confirm the instrument type, process and instrument connections, material, pressure and temperature conditions, mounting style, vent or drain destination, flow schematic and quantity. Replacement enquiries should include dimensions and clear photos as well as the existing tag reference.
Next: prepare the RFQ
How to Select 2-, 3- and 5-Valve Instrumentation Manifolds
How to select 2 valve, 3 valve, 4 valve and 5 valve manifolds for gauges, transmitters and differential pressure instruments.
Read the buyer guideFrequently asked questions
What does an instrumentation manifold do?
It groups the valve functions needed to isolate and service a pressure instrument, with equalizing, venting or draining added where the hook-up requires them.
Does a five-valve manifold always suit a differential pressure transmitter?
Not automatically. The port arrangement, mounting interface, connections and operating procedure must match the transmitter and approved hook-up.
Can valve count alone identify a replacement manifold?
No. Valve count is only one input. Porting, dimensions, connection standards, pressure rating, material and mounting arrangement must also match.