Selecting the Right Manifold Valves for Your Pressure Gauge

Pressure instruments operate in demanding environments where process pressure, extreme temperature, vibration, and maintenance activities can all compromise accuracy and instrument life. Without proper isolation, routine tasks such as calibration or replacement can expose instruments to damage, create safety risks, and increase unplanned downtime.

Pressure instruments often need to remain online while maintenance, calibration, or replacement is performed. Without the ability to properly isolate, vent, or equalize pressure, these routine activities can put instruments and personnel at risk. Manifold valves, or gauge valves, are designed to control how process pressure reaches the instrument, enabling safer operation and easier maintenance.  

Read this article to learn how different manifold valve configurations work, how they protect pressure and differential pressure instruments, and how to choose the right option for your application.

What Are the Common Manifold Valve Configurations?

Manifold valves are available in 1‑, 2‑, 3‑, and 5‑valve configurations, each offering a different level of control depending on the type of pressure instrument and the application. All configurations function as shut‑off devices, allowing the attached instrument to be removed or serviced without losing process media.

1‑Valve Manifolds (also known as gauge valves): Block or isolate a pressure instrument

A 1‑valve manifold provides simple isolation between the process and a pressure instrument. It is designed as a single block with male or female screwed inlet and outlet ports to isolate pressure instrumentation from the process media.

Features:

• Identified by a blue handle

• Commonly supplied in 316 stainless steel with PTFE valve packing

• Optional materials include Hastelloy® C and Monel®

• Graphite packing is available for higher‑temperature applications

Figure 1. 1‑Valve Manifold 

2‑Valve Manifolds: Block and bleed for safer pressure instrument maintenance

A 2‑valve manifold adds a bleed (vent) valve to the isolation function, allowing trapped pressure to be safely released before the instrument is removed. This configuration improves safety by ensuring pressure is fully vented prior to maintenance.

Features:

• One block valve (blue handle)

• One bleed valve (red handle)

• Available in in‑line, L‑shaped, and Y‑shaped configurations

• Optional materials include Hastelloy® C and Monel®

• Graphite packing is available for higher‑temperature applications

Figure 2. 2‑Valve Manifold 

3‑Valve Manifolds: Isolation and equalization for differential pressure instruments

A 3‑valve manifold is designed for differential pressure instrumentation, where protecting the instrument from pressure imbalance is critical. 

During normal operation, the block valves are open, and the equalizing valve is closed. This setup allows pressures to be equalized safely during startup, shutdown, and calibration.

Features

• Two block valves (blue handles), one on the high‑pressure side and one on the low‑pressure side
• One equalizing valve (green handle) positioned between the high‑ and low‑pressure connections

Figure 3. 3‑Valve Manifold

5‑Valve Manifolds: Full control for differential pressure applications

A 5‑valve manifold provides the highest level of control for differential pressure applications.

It combines isolation, controlled venting and pressure equalization to support safer maintenance, calibration and instrument startup or shutdown procedures.

Features

• Two block valves (blue handles)

• Two bleed valves (red handles) to vent trapped pressure to a safe location

• One equalizing valve (green handle)

Figure 4. 5‑Valve Manifold 

Which manifold valve is right for a differential pressure instrument?

When selecting a manifold valve for a differential pressure instrument, the number of valves is only part of the decision. Mounting style, port spacing, and connection compatibility are critical to ensuring proper installation and reliable performance.

Ashcroft offers 3‑ and 5‑valve manifolds in multiple styles designed for either direct mounting or remote (indirect) mounting, depending on the application and instrument requirements. Not every manifold is designed for direct attachment to a differential pressure gauge, even when port distances appear similar. (See Figure 5 below.)

• V01 type in a 3- and 5-valve are for remote mounting only.

• V02 type in a 3- and 5-valve are available for both direct and remote mounting.

• V03 type in a 3- and 5-valve are available for direct mounting of differential gauge models 1132 and 1133 only.

Figure 5. Valve manifold attachments

For direct mounting, the instrument port distance on the manifold and the differential pressure gauge must line up. Additionally, the shape or style of the manifold is critical for direct mounting.

Ashcroft provides the V01, V02 and V03 series manifolds in configurations designed for either direct mounting or remote mounting.

Direct mounting differential pressure gauges

Direct mounting creates a compact assembly by attaching the differential pressure gauge directly to the manifold, eliminating the need for capillaries or piping. This approach can reduce potential leak points and simplify installation, but it requires precise compatibility between the gauge and the manifold.

Refer to Figure 5, which outlines differential pressure gauges and the manifold mounting options available. Standard process connections are ½ NPT female, with ¼ NPT female connections available for all manifolds.

Pressure gauges approved for direct mounting

Currently, the following Ashcroft® differential pressure gauges are approved for direct mounting to a 3‑ or 5‑valve manifold:

• 1132 Differential Pressure Gauge

• 1133 Differential Pressure Gauge

• F5504 Differential Pressure Gauge
• 5503 Differential Pressure Gauge

In all cases, the gauge must have the proper connection size and location as shown in Figure 6 below. Only lower connection locations are available for direct mounting.

Required connection codes

To ensure proper alignment and sealing, the following connection codes are required:

• F5504: DM connection code when mounting to a 3‑ or 5‑valve V02 type manifold

• 5503: 51L connection code

• 1132 and 1133: 25L connection code

These connection codes are mandatory for direct mounting and must be specified at the time of order.

Port spacing and manifold compatibility

Specific manifold models are designed to match the port spacing of approved gauges:

• 54 mm port spacing (F5504 and 5503):

  • 50V023VASS60

  • 50V025VASS60

These manifolds are supplied with four mounting bolts and two Teflon O‑rings per connection port.

• 62.1 mm port spacing (1132 and 1133):

  • 50V033VBSS86

  • 50V035VBSS86

These manifolds include the ‘86’ instrument connection code, which provides a ¼ male NPT swivel adapter for proper connection to the ¼ female NPT (25L) gauge connection.

Indirect (Remote) mounting options

When direct mounting is not possible, indirect mounting allows a pressure instrument to be connected to the manifold using flexible or rigid piping. Ashcroft typically uses flexible capillary lines with swivel adapters to complete these assemblies.

Indirect mounting guidelines

• V01 series manifolds are designed for remote mounting only

• V02 and V03 series manifolds may be direct or indirect mounted

• Indirect mounting assemblies require:

  • Two 1115 capillary lines

  • Two MDV swivel adapters

The ‘XA9’ connection code is used to allow Ashcroft to properly assemble the required components. This code must be specified when indirect mounting is required for any differential pressure gauge or differential pressure switch.

Figure 6. Indirect mounting example

Note: Figure 2 illustrates an 1132 gauge with side connections (not available for direct mounting) connected to capillary lines and swivel adapters, which are then attached to the manifold.

Liquid filling of the assembly is not required. For proper coding and pricing of all components, consultation with an Ashcroft expert is recommended.

Connect with us to learn more

Now that you understand which manifold valves are used with different types of pressure instrumentation, you can identify the solution best suited to your application. If you still have questions, contact us to speak to a product expert or check out some of the related resources below.

In the meantime, download our assembly guide for help selecting the right instrument assembly.