What is an Instrumentation Manifold and Why Do I Need One?

Instrumentation manifolds are a combination of several valves in one body with multiple connections. This piece of equipment assists pressure instruments directly and indirectly in measuring and equalizing pressures, differential pressures, static, gauge, and variable in process instrumentation lines by bleeding, blocking, and calibrating.

Manifolds offer multiple functions all within one product and are available in many different styles for several applications.

Make-Up of an Instrumentation Manifold

Body Type

Manifolds have two main styles to choose between, the horizontal style manifold and the vertical style manifold. These styles dictate the orientation of the main body of the valve.

Mounting Style

Further more, there are two manifold mounting types that are important for your consideration. The two types are the remote mounting style and direct mounting style. As the name suggests, the direct mount style is where the manifold mounts directly onto pressure instruments. Direct mount valves typically use a combination of flange and threaded connections. Alternatively, remote mounting manifolds allow for installation away from the instruments using threaded connections exclusively.

Number of Valves / Layout

On a single body, manifolds offer a variety of block and isolate valves along with openings that permit connections to pipe by threaded or flanged connections. The number of block and isolate valves depends on the manifold’s operation.

Superlok has 2-way, 3-way, and 5-way manifold configurations available with color-coded functions and pressure ratings up to 6,000 PSI. The color-coding functions are labeled as follows: red for drain, vent, and test, blue for isolate/block, and green for the equalizer valves.

The following information is on the different types of manifold’s construction and is paraphrased from the Instrumentation and Control Qualification Reference Guide.

2-Way Valve Manifold

A typical composition of the 2-way valve manifold is 1 block valve and 1 drain or test valve.

For use on a pressure transmitter to test pressure, the procedure is to close the block valve and open the drain valve. When the drain valve is opened, the next step would be to connect the valve to a pressure generator to test pressure.

The 2-valve manifold is also called a block and bleed valve.

3-Way Valve Manifold

The 3-valve manifolds standard configuration includes 2 block valves and 1 valve, called an equalizer valve, which provides equal pressure on both sides.

Differential pressure transmitters often use 3-way manifolds to operate making them the most commonly used manifold configuration. The method of a 3-valve manifold with a DP transmitter is to close the block valve and open the equalizer valve to check the zero of a DP transmitter.

5-Way Valve Manifold

DP transmitters also use 5-way valve manifolds. The composition of a 5-way valve manifold is similar to a 3-way valve manifold in that it has 2 block valves and 1 equalizer valve. The two valves that make it different are the additional vent or test valves.

The method for calibration of a 5-valve manifold is to close the block valve and open the equalizing valve to check the zero of the transmitter. After equalizing the pressure, system operators connect the test valve of the manifold to a pressure generator for 3 or 5 point calibration.

Because of their advanced 5-valve technology, 5-valve manifolds are more popular for differential pressure transmitters than 3-way valve manifolds.

When to Use a Manifold

Manifolds maintain the flow of a system or line in processing applications.

Instrumentation manifolds are key components when customizing your process line. Other valve types, like needle valves and check valves, with the same threaded connections can easily connect to them. In fact, they’re capable of connecting to two or more valves in a system which makes them go-to products for connecting in confined spaces.

Additionally, pressure instruments traditionally use manifolds where calibration of another piece of equipment is necessary without entertaining a system shutdown. Manifolds are known as isolation/shutoff valves and are used with pressure instruments such as transmitters and differential pressure transmitters.

What is differential pressure and why does it need to be measured?

Differential pressure is the difference between two applied pressures and is “often the basis of other measurements such as flow, level, density, viscosity and even temperature.” It’s important to measure differential pressure because fluctuations can have significant effects and differential pressure readings determine if there’s a potential problem in the process line.

Differential pressure instruments include transmitters, gauges, sensors, and transducers. By far, the Differential Pressure Transmitter is the most common instrument used with manifolds.

A DP transmitter’s function is to “sense the difference in pressure between two ports and produce an output signal with reference to a calibrated pressure range.”

System designers use 3-valve or 5-valve manifolds in conjunction with the DP transmitter to prohibit over-range and to isolate the transmitter from the process line for maintenance and calibration.

Manifolds are most commonly used with DP transmitters because their isolation function allows the transmitter separation from the process instrumentation line helping the system to stay temporarily idle instead of shutdown.

Advantages of an Instrumentation Manifold

Certainly, each mounting style has a unique set of benefits. However, if you decide to use a manifold with your processing system, you’re already ahead of the game! In general, here are several advantages to consider when thinking of using a manifold with your system.

• They’re suitable for confined spaces because of compact size.
• They have a simpler, more compact design which reduces costs and connections.
• There’s a smaller chance of leakage with fewer connections and this aids in decreasing maintenance time/costs.
• Fewer connections improves system layout.

Now we’ll breakdown the unique set of benefits for each mounting style.

The biggest advantage of using a direct mount manifold is the improvement in energy efficiency by shortening the system’s path flows. The manifold’s regulation, directly mounted onto a pressure instrument, helps to reduce pressure drops and heat fluctuations.

Here are a few other benefits to keep in mind when considering a direct mount manifold.

Benefits of the Direct Mount Manifold

• Less expensive installation
• Less expensive maintenance
• Fewer leak points
• System still hard piped
• Integrated valves

As for the remote mount manifolds, because they’re mounted indirectly onto lines instead of instruments, their biggest advantage is that they’re used to protect instruments from temperature beyond their limits by reducing and/or increasing process temperature.

Take a look at more benefits to using a remote mount manifold.

Benefits of the Remote Mount Manifold

• Easier installation
• Easier maintenance
• Fewer leak points
• Uses tubing and tube fittings
• Uses standard instrument manifolds
• The piping is mounted to the transmitter

Choose the right Superlok Manifold for your Process at Mako Products

A manifold is a multi-faceted product that offers several functions and this makes them an essential component for use with pressure instruments. Check out our Superlok options on our Superlok Instrumentation Manifold Valves page or contact our team and we will work with you to find the perfect manifold for your process.

Contact Mako Products

References

Understanding Manifold Valves: Definition, Types and Advantages

‍Beginners Guide to Differential Pressure Transmitters

DP Transmitter Valve Manifolds

Best Practices in Pressure Instrumentation Isolation for Primary Flow

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