What is a valve manifold and where are valve manifolds used?
Valve manifolds are flow management devices of ever-growing interest for operators, maintainers, and design teams worldwide. Even under today’s landscape of ongoing innovations, they continue to be a go-to technical solution for fluid control in systems. When two or more valves are involved, that is.
Since their deployment extends across diverse processes in several industries, it is only fitting to seize the opportunity to offer knowledge on them.
What are valve manifolds? When to use them? What configurations are available?
These are some of the questions to address in this introduction feature. Please, continue reading below to get the details.
What is a valve manifold? How does it work?
Oftentimes comes an industrial application that calls for the setup of various valves in practically the same location. Such a specific requirement obeys a tailored configuration prepared to achieve the desired design and measurement targets.
There are two options to tackle this process demand.
The first one is through the arrangement of a set of individual valves. A proposal that can get the job done, carrying many disadvantages to its credit. For instance, it is pricey to install and maintain. And it requires a large and bulky structure that takes up a lot of space and leaves room for many potential leak paths.
The second possibility is much simpler and overall preferred. It’s the installation of a manifold. A valve manifolds!
A manifold is a system that combines multiple valves into a single unit. A bridge between the instrument and the process. A piping segment where, internally, the valves connect in standard configurations given by a design engineer.
The manifold is carefully assembled to allow the calibration or replacement of measuring instruments in total safety. Without having to shut down the plant! For that reason, there are different configurations available, fit for various applications.
Given how beneficial they are, valve manifolds write individual installations off the table from the get-go.
What are the uses of valve manifolds?
Valve manifolds fulfill critical operational functions, including:
Because of their versatility, manifolds are a common fixture in oil & gas, petrochemical, chemical, power generation, and water and wastewater facilities. Signs are that if you are a fluid control operator for any of those industries, you have encountered a manifold along the way.
What process variables are up for measurement in valve manifolds?
Four major process variables are up for measurement in manifolds. They are:
Each of these variables belong to an applied measuring instrument.
Since pressure is the most monitored variable in manifolds, it’s crucial to state the differences between the two possible reads, gauge pressure and differential pressure.
Gauge pressure is the pressure of a system above atmospheric pressure. The value measured is zero-referenced against ambient air (or atmospheric pressure). The reading ultimately includes the pressure from the weight of the atmosphere.
As the name suggests, differential pressure (DP) is the difference in pressure between two given points. Its value also serves as the basis to estimate other variables, such as flow rate, fluid level, viscosity, density, and temperature. Fluctuations in differential pressure tend to indicate that there’s a potential problem in the process line.
What are the different configurations of valve manifolds?
There are several design configurations available for valve manifolds. Each applies the same principle of incorporating multiple valves into a single body.
The manifold, as meant by design, is built-in with several ports that enable connections to the process, the measuring instrument, or other devices for calibration. The number and types of valves per unit are dependent on the manifold’s functionality. At the moment, there are three types of valve manifolds:
A 2-valve manifold consists of a block valve and a bleed or test valve. And it offers the same functionality as a block and bleed valve.
Operational considerations of a 2-valve manifold
A 3-valve manifold consists of two block valves and an equalizer valve. And is used with differential pressure transmitters to prevent instrument over-range. Also, to allow isolation of the transmitter from the process line during maintenance and calibration.
A 3-valve manifold has at least four ports. Two are connected to the DP transmitter itself. The remaining two ports connect to the process locations to measure the DP.
Operational considerations of a 3-valve manifold
5-valve manifolds are the most commonly used manifolds for differential pressure transmitter applications (measurement).
The 5-valve manifold consists of two block valves and one equalizer valve. Plus, two additional valves for venting or testing.
In addition, a 5-valve manifold provides the ability to block, equalize, and vent two process connections along with the option of calibrating the transmitter without removing it from the setup.
Operational considerations of a 5-valve manifold
What kind of body styles of valve manifolds are available?
Valve manifolds are available in two major body styles: Horizontal body style and vertical body style.
The basic difference between the two is the orientation of the main body of the manifold. But when to pick one over the other? The choice of style depends on the available space and the process layout.
Horizontal body style
Vertical body style
Example of horizontal body style
The main body of the manifold is horizontal with connecting ports on the smaller face.
Example of vertical body style
The main body of the manifold is vertical with connecting ports on the larger face.
What kind of mounting styles of valve manifolds are available?
Valve manifolds can be mounted using two different styles, direct mounting or remote mounting.
The direct mounting style connects the pressure instruments straight to the manifold. To do so, a combination of flange and threaded connections are in use.
There are some highly appreciated benefits to this style. For instance, it improves energy efficiency by shortening system flow paths. The pressure drop reduces and heat loss goes to a minimum. Other advantages are:
In remote mounting, the manifold’s installation is done away from the instruments. The linking is possible thanks to the use of threaded connections only.
There is a plus side to remote mounted valve manifolds:
Typical features of a valve manifold
An extensive line from several manufacturers of valve manifolds for pressure and differential pressure gauges exists in the market. To facilitate the selection process for you, here are some of the desirable features to look for:
Advantages of using a valve manifold
Operators have a lot to gain from valve manifolds. Even more so when comparing them to the arrangement of individual valves. Characteristics like the small space needs and the high reliability throughout the installation, operations, and maintenance phases go a long way. They create staggering qualities hard to ignore. So, let’s summarize them into these advantages for everyone to know:
To wrap up, we want to leave you with a summarized context of what we just shared on valve manifolds. So that you can make a better selection as a designer or operator.
Valve manifolds are devices that bring great flexibility, safety, and reliability to fluid control operations. Their clever design pushes forward the operator’s capabilities in a wide setting of scenarios, making it possible to test, vent, block, or bleed process lines without shut down.
But that’s not it!
They also simplify core aspects of process variable measurement, enhancing the gathering of pressure (gauge and differential), flow rate, level, and temperature data. All that while reducing to a minimum the chances of fluid leakage along the path.
Their high functionality is due to the specificity of the different models available:
✓ 2-valve manifold
✓ 3-valve manifold
✓ 5-valve manifold
✓ Horizontal body style
✓ Vertical body style
✓ Direct mounting
✓ Remote mounting
Each one provides features suitable to industry applications in oil and gas, petrochemical, energy generation, and more.
Any setup selected to work with is easy to install, operate, and maintain. The efficient performance, compact size, and affordability metrics succumb the bulky individual valve-by-valve arrangement as a second-best option within this field.
For all these reasons, and probably more, valve manifolds are the preferred option to handle the tough dynamic of a system with two or more valves in the same spot.