Three steps for identifying and solving common pressure regulator issues

A three-step process can help operators recognize regulator problems and provide solutions before they affect the entire system

By Shaji Arumpanayil July 13, 2022
Courtesy: Swagelok

It is important for industrial fluid systems to have precise temperature, flow, and pressure settings to operate properly. Pressure regulators (or pressure-reducing valves), among other key components, are central to ensuring those settings remain constant. The question for operators is this: What happens if a pressure regulator malfunctions or stops working altogether?

The key is to identify a failing pressure regulator before it becomes a bigger problem. Operators should monitor the system and pay close attention to unexpected drops or increases in pressure downstream, which can be indicative of a failing regulator that may compromise the quality and safety of the process.

While there can be many explanations for significant changes in pressure in industrial fluid systems, there are also common issues that, if recognized early enough, can be corrected before significant damage is done to the system. A three-step process can help troubleshoot these potential issues and help operators prevent regulator failure.

Step 1: Understand specific process needs

Before operators can perform any regulator assessment, they should identify what process requirements are involved such as system flow, pressure, temperature, process sensitivity and system media. This evaluation will provide the necessary insights into whether the regulator in question is suited for the specific application.

For example, pressure-reducing regulators control pressure from a source before it arrives at the main process. A pressure-reducing regulator’s main purpose is to maintain a steady downstream pressure in a fluid system application.

A pressure-reducing regulator’s main purpose is to maintain steady downstream pressure in a fluid system application. Courtesy: Swagelok

A pressure-reducing regulator’s main purpose is to maintain steady downstream pressure in a fluid system application. Courtesy: Swagelok

In contrast, back-pressure regulators control pressure upstream.

Use a pressure-reducing regulator to control pressure from a source before it arrives at the main process and a back-pressure regulator if you need to control pressure from upstream. Courtesy: Swagelok

Use a pressure-reducing regulator to control pressure from a source before it arrives at the main process and a back-pressure regulator if you need to control pressure from upstream. Courtesy: Swagelok

Installing a back-pressure regulator when a pressure-reducing regulator is needed, or vice versa, can lead to unnecessary pressure fluctuations that can compromise the entire process and result in downtime and maintenance expenses.

It is not easy to decide whether the proper regulator is installed for specific applications. Working with external advisors can help bring this distinct expertise to selecting the correct regulator.

Step 2: Determine the issue

Once the proper regulator has been identified and installed, it is time to accurately determine the nature of the issue. Is pressure rising beyond the set pressure upstream, or is it dropping below the set pressure downstream?

Determining the nature of the problem provides vital context to identify a solution. There are two issues that are likely to be happening if the pressure is rising beyond the set pressure: Creep or supply pressure effect (SPE).

If pressure is rising beyond your set pressure, either creep or the supply pressure effect (SPE) is likely at play. If pressure is dropping beyond your set pressure, the regulator is most likely undersized for the application. Courtesy: Swagelok

If pressure is rising beyond your set pressure, either creep or the supply pressure effect (SPE) is likely at play. If pressure is dropping beyond your set pressure, the regulator is most likely undersized for the application. Courtesy: Swagelok

Creep occurs immediately after regulator installation when debris flows through the system. The contaminants create a fine gap between the regulator’s seat and poppet, which can inadvertently cause system media to flow across the seat. The result is unwanted pressure increases downstream, which can be dangerous if the downstream components are not rated to handle the higher pressures. Fortunately, creep can be avoided with careful installation, upstream filtration, and the purchase of a spares kit with new regulators.

SPE can be identified when a change in outlet pressure occurs because of a change in the inlet (or supply) pressure. If the inlet pressure drops, outlet pressure can increase beyond what downstream components are expected to handle. If SPE might be affecting set pressures, it is time to move on to the next step in the process.

A particulate stuck in the regulator’s seat may allow pressure and flow to escape – or creep – across the regulator’s seat when it should otherwise be closed, resulting in an unwanted downstream pressure rise. Courtesy: Swagelok

A particulate stuck in the regulator’s seat may allow pressure and flow to escape – or creep – across the regulator’s seat when it should otherwise be closed, resulting in an unwanted downstream pressure rise. Courtesy: Swagelok

In contrast, if the pressure is dropping, it is likely because the regulator is undersized for the application’s flow requirements. For example, if the regulator set pressure is set at 70 psi and flow increases without changing the regulator, the pressure will likely fall below the 70-psi target. The common term for this pressure drop is droop. Using a flow curve generator tool, which the regulator supplier should be able to provide, will help operators determine if the regulator is properly sized for the application.

At this point in the process, it is likely the problem with the regulator has been identified and operators can move on to Step 3 — but there are situations where a more complex issue may be occurring that requires more investigation. Advisors from leading regulator suppliers can provide technical support to dig deeper into the issue and suggest potential solutions.

For example, advisors may discover the regulator’s diaphragm is distorted or cracked.

A diaphragm may become distorted due to excessive downstream pressure. and no longer contact the poppet, so no flow can move through the regulator. Courtesy: Swagelok

A diaphragm may become distorted due to excessive downstream pressure. and no longer contact the poppet, so no flow can move through the regulator. Courtesy: Swagelok

A cracked diaphragm will have reduced sensing – and therefore pressure control – capabilities. Courtesy: Swagelok

A cracked diaphragm will have reduced sensing – and therefore pressure control – capabilities. Courtesy: Swagelok

Excessive downstream pressure can cause a diaphragm to distort, particularly around its rim where the spring cap and body hold it in place. The distorted diaphragm may no longer contact the poppet and therefore not be able to actuate it, resulting in no flow moving through the regulator. Chemical attack or cycle fatigue from pulsations may cause a diaphragm to crack and/or form a hole, which will compromise its pressure-control capabilities. Knowledgeable suppliers will know if a diaphragm needs to be replaced as well as how to mitigate the underlying issues that caused the damage in the first place.

Step 3: Explore alternatives

Once the user has a better understanding of the nature of the problem, it is time to explore how to prevent unnecessary downtime and system damage. Not all regulators are equipped to solve the problem if it’s SPE so it is important to choose components wisely. For example, a regulator that incorporates a balanced poppet design can help minimize the area on which the inlet pressure can have an effect.

A two-stage pressure-reduction regulator also can lower the possibility SPE will occur. This can be accomplished by installing either two single-stage regulators in series or combining the regulators into a single assembly.

It is critical to choose a regulator with a larger flow coefficient, which will lower the chances of unwanted outlet pressure drops. The regulator supplier should be able work with operators to determine which regulator size is necessary for the application. It may also make sense to shift from a spring-loaded regulator to a dome-loaded regulator because dome-loaded regulators are more resistant to changes in flow. As a result, they can help better maintain set pressures in situations in which flow variations are common.

Work with suppliers to find successful regulators

The above issues are just a few of the most common causes of poor regulator performance, but there may be additional factors unique to a specific application that can adversely influence outcomes as well. Even a clogged filter may be the culprit, with a simple cleaning or replacement being all that is needed to get a system back to running properly.

Cleaning or replacing a clogged filter may be a simple fix to restore diminished pressure. Courtesy: Swagelok

Cleaning or replacing a clogged filter may be a simple fix to restore diminished pressure. Courtesy: Swagelok

Understand what the process needs are, determine the cause of the specific issue and explore possible alternatives to solve the problem. Qualified regulator suppliers should be able to help guide operators toward making the right selection suited for an application’s needs.


Author Bio: Product Manager, Swagelok