Identifying and Fixing Problems in Pressure Regulators

This simple three-step program can help to ensure regulators are working as promised and keep industrial fluid systems running at peak performance.

By Shaji Arumpanayil, Product Manager, Swagelok Company

In a typical industrial fluid system, it is crucial that fluid temperatures, flow, and pressure settings be finely tuned to ensure the system performs properly. Achieving this precision requires several key components, but one of the most essential components is a pressure regulator. Keeping pressure regulators in proper working order through effective troubleshooting can save a facility from experiencing unnecessary downtime and spending over the life of the system.

When regulators are not properly maintained and fail, pressures may fluctuate significantly downstream, which can cause safety and quality issues in the process fluid. Quick recognition of why those drops in pressure are occurring can provide maintenance teams with important information so they can solve the issue before it becomes much bigger.

While there is no way to predict every possible problem that can cause changes in pressure, several common problems occur frequently that can be solved with little effort if they are caught early enough. Following the three-step program outlined in this article can help reduce regulator failure at a facility.

Step 1: Know the Process Requirements

Before troubleshooting the pressure regulators in a system, it is important to understand the process requirements, including the system flow, system pressure, system temperature, process sensitivity, and system media. Gathering this information will allow technicians to evaluate whether the proper regulator has been in- stalled. For example, controlling pressure from a source before it arrives at the main process will dictate the use of a pressure-reducing regulator (Figure 1). On the other hand, controlling pressure from an upstream source will require a back-pressure regulator (Figure 2).

If the wrong regulator is applied to these situations, it can cause unnecessary downtime and costly repairs. Sudden changes in pressure can compromise entire systems and could mean extensive repairs. If there is any question about which regulator is necessary for a particular system, it can be beneficial to work with a reliable supplier who can offer advice on which regulator to use. Once the proper regulator has been installed, it is time to move on to Step 2.

Figure 1: Using a pressure-reducing regulator will allow operators to keep steady downstream pressure for a fluid system application
Figure 2: Depending on where pressure problems are occurring, facilities will want to use either pressure-reducing regulators or back-pressure regulators.

Step 2: Determine What is Wrong

The next step in troubleshooting pressure regulators is to determine what the specific problem is, which can be determined by seeing where the pressure is changing. Is it rising upstream or dropping below proper pressures downstream? A thorough understanding of where the problem is occurring will reveal what to do next (Figure 3).

Rising pressure is typically caused by one of two issues: creep, or supply pressure effect (SPE). Creep may occur immediately after installation if debris is moving through the system (Figure 4). Contaminants from the installation process can create a fine gap between the regulator’s seat and poppet. In this scenario, the system media will flow across the seat and cause pressure to increase downstream. It can be dangerous to al- low this to happen because the down-stream components may not be rated to handle increased pressures. Thankfully, careful installation, upstream filtration, and purchasing a spares kit with new regulators can prevent the problem from causing issues.

Figure 3: When pressure begins to rise outside of the specific parameters for a system, it could be creep or SPE causing the problem. If the pressure is dropping, the problem is most likely an undersized regulator.
Figure 4: Creep occurs when particulates clog a regulator’s seat, which can cause pressure and flow to escape even when the regulator is closed. This can cause a potentially dangerous downstream pressure increase.

Unwanted pressure increases can also be caused by SPE, which is when pressure increases downstream because of a decrease in the inlet (or supply) pressure. If the inlet pressure falls too far, it can cause increased pressure on the outlets beyond what the systems are designed to handle. If SPE is discovered, it is time to move on to Step 3.

If SPE is not discovered, pressure fluctuations can commonly be the result of an inadequately sized regulator for the specific application’s flow. For example, if the regulator fails to compensate for an increased flow, the pressure may drop suddenly beyond the proper parameters. When this happens, the pressure drop is referred to as droop. One should check to see if the regulator supplier has a tool that can help determine what size the regulator should be for a particular application. Once this cause has been determined, then it is time to move on to Step 3.

Sometimes, however, the problem is not as obvious as the previously mentioned examples. When simple explanations have been examined and dismissed, then there may be a more complicated problem that needs to be identified. Reputable regulator suppliers should be able to guide technicians through a more thorough evaluation to see what the deeper problem may be. Such an examination could show that the regulator’s diaphragm is distorted (Figure 5) or cracked (Figure 6).

Figure 6: A cracked diaphragm will limit how well a regulator can sense pressure, lowering its ability to control pressure.
Figure 7: Sometimes, the problem is as simple as cleaning or replacing a clogged filter, offering a lower-cost alternative to replacing the entire regulator.

Elevated downstream pressure can cause diaphragms to become misshapen, specifically around the rim where the spring cap and body hold it in place. When the shape of the diaphragm significantly changes, it may no longer be in tight contact with the poppet. If this occurs, the diaphragm will no longer be able to actuate the poppet, restricting flow through the regulator.

Finally, repeated exposure to certain chemicals or repetitive cycles can crack the diaphragm and/or create a hole, which will render the regulator unable to per- form its essential functions. Suppliers who understand the full range of potential regulator problems may be able to help identify whether a diaphragm needs to be replaced and can recommend the right replacement. They should also be able to diagnose why the problem occurred in the first place and remediate it before the problem happens again.

Step 3: Consider Alternatives

Depending on what problem is being fixed, alternative regulators may be the right answer. To correct SPE, for example, regulators with balanced poppet designs can reduce the area on which inlet pressure can have an impact. Additionally, it may help to install a two-stage pressure-reduction scheme, which can also lower the chances that a system will experience SPE. The two-stage method requires the installation of two single-stage regulators in a series or combining them into one.

If the problem is undersized regulators instead, find a regulator that has a larger flow coefficient, which should lower the chances that the outlet pressure will drop precipitously. Suppliers with the right amount of experience should be able to provide guidance on how big or small regulators should be for any given application. It may also make sense to choose a dome-loaded regulator instead of a spring-loaded regulator because the dome-loaded variety resists changes in flow more effectively. If the flow of a system varies significantly during the process, a dome-loaded regulator may be the best choice.

Ensuring Proper Regulator Function

While the enumerated issues are some of the most frequent causes of poor regulator performance, other factors specific to different applications may also play a role. Poor performance may be due to something as simple as a clogged filter (Figure 7), which can be cleaned or replaced at lower costs than replacing a regulator and could get the system up and running in no time. Suppliers should have the expertise to offer advice on how best to solve the problem with your regulator system and provide solutions that are specific to particular applications. Making sure a facility’s regulators are in optimal condition will ensure the fluid systems will perform as expected and provide trouble-free operation for years to come.

Shaji Arumpanayil is a Product Manager for Swagelok Company.
Previous articleFactors Shaping the Stainless Steel Flow Control (SSFC) Market
Next articleCall for Submissions- Bringing Together the Heat Exchanger Community!
Stainless Steel World Americas is part of the KCI Group of Companies. We are a leading knowledge, communication and information company connecting business-to-business professionals by building and sustaining global communities, solving their information needs and helping them to develop their professional life and friendships.