Introduction  

Pressure regulators (or pressure-reducing valves), as indispensable core control components in industrial production systems, have operational stability that directly impacts production efficiency, equipment safety, and even the personal safety of employees.

Meanwhile, in accordance with process requirements—such as system flow rate, system pressure, system temperature, process sensitivity, and the system medium—   All these requirements also correspond to different types of pressure regulators. In short, if the pressure from a source needs to be regulated before it reaches the main process, the appropriate regulator is a pressure-reducing valve. If the goal is to control the pressure coming from upstream, the suitable regulator is a backpressure valve.

When pressure regulators experience various malfunctions, timely troubleshooting and proper handling can minimize equipment damage and media wastage, while also effectively preventing safety incidents. This article will guide you through common regulator faults and on-site troubleshooting procedures.

 

Common Faults of Pressure Regulators

 

1、 Outlet pressure is too low and cannot be increased.

Fault phenomenon:

When the pressure‑adjusting screw is turned to its tightest setting, the outlet pressure still fails to reach the set value, and in some cases there is no pressure output at all, thereby compromising the normal operation of downstream equipment.

Common root causes:

• Insufficient upstream pressure or the upstream valve is not fully open;

• The front-end filter is severely clogged;

• Damage or aging of the internal diaphragm (a common cause);

• The valve spool is seized by foreign matter, and the valve stem is stuck.

• The pressure-regulating spring has become fatigued and softened, or has fractured;

• The pressure regulator was undersized, and the flow rate cannot meet production requirements.

On-site handling:

• Fully open the upstream valve and clean or replace the filter element.

• Clear the air passage and damping holes, and disassemble to clean impurities from the valve spool and valve chamber;

• Replace damaged diaphragms and failed springs;

• If the selected model is undersized, promptly replace it with a larger‑bore pressure regulator.

 

2、 Outlet overpressure; pressure fails to drop.

Fault phenomenon:

Loosening the pressure‑adjusting screw fails to reduce the outlet pressure, which remains excessively high and continues to rise, posing a serious overpressure safety hazard.

Common root causes:

• Foreign matter is lodged on the valve seat sealing surface, preventing the valve plug from closing tightly and causing internal leakage.

• Damage, aging, or swelling of the main diaphragm and the pilot‑valve diaphragm;

• The valve stem and valve plug are seized, preventing closure;

• Internal damping orifice is blocked, resulting in failure of pressure feedback;

• The pressure‑regulating spring is too stiff, or the wrong model was selected;

• When the pressure reduction ratio is excessively high (exceeding 10), the single valve operates under overload conditions.

On-site handling:

• Disassemble and clean foreign matter from the valve seat and spool, and repair the sealing surfaces.

• Replace damaged diaphragms and sealing gaskets;

• Clear the damping holes and vent holes;

• Replace the pressure-regulating spring with one of the matching specification;

• If the pressure reduction ratio is too high, switch to a two-stage pressure regulation mode after reporting, thereby preventing the single valve from operating beyond its design limits.

 

3、 The outlet pressure fluctuates erratically, with sudden spikes and drops.

Fault phenomenon:

After setting the pressure, there is no production gas consumption. /Changes in oil consumption cause the outlet pressure to fluctuate and oscillate continuously, resulting in unstable operation of downstream equipment.

Common root causes:

• Upstream pressure itself fluctuates significantly;

• The pressure-tapping line is blocked or leaking, resulting in abnormal pressure feedback;

• The valve spool is slightly stuck, and the valve stem does not move smoothly;

• The medium contains water and impurities, resulting in water accumulation in the membrane chamber;

• The pressure regulator’s nominal size is oversized, leading to surge under low-flow conditions.

• Spring fatigue and insufficient damping.

On-site handling:

• Coordinate with relevant departments to stabilize upstream gas supply and gas pressure;

• Clear and secure the pressure-tapping lines, and inspect for air leaks.

• Clean the valve spool and apply dedicated lubricant to ensure smooth operation.

• Drain accumulated water from the valve chamber and remove impurities from the process fluid.

• Replace the pressure regulator with one of the appropriate size.

 

4、 The valve body vent hole is continuously leaking air.

Fault phenomenon:

Continuous leakage from the pressure regulator’s vent, body seams, or connections not only wastes the process medium but also poses a safety hazard.

Common root causes:

• Diaphragm rupture (accounting for over 60% of such failures), allowing the high-pressure medium to flow directly into the vent port;

• Severe internal leakage at the valve seat; sealing gaskets and O-rings are aged and damaged.

• Joint seal is loose;

• The accumulated water in the valve chamber lifts and opens the pressure-relief structure.

On-site handling:

• Replace damaged diaphragms, aged sealing gaskets, and O-rings immediately;

• Tighten the joints to ensure a proper seal;

• Drain accumulated water from the valve chamber and clean the valve chamber;

• Grind and repair the internally leaking valve seat; if damage is severe, promptly report for replacement of the component.

 

5、 Valve body vibration, unusual noises, and whining sounds

Fault phenomenon:

During operation, pressure regulators may exhibit body vibration, airflow whistling, and even induce resonant rumbling in the piping; prolonged operation can damage both the valve and the pipeline.

Common root causes:

• The operating flow rate is too low, causing abnormal flow velocity within the valve and resulting in surge.

• The medium contains excessive water, oil, and impurities;

• Incorrect or blocked pressure-tapping lines;

• Slight sticking of the valve spool and spring resonance;

• The piping system lacks a surge suppressor, causing resonance.

On-site handling:

• Adjust the operating conditions, increase the flow rate, and install a buffer device if necessary;

• Perform dehydration and impurity removal on the medium;

• Calibrate the pressure-tapping lines and clear any blockages.

• Clean the valve spool and replace the fatigue‑prone spring;

• Inspect the pipeline fastening and eliminate potential resonance hazards.

 

6、 The pressure‑adjustment knob cannot be turned and spins freely, making pressure adjustment impossible.

Fault phenomenon:

• When the pressure‑adjusting knob is turned, there is no change in pressure;

• The handle is jammed, spins freely with stripped threads, and pressure cannot be adjusted.

Common root causes:

• The pressure-regulating lock nut has not been loosened;

• The adjusting screw is seized due to rust, and its threads are stripped.

• Internal valve The core is completely seized, and the spring has fractured and come out of its groove.

• The pilot valve is completely blocked, resulting in failure of pressure feedback;

• Misalignment of internal component assembly.

On-site handling:

• First, loosen the pressure‑regulating lock nut and attempt to adjust it.

• Remove rust and lubricate corroded screws; if the threads are stripped, report for replacement of the component.

• Disassemble the pressure regulator, clean any internally seized components, and clear the pilot valve and damping orifices.

• Reassemble misaligned components and replace damaged springs and screws.

 

Safety Precautions

 

• All inspections and disassemblies must be performed with complete depressurization; disassembly under pressure can cause parts to fly off and process fluids to spray, resulting in injury.

• Gas pressure regulators must never be serviced in the presence of open flames; pneumatic valves must be kept free of oil contamination in the gas supply; and hydraulic valves should be protected against oil contamination.

• Diaphragms and seals are wear parts; it is recommended to replace them every 1–2 years as a preventive measure to avoid failures.

• In scenarios where the pressure reduction ratio exceeds 10 or the pressure differential is excessively high, a two-stage pressure regulation system must be employed; the use of a single valve beyond its rated operating conditions is strictly prohibited.

• When frequent internal leakage and seat damage cannot be repaired, replace the entire valve.

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