Pressure reducing valves are automatic control devices that play an indispensable role in fluid systems across a wide range of modern industries, civil applications, and aerospace.
The basic operating principle of a pressure reducing valve is based on reaction balance and throttling. Taking a common spring-type diaphragm pressure reducing valve as an example, when inlet pressure fluid enters the valve, it is throttled by the valve seat and reduced to outlet pressure. The outlet pressure is introduced below the diaphragm through a feedback channel, where it balances the spring force above the diaphragm. When the outlet pressure changes, the diaphragm displaces, driving the valve stem and changing the flow area between the disc and seat, thereby regulating the flow rate and maintaining a stable outlet pressure.
Core Functions
- Pressure Reduction: Reduces high-pressure fluid to the required operating pressure.
- Pressure Stabilization: Maintains stable outlet pressure even when the inlet pressure fluctuates.
- Protection: Prevents equipment damage, leaks, and even accidents caused by overpressure.
- Energy Saving: Reduces unnecessary energy waste by optimally matching system requirements.
Common Pressure Reducing Valve Problems and Solutions
No pressure relief function
Causes: Top cover installed incorrectly, blocking the oil return hole; spool valve stuck; damping orifice clogged; spring too stiff or bent; seal mismatch; or blocked leak path.
Remedy: Reinstall the top cover and clear the oil return hole; align the spool valve with the valve body bore; clean the damping orifice; replace the appropriate spring; reground or replace the ball/poppet valve; clean the valve body to clear the leak path.
Output pressure fluctuates widely or is unstable
Causes: Insufficient clearance between the spool valve and the valve body, resulting in limited movement; broken pressure regulating spring or diaphragm; clogged filter; blocked breathing hole.
Remedy: Reground the spool valve and valve body bore to restore the clearance; replace the spring or diaphragm; remove and clean the filter; carefully clear the breathing hole with a thin wire.
Air/water leakage
Causes: Deteriorated seals, cracked rubber membrane, loose connecting screws, misaligned joints.
Action: Replace aged or damaged seals and rubber membranes; tighten screws; realign and tighten joints.
Pressure reducing valve cannot be tightened or handwheel threads are stripped
Cause: Misalignment between the pressure reducing valve inlet and the angle valve joint, damage to the angle valve joint, or stripped handwheel threads.
Action: Realign the joints; replace damaged angle valves or cylinders; repair or replace the handwheel.
Pressure cannot be adjusted high or rises slowly
Cause: Broken pressure regulating spring, ruptured diaphragm, clogged filter.
Action: Replace the spring or diaphragm; clean the filter.
Excessive noise
Cause: Loose or worn internal components.
Action: Tighten loose components; replace worn parts.
Condensate or impurity blockage
Cause: Accumulation of condensate or solid particles in the pipe.
Action: Drain condensate regularly; disassemble and clean the valve body and filter to remove impurities.
Pressure Reducing Valve Installation Precautions
Pre-Installation Preparation
• Confirm Model Compatibility: Select a pressure reducing valve of appropriate model and specifications based on the actual use scenario, such as the media type (steam, gas, liquid, etc.), flow rate, and inlet and outlet pressure ranges, to ensure it meets the system’s operating requirements. For example, in a household water system, the selection should be based on the household’s water consumption and incoming water pressure.
• Inspect the Pressure Reducing Valve: Carefully inspect the valve for external damage or deformation, the integrity of internal components, and any seal defects. Avoid installing a valve with quality issues that could affect subsequent use.
• Prepare Tools and Materials: Gather the necessary installation tools, such as wrenches and teflon tape. Clean the pipes to ensure they are free of debris and rust to prevent these impurities from entering and affecting the valve’s operation.
Installation Process
• Determine the Installation Location: The valve should generally be installed in a location that is easily accessible for operation and maintenance, typically vertically on a horizontal pipe. Steam pressure reducing valves are typically installed higher in the horizontal pipe to ensure proper drainage. Gas or liquid pressure reducing valves should also be installed away from the lowest point in the pipe to prevent accumulation of impurities.
• Pay attention to the direction of medium flow: During installation, ensure that the direction of medium flow in the pipeline aligns with the direction indicated by the arrow on the valve body. If installed in reverse, the pressure reducing valve will not function properly.
• Connect pipes correctly: Use appropriate sealing materials (such as raw tape, sealant, etc.) to seal pipe joints to prevent leaks. When tightening connections, ensure that excessive force does not damage the valve or pipes, while too little force may result in a loose seal.
• Consider bypass and maintenance: Where conditions permit, a bypass pipe can be installed. When the pressure reducing valve requires maintenance or malfunctions, the bypass pipe can maintain system operation, minimizing the impact on production or daily life.
• Avoid overpressure risks: To prevent excessive downstream pressure, it is recommended to install a safety valve at least a certain distance (e.g., 4 meters) from the valve outlet to ensure system safety.
Post-installation Inspection
• Check connections: After installation, recheck all connections for tightness and proper sealing.
• Perform a pressure test: Slowly open the inlet valve to allow medium to gradually flow into the pressure reducing valve. Observe whether the outlet pressure remains stable within the set range. Also, check the valve and piping for leaks. If any issues arise, address them promptly.
This is a brief introduction to pressure reducing valves. If you would like to learn more about valves, please contact us. Newton‘s professional technical team is always available to answer your questions.
