Water Pressure Reducing Valve

What is a water pressure-reducing valve? 

A water pressure reducing valve is a special valve that is used to regulate water pressure from the main water line. Water pressure reducing valve manufacturers design this valve to help reduce water pressure to safe and low levels before the water gets into the plumbing fixture in the building. Very high water pressure can be very dangerous so a water pressure reducing valve helps to control the water pressure. A water pressure reducing valve may not be necessary in every pipeline but may be very important in cases for example, where the municipal supply of water is done at very high pressure or where there is irregular water pressure. In most cases, plumbing fixtures are made to operate at a water pressure of 50 pounds per square inch (psi). However, the supply of municipal water is mostly pumped at high pressure of 150 to 200 psi. Pumping water at such high pressure into home plumping fixtures can strain them and soon start causing fail on joints and faucets to leak as well as breaking other appliances. As such, a water pressure-reducing valve will help to protect home pipes and other plumping fixtures, home appliances such as dishwashers and clothe washers in the house. 

Figure: Water pressure reducing valve

Components of water pressure reducing valve 

• Inlet port. This is where the high-pressure water enters the valve. 
• Outlet port. This is the port where the water from the valve (that has been regulated in pressure) leaves the water pressure reducing valve and enters the house water piping system. 
• Diaphragm. This is the part of the valve which is pressed upward and it opens the valve to allow water to flow from the valve and into the house water pipeline. 
• Adjusting spring. This is the spring on the valve used to counteract upward force on the diaphragm due to water flow to control opening size where water flows according to the water pressure. 
• Adjusting screw. This screw has a lock nut and both help to allow change of spring pressure. 
• Valve body. This is the part of the water pressure reducing valve that helps to stabilize the flow of returning water as it regulates the pressure. 
• Control filter. This part is used to filter debris from the mainline to help reduce damage. 

Figure: Components of water pressure reducing valve

How does a water pressure reducing valve work? 

Water pressure reducing valve manufacturers design the valve with a dome-shaped brass fitting. It is fitted past the shutoff valve on the main water pipe entering the house. This valve is designed with an adjusting screw on its top. In a water pressure-reducing valve, there is a spring-loaded diaphragm. This diaphragm widens and narrows automatically based on the water pressure level entering the valve. As the water gets into the valve at very high pressure the inner mechanisms of the valve constricts the diaphragm narrowing the water flow rate. This then helps to reduce the water pressure to around 50 psi to 80 psi. Water pressure reduction helps to reduce internal stress on the water fixtures and pipes installed ahead of the water pressure reducing valve. On the other hand, when the flowing water pressure reduces, the diaphragm opens wider allowing the flowing of more water via the valve. Tightening the top adjusting screw helps to increase tension on the spring which reduces the water pressure as it exits the valve. Also, the spring can be loosened to enhance the flow of water more freely via the valve to increase the existing water pressure. When a water pressure reducing valve is used, it helps to reduce the water stress on the internal valve appliances, shutoff valve, and faucets. This helps to protect house appliances and pipe fixtures from leakage and water pressure fluctuation. 

Why do you need a water pressure-reducing valve? 

1. To save water. When water flows into a house at very high pressure like 150 psi when only 50 psi flow is needed, there will be a lot of water wasted and not necessary for normal usage. The high pressure causes leakages in the house pipe taps and joints. 
2. To save energy. When less amount of water flows through the house pipe system, it will be possible to heat domestic water at lower power. It has been found that water pressure-reducing valves help to save heating energy by 30%. 

3. Save wastewater. When the load on the community’s wastewater reduces, the benefits on cost accrues for both environment and users. Most municipal authorities allocate sewer fees depending on the water meter reading. 

Types of water pressure reducing valves

Direct-operated water pressure reducing valve 

This is the simplest type of water pressure-reducing valve. This valve operates at low pressures of around 1 psi and works with great accuracy. Direct-operated water pressure valves do not need an external sensing line for them to work effectively as they are self-contained. This valve is made up of a spring-actuated valve controlled by diaphragm components. The diaphragm gets activated by the pressure or energy from the flowing water. An increase in downstream water pressure acting on the diaphragm closes the plug on the valve by compressing the spring which then closes the valve. When the downstream water pressure decreases, the spring force becomes greater than the diaphragm water force and this causes the valve to open. 

Pilot-operated water pressure reducing valve 

Pilot-operated water pressure reducing valves are valves suitable for use where there are large varying flow rates, fluctuating inlet pressure, or a decrease in inlet pressure. This type of water pressure-reducing valve helps to enhance precise water flow control. This type of valve is either a single or double-stage device. A one-stage water pressure reducing valve is best for controlling a small reduction in pressure. It is not suitable where large fluctuations of inlet flow rates or pressure are expected. A two-stage water pressure reducing valve uses the first stage consisting of a spring-actuated pilot to control pressure on the diaphragm. Provided the water pressure on the spring is low, the downstream will not have flow. When the pressure is increased, the spring gets compressed which causes the pilot valve to open. This helps to create differential pressure between the output valve and the inlet of the regulating valve. The differential pressure helps to actuate the main valve making the flow occur at a reduced pressure via the outlet valve. The two-stage pilot-operated water pressure reducing valve offers accurate water control for a wide range of capacities and pressures. These valves are recommended for use in clean water as the small ports can easily be clogged. 

Factors considered when selecting water pressure reducing valves

Range of operating pressure

The output and input pressure required for a certain application need to be known to help determine the water pressure reducing valve to be purchased. This will help to determine the input pressure supply range which can be comfortable for that particular valve. In addition, this will help to know the valve which can handle the output pressure and the needed accuracy. 

Flow requirements

It will be important for the vendor or water pressure reducing valve manufacturer to know the required flow rate, pipe size, and the flow rate variation expected so as to select the most suitable valve for those requirements. 

Nature of the water 

This is important as it will help to determine if the water is corrosive or has some solid particles. This will help to take the best precaution to ensure the water pressure-reducing valve does not fail while in use. 

Range of operating temperature 

The material used by the water pressure reducing valve manufacturers should be such that they can tolerate the range of the pressure to help them perform their functions effectively without loss of their mechanical or thermal properties. Such materials such as neoprene or nitrile can operate at -40 ^oC and 82 ^oC of temperatures while other materials such as perfluoroelastomer or ethyleneproplene are best for higher temperatures. 

Manufacturing materials 

Water pressure reducing valve manufacturers use different materials aiming to make a valve for a specific task. For example, brass helps to make an economical valve, plastic makes a valve that is cost-effective and can easily be disposed of, aluminum is used to make a valve where lightweight is the main factor to be considered while stainless steel valve will be needed where highly clean water and or operating temperature is required. This also helps to ensure that the seals used in the valve are compatible with the water and operating temperature. 

Applications of water pressure reducing valve

• Water pressure-reducing valves are used in enhancing consistent water flow in residential homes. 
• Water pressure-reducing valves are used in commercial and industrial applications to reduce water pressure for low-pressure working appliances. 
• These valves are used in sandy and debris-laden water applications to help filter particles and control water pressure simultaneously. 
• Water pressure-reducing valves are used to reduce water pressure for use in residential boilers that operate at low water pressure. 
• They are used in precise water pressure control in drip irrigation or other types of irrigation applications. 

Advantages of water pressure reducing valve 

• Water pressure reducing valve helps to restrict excess high pressure from main pipeline, tank or boosted supply which could easily cause damage on pipeline fixtures. 
• Water pressure reducing valve helps to reduce the noise level in cases like slamming or hammering during tap and valve shut-offs, or where the water is fed to appliances that have low-pressure ratings like washing machines, showers, dishwashers among others. 
• Water pressure-reducing valves help to enhance comfortable and consistent water flow rates. 
• It helps in controlling water flow between units, outlet points, floors in older or larger buildings. 
• Water pressure-reducing valves provide static pressure control. This helps in guarding against pressure creep at low no-flow or low demand circumstances. 
• It helps to reduce water pressure thus reducing overall water wastage. High water supply is associated with high water wastage as most domestic and commercial areas need around 50 psi of water pressure to perform normal tasks, unlike the main supply that has around 150 psi to 200 psi. 
• Water pressure-reducing valves help to save energy because home heating units work effectively at low water pressure. When a water pressure-reducing valve is used, it has been found that it leads to 30% energy reduction for the users. 
• It helps to reduce uncomfortable water flow rates from showers and indoor taps. 
• Water pressure reducing valves helps to reduce the cost of water in homes as water flows at low pressure suitable for home appliances ensuring no leakages.

Disadvantages of water pressure reducing valves 

• Water pressure-reducing valves tend to be of large sizes.
• These valves are more expensive relative to other valves. 

Troubleshooting water pressure reducing valves 

Pressure builds up in the valve above the normal pressure setting

• This could be due to the expansion of water due to the heating process. An expansion tank or pressure relief valve can be installed. This will help to restrict the pressure rise to a safe level but it will not prevent pressure rise. This happens naturally each time the heater is turned on. 
• Foreign materials clogged on the seal ring seating face. Open one or two water outlets wide to flush the water pressure-reducing valve. In case this does not provide a solution, remove the seal ring and clean it. 
• Seal ring being worn out, cut, or chipped. Replace the seal ring with a new one. For temporary repairs, you can turn over the seal ring. 
• Stem O-ring or O-ring groove is worn or cut. Replace with new stem O-ring or cartridge as necessary. 

Unsteady fixture and pressure flow 

• The water pressure reducing valve has main has low pressure for the supply of water caused mostly by high demand at a certain time of the day. This is a problem for the department of water. It occurs due to the main supply being unable to support the demand. 
• The appliances in the building have high periodic demands. The service lines in the house could be at times unable to support the load. Try to increase some of the pipeline sizes where possible. Also, it could be that the water pressure reducing valve has a low-pressure setting. In this case, try to increase the pressure before you change the pipelines. 

Inadequate, small flow from plumping fixtures 

• Fixture to pipelines could be very small or the main house supply could not be adequate for the normal demand. Try to increase the size of pipes in some sections of the system that lead to the offending fixture or appliance. If small supply is at all fixtures you can try to increase the mains house service. 
• House appliances have heavy periodic demands. Gradually increase the pressure by adjusting the water pressure reducing valve until you determine this point. 
• Debris clogging the screen. Clean the screen. 

The water pressure reducing valve is noisy: it whistles, hums, or chatters

• Whistle or hum is caused by high water flow velocity in the pipes leading to vibration. The pipe could be too tight or very small. Very small reducing valves and pipes could accentuate this problem. 
• Chatter can be due to a loose seal ring or worn-out seat washer. Check seal ring. In case you find a deep channel on the face of the seal ring, replace it or use the opposite face. In most cases, you may find that noise occurs in the tap or appliance and it originates from the reducing valve. The use of relatively small-sized streamline piping is common. Velocity would be very high and the noise of water moving at high speed is not unusual. 

Summary 

A water pressure reducing valve is a valve used to convert high pressure in flowing water at the inlet of the valve to lower pressure at the outlet section. These valves help to regulate fluctuating water pressure thus keeping them to an appropriate level. The water pressure reducing valve uses a spring-loaded diaphragm to enhance consistent and manageable water pressure. In a water pressure-reducing valve, the process of pressure control starts when the diaphragm under the spring widens and narrows based on the water pressure getting in the valve. When the pressure is very high, the internal mechanism of the water pressure reducing valve constricts the diaphragm causing water flow to narrow. As the pressure drops, the diaphragm widens allowing more water flow. There are two types of water pressure reducing valves that are direct-operated and pilot-operated. The direct-operated water pressure reducing valves is used for small loads while the pilot-operated is suitable for high loads. 

The water pressure reducing valves are used to regulate water flow in different applications such as residential buildings, industrial and commercial buildings, drip irrigation, among other applications. These valves are known for their benefits such as saving costs, saving energy, and saving on water. By using a water pressure reducing valve in your home it helps to reduce the high pressure associated with water flowing from the main supply of around 150 psi to the working pressure of home appliances of around 50 psi. The high pressure from the mains supply can cause water leakage through house pipeline joints or destroy the housing pipeline or connected home appliances such as dishwashers among others.