Water Supply Valve Types

Waterworks Valve Valve Case

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What are Automatic Control Valves?

Automatic control valves, as described by EN 1074-5: “have the integral capability to control the function using energy from the conveyed water by adjusting the position of the obturator. They can be directly operated, i.e. the force is applied (via a spring or diaphragm) directly to the obturator. They can be pilot operated, i.e. the force is applied through an adjustable pilot valve”.

How does an Automatic Control Valve work?

Principle of Automatic Control Valves for On/Off Operation

Valve Opening

If the pressure inside the control chamber is put in communication with the atmosphere or some other lower pressure zone, the upstream pressure will act on the obturator, pushing it upwards allowing the complete opening of the valve.

Valve Isolated From the Line

Should the control chamber be isolated from the line pressure and the rest of the circuitry the valve will remain in the same position, therefore producing the head loss corresponding to such opening percentage.

Valve Closing

If the control chamber is put in communication with the upstream pressure, thanks to the difference in the area between the upper flat with the diaphragm, larger than the obturator underneath, the valve will close completely.

Principle of Automatic Control Valves for Modulating Operation

Valve Opening

When the main valve is required to modulate a restriction (R) is needed between the upstream line pressure and the control chamber, in addition to a regulator (F) on the circuit. Should the latter open completely pressure inside the control chamber will be put in communication with downstream, allowing for the full opening of the main valve.

Valve Modulating

If the flow regulator (F) is throttled pressure will build up between it and the control chamber, causing the valve to modulate accordingly to an intermediate position. This is obtained thanks to the pressure difference created by the restriction (R) and to the difference in the section between the upper flat acting on the diaphragm and the obturator.

Valve Closing

Should the flow regulator (F) be completely closed, the upstream line pressure is all diverted to the main control chamber. The mobile block is moved by the force exerted on the upper diaphragm flat pushing the obturator down onto the seat, interrupting the flow through the main valve.

Components of an Automatic Control Valve

Applications of Automatic Control Valves

• Water treatment plants
• Multi-story buildings
• Water storage towers
• Reclaimed water systems
• HVAC Systems

Types of Automatic Control Valves

Pressure Reducing Valves

Pressure reducing valves can reduce higher inlet pressure to a constant downstream pressure regardless of demand and supply pressure fluctuations and enable the delivery of water at safe pressures and adequate levels for customer needs.

Pressure Relief Valves

Pressure relief valve can relieve excess pressure while maintaining a minimum upstream pressure and prevent downstream demand from sacrificing the supply of an upstream zone.

Altitude Control Valves

Altitude control valve is designed to open, allowing flow into a reservoir or elevated storage tank (tank fill), and close drip tight when a high water level is achieved. It controls water level by remotely sensing static tank head pressure through a field-installed sensing line, opens when the water level is below the adjustable set-point, and closes drip tight when the level is above the adjustable set-point.

Remote Float Control Valves

Remote float control valve is designed to close drip tight when the water level reaches the adjustable high-level set-point, and open fully when the water level is below the adjustable low-level set-point to increase tank circulation. High and low levels are separately adjustable by positioning stop collars on the float rod(s) at the desired opening and closing set-points. If desired, the on-off action of the valve can be reversed by modifying the hydraulic connections of the On-Off Float Pilot. The Float Pilot may be either valve or remote mounted.

Surge Anticipating Valves

Surge Anticipating Valve is an off-line, hydraulically operated, diaphragm actuated valve. The valve, sensing line pressure, opens in response to the pressure drop associated with abrupt pump stoppage. The pre-opened valve dissipates the returning high-pressure wave, eliminating the surge. The surge anticipating valve smoothly closes drip tight as quickly as the relief feature allows while preventing closing surge. The valve also relieves excessive system pressure.

Solenoid Control Valves

Water solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoid valves offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power, and compact design.

Flow Control Valves

Flow control valve prevents excessive flow by limiting flow to a preselected maximum rate, regardless of changing line pressure. They are hydraulically operated, pilot-controlled, diaphragm valves. The pilot control responds to the differential pressure produced across an orifice plate installed downstream of the valve. Accurate control is assured as very small changes in the controlling differential pressure produce immediate corrective action of the main valve. Flow rate adjustments are made by turning an adjusting screw on the pilot control.

Advantages of Automatic Control Valves

• Full-through radial streamlines design, small fluid resistance, large flow, and strong anti-cavitation ability.
• The sealing ring adopts an advanced star-shaped sealing ring structure.
• Removable stainless steel 304 valve seat, corrosion resistance, erosion resistance, good sealing performance.
• The diaphragm is made of nylon reinforced rubber, with three-dimensional mesh, good elasticity, high-pressure resistance, and long service life.
• Different Pilot valves are available to achieve different functions.
• Pressure Rating: 10bar, 16bar, 25 bar; CL150,CL300
• End Connections: Standard Flange Ends To EN1092, ASME B16.5, and others on Request.

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The post AUTOMATIC CONTROL VALVE – Pressure Reducing Valve / Pressure Relief Valve appeared first on ZECO Valve.

Domestic water pressure reducing valve

A water pressure regulator (sometimes called a pressure-reducing valve, or PRV) is a specialized plumbing valve that reduces the water pressure coming into the home through the main water line. This valve brings down the pressure to a safe level before the water reaches any plumbing fixtures inside the home. Too much water pressure can cause many plumbing problems, so it is very important to keep the water pressure under control. Although it is not necessary for every plumbing installation, a water pressure regulator can be essential in situations where the municipal water supply enters the home at very high pressure, or where water pressure is irregular.

Most home plumbing fixtures are designed to work best at a pressure of about 50 psi (pounds per square inch), but it is not uncommon for municipal water supplies to enter the home with pressures as high as 150 or 200 psi. If such high pressures are present on a regular basis, the strain can eventually cause joints to fail, faucets and other fixtures to leak, and appliances to break down. Clothes washers, dishwashers, and some other household appliances have built-in pressure regulators, but a whole-house water pressure regulator still offers protection to those appliances, and it also serves to protect all the pipes and fixtures throughout the house.

How does a pressure reducing valve work？

A water pressure regulator is a dome-shaped brass fitting that generally is found just past the main shutoff valve, where the main water line enters the house. It usually has an adjustment screw on top. Inside, a water pressure regulator has a variable spring-loaded diaphragm that automatically widens and narrows depending on the amount of water pressure entering the valve.

When the water enters the regulator at high pressure, the inner mechanism constricts the diaphragm to narrow the flow of water. This can reduce the pressure to a range of 50 to 80 psi, greatly reducing the stress on pipes and fixtures installed past the valve. Conversely, when the incoming water pressure drops, the diagram opens wider to allow more water to flow through the valve. An adjustment screw on the top of the regulator can be tightened to increase the tension on the inner spring (thereby reducing the pressure of the water as it exits the valve), or loosened to allow water to flow more freely through the valve (thereby increasing the outgoing water pressure).

When the system is protected by a water pressure regulator, there is less stress on the inner valves of appliances, faucets, and shutoff valves will be less likely to leak, and fluctuations in water pressure are evened out.

How to adjust pressure reducing valve

1、Locate the Supply Line

The first step is to locate the supply line that provides water to your house. This will allow you to then find the water meter that is generally installed in the basement near the supply line. If you live in an apartment or a house in a crawl space in colder climates, the meter is usually not in the crawl space as it could freeze; it may be under the kitchen sink or in a utility room. Those customers with service lines longer than 150 feet or that live in mobile homes, can find their pressure regulator in a meter pit near the road’s curbside or berm.

2、Find the Valve

Once you have found the water meter, locate the valve. The valve is made of brass and has a bell-shaped midsection with a medium-sized screw at the tip. Make sure that your supply line has sufficient pressure before adjusting the pressure valve itself.

3、Adjust the Screw

Now that you have located the valve and the screw, you need to loosen the locknut all the way with the wrench or pliers. The screw is your adjuster and it can be maneuvered only by loosening the locknut.

As you tighten the screw, the water pressure will become greater and as you loosen it, the water pressure will lessen, so turn the screw clockwise to increase the pressure or turn it counterclockwise to decrease the pressure. Do not be too hasty. You need to adjust the screw little by little, in slow increments, and check the result each time you tighten or loosen it. If the water pressure is too high, it could result in leaks and toilets running all the time.

4、Check the Pressure

Once you have adjusted the screw, the water pressure should be regulated. Check the faucets in the house to see if there is a change in the pressure compared to before. Also, once you have successfully adjusted the pressure valve, make sure there are no problems with leaks. If you find that there is no significant improvement after adjusting the pressure valve, your valve might be faulty and will need to be replaced. Changing a valve can be a bit challenging, so it is usually best to seek help from an experienced, professional plumber.

To further understand the importance of PRVs or Pressure Reducing Valves, we have to take a look into what high water pressure can do.

A high amount of water pressure can damage pipelines, crack bathroom tiles, cause leakage in faucets and showers, cause wastage of water, and may lead to huge amounts of water bills. So, installing Pressure Reducing Valves with the pipelines is the safest option.

Assume that we are on the first floor of a building and the water tank is placed on the terrace without a PRV. What happens when we turn on the faucet? The water comes out with full pressure, because of the large amount of water that is stored on the top of the building and this high pressure can destroy the bathroom tiles. And when we go to the top floor of the same building and turn on the faucet, we will barely feel the water pressure, the pressure would not be enough for a bathroom shower to work.

So here we can see as we come down in the high-rise buildings, the water pressure increases on every floor. To solve this problem and distribute the water at a safe and usable pressure point we have to install the Pressure Reducing Valve just next to the water storage.

How Much Pressure is Adequate?

In residential and light commercial buildings, the ideal water pressure is 2-5 bars. If the water pressure is less than 2 bars, it will not be enough to use a shower and if it is more than 5 bars, it can lead to water wastage and can sometimes cause leakage in faucets and the joints of pipelines. Generally, the water distribution pumps or the municipal water lines run on 3-4 bars at ground level. In the water tanks of high-rise buildings, the water pressure depends on the water quantity. When the water tanks are full the water pressure is extremely high and it reduces when the water is at a lower point.

How to Manage Water Pressure?

As we read above, the water pressure in high-rise buildings varies floor by floor. So to get an idea, of useful, and equal water pressure on every floor, various PRVs will have to be installed on every floor. The installation depends on the building’s structure and how many tanks are on it.

Are you looking for Shanghai Pressure Reducing Valve Factory?

ZECO Valve Group is a professional shanghai pressure reducing valve factory. ZECO’s engineers have designed PRVs to control water pressure, especially for high-rise buildings.

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The post How does a Pressure Reducing Valve Work & How to adjust PRV? appeared first on ZECO Valve.

What is a Spirax Sarco 25p?

The Spirax Sarco 25-Series regulators are a versatile family of self-acting pressure regulators with control pilots and interchangeable main valves for most steam applications. Options include pressure reduction (25P), combined pressure reduction with electrical on/off override (25PE), pressure reduction with air loaded pilot (25PA), and as a back pressure regulator (25BP). Designed with the user in mind, the 25-Series offers versatility and simplicity. Color coded, interchangeable springs allow quick and easy change of downstream pressure range eliminating the need to isolate the valve or break the steam line.

Spirax Sarco Pressure Reducing Valve, Pilot Operated, 3/4 in Nominal, NPT, 250 psi, 450 deg F, Cast Iron Body, Media: Steam

Components of the Spirax Sarco 25p

Operation of the Spirax-Sarco 25P Pressure Reducing Valve

The Spirax-Sarco 25P series pilot-operated reducing valve is widely used in steam systems. Accurate and stable pressure control can be realized irrespective of a change in upstream steam pressure or fluctuation of downstream load.

The Spirax-Sarco 25P series pilot-operated reducing valve is unique in that one, or several, pilot valves can be installed or exchanged on the same valve. Besides being stable and reducing pressure, it can also control the temperature, the upstream pressure or the remote switch. 

Operation

Normal positions before start-up are with the main valve closed and the pilot valve held open by spring force or air pressure.

Entering steam passes through the pilot valve into the main diaphragm chamber and also out through the control orifice. As flow through the pilot valve exceeds flow through the orifice, control pressure increases in the diaphragm chamber and opens the main valve. As steam flows through the main valve, the increase in downstream pressure feeds back through the pressure sensing line to the underside of the pressure diaphragm. 

When the force below that diaphragm balances the compression force of the spring above it, the pilot valve throttles. The control pressure maintained in the main diaphragm chamber positions the main valve to deliver just enough steam for the desired delivery pressure. Adjustment of the spring or air pressure above the pressure diaphragm changes the downstream pressure set point. 

When steam is no longer required, the sensing line pressure increases closing the pressure pilot and the control pressure bleeds back through the control orifice. This allows the main valve to hold the desired reduced pressure, and it may close tight for a dead-end shutoff.

Advantages of Spirax Sarco 25p

• Combination of pilots allow for different types of control in one regulator
• Patented self scrubbing guide for long, trouble-free service
• Fatigue-tested diaphragm designed without a piston to prevent danger of sticking
• Stainless steel internals for excellent durability and resistance to corrosion

Typical Installation of Spirax Sarco 25p

The regulator should be installed in a horizontal line with suitable bypass and isolating valves. A steam trap should be installed upstream to prevent condensate from reaching the regulator. The trap and regulator should both be protected with a strainer. The pressure sensing line should be located in a straight section of the downstream piping at least 10 pipe diameters from the nearest fitting. Complete installation instructions are given in IMI3.000

Maintenance of Spirax Sarco 25p

Complete installation and maintenance instructions are given in IMI 3.000, a copy of which is supplied with each regulator. Available spare parts are shown on TIS 3.027 & 3.0271.

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