1. What is a Water Pressure Reducing Valve?
Also called water pressure regulators, water pressure reducing valves are compact, inexpensive valves that perform two functions:
You will get efficient and thoughtful service from SUPCON.
- They automatically reduce the high incoming water pressure from the city mains to provide a lower, more functional pressure for distribution in the home.
- They "regulate" by maintaining a set pressure in the home usually 50 lbs. thereby insuring that the home piping and appliances operate under a safe, more moderate, but satisfactory pressure.
2. What is Water Pressure?
When a fixture in a home is opened and water flows from it, it is because the water is "pushed." This "push" is pressure. The speed at which water flows from the opened outlet depends on the amount of "push" or pressure which exists at that time in the system. In short, the higher the pressure, the stronger the "push" behind the water.
3. What is Wrong with High Water Pressure?
High water pressure, which is generally considered anything above 60 lbs., has some advantage, such as in firefighting systems. However, in the home plumbing system, it can be damaging because water can erode or wear away many materials. A big "push" in home plumbing can also cause leaking water heaters, banging water pipes, dripping faucets, dishwasher, and clothes washer noise and breakdown, or leaking water pipes. Water flowing at a rate in excess of that necessary to satisfy normal fixture or appliance demands becomes damaging, wasteful, and reduces the life expectancy of equipment in the system. But, probably most important to the average homeowner is that it can add to the cost of water, energy, and waste water bills.
4. Does High Water Pressure Cause "Water Hammer?"
Yes, and water hammer is very simply the noise generated by the shocks of high-speed water flowing in a pipe when a fixture is suddenly closed. The sudden stoppage causes a "bounce back" of the water and is called water hammer, causing banging pipes, noisy systems, and damage to appliances. It might be comparable to driving your car at slow speed into a wall where the effect is negligible. However, if you drove the car at a much higher speed, the impact would be greater and, consequently, so would the bounce back or shock. Another description of the water hammer effect of high water pressure can be easily demonstrated. First, walk around a sharp corner and then run around the same corner. We can equate walking around the corner to a lower, more functional, controlled water pressure. However, when you run around the corner, the momentum forces your body to swing in a wider, uncontrolled arc. This principle is based on the fact that moving objects, and this includes water, tend to move in a straight line. They resist changes in direction. Therefore, in a home where the piping has many changes in direction, water hammer shock can be limited by reducing the water pressure.
5. What is the difference in water flow from a fixture when the pressure is at 100 lbs. vs. a pressure of 50 lbs.?
Reducing the pressure from 100 lbs. to 50 lbs.will result in a savings of approximately 1/3 because 1/3 less water flows at this lower pressure. Remember, there is more "push" behind the water at 100 lbs. than at 50 lbs. and most of this water is wasted. Almost twice as much water flows at 150 lbs. than 50 lbs., most of which is wasted. Moderate savings would result if your supply pressure was 65 lbs. However, even at this lower pressure, savings with a water pressure reducing valves would be 20%.
6. Are there any studies to support this savings figure?
Yes. In the Washington Suburban Sanitary Commission conducted a test program in 2,400 dwelling units that has attracted widespread interest from more than 40 states and various foreign countries. One of the devices used in their conservation study was a water pressure reducing valves. It is interesting to note that their report concluded that in test locations using water pressure reducing valves, there was a water consumption reduction of 30% in October and November and 37% in December.
7. Where are Water Pressure Reducing Valves most commonly used?
Water pressure reducing valves are commonly installed at the meter in residential, commercial, and industrial buildings. This location is desirable because it then controls the water pressure flowing to all appliances and outlets within the building and provides an inexpensive means of supplying lower, more functional water pressure to outlets and appliances.
8. Why do we now call Water Pressure Reducing Valves "Primary Conservation Controls"?
Most people have considered water pressure reducing valves as pressure controls because, as described in the foregoing, they are used to protect appliances and piping from the effects of high water pressure. However, because of water and energy shortage in addition to cost problems, water pressure reducing valves have become increasingly more important because they automatically provide the advantage of conserving water and energy.
9. How do Water Pressure Reducing Valves save water?
As mentioned before, 1/3 less water flows 50 lbs. than at 100 lbs. Therefore, when you reduce the city main pressure to a more moderate pressure of 50 lbs., you can look forward to conserving up to 1/3, or more, of the water previously consumed and this will be reflected on your water bills.
10. How much does a typical family of four use?
A typical family of four uses an average of 255 gallons of water each day for interior plumbing. This is broken down by: dishwashing - 15 gallons; cooking/drinking - 12 gallons; utility sink - 5 gallons laundry - 35 gallons; bathing - 80 gallons; bathroom sink - 8 gallons; toilet - 100 gallons. When you multiply this by a year, typical family usage totals 93,000 gallons of water. If you have teenagers, you would undoubtedly use more than the above averages.
11. How do Water Pressure Reducing Valves affect the wastewater system?
When we can save 1/3 of the water previously consumed, this also represents a similar saving of water which will not be going into the sewer system where it has to be treated. Water does not evaporate after we use it and it has to be piped to the wastewater system. Many sewer bill taxes or surcharges are based on the amount of water you use, with the assumption that this water is going into the wastewater system. This is billed to you as a sewer surcharge and, in many cases, the sewer tax can equal the water cost. Therefore, when water pressure reducing valves save 1/3 of the metered water, they also contribute to saving up to 1/3 of the wastewater, which is extremely important because it benefits both the user, by a lower sewer bill, and the community, as this is water they do not have to treat.
12. How do Water Pressure Reducing Valves save on energy?
The Environmental Protection Agency estimate that 30% of the water used in households is heated and, in order to heat this water, it takes energy. If a water pressure reducing valve can reduce consumption by 1/3, we automatically cut down on the amount of hot water we're using in lavatories and showers and, therefore, we automatically reduce the amount of energy required to heat that load. Thus, it can be easily seen that water conservation has a direct relationship to energy conservation. An average shower, for example, costs approximately 17 cents in energy and a shave with the faucet running cost 10 cents in energy.
13. How do these savings benefit the water and energy utilities?
A high rise office building in Chicago was designed using water conservation products which resulted in savings of more than 3,000,000 gallons of water per year. This is significant in that the municipal water utility did not have to pump the extra gallons, the water purification plant didn't have to treat it, while the building itself saved on pumping of 3,000,000 gallons, resulting in significant savings in energy by conserving hot water. Also, there were further savings by the fact that 3,000,000 gallons of water, or the normal portion thereof, did not have to be distributed to the wastewater system and consequently the water treatment plant did not have to retreat this water. The heating of water takes energy and it should also be remembered that "pumping" water from one place to another also requires a considerable amount of energy.
14. How do Water Pressure Reducing Valves save on maintenance?
We have previously described the effects of high water pressure on piping and appliances. When having these appliances work under a lower pressure, their life expectancy will be much longer and will also cut down on service calls caused by problems with dish washers and clothes washers, leaky water heaters, leaking water pipes, and the potential water damage which could be resulting.
15. Do codes require Water Pressure Reducing Valves?
Yes. They are required by the Federal Housing Administration, the regional plumbing codes such as IPC and UPC, and numerous city and state codes. The requirement is that whenever the city main water pressure exceeds 80 lbs., a water pressure reducing valve must be installed. However, because of the recently acknowledged advantages of water pressure reducing valves conservation wise, they could be economically installed even where supply pressures are in the vicinity of 60 lbs. because of the water and energy saving benefits they can provide.
16. How long will a Water Pressure Reducing Valve last?
Water Pressure Reducing Valves have been described as "life-of-mortgage" products, because historically a malfunctioning water pressure reducing valve is not replaced but simply cleaned or repaired via an inexpensive service kit. Design-wise, it is similar to the kitchen faucet in that dirt or foreign matter on the seating area can cause problems and actually it is no more difficult to repair a water pressure reducing valve than it is to fix the kitchen faucet.
17. If I install a Water Pressure Reducing Valve, what savings can I expect?
An average savings would be from $50 to $150 per year, probably much higher. Based on the fact that 1/3 less water flows at 50 lbs. than 100 lbs., you can expect to save up to 1/3 of the water previously consumed. As a typical family of four uses 90,000 gallons per year, that would mean a savings of approximately 30,000 gallons of water. The higher the pressure, the higher the savings. Lower pressures result in less savings. (Your water Company can provide the rate.) Remember also, however, that 1/3 of the water used in homes is heated; so 1/3 of the 30,000 gallons of water saved divided by 2 to reflect a cold water mixing factor would mean a savings in heating up to 5,000 gallons of hot water per year. If you figure 4 cents to heat a gallon of water, the savings would be $200.00. You can also figure on a savings in your sewer surcharge bill, since most of the 30,000 gallons of water saved will not be going into the wastewater system, therefore, you will not be assessed on that. (Contact your local authority for any assessment charges.) You would also have to figure the savings, generated by not having to have appliances repaired or replaced more frequently. This is a nebulous figure but, based on your own experience over the past years, you could look for a reduction in the frequency of maintenance and certainly for an improved performance by these appliances.
18. Should we consider using other water and energy conservation devices?
Certainly. The water pressure reducing valve is the hub of a conservation program; but you should also consider flow control devices, low-flush toilets, improved water heating equipment, and better disciplined habits by the user. However, if none of these devices were installed, the water pressure reducing valve would still serve to contribute important and significant savings in energy and water, resulting in average savings of anywhere from $50 to $150 per year, or more depending on your local rates.
19. Do flow-restricting devices actually save water?
Yes, and they can effectively be installed on showerheads, fixtures, and tankless heater boilers. Many showerheads, for example, apply water at a rate of 6gpm. Applying a 3gpm flow restrictor will cut the flow in half providing savings in water and energy. It should be remembered however that their capacity is based on a "fixed" supply pressure like 50 lbs. and operating under a higher pressure will permit greater flow. That's why we say a water pressure reducing valve is the "hub" of a program because it maintains a constant pressure throughout the home, thereby improving the performance of flow-restricting devices.
20. What are some tips the user can employ to save water and energy?
- Put a stopper in your sink or use a dishpan when you wash dishes.
- Washing with running water uses 30 gallons per meal.
- Keep a bottle of drinking water in the refrigerator running the water from the faucet until cold will waste a gallon.
- Wait until you have a full nine-pound wash before you run your washing machine. The average machine uses 50 gallons per load.
- Turn the hot water off while you shave, and turn the cold water off while you brush your teeth. Shaving with a running faucet uses about 20 gallons.
- Take showers instead of baths. The usual bath requires 36 gallons, the usual shower, only 25. Ten gallons is enough for a shower if you turn it off while you lather.
- Don't use the toilet bowl to dispose of cigarette ashes, facial tissues, and other materials. A normal flush requires 8 gallons.
- Use dishwasher only when completely full.
- Fix dripping faucets promptly. Nearly two gallons can be wasted per day of dripping.
- Running toilets can waste four gallons per hour. Keep them in good repair.
- THINK before you turn on the tap.
21. What does a Water Pressure Reducing Valve cost?
There are, of course, different styles of water pressure reducing valves and various installation charges throughout the country. An estimate can be obtained from your local qualified plumbing contractor. To determine how much you, as an individual, would be saving, it would be necessary to consider the factors in question 17, in comparing with your current water and energy bills.
22. How do I know if I have high water pressure?
A rule of thumb is: If you hear banging pipes in your home or observe water splashing in your sink, you probably have excessive pressure. However, for a precise reading, your local plumbing contractor or utility can test your pressure with a gauge.
23. How can I get a Water Pressure Reducing Valve installed?
The easiest way would be to call your local qualified plumbing contractor who can provide you with an estimate and also advise of the various types of water pressure reducing valves available and the one best suited for your home. Although water pressure reducing valves are fairly simple to install and could be a do-it-yourself project, there are some laws which mandate that only a licensed plumbing contractor be permitted to work on the home potable drinking water system for health and safety purposes.
Question about Pressure Reducing Valves
-
Plumbing
-
Thread starter
Steve4Physics
-
Start date
Jan 28,
-
-
Tags
-
Pressure
Valves
In summary, a pressure reducing valve is useful to protect the plumbing from excessive (dynamic) pressure, but it is only useful if the static pressure is too high.
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
- TL;DR Summary
- `What is the purpose of pressure reducing valves that only reduce dynamic pressure when the (higher) static pressure is what causes problems?
I&#;ve asked this question in a Plumbing Forum and got no answer. So I thought maybe the Physics Forum might be able to help.
My home has a high water supply pressure (>5bar) so I&#;m considering using a pressure reducing valve (PRV). This is basically to help protect the plumbing, as the house (and the plumbing) are pretty old.
Most PRVs only reduce the dynamic pessure (while the water is flowing) but not the static pressure (when there is no flow).
But it is (presumably) high static pressure that, over time, causes seals to leak.
So what is the purpose of PRVs that only reduce dynamic pressure?
- Higher-order topological simulation unlocks new potential in quantum computers
- Using a gamma ray burst to search for violations of Einstein's relativity postulates
- Researchers present new diagnostic tool for laser-plasma accelerator using metal foil as 3D scanner
Physics news on Phys.org
Lnewqban
Homework Helper
Gold Member
- 3,701
- 2,095
https://www.build.com/product/summa...ynXApxWnDAPhzmpOMfQaArnzEALw_wcB&gclsrc=aw.ds
I believe that this simpler solution would be more suitable in your case:
anorlunda
Staff Emeritus
Insights Author
- 11,308
- 8,736
Remember that if the pressure is too high with zero flow, passive reducing valves won't reduce, and pressure relief valves will be open and spilling water 100% of the time.
If the static pressure is too high, you need a shutoff valve in series with a reducing valve. The shutoff opens only when you need enough water flow for the reducing valve to reduce the downstream pressure to an acceptable value.
If the high pressure is from your city feed, you may need a day tank in your house filled by the city and emptied by your consumption. An active pressure regulator would control the valve admitting city water.
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Lnewqban said:
https://www.build.com/product/summa...ynXApxWnDAPhzmpOMfQaArnzEALw_wcB&gclsrc=aw.ds
I believe that this simpler solution would be more suitable in your case:
Unfortunately a pressure relief value (as shown in your link) would be unsuitable because the mains input pressure (say 6 bar) would always exceed the required house-pressure (say 3 bar). That would mean the pressure relief valve would always be relieving itself (ha-ha) and flooding my kitchen.
Pressure reducing valves and pressure relief valves have different purposes.
In any case, I can get a get a pressure reducing [edited] valve that does what I want - controlling both static and dynamic pressure (e.g.
But my question is: what is the purpose of a pressure reducing valve that can only control dynamic pressure? It seems pointless.
Unfortunately a pressure relief value (as shown in your link) would be unsuitable because the mains input pressure (say 6 bar) would always exceed the required house-pressure (say 3 bar). That would mean the pressure relief valve would always be relieving itself (ha-ha) and flooding my kitchen.Pressure reducing valves and pressure relief valves have different purposes.In any case, I can get a get a pressure reducing [edited] valve that does what I want - controlling both static and dynamic pressure (e.g. https://www.screwfix.com/p/reliance-valves-predator-pressure-reducing-valve-15mm-x-15mm/914hr ).But my question is: what is theof a pressure reducing valve that can only control dynamic pressure? It seems pointless.
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
anorlunda said:
Remember that if the pressure is too high with zero flow, passive reducing valves won't reduce, and pressure relief valves will be open and spilling water 100% of the time.
If the static pressure is too high, you need a shutoff valve in series with a reducing valve. The shutoff opens only when you need enough water flow for the reducing valve to reduce the downstream pressure to an acceptable value.
If the high pressure is from your city feed, you may need a day tank in your house filled by the city and emptied by your consumption. An active pressure regulator would control the valve admitting city water.
Thanks for the reply. However (as already noted in Post #4)
I can get a pressure reducing valve that does what I want - controlling both static and dynamic pressure.
But what I really want to know is: what is the purpose of a pressure reducing valve that can only control dynamic pressure? If damage is caused by high continuous static pressure, why do they even make pressure reducing valves that only control dynamic pressure?
Thanks for the reply. However (as already noted in Post #4)I can get a pressure reducing valve that does what I want - controlling both static and dynamic pressure.But what I really want to know is: what is theof a pressure reducing valve that can only control dynamic pressure? If damage is caused by high continuous static pressure, why do they even make pressure reducing valves that only control dynamic pressure?
Lnewqban
Homework Helper
Gold Member
- 3,701
- 2,095
Please, see:
https://www.spiraxsarco.com/learn-a...elf-acting-pressure-controls-and-applications
In applications where flow demand can greatly change, and abundant supply pressure and flow is available.Please, see:
anorlunda
Staff Emeritus
Insights Author
- 11,308
- 8,736
Steve4Physics said:
But what I really want to know is: what is the purpose of a pressure reducing valve that can only control dynamic pressure?
Like I said, they are useful in series combination with a shutoff valve. That valve you linked in #4 probably combines both shutoff and reducing functions in one unit.
Like I said, they are useful in series combination with a shutoff valve. That valve you linked in #4 probably combines both shutoff and reducing functions in one unit.
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Here in the UK it seems we use pressure reducing valves (for dynamic pressure only) with no additional (pressure-sensitive) shut-off valve.
And all the information I've read simply says PRVs are used to protect the plumbing from excessive (dynamic) pressure - but ignore the issue of static pressure. So I'm still puzzled.
I'm going to one of the manufacturers and ask their technical department if they can explain. If I find out anything useful/interesting, I'll post it here.
Thanks @Lnewqban and @anorlunda Here in the UK it seems we use pressure reducing valves (for dynamic pressure only) with no additional (pressure-sensitive) shut-off valve.And all the information I've read simply says PRVs are used to protect the plumbing from excessive (dynamic) pressure - but ignore the issue of static pressure. So I'm still puzzled.I'm going to one of the manufacturers and ask their technical department if they can explain. If I find out anything useful/interesting, I'll post it here.
russ_watters
Mentor
- 23,353
- 10,636
Steve4Physics said:
Most PRVs only reduce the dynamic pessure (while the water is flowing) but not the static pressure (when there is no flow).
But it is (presumably) high static pressure that, over time, causes seals to leak.
So what is the purpose of PRVs that only reduce dynamic pressure?
High static pressure over time should not cause leaks. Though pressure cycling can.
Primarily I would think the prv is there so that the system operates properly. The various devices on the system are designed for certain operating pressure and associated flow rate. It the operating pressure is too high, the flow can be too high or hard to control.
High static pressure over time should not cause leaks. Though pressure cycling can.Primarily I would think the prv is there so that the system operates properly. The various devices on the system are designed for certain operating pressure and associated flow rate. It the operating pressure is too high, the flow can be too high or hard to control.
berkeman
Mentor
- 67,901
- 21,342
My wife works in the home warranty business, and she encounters leaks and appliance failures pretty regularly that are attributed to high water pressure by the plumbers who diagnose the problems. If the pressure is high enough, the home warranty may not apply...
Tom.G
Science Advisor
Gold Member
- 5,389
- 4,206
It is used (and required here in the USA) on hot water heaters. If the inlet valve to the water heater and all usage valves are closed and the heater comes on, the internal tank pressure can be high enough to burst the tank. Deadly if anyone is nearby. The PRV is installed on the hot water tank to relieve the over-pressure by directing the water to a drain.
The device you are looking for is a Pressure Regulator, or often called a Pressure Regulator Valve. This valve CLOSES when the outlet pressure is greater than the set value. The type you mentioned in the first post OPENS with high pressure, opposite of what you need.
Here is a link to one description of a Pressure Regulator:
https://www.thespruce.com/water-pressure-regulator-
(above found with:
http://www.google.com/search?&q=domestic+water+pressure+regulator)
Also see a manufacturers page at:
https://www.zurn.com/products/water-control/pressure-reducing-valves
Hope this helps!
Cheers,
Tom
The valve described in the first post, a PRV, is a Pressure Relief Valve.It is used (and required here in the USA) on hot water heaters. If the inlet valve to the water heater and all usage valves are closed and the heater comes on, the internal tank pressure can be high enough to burst the tank. Deadly if anyone is nearby. The PRV is installed on the hot water tank to relieve the over-pressure by directing the water to a drain.The device you are looking for is a Pressure Regulator, or often called a Pressure Regulator Valve. This valve CLOSES when the outlet pressure is greater than the set value. The type you mentioned in the first post OPENS with high pressure, opposite of what you need.Here is a link to one description of a Pressure Regulator:(above found with:Also see a manufacturers page at:Hope this helps!Cheers,Tom
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Tom.G said:
The valve described in the first post, a PRV, is a Pressure Relief Valve.
It is used (and required here in the USA) on hot water heaters. If the inlet valve to the water heater and all usage valves are closed and the heater comes on, the internal tank pressure can be high enough to burst the tank.
Thanks Tom. For information, in Post #1 I wasn&#;t asking about pressure relief valves - which, as you described, are typically used for safety in pressurised water-heating (and also high-pressure steam) systems.
I should have made it clearer.
I was referring to pressure reducing (regulator) valves.
Part of the confusion may be that the same acronym, PRV, is used for both types of valve.
Thanks Tom. For information, in Post #1 I wasn&#;t asking about pressure relief valves - which, as you described, are typically used for safety in pressurised water-heating (and also high-pressure steam) systems.I should have made it clearer.I was referring to pressure reducing (regulator) valves.Part of the confusion may be that the same acronym, PRV, is used for both types of valve.
sophiecentaur
Science Advisor
Gold Member
- 29,332
- 7,067
anorlunda said:
If the high pressure is from your city feed, you may need a day tank in your house filled by the city and emptied by your consumption.
This is a good idea as it means the only part of your system that's at a silly pressure will be a single valve at the tank input. It's no longer popular in UK but it was the norm for non-drinking water systems in the past - to protect a complicated hot water system from stress and to maintain a reliably constant pressure for simple shower systems. As for cold water, the only snag with an upstairs 'cold tank' to store water is hygiene and spiders. A separate feed for the kitchen, direct from the mains, would be normal.
The old fashioned arrangement used a slide valve, operated by a floating (brass) ball with a hard rubber pad over a (brass) orifice. Those used to last for a hundred years, sometimes needing a new rubber pad after twenty years or so. (Note the old fashioned, fail safe, syphon operation in the figure.)
Tom.G said:
The type you mentioned in the first post OPENS with high pressure, opposite of what you need.
That type is ideal for constant head fuel systems in motor cars where excess fuel passes back to the tank. Seems to be standard these days.
This is a good idea as it means the only part of your system that's at a silly pressure will be a single valve at the tank input. It's no longer popular in UK but it was the norm for non-drinking water systems in the past - to protect a complicated hot water system from stress and to maintain a reliably constant pressure for simple shower systems. As for cold water, the only snag with an upstairs 'cold tank' to store water is hygiene and spiders. A separate feed for the kitchen, direct from the mains, would be normal.The old fashioned arrangement used a slide valve, operated by a floating (brass) ball with a hard rubber pad over a (brass) orifice. Those used to last for a hundred years, sometimes needing a new rubber pad after twenty years or so. (Note the old fashioned, fail safe, syphon operation in the figure.)That type is ideal for constant head fuel systems in motor cars where excess fuel passes back to the tank. Seems to be standard these days.
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
sophiecentaur said:
This is a good idea as it means the only part of your system that's at a silly pressure will be a single valve at the tank input. It's no longer popular in UK but it was the norm for non-drinking water systems in the past - to protect a complicated hot water system from stress and to maintain a reliably constant pressure for simple shower systems. As for cold water, the only snag with an upstairs 'cold tank' to store water is hygiene and spiders. A separate feed for the kitchen, direct from the mains, would be normal.
For information, I have no cold water tank. Mains (at high pressure) supplies cold water at all taps and the input to a 'combi' boiler. The combi boiler then supplies hot water to taps and also incorporates a completely separate water-circuit for central heating.
One consequence is that the (non-central-heating) plumbing is subject to the full mains supply pressure unless a pressure reducing valve is used.
How to Choose the Right Customized Trunnion Ball Valve?For information, I have no cold water tank. Mains (at high pressure) supplies cold water at all taps and the input to a 'combi' boiler. The combi boiler then supplies hot water to taps and also incorporates a completely separate water-circuit for central heating.One consequence is that the (non-central-heating) plumbing is subject to the full mains supply pressure unless a pressure reducing valve is used.
For more pressure controller valveinformation, please contact us. We will provide professional answers.
Explore more:INDUSTRIAL BASKET STRAINER
sophiecentaur
Science Advisor
Gold Member
- 29,332
- 7,067
Houses are smaller. Roof spaces are smaller and you can&#;t have a tank in a flat. So a system that&#;s really quite elegant and low tech is just not used much.
Having your own tank would be great where supplies are uncertain or where gauge pressure can become negative.
Old can be good.
pbuk
Science Advisor
Homework Helper
Gold Member
- 4,704
- 2,970
Steve4Physics said:
Most PRVs only reduce the dynamic pessure (while the water is flowing) but not the static pressure (when there is no flow).
Steve4Physics said:
Here in the UK it seems we use pressure reducing valves (for dynamic pressure only)
I don't know where you are getting your information from, pressure reducing valves approved for domestic installation in the UK where they are required control both static and dynamic pressure. As you say there would be no point in only controlling dynamic pressure; they are most often required to prevent your hot water cylinder from overpressure. Typically (from memory) the cylinder will have a relief valve set at 7 bar and the incoming mains is regulated down to 3 bar.
I don't know where you are getting your information from, pressure reducing valves approved for domestic installation in the UK where they are required control both static and dynamic pressure. As you say there would be no point in only controlling dynamic pressure; they are most often required to prevent your hot water cylinder from overpressure. Typically (from memory) the cylinder will have a relief valve set at 7 bar and the incoming mains is regulated down to 3 bar.
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
https://images.app.goo.gl/UVGHCNQ9ot8A5Xpn6
A quick Google turned up this image. Common setup in the USA.
berkeman
Mentor
- 67,901
- 21,342
Averagesupernova said:
https://images.app.goo.gl/UVGHCNQ9ot8A5Xpn6
A quick Google turned up this image. Common setup in the USA.
Hey, how did you do that? Clicking on the link takes me to the image plus shows links to the original website where Google Images found it. Neat!
Hey, how did you do that? Clicking on the link takes me to the image plus shows links to the original website where Google Images found it. Neat!
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Averagesupernova said:
https://images.app.goo.gl/UVGHCNQ9ot8A5Xpn6
A quick Google turned up this image. Common setup in the USA.
Do you know if pressure reducing valves in the USA are required to control static pressure, or dynamic pressure or both?
Do you know if pressure reducing valves in the USA are required to control static pressure, or dynamic pressure or both?
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
Four screenshots. Android . You can see what I typed in. Hit the image you want, click the upper right circle with three dots, option comes up to share. Copied to clipboard, pasted into pf page. You click on the link.
I'll post some screenshots that should explain it.Four screenshots. Android . You can see what I typed in. Hit the image you want, click the upper right circle with three dots, option comes up to share. Copied to clipboard, pasted into pf page. You click on the link.
Last edited: Feb 1,
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Averagesupernova said:
I'll post some screenshots that should explain it.
Thanks
Thanks @Averagesupernova . But none of the images say if the valves are controlling static pressure, dynamic pressure or both.
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
Steve4Physics said:
Thanks @Averagesupernova . But none of the images say if the valves are controlling static pressure, dynamic pressure or both.
What the image is calling a pressure reducing valve caps the pressure at an amount that is determined by how far in the bolt with the locking nut is turned. If the valve works correctly the pressure will NEVER exceed the set point. Of course if there is a lot of demand, the valve will fall short and not allow enough flow to maintain pressure. But, many other things dictate this as well such as pipe size, length, etc. It is commonly known as a pressure regulator.
What the image is calling a pressure reducing valve caps the pressure at an amount that is determined by how far in the bolt with the locking nut is turned. If the valve works correctly the pressure will NEVER exceed the set point. Of course if there is a lot of demand, the valve will fall short and not allow enough flow to maintain pressure. But, many other things dictate this as well such as pipe size, length, etc. It is commonly known as a pressure regulator.
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
https://en.wikipedia.org/wiki/Pressure_regulator
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Averagesupernova said:
What the image is calling a pressure reducing valve caps the pressure at an amount that is determined by how far in the bolt with the locking nut is turned. If the valve works correctly the pressure will NEVER exceed the set point
For information, note that's only true for pressure reducing valves that control both static (non-flow) and dynamic (flow) pressures.
Another type only controls dynamic (flow) pressure. So when the flow stops, the (now static) pressure rises to whatever the inlet pressure is.
For information, note that's only true for pressure reducing valves that controlstatic (non-flow) and dynamic (flow) pressures.Another type only controls dynamic (flow) pressure. So when the flow stops, the (now static) pressure rises to whatever the inlet pressure is.
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
Apparently you haven't accepted the definition of a pressure regulator.
Steve4Physics
Homework Helper
Gold Member
- 2,317
- 2,171
Averagesupernova said:
Apparently you haven't accepted the definition of a pressure regulator.
I&#;m simply using the terminology I&#;ve read. For example:
https://uk.rs-online.com/web/generalDisplay.html?id=ideas-and-advice/pressure-reducing-valves-guide
says:
&#;Many types of PRV achieve this role under both flow and no-flow conditions. Models that can do this are known as static PRVs or drop-tight valves. They are designed to guard against gradual pressure creep when there is no demand on the outlet side (i.e. when the water is at rest, or static)&#;
&#;
Models that only offer this function under flow conditions, and thus do not prevent pressure creep when there is no demand, are known as dynamic PRVs&#;&#;
I&#;m not too bothered by the name. My question was (and still is): what is the point of a &#;dynamic PRV&#; (or whatever other names are used) since it can&#;t protect against high static pressure?
I&#;m simply using the terminology I&#;ve read. For example:says:I&#;m not too bothered by the name. My question was (and still is): what is the point of a &#;dynamic PRV&#; (or whatever other names are used) since it can&#;t protect against high static pressure?
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
Steve4Physics said:
I&#;m not too bothered by the name. My question was (and still is): what is the point of a &#;dynamic PRV&#; (or whatever other names are used) since it can&#;t protect against high static pressure?
My point is that if you are going to get hung up on words and names then maybe you need to examine the inner workings of such valves. We can imagine how a valve of a certain type may be used, and that could satisfy you, or maybe not if you can't imagine such an application. I also wonder if you realize how flow and pressure are closely related. I can stick an orifice in my cold water line on my washing machine because when I set the washer to warm it still is too cold for my taste. I can call it a static pressure reducing valve or a flow reducing valve. Either is correct and will accomplish what I want. Admittedly using an orifice and calling it a pressure reducing valve is taking a few liberties.
-
BTW, this talk of static vs dynamic pressure reducing valves is confusing. If there is a formal definition, I would think that a dynamic anything would be more complex than static, so I have assumed in this thread that a static valve would be the equivalent of a flow reducer as implied above.
My point is that if you are going to get hung up on words and names then maybe you need to examine the inner workings of such valves. We can imagine how a valve of a certain type may be used, and that could satisfy you, or maybe not if you can't imagine such an application. I also wonder if you realize how flow and pressure are closely related. I can stick an orifice in my cold water line on my washing machine because when I set the washer to warm it still is too cold for my taste. I can call it a static pressure reducing valve or a flow reducing valve. Either is correct and will accomplish what I want. Admittedly using an orifice and calling it a pressure reducing valve is taking a few liberties.BTW, this talk of static vs dynamic pressure reducing valves is confusing. If there is a formal definition, I would think that a dynamic anything would be more complex than static, so I have assumed in this thread that a static valve would be the equivalent of a flow reducer as implied above.
sandy stone
- 231
- 148
So, what the OP refers to as a "static pressure reducing valve" is what I would call a pressure regulator with positive shutoff - obviously what you want in a domestic water system when you are trying to protect a water heater when there is no water demand in the house. If the shutoff were not positive then of course with no demand, the pressure downstream of the valve would eventually rise to the supply pressure - as referenced in the quote in post #26.
Pressure regulators without guaranteed positive shutoff, "dynamic pressure reducing valves", are common in industry, where a continuous process requires a certain set pressure, and a period of no demand would be very unusual, i.e. a process shutdown.
pbuk
Science Advisor
Homework Helper
Gold Member
- 4,704
- 2,970
Averagesupernova said:
BTW, this talk of static vs dynamic pressure reducing valves is confusing. If there is a formal definition, I would think that a dynamic anything would be more complex than static, so I have assumed in this thread that a static valve would be the equivalent of a flow reducer as implied above.
That is the wrong assumption. A flow reducer is a flow reducer, it does not regulate any fixed downstream pressure, and it is not a valve so it is not a pressure reducing valve at all.
Dynamic pressure in a pipe is the pressure when a fluid is flowing in the pipe. A dynamic PRV attempts to maintain downstream pressure at a fixed value as the flow rate increases (but can only do this for a certain range of flow rates). Static pressure in a pipe is the pressure when no fluid is flowing in the pipe. A static PRV closes completely to maintain downstream pressure at a fixed value regardless of upstream pressure (but can only do this for a certain range of upstream pressures).
In many industrial applications it is only necessary to control dynamic pressure but valves used in such situations will not close fully when flow stops and are called dynamic PRVs because they only regulate dynamic pressure. In a domestic installation PRVs are used to protect the domestic plumbing (and particularly unvented hot water vessels) from the utility supply pressure and so it is absolutely essential that the PRV regulates pressure whether there is flow (dynamic) or not (static) and they are therefore sometimes called static PRVs, although often the word static is omitted because these are the only PRVs that are manufactured for these installations.
That is the wrong assumption. A flow reducer is a flow reducer, it does not regulate any fixed downstream pressure, and it is not a valve so it is not a pressure reducing valve at all.Dynamic pressure in a pipe is the pressure when a fluid is flowing in the pipe. A dynamic PRV attempts to maintain downstream pressure at a fixed value as the flow rate increases (but can only do this for a certain range of flow rates). Static pressure in a pipe is the pressure when no fluid is flowing in the pipe. A static PRV closes completely to maintain downstream pressure at a fixed value regardless of upstream pressure (but can only do this for a certain range of upstream pressures).In many industrial applications it is only necessary to control dynamic pressure but valves used in such situations will not close fully when flow stops and are called dynamic PRVs because they only regulate dynamic pressure. In a domestic installation PRVs are used to protect the domestic plumbing (and particularly unvented hot water vessels) from the utility supply pressure and so it is absolutely essential that the PRV regulates pressure whether there is flow (dynamic) or not (static) and they are therefore sometimes called static PRVs, although often the word static is omitted because these are the only PRVs that are manufactured for these installations.
Averagesupernova
Science Advisor
Gold Member
- 4,577
- 1,319
Averagesupernova said:
My point is that if you are going to get hung up on words and names then maybe you need to examine the inner workings of such valves. We can imagine how a valve of a certain type may be used, and that could satisfy you, or maybe not if you can't imagine such an application. I also wonder if you realize how flow and pressure are closely related. I can stick an orifice in my cold water line on my washing machine because when I set the washer to warm it still is too cold for my taste. I can call it a static pressure reducing valve or a flow reducing valve. Either is correct and will accomplish what I want. Admittedly using an orifice and calling it a pressure reducing valve is taking a few liberties.
I'm not going to argue with you
It should be obvious that in this thread I'm not too hung up on what stuff is called. At least in this thread. Otherwise I can certainly be a stickler on definitions. I thought the OP was confused enough that it warranted a suggestion on studying how these devices work. I was not convinced that the OP fully understood how flow and pressure are related.I'm not going to argue with you @pbuk since you what you have said is correct. The word valve certainly does imply that it has adjustable properties and obviously an orifice has no adjustable properties. And yes, I admit my useage of static and dynamic are reversed in this case. I won't edit my posts. It would simply cause more confusion.
Related to Question about Pressure Reducing Valves
1. What is a pressure reducing valve?
A pressure reducing valve is a type of valve that is used to control and reduce the pressure of a fluid or gas in a system. It works by automatically adjusting the flow of the fluid or gas to maintain a consistent and safe pressure level.
2. How does a pressure reducing valve work?
A pressure reducing valve works by using a diaphragm or piston mechanism to sense the pressure of the fluid or gas and adjust the valve opening accordingly. When the pressure reaches a certain level, the valve will close to reduce the flow, and when the pressure drops, the valve will open to allow more flow.
3. What are the benefits of using a pressure reducing valve?
The main benefit of using a pressure reducing valve is that it helps to maintain a safe and consistent pressure level in a system. This can prevent damage to equipment, reduce the risk of leaks or ruptures, and improve the overall efficiency of the system.
4. Where are pressure reducing valves commonly used?
Pressure reducing valves are commonly used in a variety of industries, including water supply and distribution, oil and gas, chemical processing, and HVAC systems. They can also be found in residential and commercial buildings to regulate water pressure.
5. How do I choose the right pressure reducing valve for my application?
When choosing a pressure reducing valve, it is important to consider factors such as the type of fluid or gas being controlled, the desired pressure range, and the flow rate. It is also important to select a valve that is compatible with the material and conditions of your system. Consult with a professional or refer to manufacturer specifications for guidance in selecting the right valve for your specific application.
If you are looking for more details, kindly visit ball in cage valve.
Comments
Please Join Us to post.
0