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  #1   IP: 98.108.228.97
Old April 20th, 2011, 09:14 AM
johnlvs2run johnlvs2run is offline
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Default how to reduce the pressure to the kitchen faucet

How can I reduce the water pressure to the kitchen faucet?

The pressure has to be 70 psi coming out of the wall, to run the RO system, so just turning down the valve is not an option.

That gives me an idea though, I could put a straight valve on the end of the first one.

However, is there some type of reducer that I could put on the end of the valve, for example that would reduce the pressure from 70 to 20?
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  #2   IP: 130.76.32.217
Old April 20th, 2011, 04:10 PM
suemarkp suemarkp is offline
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Quick and dirty way: Find a smaller diameter pipe feeding the sink, or put in some type of restrictive fitting (adapt it down to a 1/4" or 1/8" fitting).

Otherwise, since it appears that your RO filter is using the sink shutoff too, you'd need to turn off your water main and then replace that shutoff with a TEE. Install one shutoff to the RO filter and add a second one to feed the sink. Turn down accordingly.

What about the hot water -- will closing the hot shutoff more help give the temperature and pressure balance you're looking for after you reduce the cold?

Why do you want to reduce all the way to 20 PSI? Are you blowing seals in the faucet?
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  #3   IP: 74.106.208.60
Old April 20th, 2011, 04:46 PM
johnlvs2run johnlvs2run is offline
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Thank you for your reply.

The hot water is turned off in the kitchen.

Quote:
Originally Posted by suemarkp View Post
Why do you want to reduce all the way to 20 PSI?
That was just a guesstimate. The faucet used to be 4 gpm and still had plenty of pressure. Now it's .5 gpm.

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Originally Posted by suemarkp View Post
Why do you want to reduce all the way to 20 PSI? Are you blowing seals in the faucet?
Yes, it blew off the gooseneck this morning.
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  #4   IP: 24.19.180.107
Old April 20th, 2011, 08:17 PM
suemarkp suemarkp is offline
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If it is blowing fittings off, then using a reducer won't work. Even with a pin hole, the pressure will work its way up to the static system pressure when you're not using any water. I think all you can do in this case is to install a pressure reducer, and you'll still need the TEE fitting since you don't want to reduce pressure to your RO filter.

Pressure regulators aren't cheap. The cheapest ones I've seen are for RV's because RV parks are notorious for high water pressure. However, they tend to have fixed outputs of 40 to 60 PSI. You probably want an adjustable one:

http://www.freshwatersystems.com/p-6...term=P60-M1-4B
http://www.isopurewater.com/-p-2441.html
http://www.westsidewholesale.com/plu...ronze-3-4.html
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  #5   IP: 74.106.208.60
Old April 20th, 2011, 10:21 PM
johnlvs2run johnlvs2run is offline
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Quote:
Originally Posted by suemarkp View Post
If it is blowing fittings off, then using a reducer won't work. Even with a pin hole, the pressure will work its way up to the static system pressure when you're not using any water. I think all you can do in this case is to install a pressure reducer, and you'll still need the TEE fitting since you don't want to reduce pressure to your RO filter.
That is interesting. Are you sure about that? When I blow through a restricted breathing device (piece of pvc with ball valve), the pressure at the end is very little, even covering it up with my hand. LIkewise it seems that a reduced volume in the line would reduce the pressure per volume on the faucet.

Thank you for the links.

There is a tee fitting connected after the valve, then the line to the faucet is connected from the tee, and a smaller line goes to the RO system.
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  #6   IP: 199.200.27.7
Old April 21st, 2011, 02:46 PM
HooKooDooKu HooKooDooKu is offline
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Quote:
Originally Posted by johnlvs2run View Post
That is interesting. Are you sure about that? When I blow through a restricted breathing device (piece of pvc with ball valve), the pressure at the end is very little, even covering it up with my hand. LIkewise it seems that a reduced volume in the line would reduce the pressure per volume on the faucet.
You are talking about the difference is static v dynamic pressure.

When water is flowing through a pipe/hose/tubing, the pressure at the end of the pipe is lower than the pressure at the start of the pipe. This is basically caused by "friction" between the water and the pipe. In the case of a valve or other restriction, the "friction" increases significantly and drastically lowers the pressure.

But when water is NOT flowing, the pressure inside the pipe becomes the same everywhere in the pipe, regardless of the size of any one section of the pipe.

A pressure regulator works by being a dynamic constriction that changes in size based on how much water is flowing through the regulator. As more water is needed, the constriction opens. As less water is needed, the constriction gets smaller. The constriction keeps changing so that the outlet pressure remains at a set point (usually around 50psi) to the point that it closes when flow reaches zero.

While I have no experience with RVs, in homes, the rule I've heard is that the water pressure inside your home should not exceed about 50 psi. If it does, then you need to install a regulator at the point the water line enters the home. Most regulators have a set screw that allows you to adjust the outlet pressure to a desired level, however, there needs to be a 15 psi pressure differential between the incomming pressure and the out going pressure.

While I don't know if anything can be found suitable for an RV, I've seen (and used in irrigation) fixed pressure regulators. Usually these are made of PVC and are pre-set to 25, 30, 40, or 50 psi (depending upon which you buy) and work with pressures upto 150psi. However, these PVC models usually have a cya disclaimer stating that they shouldn't be used with constant pressure (i.e. they are usually used in irrigation and are supposed to be installed AFTER irrigation valves).

However, if your situation is that you have an RV that you connect to an outside water source through some sort of hose, and you're having pressure problems, I would think something could be rigged up with one of thes PVC pressure regulators connected to some hose threaded connectors you could put inline with the hose that feeds an RV.
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  #7   IP: 98.108.245.41
Old April 21st, 2011, 02:55 PM
johnlvs2run johnlvs2run is offline
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Quote:
Originally Posted by HooKooDooKu View Post
But when water is NOT flowing, the pressure inside the pipe becomes the same everywhere in the pipe, regardless of the size of any one section of the pipe.
But that does not increase the reduction in flow. For example if you have a .5 gpm aerator on a faucet, it doesn't suddenly become 4 gpm just because it's been off for awhile. The same principle applies to the outlet from the wall.

Quote:
Originally Posted by HooKooDooKu View Post
in homes, the rule I've heard is that the water pressure inside your home should not exceed about 50 psi. If it does, then you need to install a regulator at the point the water line enters the home. Most regulators have a set screw that allows you to adjust the outlet pressure to a desired level
This is for a house, not RV. I've not seen a regulator like that, unless it's in the meter box. I will check. The 65 psi is good for the RO system.

Quote:
there needs to be a 15 psi pressure differential between the incomming pressure and the out going pressure.
Do you mean the incoming pressure needs to be 70 to reduce it to 55, or 65 to reduce it to 50?

Here is an example of the type of flow restrictor that I'm looking for.


Last edited by johnlvs2run : April 21st, 2011 at 02:59 PM.
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  #8   IP: 199.200.27.7
Old April 21st, 2011, 03:45 PM
HooKooDooKu HooKooDooKu is offline
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Quote:
Originally Posted by johnlvs2run View Post
Do you mean the incoming pressure needs to be 70 to reduce it to 55, or 65 to reduce it to 50?
At a minimum... correct.

The typical brass regulator I've seen for residential application comes with a set-screw you use to set the outlet pressure. However, the outlet pressure can not be MORE than 15psi BELOW the inlet pressure (or what ever number the specifications say for the regulator - 15 psi minimum differential is what I recall seeing on my WATTS regulator for my home).

Quote:
Originally Posted by johnlvs2run View Post
But that does not increase the reduction in flow. For example if you have a .5 gpm aerator on a faucet, it doesn't suddenly become 4 gpm just because it's been off for awhile. The same principle applies to the outlet from the wall.
gpm is meaningless when the water is turned off. It's a basic principle of fluid dynamics that in a static system (where there is no water flow) the water pressure is the same everywhere. So in the case of the faucet, when there is no water flowing in your home, there is just as much pressure at the faucet handle as there is all the way back to your water meter (or pressure regulator).

But when water is flowing, the water pressure changes as it moves through the system. So if you have 70 psi at the meter, by the time the water flows through all the pipes in your house to get to the shower handle, the pressure might have dropped to 65 psi (depending upon the size and lenght of the pipes). Then if the water isn't turned on to full blast, the restriction of the faucet drops the pressure to perhaps 30 psi. Then as it hits the restrictor behind the shower head, perhaps it drops to 15 psi. The result is that just before the water exits the shower head, the water pressure is 14.99 psi (because it drops to zero the moment it exits the shower head... the water pressure turns into kenetic energy of the water moving through the air).

But when you turn the faucet handle off, the water pressure AFTER the handle (to the restrictor and shower head) fall to zero, and the pressure before the handle raises back upto 70 psi because the water isn't flowing through the pipes in your house.

Same thing happens at a kitchen sink. If the pressure at the water meter is 70 psi, then the pressure in the tubes that connect the water line to the faucet are at 70 psi, regardless of the size of a restrictor you place between the water line and tubes. The only exception would be a device such as a pressure regulator because the regulator completely closes before the outlet pressure goes above 50 psi (or what ever is it's set value).

So what suemarkp said still goes... it doesn't mater what sort of restriction you place in a pipe (excluding a closed restriction)... the pressure is the same on both sides of a restriction when ever the water is not flowing.


But simple bottom line from what I understand of general household plumbing... 50 psi seems to be the minimum standard everything is designed to handle. If your home has more than 50 psi comming into it, then you need to add a pressure regulator to your home so that the pressure inside your home isn't above 50 psi.
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  #9   IP: 173.238.37.130
Old April 21st, 2011, 05:16 PM
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You need a pressure reducing valve. Anything else is just a flow restrictor and as soon as you turn off the water the pressure will rise.
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  #10   IP: 98.108.245.41
Old April 21st, 2011, 05:36 PM
johnlvs2run johnlvs2run is offline
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Quote:
Originally Posted by joed View Post
You need a pressure reducing valve. Anything else is just a flow restrictor and as soon as you turn off the water the pressure will rise.
I am not convinced that an 1/8 inch diameter hole would have the same pressure times volume of water as does a hole that is 8 times bigger. In any case, that does not matter, because when the water is off, it is off. It is only when the water is on that this matters. The faucets all have ball valves that do great with turning the water off and on.

What I'd like to know, if anyone here knows, is where I can get the little stainless steel flow restrictors, as in the photo I posted above. I have found only one source and would like to do some comparative shopping.
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