Pressure regulator?

[Secondmanup]

I had an epiphany. We all use pressure regulators to keep our incoming water pressure from 40-60 lbs approx. too much and you can blow a connection. Ok. Understood. Here’s the prob I have with the industry standard on inline pressure regulators. It’s strictly impossible for that device to reduce water pressure in a static mode. Mine is a pass through device with a simple reduction in orifice in the middle of the device. The problem is, if let’s say on the incoming side you have 100 psi on the outgoing side, there is simply 100 psi on the other. In a static situation the pressure equalizes. So simply put, your internal RV plumbing is still holding back 100 psi. The only possible way this device could reduce psi is in a dynamic situation or, when water is actually being used in the RV. It uses a gated or reduced orifice to decrease flow and uses friction to dissipate psi or energy. The point of this is to generate discussion. I understand hydraulics and know this to be very basic. I’m open to the fact I’m missing something. Help me out or are we just using products because it’s what we all do and follow each other? This seems to be a massive mission the industry.

[TitanMike]

In theory the regulator limits the downstream pressure to whatever the regulator is set for. There should be no higher pressure on the use side. That is unless the water on the use side warms up and expands. In most situations there is enough periodic use to reduce the pressure to near the set pressure on the regulator.

Ideally there should be an expansion tank to take the strain off "connections" when system water heats up and can't bleed back into the supply side.

[eye95]

I am not very knowledgeable in this area. So, pardon me if this question sounds ignorant.

In the dynamic situation, 100 psi on the supply side is reduced to 60 psi on the RV side, but in the static situation, no water running, the pressure will be 100 on both sides? Does that mean when you shut off a faucet, the pressure on the RV side will build up from 60 until it reaches 100? In other words, water will continue to pass through the regulator until the pressure on both sides equalizes?

If so, this is not good news!

[14apex]

Agree. ...probably better that we utilize something like this one?

[Secondmanup]

I hear you. In theory yes. However it is physically impossible for the pressure to be reduced in a static, or non moving setting. The hose bib is on, but no water is bring used in the RV. Think about it if air was being used. If the device, like mine, just has a narrow restriction in the middle, the pressure is absolutely no different on one side vs the other. This is just pure fact.

[Secondmanup]

No different unless it is moving. I pump water in my career. I’ve got a good handle on it.

[Secondmanup]

It just makes me think we do things just because. However after thinking about it...it’s not possible to actually work. A pressure regulator that is designed for a house is different. It does handle pressure in a static position. It’s designed much differently.

[14apex]

Originally Posted by TitanMike

In theory the regulator limits the downstream pressure to whatever the regulator is set for. There should be no higher pressure on the use side. That is unless the water on the use side warms up and expands. In most situations there is enough periodic use to reduce the pressure to near the set pressure on the regulator.

Ideally there should be an expansion tank to take the strain off "connections" when system water heats up and can't bleed back into the supply side.

Agree. The last two RVs we've had did not come with an expansion tank, so I installed right away. In addition to the improvement when using the onboard tank/pump for water, it sure seems that the "give" it allows for varying water pressure is a nice added feature to help prevent blow-outs(?).

[TitanMike]

Originally Posted by Secondmanup

I hear you. In theory yes. However it is physically impossible for the pressure to be reduced in a static, or non moving setting. The hose bib is on, but no water is bring used in the RV. Think about it if air was being used. If the device, like mine, just has a narrow restriction in the middle, the pressure is absolutely no different on one side vs the other. This is just pure fact.

Have you actually measured the pressure on the use side?

I have a few of "those type" regulators and mine have a spring and washer valve inside that's set for a single pressure. I've never had the inside pressure creep up but my gripe with this type is that the entire regulation mechanism is contained within the flow path and when I shower I get more dribble than spray.

A couple years ago I changed to the same type regulator as 14apex posted.


FWIW, here's a diagram of an inline pressure regulator very similar to what we see in the RV world. Once the pressure on the use size rises to the pressure set by the spring, both water pressure on the use side AND the spring close off the flow and it doesn't begin again until pressure on use side drops.

[Secondmanup]

Yes, true if a pass through pressure reducer was used. You understand what I’m saying. Also yes, it would build back up to 100 psi,
I Just saw a pic posted of a pressure regulator that mimics what your house regulator does. This would handle static pressure.

[Secondmanup]

14apex nailed it. This is what is needed to handle static pressure.

[Secondmanup]

Tristanmike I haven’t but I am going to build a testing device. Thank you for the diagram.

[Secondmanup]

Titanmike
In the description of this valve diagram, does this still provide regulation though in a static situation or only dynamic. I get how it’s working but still unsure. Like I said I’ll build a tester.

[Secondmanup]

Well in all fairness I did find a video of a guy testing online pressure regulators. By his testing it does appear it holds the pressure at the limit set while in a static setting. The construction of these are then much different than I thought. Titanmike’s diagram showed that. All this said I like to hash out info on these topics. One thing I did find is it appears the inline vs diaphragm versions yield less flow as per people’s experience. I’ll prob buy the diaphragm type.

[Adrian Gordon]

Originally Posted by Secondmanup

I hear you. In theory yes. However it is physically impossible for the pressure to be reduced in a static, or non moving setting. The hose bib is on, but no water is bring used in the RV. Think about it if air was being used. If the device, like mine, just has a narrow restriction in the middle, the pressure is absolutely no different on one side vs the other. This is just pure fact.

Assuming that your original assumption of the design of the pressure reducer was correct, simply a narrow restriction in the middle, wouldn't it work as a venturi, reducing pressure within the narrowed section of the device as the velocity of the water increased and then allowing the velocity to slow as the water exited the restriction thus increasing the pressure again?

[Scrapper]

Originally Posted by Secondmanup

I had an epiphany. We all use pressure regulators to keep our incoming water pressure from 40-60 lbs approx. too much and you can blow a connection. Ok. Understood. Here’s the prob I have with the industry standard on inline pressure regulators. It’s strictly impossible for that device to reduce water pressure in a static mode. Mine is a pass through device with a simple reduction in orifice in the middle of the device. The problem is, if let’s say on the incoming side you have 100 psi on the outgoing side, there is simply 100 psi on the other. In a static situation the pressure equalizes. So simply put, your internal RV plumbing is still holding back 100 psi. The only possible way this device could reduce psi is in a dynamic situation or, when water is actually being used in the RV. It uses a gated or reduced orifice to decrease flow and uses friction to dissipate psi or energy. The point of this is to generate discussion. I understand hydraulics and know this to be very basic. I’m open to the fact I’m missing something. Help me out or are we just using products because it’s what we all do and follow each other? This seems to be a massive mission the industry.

That is what happens when you use a flow regulator and not a pressure regulator. Flow restriction devices are some times sold as a regulator but as you found out it only does the job it's designed to do while water is flowing through it. Once the water stops flowing the downstream pressure builds up to match the supply pressure.

We used a variable speed water pump that would speed up as the main motors started drawing more amps to shred cars because flow restricters did not stop the flow of water when it wasn't needed.

[eye95]

Is this why you get a burst from a flow-restricted shower head when you first hit the button to turn the shower head back on? Because the pressure after the flow-restrictor has slowly increased to match the pressure ahead of the flow-restrictor?

Another question: We purchased water pressure protection from Walmart. How can we tell if it is simply restricting the flow when water is flowing or is protecting us from high water pressure when the water is static?

Thanks in advance.

[NavyLCDR]

Originally Posted by eye95

Is this why you get a burst from a flow-restricted shower head when you first hit the button to turn the shower head back on? Because the pressure after the flow-restrictor has slowly increased to match the pressure ahead of the flow-restrictor?

Another question: We purchased water pressure protection from Walmart. How can we tell if it is simply restricting the flow when water is flowing or is protecting us from high water pressure when the water is static?

Thanks in advance.

https://www.homedepot.com/p/Water-So...YKKQ&gclsrc=ds

[TitanMike]

Originally Posted by eye95

Is this why you get a burst from a flow-restricted shower head when you first hit the button to turn the shower head back on? Because the pressure after the flow-restrictor has slowly increased to match the pressure ahead of the flow-restrictor?

Another question: We purchased water pressure protection from Walmart. How can we tell if it is simply restricting the flow when water is flowing or is protecting us from high water pressure when the water is static?

Thanks in advance.

On your first paragraph, that "burst" in the shower can also be caused by the cold water that came into the water heater is heated and expands. If it's only a short burst that would be my thought.

If you want to know if your "regulator" is holding proper pressure in your RV just invest in a cheap pressure gauge. Install one of these:



Put a tee in a water line under the kitchen sink or in your wet bay if you have one. Standard 1/4" NPT fitting so they're available just about everywhere.

Less than $10 at Home Depot. Less than $8 on Amazon.

Nice thing about having a gauge installed on the actual plumbing lines is you can see what pressure your water pump is delivering. No can do with the outside gauge mounted inline with your city water line.

[eye95]

Good point about the inside gauge showing the pressure even when using the pump to create pressure.

Has anyone invented a gauge that will talk to an iPad or an iPhone? It would save having to go look at the gauge. More importantly, you could configure the app to contact you if there is a “pressure event”.