Loss of Pressure in Water Main 1

[Beantown89]

Will an air pressure relieve valve work to restore water pressure in a water main?

A service line running from the main going to a bathroom at a campground, keeps going offline at peak usage on the weekends. The bathmroom is most likely a high point in the water system elevation.

Should placement the air valve be in a vault, so it can't be tampered with?

 

[BigInch]

Sounds like its more of a flow and pressure deficiency at the source than a problem with air in the line. Even with air in the line, you shouldn't normally be having a problem restoring service to a bathroom as long as there is adequate supply pressure.

(At a youth camp put everything in a vault.)

http://virtualpipeline.spaces.msn.com

 

[Catcher66]

I agree that accumulation of air in the line should not prevent water from flowing from the tap as long as adequate pressure exists.

Protecting the equipment from vandalism should be considered, but placing the valve in a vault may create a potential cross connection. Ensure that the discharge point for the valve will not become submerged if the vault were to fill with water.

 

[redbridge]

If the bathroom is at the high spot then the fixtures will act as an air release valve.

What size is the service line? What is the length of the service line?

 

[gerhardl]

If you have or put a pressure gauge near or on the water main for the branch you can observe both 'normal' input pressure, and pressure at peak use.

At peak pressure you must at least have enough input pressure to overcome the height difference (1 bar for each 10 meters (1 bar plus for friction, plus for further downgoing inlet pressure because of added usage to already existing overuse)).

Air will only be sucked into your system if it is empty of water (not enough water pressure to feed the line, or drained at will) or under vacuum (not enough water pressure to feed the line to the top (main acting as a vacuum pump??)).

Air will splutter out together with the water at the tap as you open up the system with a tap if you have positive water pressure to reach the height of the outtake.

Note: Your concern for air as damping or stopping a system would be more valid for a waterborn heating system with radiators with very slow 'natural' circulation, totally closed, with top of radiators as 'air gatherers' when you start the system. But here also you will force out the air pockets if you locate the correct tap for air outlet at the local highpoints. This system is more sensitive for air as water pressure is very low, and local pockets and highpoints many.

 

[bimr]

What does this mean?

"keeps going offline at peak usage"

Are you trying to say that the water pressure drops?

 

[bimr]

If you are losing water pressure, then you need to increase your water pressure in the system or increase (or replace if plugged up) the size of the water service connection, or maybe both.

 

[BigInch]

probably no water

http://virtualpipeline.spaces.msn.com

 

[Beantown89]

Thanks for all your comments. The pipe that runs to the bathroom is a 2" PVC and this pipe does lose pressure on the weekends, when demand is high. But the pressure returns within 24 hours mysteriously, but only after the bathrooms are closed for a while.

The main water pipe which the 2" PVC connects to is a 6" Asbestos Cement Pipe. The 6" Asbestos Cement pipe is due to be replaced this fall, because it has supposed leaks.

So supply pressure is the issue compounded by numerous leaks which causes the pressure drop at the bathroom.

We are planning on installing a pressure gauge in the branch of the water main.

Thanks for input to all.

 

[BigInch]

Its simply not enough supply pressure and once pressure is lost, it apparently takes 24 hours or so for the system to repressure, probably overnight or something.

http://virtualpipeline.spaces.msn.com

 

[BigInch]

You might be able to solve the problem with a large pressure tank and booster pump, but then again you just might want to see what solutions (if any) come along with the upcoming replacement of the mainline.

http://virtualpipeline.spaces.msn.com

 

[vzeos]

If the water pressure returns slowly over a 24 hour period, this indicates that you have a restriction in the 2” line limiting its capacity. Apparently, what is happening is that the 2” line is able to pack to full pressure during off peak hours because the demand is less than the restriction capacity but during peak hours the demand is higher than the restricted capacity so it takes a long time to recover pressure. The first thing to do is to make sure that all valves in the line are fully open. Operate the valves to work loose any debris. Check meter, back flow preventer, strainers for clogging. Don’t discount the connection to the 6”, it could also be blocked. If you can measure the volume (say, cu ft per flush X # of flushes) of water drawn before loss of pressure, you can estimate how far upstream the restriction is.

 

[bimr]

You might want to check the fixtures in the bathroom as well. If you have the commercial grade sloan valves, the sloan valves will not shut off when the pressure is low. The sloan valves need a minimum water pressure to operate.

 

[TBP]

Is this system fed from a well? If so, you could simply have a case of the demand outstripping what the well can supply during peak periods.

 

[Beantown89]

The system is fed from a town water supply. All the gate valves, that were visible to inspectors, were checked to make sure in open position. I know atleast one gate valve was not operable. I don't know if the road box was broken or valve wouldn't turn. I'll check more into gate valve inspection notes.....