Water Main Surge Relief Valve
Water Main Surge Relief Valve
(OP)
I am looking for information/manufacturers of surge relief valves to relieve water hammer from a 60" water main. Probably an 8" or 12" valve. I've tried searching the internet, but haven't been able to find anything specific to large water mains.
Thanks for any help.
Thanks for any help.





RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
BobPE
RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
A formal waterhammer study shouldbe used to size the devices.
The maximum velocity recommended through these valves is 12 m/s. The larger the unit the lower the maximum recommended velocity.
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RE: Water Main Surge Relief Valve
I was just told to start looking into surge relief valves, but I have now received more detailed information that we want a relief valve for the case of overall high pressure of the system (in case one of the valves from a high pressure to low pressure zone fails to respond) - so a pressure relief valve instead of surge relief valve.
I have been told that these valves are high maintenence. From what I've seen on manufactures websites are just annual visual and pressure checks. Have any of you had any experience one way or another?
Thanks
RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
The valves are quite complicated as you indicate, however, they are not used too frequently if the system works right!!! The valves must be looked at and cycled to make sure they are operational, but they usually dont need much replacement maintenance and are very reliable.
I am a little confused though from you posts, these valves work by the anticipation of a surge which is the high pressure wave arrival at the pump station. A transient starts with the low pressure wave upon pump shutoff at which time the vlves are closed as not to let air into the system which could magnify the problems. Prior to arrival of the high pressre positive wave, the valves open to waste water and reference the high pressure wave to atmosphere. These valves do nothing for this low pressure wave. If you want to control the negative or low pressure wave, a surge tank design will have to be placed into service.
Usually, the anticipation function of the valve is done using a regular low tech timer that opens the valve a pre determined period of time after pump shut down...
BobPE
RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
yes I know the valve, they should not open on the low pressure wave. The timer that starts the valve operation is set based upon system characteristics. I too have designed them into systems for years, albeit larger systems where mistakes of misdesign cannot be tolerated.
You are right though, transient wave propogation does not allow large volumes of water to move into or out of the pipe, but very small amounts do move in and out as a function of the wave pressure. Opening the surge anticipation valve on the low pressure wave will allo a movement into the pipe possibly magnifying the affects of the transient.
I have seen transient cycles from a single event last for minutes making several dozen cycles to dampen, its a crazy pehnomea.
BobPE
RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
I am working on a sewage pump station modification right now where they have surge anticipation valves. I need to make recommendations on their optimal timing and would like to undertand the rationale for why their premature opening causes problems. What is it about the air introduced that makes these things a problem?
It seems to me that they would act like a vacuum relief valve, except they are located in the pump station. Am I wrong?
RE: Water Main Surge Relief Valve
I have recently come across the Charlatte range of hydraulic dampeners and in my modelling of rising mains give the necessary mitigation of transients on difficult pipelines. Has anyone in this forum experience of using these devices on raw sewage applications?
One downside is that they are registered pressure vessels and thus require the routine maintenance and inspections that go with such units.( This may be different outside Australia). Your responses please.
In regards to surge anticipation valves they do work however if soneone fiddles with the pilot regulators or they become comntaminated then transsients will not be mitigated. They should have the same status as a relief valve in that they are a safety device. Therefore should be tested frequently, be sealed upon setting and not be capable of isolation unless redundancy is provided.
I recently visited a site where such a device had been disconnected from the header because the operator had never seen it work and couldnt be bothered checking it.
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RE: Water Main Surge Relief Valve
I will have a contractor install a set of them in the next couple of weeks where the air relief valves are regularly destroyed by collum separation. Will let you know.
Charlatte has been most helpful in evaulating and sizing the vessels.
Cannot get around the ASME code since it is not "just water"
Hydrae
RE: Water Main Surge Relief Valve
One presupposition that is not mentioned but important to know, the only possible way to help yourself is to act before the surge occurs by "anticipating" the surge. That is because a true surge or water hammer event moves much too fast for any known mechanical device to respond to, the speed of sound in water, 4,000 plus feet per second, which no valve made can possibly deal with.
Only other thing I got to say is that whoever suggested that the surge should be analyzed first is correct. Surge anticipators of any kind are not the best solution.
I always have a saying that is applicable here.
If you create a monster (surge) in the system, good luck trying to stop it.
Designing for a no pressure surge system is always superior to trying to respond to it once you have already created it.
PUMPDESIGNER
RE: Water Main Surge Relief Valve
1. Fast closing valves can be changed to slow or linear closing valves.
2. Sequenced shut downs so that no long run of pipe experiences valve closures near the end of the pipe run. If a valve is closed near the end, open another valve up close by at the same time or just before valve closure.
3. Modify pipe systems by completing a loop, adding pipe.
4. Reduce flow rates.
There are many possibilities, but really they all deal with the same things: surge is an inertial problem created by mass moving at velocity. Reduce the mass, reduce the velocity, reduce the time of closure.
Be creative and always attempt to change something in the mass, velocity, time of closure.
I assumed that air was not involved, because air is a whole other issue.
PUMPDESIGNER
RE: Water Main Surge Relief Valve
Evaluating the system conditions for selecting a pressure relief valve is easier than for surge. Going beyond the initial reaction to contact a valve rep is sometimes necessary, particularly for surge and in cases where damage to the pipe could develop. Pipeline collapse caused by negative pressures is a well documented problem. Computer numerical analysis software is available to evaluate the system for surge conditions. The Method of Characteristics is the numerical analysis used for surge conditions. Tullis, Univ of Utah has written books which focus on valves and transients; you may want to learn more on transient analysis from Wylie, Univ of Michigan, an authority on the application of the Method of Characteristics for hydraulic transients. Good Luck
RE: Water Main Surge Relief Valve
RE: Water Main Surge Relief Valve
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RE: Water Main Surge Relief Valve
What's different between Surge relief valve and Pressure relief valve? As I understand Surge relief valve is one set valves, it is incl. pilot valve, control valve, strainer, etc. but Pressuer relief valve only means one kind of pressure relief valve. is it right?
Thanks in advance.
RE: Water Main Surge Relief Valve
A pressure relief valve respondes to the upstream pressure, to releive pressure above a set value, there are two types
Direct acting such as on your hot water heater which vent pressure flow over a curve, venting a small amount when the pressure is just above the setpoint and venting a larger quanity when the pressure is a significant value over the setpoint.
Pilot control, which the pilot opens and closes the mainvalve until the setpoint value is achieved. the pilot control adjusts the mainvalve until the setpoint is acheived maintaining a constant pressure upstream of the valve.
A pressure relief valve can also be used as a backpressure valve also known as pressure sustaining valve, in this application the pilot controlled is preffered.
A surge relief sometimes called a surge anticipator has a complex pilot system that monitors for a sudden drop in pressure which preceeds the water comming back and opens the valve before the high pressure wave returns to the source and the valve vents the pressure, the pilot system contains several componets and is not easy to troobleshoot or tune. The surge anticipator will also act directly as a pressure relief, which is the control function that returns the valve to the closed position after an event.
All pilot operated valves need strainers on the pilot system for proper operation, the strainer can be a y type or an in the flow type.
Hydrae