Thread: Relief Valve question
05-18-2000, 04:15 PM #1Ward WatsonFirehouse.com Guest
Relief Valve question
Here's my question. Yesterday while training, I was exercising my relief valve. I set it at 160 psi, due to the fact that I was going to be pumping at around 150 psi. Everything was fine while I was on tank water, but when I switched over to a hydrant supply, my relief valve indicating light came on. The pressure from the hydrant was around 100psi. I checked to see if it was relieving, but it wasn't. After adjusting the pilot valve several times without any change I figured it must be in an electrical component. The pump is a Waterous two stage. Thanks in advance for any advice.
05-18-2000, 06:28 PM #2Capt. ZadaFirehouse.com Guest
How did you check to see if it was relieving?
05-18-2000, 06:38 PM #3Ward WatsonFirehouse.com Guest
Mainly by watching the main pressure gauge, and trying to listen for the rpm's to change.
05-19-2000, 02:47 PM #4wv-engineerFirehouse.com Guest
The releif valve should have been operating(open). The reason is you set it at 160psi from the tank. The pump from tank was developing 150psi, when you switched to hydrant with 100psi your pump was still develping 150psi. You now have 250psi(100 from hydrant and 150 from pump), ruffly, their is a little variable in this. This is why the relief valve needs set when the first line is charged.
To check this, do what you did in your posting agian. When you switch to hydrant and the releif valve opens, start turning the relief valve to increase the setting until it closes. It should go up to around 250psi, original EP from tank plus 150psi the pump in developing, with out changing the throttle.
05-20-2000, 04:06 PM #5Ward WatsonFirehouse.com Guest
I will try what you recommended. During the pumping operation I did make several adjustments with the pilot valve, without any change. Also, when I switched over from tank to hydrant water supply, I shut down my tank to pump valve prior to doing any of this. Thanks again, I will try it.
05-21-2000, 04:28 PM #6BIG PAULIEFirehouse.com Guest
I think I know what the problem is. Waterous relief valves operate in the net engine pressure range of 70 to 300 psi. Net engine pressure is the engine pressure developed totally from the horsepower from the engine in your apparatus such as in your tank water operation. When a positive pressure water supply is connected to your pump the engine pressure is now devloped from a combination of net engine pressure and hydrant pressure. In the case of your operation the overall engine pressure was 160 and the incoming pressure was 100. 160 minus 100 equals 60 which is your net engine pressure. At 60 psi net pressure your relief valve will not work.
05-26-2000, 02:27 PM #7tar@waterouscoFirehouse.com Guest
In reply to your question regarding the relief valve on your Waterous pump, our service department has the following recommendations. When you operate your Waterous discharge relief valve when being supplied by a hydrant, the lowest pressure your relief valve will open is 70psi + the hydrant pressure.
Example: If you have 100psi hydrant pressure, add 70psi for the relief valve and you will find the lowest relief valve opening pressure to be at 170psi.
In regards to your question about your relief valve indicating light coming on, you may have encountered one of the following conditions:
* The relief valve system itself could be
sticking when required to operate.
* The micro switch for the relief
valve indicating lights could be out of
adjustment. To assure the switch is in
adjustment follow this procedure;
A .015" feeler gauge placed between the
switch plunger and actuating rod will
light the "open" indicator, but the
insertion of a .010" gauge will not.
If you have any further questions, feel free to contact the Waterous Pumps Service Department at 651-450-5200.
Todd Rogers @ Waterous Co. Service Dept.
05-26-2000, 09:52 PM #8DDFirehouse.com Guest
Good diagnosis Paulie, it looks like the people at Waterous agree with you.
I appreciate Waterous giving the technical assistance. They are always be willing to help me when I have needed information.
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