Thread: Pump Questions
10-02-1999, 10:09 PM #1e33Firehouse.com Guest
Looking to understand the difference between pressure governors and relief valves and the workings of both. I am not too pump literate...so im just curious. Thanks in advance.
10-03-1999, 12:57 AM #2DDFirehouse.com Guest
Both pressure governors and relief valves prevent a buildup of pump pressure when a line or valve is gated down or shut off. Governors control the increase of Pump Pressure by reducing the engine RPMs to maintain a selected pump pressure. Relief valves open once a selected pressure is exceeded. They dump water back into the suction side of the pump or onto the ground. The dump valve on an intake used with large diameter hose (LDH) is an example of a simple relief valve. Spring pressure is used to keep the valve closed. Hydraulic pressure of the water pushes against the valve and forces the spring to compress. The valve opens and dumps water which reduces the pressure. The spring pressure may be adjusted by the means of a handwheel attached directly to the valve like on a Kunckle or Ross valve. Normally a remote device is located on an engine pump panel to adjust the pressure at which the relief valve opens. The operation of all discharge valve and nozzle gates needs to be slow enough to allow the pressure control system to operate and protect the water sytem, pump system, hose & you.
10-03-1999, 10:06 PM #3E7engineerFirehouse.com Guest
DD is correct. (if you don't mind, if I add some). Pressure Governers operate the throttle pon the engine. As more pressure is needed, the governer opens the throttle and the engine RPM's increase, increasing the pump pressure. The main problem that I have encountered, is that when you run out of water. The governer trys to compinsate by increasing the engine RPM. If there is no water to pump, the governer basiclly causes the engine to run away or go to full throttle. On the Pressure relief, it operates on the pump only. It does not control engine RPM. when too much pressure is noticed, it dumps the excess pressure back into the suction side of the pump or the tank.
10-09-1999, 11:09 AM #4ShakerPinesFDFirehouse.com Guest
.....but either way, if you don't pay attention to your pumper, you will do oodles of damage.
10-10-1999, 10:13 PM #5Dalmation90Firehouse.com Guest
The main problem that I have encountered, is that
when you run out of water. The governer trys to compinsate by
increasing the engine RPM.
Just like shock in a human...blood loss --> rapid pulse & low BP!
10-10-1999, 10:43 PM #6FF McDonaldFirehouse.com Guest
All of these things are nice to have on your pumper... but don't overlook the best piece of equipment that you can have, a trained Firefighter operating the pump from the pump panel!!!
10-25-1999, 09:19 PM #7Drive P17BFirehouse.com Guest
I think by what you are saying you are using the pressure governer or pressure relief valve when you are pumping from the tank, am I correct? The main reason you use either one is to control pressure fluctuations. On a tank I will only allow 1 line to be charged until I get a constant water source. The reason for this is that even with only one 1 3/4 line going you only have water for around 5 minutes of constant flow with a 500 gal. tankOf course depending on all the variables. I will only set up the pressure relief valve after I have 2 or more lines going and a hydrant. If you have a different opinion let me know
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