Pressure relief valves vs. pressure regulators

I recently switched departments and went from apparatus equipped with pressure regulators to apparatus with pressure relief valves. I think that i like the pressure regulators more (alot more) but this may be becuase I have spent so much more time with them and therefore am more comfortable with them. What I am looking for is for folks to compare and contrast the advantages and disadvantages of each. Most of the people I currently work with have only used pressure relief valves and can't justify their use over pressure regulators. To me the pressure relief valve is old technology. With the pressure regulator the changes in engine rpm as lines are open and closed give me as an operator a much clearer idea of what is going with my lines. This combined with the engines ability to throttle engine speed down when transferring from tank water to the hydrant make the pressure regulator the obvious choice when specing new apparatus. Not to mention the ability to throttle up to support additional lines as they are placed in service.I would appreciate any info.

We spec'd our last three engines with both. We have pressure governors which are great when operating off the tank and transferring to the hydrant, and work good when the hydrant pressures aren't exceedingly high and/or you're flowing big water. The pressure relief valves (we have Hale TPM's) are much better on hydrants with obscene pressures; our hydrant pressures range from about 60 psi to over 225 psi. The TPM will relieve internally to a point, then can dump the excess pressure to the ground to prevent the guys on the lines from getting knocked over. We train to use both. You have to be careful when using both, as they can work against each other. But it's a nice benefit when both are set correctly, the engine throttles up and down as needed, and if the engine is at an idle and the pressure is still too high, the TPM dumps to protect the guys on the hoselines.

The relief valve that you mentioned, was that an intake relief valve or discharge? If it is a discharge do you also have an intake relief valve on the punp intake valve?

the key with an electronic governer is that it can only drop the pump to idle speed of the engine. As mentioned before high hydrant pressure working in relay has the potential to gennerate pressures that a governer can not compensate for.
As for relief valves these require operator input. when one line is shut down the operator has to throtle the engine back to reduce the pump pressure and close the relief valve. If this is not done it is possible to "overrun" the relief valve. Todays 500hp engines can do this with out blinking.

If using both set your relief valve just above the gov. setiing so they do not do battle. But most of all always use some sort of pressure relief/ adjusting devise for the safety of the firefighter and the equipment.

DC STARTED USING ELECTRONIC PRESSURE REGULATORS ON THEIR NEW RIGS A COUPLE YEARS AGO (HALE TPM's), AND I LOVE THEM. AS A TECHNICIAN, THEY GIVE ME A BETTER FEEL OF KNOWING WHATS GOING ON IN SIDE THE BUILDING. WHEN I FIRST CAME ON TO THE DEPARTMENT SOME 16 YEARS AGO, WE USED PRESSURE RELIEF VALVES THAT WAS A NIGHTMARE... HALF THE TIME THEY DID'NT PERFORM THE WAY THEY WERE SUPPOSED TO, SO THE TECHNICIAN HAD TO ALWAYS STAY AT THE PANEL TO MAKE SURE PRESSURES DIDN'T SURGE WHEN THE HYDRANT WAS CHARGED OR WHEN THE PIPE WAS OPENED OR CLOSED.
THE NEW TECHNOLOGY THE PRESSURE REGULATOR HAS GIVEN ME MAKES MY JOB A LOT EASIER!!

- BE SAFE! -