Does high discharge pressures hurt the engine/pump?

One characteristic that always gets brought up in low pressure hose(low fricition loss characteristics)and low pressure nozzle discussions is the fact that they save wear and tear on the apparatus engine and pump. I don't think this is an issue. Any thoughts?

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Permalink Reply by Paul Shapiro on July 31, 2011 at 11:50am

OK Ben and Paul. Let's get something straight. This forum , in my opinion is about learning and sharing ideas. It's not about stroking our own egos and slaming each other. I hope you will agree.My comments were totally geared toward striking up a debate. The comment about me being the best engineer came frome a friend that I haven't talked to in years.(I thought it was obvious that he was joking around). If you look back at my posts you will see that I did say that there was wear on the equipment even in the pressure operations that you have mentioned.I think what I will do is contact(again) the manufacturers and see what they have to say.

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Permalink Reply by Ben Waller on July 31, 2011 at 2:41pm

I did not slam anyone and I have no ego involved in this.

I did point out some referenced facts and what those facts infer to actual pump operations and pump testing.

I also pointed out that wear from driving an engine has nothing to do with relative pump wear between low-pressure and high-pressure pump operations, since no pumping is involved when driving engines that don't have pump-and-roll capability.

I have contacted a manufacturer (Waterous, who makes our engine and quint pumps) and have all of their pump and pump maintenance information, including a pump cutaway DVD movie of the pump in operation. I also have a pretty good set of slides of pump damage from wear that covers pump casing, packing/wear ring, shaft, and impeller wear starting with 1940's-era pumps and ending with modern pump construction. They show different types of wear, but excluding ingesting large foreign bodies, most pump damage comes from one or more of four sources:

1) Friction/heat wear damage from routine operations and pump testing
2) Friction/heat wear damage from sand and grit in the water supply
3) Chemical wear damage from the chemicals in potable water sources
4) Small foreign body damage from rust/scale from the water system and pump intakes.

All of those things are exacerbated by higher heat(friction) and pressure.

As for your being the best engineer, I have no dog in that hunt and I understand the joking nature of that comment.

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Permalink Reply by RsqRog on July 31, 2011 at 2:47pm

Hey hey there big Paulie, its good to see you are still out there starting thought provoking discussions. Here is my 2 cents worth, this time in a serious fashion.

As firefighters we need to know what our tools are capable of. Our apparatus and pump are just simply some very big and expensive tools. We can not accurately predict what we will need or might need at any given incident. A professional and capable engineer will know what his apparatus can do. The only way you can learn it, is to do it, if that causes "wear" on a pump then so be it. Thats what preventative maintenance schedules, and fire apparatus mechanics are for.
I have pumped a lot of very high pressures, both during training and real incidents, never have I had a pump failure. Does pumping high pressures cause excessive pump wear? I would think not, does a pump experience wear from use? of course it does, its a mechanical device. does high pressure pumping cause "excessive" wear that would out weigh the need to not train or use high pressure pumping evolutions? most definitely not.

My 2 cents, much respect, and yes you are right, its Roger, now go and accept the friend request i sent you on here.......

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Permalink Reply by Paul Shapiro on July 31, 2011 at 6:24pm

Ben Sorry that was not directed towards you even thoigh your name was mentioned.
I have been thinking about this and realized I never talked about the pressure range that I consider high. Its not the highrise stuff. I practice some high pressure smooth bore tip operations and the pressure never exceeds 200 psi. I also practice 1-3/4" high flow operations that don't exceed 205 psi using the correct hose.Neither of these operations are done alot, maybe 5 times a year.

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Permalink Reply by Ben Waller on July 31, 2011 at 7:35pm

No problem. Just remember that if you switch to low-pressure (50 PSI) nozzles like the Akron Assault series, you can take 50 PSI off of whatever you consider "high pressure" regardless of whether you're pumping the fog tip or the smooth bore.

We switched to them about a year ago and except for one 2-1/2 playpipe with stacked tips, they are the only handline nozzles we have.

We use them with both water and Class A foam, we pencil with both the fog tip and the smooth bore, and we have even drilled on hydraulic ventilation with both tips. The smoothbore doesn't vent as efficiently as the fog tip, but with a broken stream (bail about 40% open) it can be done.