Pumps- Single Stage vs Two Stage

[firechief1101]

What is the most common pump in operation today?<br />Single or two stage. What benefits does a two stage give over a single stage? We are on our 3rd.<br />two stage pump. Currently a Hale that performs very well with a 400hp. N-14 Cummins in front of it. We had 2 Waterous before that. Just wondering what other locations around the Country use.<br />Out in good time, do good service, first water...

[berger3447]

Some of our older trucks have 2-stage pumps, but most of the newer trucks I've seen anywhere, ours included, have single stage pumps. I am told (makes sense to me) that the newer pumps generally operate from 1500-2000 gpm's anyways, without the second stage, so they're simply not needed much anymore. A good single stage pump will deliver both pressure and volume without needing a mechanism that changes the entire routing of water through the pump. It's also less to have to think about, but then again if a 2 stage pump is too complicated for someone, they've got other more serious issues to deal with...

[LACAPT]

We have not used 2 stage pumps in our dept. since the late 50's. The major advantage to 2 stage pumps is when having to pump up multiple stories in hi-rises, you have the volume and the pressure in that situation, the disadvantage is that 2 stage pump required a lot of upkeep maintenance. With the way single stage technology has developed in the last number of years 2 stage pumping has become a thing of a specialty rather than the norm.

[391HD]

I would guess the single stage pump is the most popular. Today's diesel engines are powerful and have no problem turning a single impellar centrifugal pump.

I think the advent of the two stage class A pump came about as a way to increase pressure on apparatus with under-powered gasoline engines more than a half century ago. Remember, at that time, "high pressure fog" and Lloyd Laymen's theory of interior firefighting was being used. Manufacturer's actually developed multi-stage centrifugal pumps to compete with FMC's John Bean Royal piston pump that produced over 800 psi @ 70 GPM.

Two-stage pumps in series operation restrict out-put volume to 1/2 to 2/3 of its rated capacity. A common problem with these pumps was the transfer valve sticking in either the parallel or series mode. A big problem if you arrived at a major blaze and couldn't pump volume because of this.

A single stage pump is less complicated than a multi-stage. In the heat of battle, things always run better when you keep it simple.

[911WACKER]

We chose a single stage on our last pumper becouse we try to employ the KISS theory around here.

K-keep<br />I-it<br />S-simple<br />S-stupid

Less the engineer has to worry about and besides, as stated by another brother the two-stage pumps tend to stick from time to time. <img src="smile.gif" border="0">

[BonCreChief]

We only have a couple of 2 stage pumps left a Hale and a Darley. Both have given excellent service but the upkeep on the transfer valve is constant. We have found with the newer engines and pumps we do not need the 2 stage capability. Our newer trucks have Hale 1250 single stage and do the job really well without the extra work on the pumps. In our particular situation we will specify single stage on our future trucks. Some of our neighboring departments still use 2 stage on their aerials because they feel they can achieve the pressure they need much more easily. As in other things in firefighting it depends on particular needs and preferences.

[jmichael]

I think most newer pumps are single stage ours are. The old ones are 2 stage. A single stage will heat up quicker than a 2 stage. Keep your water tank as full as possible when recirculating for a period of time. I am thinking the temperature of the water will raise about 3 degrees F. for 100 gallons of water in about 5 minutes for a single stage pump. Recirculating for longer periods of time the operator needs to be careful of the pump temperature.