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# Thread: How much can you flow

1. ## How much can you flow

Can you efficently flow = > 1000 GPM from a 2 1/2 discharge port directly into 5" LDH and get the required pressure (approx. 190-210psi) over say 100' to a ladder truck?

Pressure is relative to obviously hight of ladder.

Most concerned with getting the water and pressure using a 2 1/2 discharge to LDH rather than using 3 3" lines.

2. Technically yes.

Strictly according to the math, a 2 1/2 discharge is capable of flowing nearly 2000gpm under enough pressure.

The weak point will most likely be your LDH, which is most often capped at 175 PSI operating pressure (although there is higher pressure stuff out there). To push normal LDH to 210 is still under the test pressure and half of the burst strength, but you're starting to push your luck as well.

I have not had the chance to flow test it accurately yet, but in relay pumping drills through a 2 1/2 discharge to 4" LDH, we were unable to starve the receiving aerial even with the stick stream and several handlines out. We run only 1050 gpm engines though (1250 US Gallons).

3. yea we have LDH that can handle those pressures, but our neigboring dept. does not. Thats why they use the 3 3" to siemese to truck. Thanks for your reply.

Originally Posted by mcaldwell
Technically yes.

Strictly according to the math, a 2 1/2 discharge is capable of flowing nearly 2000gpm under enough pressure.

The weak point will most likely be your LDH, which is most often capped at 175 PSI operating pressure (although there is higher pressure stuff out there). To push normal LDH to 210 is still under the test pressure and half of the burst strength, but you're starting to push your luck as well.

I have not had the chance to flow test it accurately yet, but in relay pumping drills through a 2 1/2 discharge to 4" LDH, we were unable to starve the receiving aerial even with the stick stream and several handlines out. We run only 1050 gpm engines though (1250 US Gallons).

4. NV,
Not sure what you mean by "efficiently," but I'll give you my take. As you probably know, the friction loss of 1000 gpm through the 5" vs. 1000/3 (333 gpm) through 3" is about the same give or take a few psi. For 100' of either, it depends on your hose,etc.,but should run in the 5 - 15 psi range of loss. So the friction loss difference is negligible and the total friction loss between the engine and ladder is say 10 psi, which is pretty low. You would need the same inlet pressure at the ladder with either arrangement under whatever condition you are flowing, so the required pressure is the same all the way back to the engine pump discharges.

The critical issue will be the losses in the pump discharge piping between the pump and discharge outlet. We don't know the details of your dishcarge piping, but we can make some assumptions. Although there would be some losses flowing 333 gpm through a single 2 1/2" discharge, the losses should be generally pretty low. 1000 gpm though through the same outlet is some real loss. I would estimate that the difference between the two would be in the 30-50 psi range. So to get the same pump dischrge pressures between the two hose configurations, the 1000 gpm through a single 2 1/2" discharge will probably require the 30-50 psi higher pump discharge pressure.

1000 gpm from a 1500 gpm pump with some of the higher hp diesels and my rough guess would be you wouldn't have a problem adding that extra 30-50 psi for 1000 gpm of flow. Especially if you have good hydrants and 5" supply to the engine bringing that 1000 gpm to the engine with some significan residual pressure, I think it would be a non-issue for the pump to make up that additional 30-50 psi at 1000 gpm.

And as others have mentioned, you have to have 5" that can handle the pressure you need to feed the ladder.

If you have some decent hydrants, premium diesel power and the 5" rated for the pressure, I would think 5" is more "efficient" to use. The only way to know for sure is to flow test it or get the specifics and run some hydraulic calcs.

I hope this helps.

5. Both Mcaldwell and Kfactor gave you great answers.

But,most of the time trying to supply 1000gpm through a ladder pipe the
biggest loss occurs at the ladder truck itself. The friction loss in the ladder
truck (not quint) depends on the type and diameter of pipe used in the truck's plumbing.

ei. a pre-piped waterway that uses galvanized threaded pipe at the base
compared to a welded stainless steel setup. Big difference!

A few years back we did a test.
1250gpm Pumper at the hydrant
100 ft. 4" from pumper to aerial that had threaded galvanized pipe
at the turntable...elkhart SM 1000H noozle.

With the same setup repeated test to our Bronto Skylift. Same nozzle

We used in-line gauges at the at the noozles and a flow meter at the 4"
discharge.

At 200psi pump pressure we were unable to to flow 1000gpm from the aerial

When we repeated the test using the Bronto Skylift (1991 model)s/s piping
what a difference the piping made....we were able to flow 1000gpm
with the supply pump at 135psi pump pressure.

And yes it was at the same elevation.

As for flowing 1000 gpm from a 2.5" outlet no problem...needs only
40psi at the outlet approx. You should use only the side discharges at the
pump panel, as plumbing to the rear discharge 2.5" can cause significant
losses depending on diameter and material used.

Too bad it isn't easy to say without testing with flow meters.

Hope this helps a bit...

Don

6. I'll agree with kfactor. The piping between the discharge valve and the outlet will be the weak point. We have a 1,250 Waterous pump that originally had 2.5" pipe between a 2.5" valve and the discharge outlet. Flows over 800 gpm were hard to achieve. We replaced the valve with a 3" valve that has a 4" threaded flange on the discharge side. Ran a 4" pipe out the side and adapted it to our hose thread. Waterous says we should be able to do 1,250 gpm through this set up. We did this about 4 years ago, and invested less than \$1,200 for the whole package.

7. NVdualrole,

Every one here has given you great answers. One thing I want to touch on is something Mcaldwell said and that is "The weak point will most likely be your LDH, which is most often capped at 175 PSI operating pressure (although there is higher pressure stuff out there). To push normal LDH to 210 is still under the test pressure and half of the burst strength, but you're starting to push your luck as well."

5" hose is made to pump ideally at 150-180 psi. Once you go over 180 psi you create turbulance which in turn creates friction loss big time! Using a single 2 1/2" line off a 2 1/2 ' dischage realistically you will get about 500 - 600 GPM at most. Using a 5" line you should be able to get a 1000 GPM. Here again depending how your pump is piped and how the ladder water way is piped. You are better off I find (in my experience) using two 3" lines to the ladder and you will have no problem flowing in excess of 1000 GPM. (My opinion the fire departments under use 3" hose anymore, but that is a subject for another topic or thread.)

8. ## Friction Loss with LDH

Quote: 5" hose is made to pump ideally at 150-180 psi. Once you go over 180 psi you create turbulance which in turn creates friction loss big time!

Chief -

I have never factored PSI into any friction loss equation. The formula for calculating friction loss only considers three factors - volume, hose diameter, and hose length. I can pump 500 GPM at 200 PSI and deal with minimal friction loss. However, I can pump 1500 GPM at 100 PSI and will have to consider friction losses.