Question on FDNY pump operations

[BIG PAULIE]

This question is for the FDNY pump operators. It's my understanding that the FDNY 1-3/4" line uses a 15/16" tip at 50 psi nozzle pressure for a flow of 185 gpm. Correct me if I am wrong , the hose comes out of a storage bed of X amount of feet. How does the pump operator calculate the engine pressure if the amount of the hose in the stretch is unknown? With the size of the buildings in NY it seems as though this may happen a lot.

[johnusn971]

Originally posted by BIG PAULIE:
This question is for the FDNY pump operators. It's my understanding that the FDNY 1-3/4" line uses a 15/16" tip at 50 psi nozzle pressure for a flow of 185 gpm. Correct me if I am wrong , the hose comes out of a storage bed of X amount of feet. How does the pump operator calculate the engine pressure if the amount of the hose in the stretch is unknown? With the size of the buildings in NY it seems as though this may happen a lot.

Dispatch tells you the approximate location of the fire. If the fire is on the 5th floor, you need 2 to 3 sections of 50' hose. It really isn't hard, and it is done quickly. Over 90% of our building are in our CIDS computer, with that the officer can do a quick math calculation to decide the amount of hose length needed. All in it is done in less than 5 minutes, from dispatch to scene.
Sorry, I was just stretched the amount the officer told me to for E75
Doc DC3.

[DOG 4035]

BIG PAULIE, we estimate.


In a perfect world you would have perfect flows,and so and so on....

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"It's not the size of the dog in the fight, but the size of the fight in the dog." STAY SAFE-STAY LOW

[NozzleHog]

Originally posted by BIG PAULIE:
the hose comes out of a storage bed of X amount of feet. How does the pump operator calculate the engine pressure if the amount of the hose in the stretch is unknown?

It's not unknown. The responsibility for this is assigned to the Control Man. He is the last man on the line to stretch and part of his job is to properly estimate the required number of lengths for the type of stretch ordered by the officer. He must keep track of how much hose has been stretched and what type of tip is being used and communicate this to the chauffeur. Sometimes this is estimated by knowing the amount of hose carried in the bed and then subtracting the amount left in it.

[N2DFire]

Ummm - O.K. I will be the first to admit I'm not a pump operator (and I'm sure a lot of my fellow FF's are glad too )

Now . . .

What Big Paulie is asking (if I read him right) is how do you pre-determin Pump Discharge Pressure (PDP) or what "Rule of Thumb" do you go by to get it when every stretch is (or may be) a different length and you don't know till you get the call what it will be.

Say all you used was a preconnect of a known length (say 200 feet) you now have everything you need to rough calculate PDP (NP, Hose lenght & type for friction loss, Nozzle type, etc) so you can say if you pull Pre-connect XYZ start it at 85 psi Pump to have 50 psi NP and ajust for elevation.

Now for FDNY (and a lot of other places) it just don't work that way. You have to grab the knob and pull till you get to the fire & then say O.K. I got 300 feet of hose on the ground (or as johnusn971 mentioned - look it up in your pre-plan documents enroute) but it is only now at the moment of arrival (or dispatch if you have a pre-plan) that you know the length of your pull - so how do you "rough guess" your PDP ?

Say for instance PDP = NP(50psi) + 10psi per 100 feet + 10psi per 10ft elevation. So you could quickly say that you needed a PDP of roughly 80psi for a 200 ft pull to the second floor of a "typical" residental home.

Thats what I think Big Paulie is after - so c'mon all you people that know how to do this a lot better than I do start filling in the blanks.

Take Care - Stay Safe
Stephen
FF/Paramedic

NOTE All numbers & calculations cited here are for illistration only and are in no way meant to indicate a true or workable formula !!

BTW Big Paulie - we use the pre-measured preconnects almost exclusivly in our area so we have the starting PDP pre-calculated so I'm sorry I can't give you a good "guestimation" rule.