Thread: Five inch discharge
06-18-1999, 11:00 PM #1DDFirehouse.com Guest
Five inch discharge
I want to add a 5" discharge to a 1250 gpm pump. The largest discharge currently is 2-1/2". Do most companies plumb the pump to discharge into a 5" hose or do they use a 5" wye with and supply it with two 3" lines.
06-19-1999, 12:31 AM #2FyrtrksFirehouse.com Guest
First off look behind the Stainless steel and see what you have on the pump proper. I have not seen many discharges larger than 3" on the pump. You want to have as little friction loss as possible. Have your adpter as close to the inpeller as possibile, cast in the case is best but at the edge of the case is okay. Then you can have it fed by 2 2.5" or 3" regular discharges on the outside of the truck. Then fed by only one. Last but not least would be to feed it through pony hoses.
The key is as little friction loss as possible!!
[This message has been edited by Fyrtrks (edited June 19, 1999).]
06-19-1999, 01:10 AM #3TRUCK 110Firehouse.com Guest
One thing you also need to consider, is the NFPA reg's on LDH..I hope you realize that you are not to pump 5" Hose ABOVE 185 psi. I believe that is in the NFPA 1962 Reg.. You may also want to look into a slow close valve too.. Also according to the Reg's..you need a Discharge Relief Outlet for the Discharge, so that overpressurization above 185, is discharged into the Street before the Hose Breaks..We bought for 4", and they were $550/unit. This proposition is going to be costly, but I guess Safety has not cost.
Thanks for the Posting..Be Safe
06-19-1999, 02:45 AM #4LedbellyFirehouse.com Guest
Here's my 2 cents...without knowing exactly how you want to use the 5" discharge; we have a manifold that goes on hydrant, you hook two 3" lines to engine, one suction and one discharge, and it allows you to boost pressure down the 5". We also have two Pierce's that came with 4" discharges...we have a 4 to 5" coupling so we could pump the 5" if necessary; to tell the truth I can't remember what it looks like inside, ie how it is plumbed off the pump.
Hope this is more help than hindrance?
06-19-1999, 08:23 AM #5Dalmation90Firehouse.com Guest
For 1250gpm, I would try an 2.5" to 5" adapter right off your #1 discharge...in theory (sp?) you'll get capacity from it. Designing a pump from new, dual 3" feeds from the top of the pump would minimize FL.
Also, there is 5" hose on the market rated for service pressures as high as 300psi...what you buy depends on how you need to use the hose.
06-19-1999, 08:42 AM #6S. CookFirehouse.com Guest
I agree with Dalmation90, that's the way we're doing it and have no problems.
Just put an adapter on your existing discharge. A 2-1/2 can discharge alot of water. Open butt at 50 psi from a hydrant you get around 1300gpm so why should you have any problem getting good flows from the 2-1/2 on your rig.
Truck 110 is right on the money with a relief for the discharge too. Set it at each use so it just trickles at the pressure you're flowing for the line (it's easy to modify the valve to do this without having to find the little wrench). That way if the engine you're pumping to shuts down, you don't get the hammer.
06-19-1999, 03:03 PM #7firefighter60Firehouse.com Guest
Our first out engine has a 5" discharge on it. The plumbing for that discharge is the first one coming off of the impeller housing and is run with a single 3" piece of pipe. No pressure relief on it other than the pumps pressure relief valve but that is no problem for us as ours are set at 175psi. We have no problems flowing with this setup.
06-19-1999, 11:34 PM #8DDFirehouse.com Guest
Thanks to all for the information. Our intention is to use the relief valve and engine speed reduction governor (it has both)
on the relay engine. We have a 5" intake relief valve on the receiving engine. It dumps to the street and has a slow closing screw type gate. Will we still need a discharge dump valve? The discharge pressure of the relay engine at the plug will not exceed 150 psig per SOP. It looks like the 2-1/2" FNST X 5" Stortz is how the discharge will be set up. That is what we were hoping would work.
06-20-1999, 09:35 PM #9TRUCK 110Firehouse.com Guest
In respect to the Discharge Dump Valve..The choice is yours..It is to protect the people who operate near the Discharge side of the pumper..Also per NFPA, the Discharge is to be on the Side AWAY from the Pump Operator. If you have a Top mount, you have no problem. I have to know the NFPA regulations, because it is part of my requirements for my Teaching of Students. Dalmation is correct about High Pressure Supply Line, it just costs alot for the Hose, but the Discharge Relief Valve still is required for LDH, just set alittle Higher for Relief. Just please consider the Safety of All involved, as I know you will.
Thanks for the Post. Be Safe
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