We have had 4" LDH discharges off the officers side on our apparatus for the past 25 years or so. On our next pumper we are thinking of adding a 2nd LDH Discharge on the rear.
What are your thoughts with doing so?
Has anyone had any problems or suggestion?
What are the largest valves and piping mfr's will use.
What is your favorite valve type to use? (Manual, air, hydraulic, electric) and what mfr valve for the ldh do you like?
Our '95 has large discharge on rear and also on officers panel. Both are manual valves. Officer discharge is 4" pipe, rear is 3.5" pipe. Both have 5" Stortz adapters on the end. Was intended for supplying old aerial that had no pump and secondary supply to Teleboom.
New engine has large discharge on officer side only as old aerial and teleboom are both gone now. It has electric valve.
I'm old fashioned....I like manual valves.
How often do you use the existing LDH discharge? Is it used at capacity or just as another discharge? I would think you would need to have a big pump to fully use two LDH discharges. Four inch is probably the largest discharge plumbing on regular pumpers. Industrial trucks can have much larger discharges but they are using 3,ooo pumps. You can more a lot of water with a 4" pipe going to 5" hose.
If at all possible I'd use a manual discharge. Our air operated valve on one of our engines in failing for the second time, and electrics will also fail. At least on most electrics you can usually put a wrench on things to open the valve in a pinch...
We've got one pumper with a 4", another pumper and our aerial both have single 3". All with manual valves; officer's side, top forward-most discharge on the panel of each.
Just spec'd a new pumper with a 3" on the officer's side that will have an electric-actuated valve instead. I can't remember if we went with Akron or Elkhart for the valve control, but I know the valves themselves are all Akron, so I'd venture to say we probably went with Akron all-around.
We use our larger discharge for standpipe and sprinkler systems, but have used them also in nursing/relay pumping in the past as well. All the discharges, 3" and 4", have 5" Storz adapters on them.
As for adding a second, if it fits your department's needs, I say go for it. Just be sure to look at the cost and weigh the benefits before committing.
IMO adding an additional LDH discharge at the rear, or having one at the rear at all is not a great idea. There is no real benefit to a rear discharge versus one in the pump area, yet there is a significant cost increase for plumbing one to the rear as well as adding another obstacle to the backstop/ hose bed area and potential loss of compartment space along the way.
Like everything else in the fire service, the only right answer is "it depends..."
My Dept has top mount pumpers with 3" pipes and 4" storz adapters feeding 4" hose. There is a LDH discharge on each side, and a 2.5" on the back for the bundles. We have found no problem supplying 4" lines. We recently looked into this in depth when speccing a new rig, the costs of upgrading the piping from 3" to 4" were not worth it.
The new rigs will be side mount pumps to reduce the length and cost of the truck. Since you can't have a discharge larger than 2.5" on the operator panel, we put our second 3" discharge on the rear. It will be 3" pipe capped with a 4" storz adapter to 2.5" threaded male. That will be primarily for the bundles, but will also come in handy to supply another engine or the aerial. The side discharge goes from 4" storz to 2.5" to 1.5". We specify less discharges and use adapters on the LDH discharges vs paying for more pipes, valves, and gauges.
For the new rig we are using manual discharge and intake valves-with the exception of the officer side intake, which will be electric so the driver doesn't have to run around the rig. Hale intake/discharge valves on the Hale pumps, Akron or Elkhart discharges on everything else. Various intake valves (TFT, Jaffrey, etc) on the rigs without electric ones.
If you are not using integrated intake valves, I recommend the TFT. We have had far less corrosion/maintenance issues with those vs any other ball intake valve.
I'd see a second LDH discharge as a potential benefit. Of course this depends on your water sources. if you have decent hydrants that will allow multiple LDH lines, or the engine may be used at as a supply pumper and has a decent sized pump, your ability to flow dual lines may be a true advantage. As for rear vs. another off the side, I guess I'd consider those times you'd make a reverse lay on tight streets or private driveways?
Having a rearmount pump, I like rear intakes and discharges, no messing with cars, curbs or other obstacles; if the street is clear the line can be easily laid. Of course with a rearmount the piping cost is minimal. We run two 4" piped discharges with 5" stoz reduced to 2.5" NST males as our LDH discharges and two more 3" piped preconnected lines (2.5" handline and 3" portable mini gun) off the rear. All manual valves (handwheels).
I think a 2nd LDH discharge is a great idea. I prefer manual valves, especially with worm gear actuators. The latest thing we've gotten on a few trucks are electric motors on worn gear actuator, with the opposite end of the worm gear shaft exposed to the pump panel with a hex nut. This allows a quick manual override with a 3/8" drive socket and ratchet.