Pump/Roll grassfire fig advice

[neiowa]

Putting together a rig. #1 priority is pump/roll capability. Large tank. #2 is relay pump.

Have all wheel drive chassis. existing PTO drives high output hydraulic pump.

Question? Advice/experience with hydraulic driven water pump vs pto driven water pump. Could go either way. What +/- each option.

[ranger1141]

We used to use PTO pumps on our type 6 brush trucks and are still using them on our tractor-plows. They can be good pumps. The one problem that occured with them is that if the truck or tractor-plow died, you had no water for protection. That could be very bad. Haven't had much experience with hydraulic pumps on a grass rig. USFWS uses a hydraulic pump on their MarshMaster - low ground pressure unit around here. It runs off the hydraulic system of the piece of equipment. Again, if part of the hydraulics fail, you can't go anywhere and you have no water. What we have switched to on our brush trucks is a 9HP Darley/Davey (18HP on our 3-ton type 4 engines), rear mounted fire pump on a skid. I really like this pump. If my truck dies, I still have water for personal protection. If my pump dies, I still have my truck to get the heck out of there. Just another option to throw out there for you.

[neiowa]

Point noted given priority #2 of relay pump need 1250+ gpm. That would be a very big (and heavy) independent engine driven pump. Plan is drive pump using the prime mover's engine.

Story I have received is that PTO driven pump will surge as engine speed varies as you drive crosscountry where hydraulic drived pump does not. Hydrulic obviously more expensive to install and maintain. Any experience out there?

[CAPN22]

Why not use a Twin pump set up.
1250 GPM split shaft for volume.
Then useing an overdriven PTO with a 500 GPM pump for pump and roll.

Install a relief valve in the pto pump to bypass back to the water tank. To correct surges.

Or better yet, 1250 midship split shaft something like a Waterous or Darley 400 gpm engine driven for pump and roll and aux capacity.

Now your 1250 is a 1650 and pressue fluctuation issues are no longer a concern.

Personally stay away from Hydralic pumps. They are not that stable, are finiky at best and there is a real heat issue with the pump amd motor. Large cooling units would be needed as well as about a 30 to 50 gallon resavour for flow volumes.