48V DC pump for fire fighting?

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LouB
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48V DC pump for fire fighting?

Post by LouB » Mon, 14 Jan 2019, 09:26

I'm in the process of moving as much of my equipment as possible away from fossil fuels and oils. To that end, we have moved to a BEV (Renault Zoe) and also have an electric push mower (Victa) and electric ride-on mower (Ryobi. For safety reasons we have held onto our 5HP fire fighting pump (Robin EY20D),

We live on a few acres in a bushfire prone area, with no town water. Water has to be pumped from our dam or from the house tanks.

I've been looking at, and wondering if, the better 48V DC pumps, either submersible or floating, could be the way to go. The larger ones (4"+) are advertised as having a head of up to 100M and flow rates of at least 50L/minute. I was thinking that one of these could be run from the 48V battery system of the Ryobi ride-on mower. We have electric (240V AC) pumps now that pressurise the house plumbing system, but these are likely to fail in an emergency when the Grid almost inevitably goes down.

Note: that is no intention of fire fighing among the surrounding trees and bushes, but merely of hosing the house (2 storey) down to prevent ember attack. The dwelling is mostly brick and metal.

My question is: does anyone with experience of this type of pump think it could do the job?
If not why not?
Or is there a better solution?

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Re: 48V DC pump for fire fighting?

Post by jonescg » Mon, 14 Jan 2019, 09:58

Surely you could couple a DC motor often used for forklifts and the like to a pump? Nice and simple, and it doesn't rely on an inverter to function. At a pinch you can hook it up directly to the battery.
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Re: 48V DC pump for fire fighting?

Post by T1 Terry » Mon, 14 Jan 2019, 11:32

We live across the road from Murray wetlands (a flooded paddock the Murray/Darling people retain as flood land now) and I have set up 2 x 12v solar panels on a floating raft made from 2 plastic 205ltr drums. I run a 12v motor that is coupled to a 240vac motor that is part of a Davey self priming pump. I use a 4 cell 90Ah Sinopoly cell lithium battery with a Junsi monitoring the cell voltages and the alarm triggers an adjustable timer board so the relay holds open from 1 sec to 1 hr depending on the setting.
I did have the timer set to 1 hrs and the Junsi alarm triggered set at 3.25v low voltage cut and 3.6 high voltage cut for any cell and 13v to 16v for the battery. If the low cell alarm was triggered the pump was turned off for 1 hr to allow the battery to recharge. Worked fine for weeks, but yesterday it didn't trigger the pump. The problem was the 1 hr no load had allowed a cell to go above 3.6v triggering another 1 hr timer cycle and this just compounded throughout the day. This morning after running the pump for 30 mins to pull the cell voltage down, I rest the time for 15 mins and all seems to be well with the world again.
The pumping distance is probably around 500 mtrs, under the road, under the front yard, under the house and to the tank at the back of the property. The lift is approx. 300 mtrs. We run a garden sprinker on the front lawn and the excess water goes up to the tank and this siphons into a much bigger tank with a float valve. In a little less than 2 weeks the big tank has gone from empty to full and the smaller tank is starting to fill up and the dirt front yard has kikuyu grass patches trying to join up even though the day time temps are over 40*C every day.
I would say the pump would supply 3 garden houses on full output when the pump is running, all powered from 250w of solar. A bigger solar array and a bigger battery would run the pump a lot longer if needed.

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Re: 48V DC pump for fire fighting?

Post by LouB » Mon, 14 Jan 2019, 12:02

In answer to jonescg: I don't really understand where the inverter comes into it. My interest was with pumps such as the one in this ad:

https://www.tuhorse.com.au/4-500w-48v-s ... -delivery/

Your situation and ingenious setup is interesting T1 Terry. In the absence of bushfire, we normally only use the before mentioned ICE fire pump to water a few veges and some fruit trees. This we do from the dam which is approx 220 M distant and some 6 M downhill. In a bush fire situation, pumping fom the dam could be dangerous. Meaning that the pump itself could be separated by 150 M of burning vegetation from the firehose outlet. My fire plan has always been to limit water pumping to the 3 large concrete tanks grouped about the house and shed and to leave the bush to take care of itself.

Our house water tanks are amply supplied off the house and shed roofs.

The reason for looking at using the 48 volt battery setup of the Ride-on mower is that it should provide the convenience of easy mobilty. Conceivably I should be able to move the mower about from tank to tank and just drop the pump into the inspection hatch of each.

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Re: 48V DC pump for fire fighting?

Post by jonescg » Mon, 14 Jan 2019, 13:00

Oh - only a little guy. I thought you were chasing a 10 hp pump for firefighting or something.
Any electric water pump for a household running on mains power will have an AC motor, and this calls for an inverter. But if you aren't chasing high power then yes a simple, small DC motor should be fine.
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Re: 48V DC pump for fire fighting?

Post by T1 Terry » Mon, 14 Jan 2019, 14:07

Are yes, I bought a 24v one of those bore pumps just in case I couldn't get the other pump to work properly https://www.ebay.com.au/itm/DC-24V-284W ... 2749.l2648. Maybe you could add a resistor in between to drop the voltage or run 2 of them in series, way cheaper than the one you linked to but doesn't have the fancy level switches. Maybe a combination of a solar powered pump from the dam to a fire fighting water tank and a pump from there for fire fighting so you aren't dependant on the rain to keep enough water in the tanks if a serious bush fire session hits after a long dry.

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Re: 48V DC pump for fire fighting?

Post by LouB » Tue, 15 Jan 2019, 11:28

I only put in the link to the Tuhorse brand pump as an example of the sort of thing I was considering. I really don't yet know what to go with, or whether, as it's intended for an emergeny fire fighting pump, I may have to stick with the petrol one. A pity if that were the case as I was hoping to prove, to myself at least , that fossil fuels could be done away with altogether.

So far, touch wood, we have never run out of water from our tanks. Even through the last two drought periods we have always had at least 50% water storage remaining.
Perhaps we are overcautious, but we installed 3 X 37,000 Litre concrete tanks and have a 12,000 Litre galvanised steel tank kept aways full, just for emergencies.

In practical terms: what sort of pressure do you get from the 24V pump. For instance: with hose attached, will it send a water jet vertically to at least 6 metre height? That being the kind of performance I would need to spray water onto the roof and gutters.

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Re: 48V DC pump for fire fighting?

Post by T1 Terry » Tue, 22 Jan 2019, 09:35

Sorry for the delay in replying, been extra busy with work. I haven't actually wired the 24v well pump up to see just what it does because the 12v pump is doing everything I need at the moment. That 24v pump says it can lift water 40 mtrs, so, with a nozzle appropriately sized for the flow rate, wouldn't that indicate to could spray a column of water 40 mtrs in the air? No idea what the flow rate is at different lift heights, maybe the manufacturer has those figures

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Re: 48V DC pump for fire fighting?

Post by LouB » Wed, 23 Jan 2019, 09:55

Thanks for your input Terry.
I have found it quite difficult to equate max flow and max head specifications to actual measured performance of pumps. For example: we do not have mains pressure (reticulated) water supply, and so have to rely on electric pumps for the house and garden. The pump servicing the house is an 230V 750W Grundfos electric pressure pump. It has an 1" outlet and is rated at a flow rate of up to 2 cubic metres/hour, with max head of up to 44 metres. It does a good job providing sufficient pressure for up to 3 upstairs taps running at the same time. However, if, while standing on the ground, I attach an 3/4" hose with nozzle and point it up at the roof, the water jet reaches to the gutters (approx 6 metres from ground) but not much further. Certainly not high enough to reach the roof apex that is approx 2 metres higher.

The same hose and nozzle will spray right over the roof when powered by the 5 hp petrol powered pump.

I understand that 750W equates to only approx 1 hp and the petrol engine produces 5 x that, but it does show that max flow and head are not the whole story. Perhaps operating pressure could be a more useful measure when intending it for fire fighting?

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Re: 48V DC pump for fire fighting?

Post by T1 Terry » Fri, 25 Jan 2019, 13:00

Good pumps have a graph type chart to shows ltrs/min on one axis and head pressure on the other axis. You can get 2 cubic mtr/hr straight out of the pump, or you can get some water to reach 44 mtrs head height, but you can't have both at the same time unless you use a really powerful motor to drive the pump and just control the rpm to limit the flow rate.
Fire fighting just relies on flow rate, they don't really try to pump up hill unless it is one of those high rise nozzle trucks that fight tall building fires or from above a fire where they can not get direct access to the fire. They have mega big pumps pressuring those things.

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