# Thread: Does anybody flow LESS than 60 gpm on their preconnected 1 3/4"?

1. ## Does anybody flow LESS than 60 gpm on their preconnected 1 3/4"?

Asked the engineer at my house the other day, "whaddya pump our preconnects at?" As if I had to qualify it by saying preconnect, it's the only f-n' attack hose we've got...
110# he says. 200' 1 3/4", automatic nozzle (maybe, see below).
"You know that's only like 58 gallons of water, right?"
"Nahh, it's more than that."
"Why do you pump at 110?"
"I don't know, that's how I was taught. Much more than that and you can't bend it around in a house."

Since I can say "well, at my last dept..." here, how did we ever manage, what with our TFT's and 150 GPM...

Anybody flow that LITTLE? After a night at the PUB I can flow 58 f'n gallons...

Edit: Oh yeah, Elkhart SM-20F, looks like a little bit older model. Says 200 GPM on the side. It isn't a range like the newer ones, 50-200 I think? Anyway, is that the peak GPM available? As far I as I know, this is an automatic. ?. Also, this whole One for One hydraulics thing Elkhart has going, it doesn't seem to jive with conventional friction loss and pumping formulas. Any help there?

The way I learned: (Quantity X 4)squared per 100'. 110# = ~56 GPM
Elkhart Website: Each # over 100 is 1 GPM+100 GPM. 110# = 110 GPM

2. Whats a 1 3/4" ?????

3. Sorry, it's a diameter of fire hose. I think the METRIC conversion is to square by prime factor of the diam., multiply by the reciprocal, and then find the third derivative. At this point, the standard deviation of the last figure will then be entered into the exponential equation, (e to the 7th)/1-(e to the 4th), which if you remember is the one that approaches but never really gets to zero. At this point, firefighters will probably be wondering where their water is. Just run the pump up until they scream, gate back a few pounds. Which brings us to metric conversion for pounds...

4. Nope.

there are 25.4 millimetres to the inch so 1 3/4" = 44.45 mm or .045 of a metre.

1 PSI = 6.894757 Kilopascal.

60 GPM = 227.1247 Litres per Minute.

200 foot = 60.96 Metres.

In New Zealand Fire Service we use

45 mm = 1.771648 inch

70 mm = 2.755897 inch

90 mm = 3.543296 inch

Lines on the coil, not on the Bight because it breaks the line down at the crease.

We use Elkhart variable Branches/Nozzles, of different ratings, there is a select lever at the rear you can use to change the Gallonage/Literage flow rate at the Branch/Nozzle.

Smooth bore Branches/Nozzles are used on Monitors/Deck Guns, Forestry/Grass fires. Or if you want to re-enact Fire Service history during WW2.

Elkhart could not give a rats A&%* about what the friction loss is in New Zealand through our Lines/Hoses. They give a maximum volume flow that MAY be achieved for a given Branch/Nozzle.

1 lenght of line/hose laying flat on the ground is going to be a wee tad different to 3 lengths with the last length going up a ladder into the structure.

Here you have to work on the following ( and I will keep it simple at 10 Litres per second or 2.641721 Gallons per Second) which means 158.50326 Gallons per minute or 600 Litres. This is being pumped at 500 Kilopascals or 72.51887 PSI

1 25 Metre length of 70 mm Line laid flat will suffer a 25 Kilopascal loss across its own length.

OR

or 1 27.34025 Yard length of 2.755897 inch Hose will suffer a 3.625943 PSI loss across its own length.

meaning 475 KPA or 68.892927 PSI effective at the other end of one section.

Now we have three lengths so the combined loss is 75 KPA or 65.266984 PSI

We have gone one floor vertically in the building so for the vertical loss we have 30 KPA or 4.351132 loss as well, making our final losses over three lengths and one floor in height 105 KPA, or 73.244059 PSI.

I am the pump operator required by the Branchman/Person on the end of the hose, to pump 500 Kpa to him so he can flow 10 Litres a second.

3 x 25 = 75 for the three lengths
75 + 30 for the floor vertical.

= 105 total friction loss.

SOOOOOO. 500 Kpa + 105 KPA = 605 KPA at the pump.

OR 87.74783 PSI

this is assuming you are using a 70 mm line of 25 metres length.

Now do I prefer being able to add 25 for every length and 30 for every floor vertical, or stuff around with pocket calculators while my mates are putting wet stuff on hot stuffand expecting water PRESSURE.

You bet I do.

Just a note, if the branchman opens the branch out to flow 15 Litres per second, I will see a coresponding drop on the pump pressure gauge for that line, a wee adjustment on the lever will bring it back up to 605 KPA and he is happy.

5. umm...that seems really low, he's running 110 PSI at the pump? Thru auto. nozzels?
I know we run lower pressures to help move thru the structure and then add pressure for the attack.

6. We flow our 150' 1 3/4" at 150psi. Gave up on formulas, too much thinking. We have a 450gal tank. Timed how long it took at different pressures to get it empty in 3 minutes. (450/3 = 150gpm). Ended up at 150psi.

7. Formulas will only provide an estimate of what the flow really is. Your hose and the plumbing on the truck makes a difference too. To know for sure you must test it. You don't need a bunch of fancy instruments. Bones' method is as good as any. We recently tested the flow capability of our crosslay using all the fancy stuff. Came out real close to the draining the tank method.

Just for reference, we are using the Akron Turbo Jet nozzle with the selector on 200 gpm, pump pressure of 150 psi, provides a 150 gpm flow. We stay at or below 150 psi because that is the maximum recommended pressure for our foam injection unit.

Stay Safe

8. Sounds like 150 psi is a pretty good rule of thumb for pump pressures. The personel at the end of the line should certainly advise you if they are not getting enough water.

9. 200ft x 1 3/4 preconnects with TFT Auto's
we start at 150psi and adjust from there is necessary

Fire Service Survival Rules

1 - Cook at 350
2 - Pump at 150
3 - When in doubt, isolate and deny entry
4 - When in trouble, claim lack of adult supervision

We do not use hose beds here, Lengths of hose are carried coiled up or flaked into trays inside lockers.

Flaked trays are used for hydrant supplies out of the rear locker of the truck, 90mm line. that is as close as we get to your hose beds.

Out of side lockers above the pump panel, and other side of the truck, we will store 70mm and 45mm flaked line for immediate use.

Coiled hose is exactly that, start at the pump conector end and roll the hose up, That gives two ways to deploy the line, bowl it out along the ground, or holding onto the lugs and spinning off line as you advance forward.

Normal usage would be to run 70mm line up to your point of entry, and then lay a 45mm line in an "S" to use for fighting, the 45mm makes the entry teams job easier with more control on the line.

Exposure protection will normally be 70 mm lines.

"On the Bight" is where you fold the line in half, and then coil it from the fold back to the two connectors, you must start with the pump end connector on the bottom of the folded line.

This is only used on canvas percolating forestry line, as it is easier to bowl out in rough ground.

On our standard non-percolating line the crease tends to break the bonding between layers of the hose construction, and can cause some impressive splits under pressure, and that "Oh Bugger, where did my water go" feeling at the sharp end.

PS. our water spins in a vortex the other way to yours, so all our pumps are backwards.

11. My brain hurts.

12. We have our automatic control preset at 125 PSI for our 150', 1 3/4" preconnects.This gives us a good flow to start and the one guy can handle the line. If the nozzleman wants more he'll ask for more. Lines are equipped with automatic nozzels and the 125 PSI is best form the foam lines.No need to take your shoes off to figure out the flow.

13. Here in New South Wales, Australia, we use 1 1/2" (38mm) hose, with selectable gallonage (literage) Akron Turbo-jet nozzles, the settings on the nozzle are 115 l (30 gal), 230 l (60 gal), 360 l (95 gal) and 475 l (125 gal), per minute. For interior attack we start at a minimum of 230 l (60 gal), and turn it up as required. The 115 (30 gal) setting is used for small trash fires, mopping up and the like only. Pressures at the pump vary between 700kpa (105 psi) and 1000kpa (140 psi) as general guide, with more lengths in the line causing greater pressure at the pump being given by the operator. We tend not to use this type of hose for smaller fires though, as typically most urban pumping apparatus in this state have a high pressure booster reel(s) 25mm (1") or 28mm (1 1/8") running about 2500kpa (350 psi) to 3000kpa (420psi). Flow rate on these booster reels is about 150 l (40 gal) to 230 l (60 gal) per minute.

14. It's getting damn late in the day down here, so I'm going to cheat and ask Flying Kiwi to do the math for me seeing as how he obviously has a good handle on this topic!

We have 38mm (1.5inch) lines with TFT auto's attached, which are supposed to be pumped so that the guy at the business end is receiving 700kpa (100psi) after taking into account friction loss. Any idea what we are really flowing? We don't run pre-connects so the number of lengths varies, but we factor that in when calculating friction loss to enable us to reach a total pump pressure which will give us our desired 700kpa at the branch.

15. im not positive but on structure fires our preconnect we run 150

on car fires we run 100

16. Lines are equipped with automatic nozzels and the 125 PSI is best form the foam lines
Our foam system runs at 200psi.

17. So Kiwi, I ask this in all seriousness: The vortex you speak of that makes your pumps spin opposite of ours, and your toilets to drain opposite ours, and your weather patterns to move, I would imagine, opposite ours, this is all due to the Coriolis Effect. Do you guys move your nozzle counter-clockwise? It is because of this that smoke moves away from us up here when we go clockwise, it seems to me that to get the same benefits, you guys would have to go opposite. Hmmmm....

18. Why would our pumps turn in the opposite direction, when that is a factor governed by the rotation direction of the motor?

Gotcha.

Just goes to prove people can be baffled by science.

19. Ok a question...

How many of you have actually tested and figured your pressure and flows? As described earlier with the tank method, or by using gages. Or do you just take it for granted that your FL is X and so on and so forth.

The next Town over took delivery of a new truck (name withheld). They could not make foam from there #1 preconnect....no matter what.
So they went back to the basics...when the check the flow from the discharge, they found a tremoundous loss..right there at the beginning...wanna know why? There were 7, yes 7 elbows from the pump discharge to the outlet in the preconnect bed. 7 in less than 3 feet......have some friction loss there boyz.

20. HFD, that's kinda where I'm headed, I just have to round up the gauges and crap to do some testing. Probably before the month is over though. Since you asked, maybe you've done this before. I'm trying to score an 1 1/2" coupled inline pressure gauge to attach our nozzles to in order to get a base pressure figure. We've also got Elkhart's SM-20FG, which has a range of 60-200 GPM. On the side, it says 105 GPM at 85 psi. (Or vice versa, but that is irrelevant for this question) Is it the acme of foolishness for me to inquire if a gauge is at the base of the nozzle and reads 85 psi, should I be getting 105 GPM? Any formulas I should know? I have an older fog discharge one, don't know if it's changed. I also have a catalog from Akron Brass with a table in the back for base pressure and theoretical flows.

Awww, Kiwi thath low. Baffled by thience? I get baffled by much leth! Wait lemme get thith fithhook out of my mouth...Ahhhh, much better. But go ahead, pick on the guy that has never been south of the equator.

21. I think the one for one thing you are talking about refers to the Elkart Chief nozzles. Using different shafts in the nozzle bore you can dictate the gpm of the nozzle...i.e. choose 250 gpm @75 psi. for each psi you flow below or above that pressure you change the flow by 1 gpm. For example, flow 60 psi thru the nozzle, you get 235 gpm. This is only true for a relatively small span of pressures. Check out the chief nozzles, and talk to an Elkart saLES REP. I have also seen it stated that when using 200 ft of 1 3/4" line, each psi at the pump yields 1 gpm at the nozzle. Pump at 150, get 150 and so on.
Larry

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