Thread: Pump Pressures

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    Default Pump Pressures

    In my department we don't pump our engines to account for friction loss most of the time. The officer tells the A.O. what pressure he wants at the pump, which is usually 100 psi or less (FYI, we're using adjustable fog nozzles). They say that if they want an adjustment in pressure, they'll call for it. Their reasoning is they want to be able to move the hose through the structure with ease (keep in mind that we're usually staffed at our minimum of three personnel per rig). Does anyone else's department/company operate in the same manner? What do you think?

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    We ran flow tests to verify the gpm from our nozzles on our preconnects was giving us the 150+ gpm that we wanted. That is what our lines are pumped at. I, as the usual officer on the engine, am not interested in telling my driver/operator what pressure to pump at during a fire call. That's his job. Your setup may work for you, and if it does, who am I (or anyone else) to tell you to do differently.

    My question though, what happens if a second line comes off? Does the officer have to come out and tell them what to pump that line at also? I can think of a lot more things for an officer to be doing than telling the operator pump pressures.

    There is nothing wrong with asking for a little more/less pressure on the line during operations if the need arises.
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    which is usually 100 psi or less (FYI, we're using adjustable fog nozzles).
    What brand of nozzles are you using automatic, adjustable gallonage, fixed psi?

    How long is your normal strecth. What is the desired GPM? Alot of questions need to be asked. Strecth out the hose get an in line gauge or pito gauge and go to work.

    Remember all nozzles work differently. if a nozzle needs 125 psi to operate properly than so be it. Running the nozzle at less than required psi will not give the flow you may be looking for.

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    Nope...And let me say thats the first Ive heard of that.

    Ours are pumped at set pressures, based on hose length, type of nozzle, what you are flowing (water or foam) and required GPM. This is then adjusted either up or down as requested by the hose team.
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    I cant see how running at a lower pressure makes much difference on moving hose. Once the air is bled out, its about the same amount of water in the hose if it 100 psi or 150 psi. I feel pretty sure yall arent getting the full potential out of you nozzles the way yall run. Our engines are preset at 170 psi on crosslays, 200' X 1 3/4" with TFT fog nozzles.

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    Quote Originally Posted by hvfd507
    I cant see how running at a lower pressure makes much difference on moving hose. Once the air is bled out, its about the same amount of water in the hose if it 100 psi or 150 psi. I feel pretty sure yall arent getting the full potential out of you nozzles the way yall run. Our engines are preset at 170 psi on crosslays, 200' X 1 3/4" with TFT fog nozzles.
    Dont take this wrong, just some freindly advice Thats in the ballpark for what we used to run our 200' pre-connects. That is untill I stumbled on the handline flow chart on TFTs website. We were off by quite abit (low). Check it out for yourself.
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    We have a preset pressure that we operate at to start, and then adjust as needed from there. Since we have preconnected attack lines, almost all incidents at least start of by pulling one or more preconnects, so our engineers are all familiar with our starting pressure. After that, if other lines are added into the operation, some figuring will be done or take a peak at a quick reference chart. Take the max gpm of your nozzle, figure the friction loss for the size and length attack line you'll be using at that gallonage, add that to the recommended operating pressure of your nozzle, and you should arrive at the recommended pump pressure for that set up. Any less pressure than that, and you won't be getting the full potential out of that nozzle. If you don't want or need full potential, like in an overhaul situation, then we request the operator to back off a bit to to make the hose a little more flexible, but I'd never want to take a soft line into an initial attack.

    Each attack line can be different length, size, and gpm nozzes, and the same math works. Your pump pressure needs to be as high as the highest pressure required by the different attack lines, so the one requiring the most pressure gets full pump pressure, and any other lines being used that require lower pressure will be gated down to the required pressure for that line.
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    You are underpumping your handlines and will not be delivering the gpm's to overwhelm the fire. This is a dangerous game to be playing.

    I would suggest figuring out the minimum gpm's your dept wants to deliver and pre-determine your pump pressures accordingly.

    Reccomended minimums that I have found are 150 gpm residential and 250 gpm commercial.

    I'd rather have enough gpm's to kick the fires *** and then radio to lower the pressure once knockdown has been accomplished, if you really felt it was necessary.

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    Good answeres thus far...thank you.

    My question though, what happens if a second line comes off? Does the officer have to come out and tell them what to pump that line at also? I can think of a lot more things for an officer to be doing than telling the operator pump pressures.
    Bones, I'm sorry for the misunderstanding. The officer doesn't tell the A.O. the desired pressure at every incident. He has a pressure he wants the A.O. to start out at for every fire. For example, mine wants me to start pumping the line (at the pump mind you) at 100 psi. He (and most captains) establish this with their drivers from day one.

    What brand of nozzles are you using automatic, adjustable gallonage, fixed psi?

    How long is your normal strecth. What is the desired GPM? Alot of questions need to be asked. Strecth out the hose get an in line gauge or pito gauge and go to work.
    CaptainS, we are using Akron adjustable galonage. Our typical stretch is 150 - 200' of 1.75" hose. Most of our rigs don't have 2.5" preconnected, nor is the 2.5" line used much (but that's for another thread). As for desired gpm...I have never heard an officer at my department talk about that. Honestly, I don't think that even crosses their mind. All they want is water coming out of the nozzle and not so much nozzle reaction that they have to fight with the hose.

    I would suggest figuring out the minimum gpm's your dept wants to deliver and pre-determine your pump pressures accordingly.
    ewelk33, Your post makes sense. I would love to do what you suggested, but I have to follow the orders of my officer, which means I'll start pumping at 100 psi @ the pump.

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    I have never heard an officer at my department talk about that. Honestly, I don't think that even crosses their mind. All they want is water coming out of the nozzle and not so much nozzle reaction that they have to fight with the hose.
    Like most of the post have already stated if you are not putting out enough water, you may be putting the crews into some danger. If i am not mistaken there are three or four settings on the turbo-jet 100 , 150, 175 200. I think there may be two series nozzles as well(some on help me out with this).

    Anyway I think you will need a minum of 125 at the nob for the nozzles to work at the minimum flow rate and if you adjust the flow settings you need to let the mpo know so he can compinsate.

    One way to compensate for lower nozzle re-action is to go to a low pressure fixed gallonage nozzle. Akron make the assault and i am not sure of the TFT equivelant. You can get 150 gpm at 75 psi or 175 at 100 psi. One simple setting at the pump ( don forget to account for elevation and length of stretch).

    The bottom line is if a nozzle is supposed to work at a certain psi work the nozzle as it is supposed to otherwise undesirable outcomes may happen.

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    CaptainS,

    I agree with you. I didn't know about the low flow Akron nozzles; I wish we had them. If I had the four or five bugles on my collar, I would make the necessary changes you've stated above, in addition to adding smooth bore nozzles for some of my attack lines.

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    Turd are your Dept initials TFD?? Just curious. Your lingo sounds like the way those guys talk...if your are from TFD

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    If you're pumping 100 PSI on 200' of 1 3/4" line youre gettin about 30-40 GPM

    If you're poumping the 150' line like this its about the same.

    Please don't take this the wrong way, but this is why we burn buildings down. Instead of addressing the root issue of handline managment and proper nozzle selection, your officers have made a decision to cheat on the wrong side of the equation. I understand where you are coming from, I used to run with a fire dept that had a similar problem. I'll tell you this. I work on an engine with one other ff, thats rignt...only 2 of us. We have 5 other FF's on duty that arrive in other vehicles to fires. We stretch and operate 200 and 250' 1 3/4" preconnects with 180 GPM nozzles with 2 or 3 people. Its all about the training and managment ability. Why cheat and potentially lose a building or injure ourselves.

    What I gather of the whole situation is that there is a gross misunderstanding of hose and nozzle theory and capability. Posting your question makes me think you are about to try and address this issue. I hope you do, its worth making a fuss over. Do your homework and prove your case. Check with your local fire acadamy and see if you can borrow a flow meter to run tests to show what you are pumping compared to what you should be pumping.

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    The officer tells the A.O. what pressure he wants at the pump, which is usually 100 psi or less (FYI, we're using adjustable fog nozzles).
    IMO, this is downright dangerous. Assuming a 1 3/4" stretch of 4-6 lengths with ANY fog, you are not even close to a acceptable fire flow. We start out at 170psi at the pump for our primary water, usually to feed 6 lengths of 1 3/4" with a 15/16" solid tip. We're shooting for about 180gpm (the standard fire flow).

    Go do the math with 100psi at the pump and your average lay of hose by size, then factor in your nozzle's specs. You will find you are DANGEROUSLY below the 180 gpm mark.

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