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  1. #1
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    Default Pump Valve Operations

    We recently had a discussion at a training class on pump operations. The discussion was on if you should or should not ever operate a valve partialy open. Our chief said you should never do this. I class I attend at fire school said the oposite. They stated for example if you were at a rural fire using a drop tank, had several hand lines out with interior attack crews working the fire and you started the fire attack with tank water, once you establised a water flow you wanted to fill the tank on the truck using the tank fill valve you should open it part way so not to drop water pressure to your hand lines. They also went over other scenerios that this would be true on. I know it is probably hard on a valve to open it part way, but this seems to make sense to me. Any thoughts?


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    Discharge valves can be gated or "throttled" as much as necessary to acheive the desired output pressure/flow. You are correct in that once you have a water supply you can crack your tank fill valve open to slowly refill the tank so as not to steal too much water from the pump, allowing it to maintain the required amount of water/pressure to supply the handlines.

    Remember the tank fill is no different than any other discharge, it takes water thats coming in away and routes it into the tank. The more water you pump into the tank the less you have available to put into attack lines.

    The valves don't care if they aren't open all the way, it just makes a little extra noise and chatter. If you have locking pump valve handles, you can lock them so the turbulence of the valve being partly open doesnt cause it to vibrate closed.

    Your Chief is either wrong or he said something you may have misunderstood.

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    MembersZone Subscriber mcaldwell's Avatar
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    Yup,

    It is ball-valve nozzles and other stream discharge appliances (i.e. some monitors) that should normally be operated fully opened, or fully closed. Pump discharges can be set where required to balance flow and pressure.

    If you didn't have the means to throttle a hoseline discharge, you would not be able to run two different size hoselines off the same pump. A 1 3/4 preconnected handline for example, often needs to be run between 120 and 150 psi for a 150 or 200 ft lay. If you also tried to run a 200 ft, 2 1/2 inch handline off the same pump with a wide open discharge, you would be giving that line 150 psi also. If that is how your Chief expects you to run your pump, I hope you have the entire 2005 Mr. Olympia semi-finalist lineup for FF's. The nozzle reaction would be almost uncontrollable, and definitely not movable (except backwards of course ).

    Just another consideration for training; Some new trucks have electric valves that cannot be throttled. They have two settings, open or closed, and no in-between. That may affect the way you set your pump and discharges, and may require some extra planning.
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    One consideration of opening the pump to tank valve or recirculate valve while supplying handlines is the pressure that will be sent to the pump. Often manufacturers will tell you not to do this as teh water at higher pressures may damage the tank baffles. This is another reason why most just crack the valve to refill the tank. Operationally, keeping the tank full is very important in case you lose your water supply.

    mcaldwell: Have you seen electric "all open/closed" valves on the discharge side of the pump? This would cause the pump to only be able to supply one pressure to all discharges, which would be stupid. We have these valves on the supply side of a pump for valves over 3".
    Last edited by RFDACM; 05-17-2006 at 09:21 AM. Reason: clarification

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    MembersZone Subscriber mcaldwell's Avatar
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    RFDACM,

    That is how our aerial (Telesqurt), and a couple of other I have seen, are plumbed. It has a couple of control valves for the waterway that are as mentioned (they can serve as both supply, and discharge), and while it is not normally a problem, if we are using the waterway as an improvised standpipe, it does become an issue.

    As long as you factor that in, and balance your other handlines and/or discharges around it, it is quite manageable.
    Never argue with an Idiot. They drag you down to their level, and then beat you with experience!

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    Forum Member Haweater's Avatar
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    Quote Originally Posted by RFDACM
    One consideration of opening the pump to tank valve or recirculate valve while supplying handlines is the pressure that will be sent to the pump. Often manufacturers will tell you not to do this as teh water at higher pressures may damage the tank baffles. This is another reason why most just crack the valve to refill the tank.
    What manufacturer is telling this? I have never heard of such a thing (not that that makes it wrong, I'm sure there's still an aweful lot I haven't heard of in this profession!)
    I have filled the tank on the truck by everything from pumping to just letting the hydrant pressure do it without even having the pump engaged (use tank suction, not tank fill; then it bypasses the pump) and have never heard of damaging baffles by putting water in too fast.
    Cheers,
    G

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    Quote Originally Posted by Haweater
    What manufacturer is telling this? I have never heard of such a thing (not that that makes it wrong, I'm sure there's still an aweful lot I haven't heard of in this profession!)
    I have filled the tank on the truck by everything from pumping to just letting the hydrant pressure do it without even having the pump engaged (use tank suction, not tank fill; then it bypasses the pump) and have never heard of damaging baffles by putting water in too fast.
    Cheers,
    G
    We had a member crack a tank by filling it too quickly... but the baffles were fine, it just blew the top off... it's an OLD engine and there just wasn't anywhere for the air to vent to.

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    Forum Member Haweater's Avatar
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    Quote Originally Posted by Firetacoma1
    We had a member crack a tank by filling it too quickly... but the baffles were fine, it just blew the top off... it's an OLD engine and there just wasn't anywhere for the air to vent to.
    Okay, point for firetacoma1..... 'Tis true that with unvented tanks there are many ways to damage them with speed of fill. At the same time, I saw pictures of an old tanker that wasn't vented.... protocol was to climb up top and open the hatch before filling or dumping. Operator got in a rush and didn't bother before opening the large dump. The vaccuum created caved the sides of the tank in!

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    Quote Originally Posted by Haweater
    Okay, point for firetacoma1..... 'Tis true that with unvented tanks there are many ways to damage them with speed of fill. At the same time, I saw pictures of an old tanker that wasn't vented.... protocol was to climb up top and open the hatch before filling or dumping. Operator got in a rush and didn't bother before opening the large dump. The vaccuum created caved the sides of the tank in!
    There is a picture of a similar incident in the IFSTA water supplies manual. I believe the one in the manual is a converted smooth bore milk tanker... Flat as a pancake!
    Service is the rent you pay for having space on earth.

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    Math's pretty amazing

    If you just take a tank's top on a rectangular tank, discounting the sides...

    Say it's 7' x 10', that's 70s.f. = 10,080 square inches.

    I let you finish the math for each 1 pound per square inch of pressure caused by air that can't vent quick enough

    As for filling the tank...with the pump up near 150psi, a 2.5" pump-to-take plumbing could come darn close to using up all the pump capacity even on 1500gpm if you opened it up all the way.

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    I have seen the top of a tank come off too, we was in a city mutual aiding them on a big industrial building fire, in which they was running a tanker shuttle and using hydrants, and they was filling the tankers right off of one of the hydrants a few miles away, but didn't have an engine hooked to it, so they kept turning it on and off at the hydrant, don't ask me why they didn't put a valve on it, but they turned it the wrong way one time and blew the top of the tank of the one tanker. but getting back to the question about the cracking of valves, I think one of the main reasons that they don't want you filling your tank at more than 100 PSI is b/c there is a lot of company's that use rubber hose from the pump to the tank, since they mounted to each other and the flexing of the truck wouldn't allow steel pipe to be connected without breaking all the time, so that's why I figure they say that one so you don't blow that hose.

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    Default Mav

    We have some pneumatic valves on the delivery side of our pumps (monitors) and some pneumatic tank to pump valves. We also have some pneumatic transfer valves (series/ parallel). These are on our older Darley SEH 1000 pumps. We are taught to open these valves then build pressure using the throttle to prevent slamming the valves open or shut.

    Our newer pumps (Darley LDMH 1000) are all gated valves. However we still crack the valves before building pressure so you are not fighting the pressure in the pump casing when operating valves.

    We also back fill our tanks by cracking gated valves but this is impossible (gating) with pneumatic valves. However we have 42 litres per minute pump cooling that flows back to the tank regardless so we can ever so slowly refill our tanks during pump operations.

    If we leave the tank to pump open on the pneumatic valves the tank fills quiker but when it is full the excess water dumps to waste and if you close the valve you are doing it against hydrant pressure (typically 700 to 800 kpa 100+psi). You are obviously also stealing water from your attack hoses too.

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    Quote Originally Posted by Haweater
    What manufacturer is telling this? I have never heard of such a thing (not that that makes it wrong, I'm sure there's still an aweful lot I haven't heard of in this profession!)
    I have filled the tank on the truck by everything from pumping to just letting the hydrant pressure do it without even having the pump engaged (use tank suction, not tank fill; then it bypasses the pump) and have never heard of damaging baffles by putting water in too fast.
    Cheers,
    G
    Open up the pump access panel and look at the front of the tank. There's likely a yellow sticker (usually on the passenger side) on the front of the tank that states not to fill over 100 psi or at a rate more than 10% of the capacity. My understanding is there's a baffle right behind the tank fill, if you hit it with too much pressure, you'll dislodge or damage it, compromising the tank's structural integrity.

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    Quote Originally Posted by JSMV72
    We recently had a discussion at a training class on pump operations. The discussion was on if you should or should not ever operate a valve partialy open. Our chief said you should never do this. I class I attend at fire school said the oposite. They stated for example if you were at a rural fire using a drop tank, had several hand lines out with interior attack crews working the fire and you started the fire attack with tank water, once you establised a water flow you wanted to fill the tank on the truck using the tank fill valve you should open it part way so not to drop water pressure to your hand lines. They also went over other scenerios that this would be true on. I know it is probably hard on a valve to open it part way, but this seems to make sense to me. Any thoughts?
    When you operate a valve partially open, the water, but more likely any sand, dirt, rust, and calcium eats away at the valve ball to some degree but so what. Valves are easy to rebuild, I do it all the time. Tank filler valves always being partially opened, suffer the brunt of this and are often in really bad shape but it takes at most an hour to replace the parts in one and it is only necessary every couple of years.

    As a wise old mechanic once told me, "tools are made to be used." He would get out a torch and bend a wrench to fit if a nut was in an awkward place...just the cost of doing business.

    You could run your tank filler wide open, but you'd have to open your throttle up wide to compensate and then when the tank was full you'd blow water all over the ground and possibly in the hose bed, and you'd have to be darn fast on the controls to do this smoothly.

    I always operate with the tank filler barely cracked. Keeps the tank full and the pump water cool.

    Birken

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