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DRAFTING WITHOUT A PRIMER PUMP
Replies to This Discussion
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Permalink Reply by Markus Lawrence on -
Does anyone remember how to draft if you lose your priming pump. I remember doing it once, its been awhile. I think we set it up just as if we were going to create a partial vacuum ( making a tight seal). Closed the tank to pump, drained the pump of water with hard suction hooked up from engine into a draft pool. Then in"pump", opened the tank to pump valve letting water in pump from the tank filling the pump with water as well as the hard suction with water and then throttling up slowly while opening a discharge slowly drawing water from the draft pool to the pump. Is that correct?
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Permalink Reply by Larry Lasich on -
If you have a jet syphon on a suction foot hook a line to it. Then you pump booster water to that line and force water up into the hard suction. Keep the air vent open until water comes out and then close it. At that point you should have water in the pump and can close the tank to pump. Keep the discharge that is supplying your jet syphon running. It will insure that you are maintaining prime, even if none of your other lines are in operation.
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Permalink Reply by Adam Miceli on -
My first FD did this evolution in pump training. I recall backfilling the connected suction line from the tank, then engaging the pump? It's been just a few years... I know they taught backfilling the suction lines routinely to make the draft easier where there was a higher or longer lift/draft.
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Permalink Reply by Markus Lawrence on
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yeah i think youre right. im gonna go back to work from vacation and ask around again and maybe just try it down at our tower this tour.
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Permalink Reply by Todd "Walt" Walton on -
If you have a valve between the hard suction and the intake you can have the pump circulating water but not discharging water and when you open the valve water backfills the hard suction and by throttling up and opening the tank fill you can stop the water from flowing into the dump tank and get it drafting into the pump.
Same concept if you don't have the valve. With the pump wet and not engaged get everything connected, engage the pump and with the tank to pump open the excess water fills the hard suction. Again by throttling up and opening the tank fill you can stop the water flowing out and get it flowing in.
Couple thoughts on this. You have to do this in a controlled manner because you have to reverse the flow of water in the hard suction. It takes practice and some luck. I've demonstrated it for one group and couldn't get it for the next. The biggest thing is, when your tank is dry you are dead in the water so to speak. Our low level strainers have jet siphons on them.
If things went to hell and I lost draft and my primer with a tank of water on scene I'd probably pull the strainer off and stick a line in there to create a jet siphon to get going again.
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Permalink Reply by Markus Lawrence on
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THANKS TODD, THAT MAKES SENSE. I'VE BEEN ABLE TO DO IT MYSELF AS WELL, BUT ALSO HAD A PROBLEM RECREATING THE DRAFT WITHOUT USING THE PRIMING PUMP. IT DOES TAKE "TOUCH" AND LUCK I AGREE. COULD YOU EXPLAIN HOW TO CREATE A "JET SIPHON" IM NOT SURE WHAT THAT IS. THANKS
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Permalink Reply by Todd "Walt" Walton on
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You can buy commercially available jet siphons that go on the end of a section of hard suction that are designed to transfer water from one dump tank to another. Basically they are a ring that is threaded to attach onto the hard suction with a discharge orifice in the middle. The jet siphon connects to a piece of 1 13/4" hose to supply the water.
It works by utilizing the venturi effect. Basically it's the same concept as when you hydraulically ventilate out of a window only instead of moving air this moves water. With the jet siphon on the low level strainer the pump operator is able to charge the line to the strainer and get water to the intake valve so it reduces the time, or sometimes the need, to use the primer when the valve is opened.
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Permalink Reply by Kelly Vandygriff on
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Each of you are passing along very useful information for drafting without using your primer. I think it was previously mentioned that you must keep water in your apparatus tank for this purpose. A lot of times in our area, we end up emptying our dump tank prior to the return of tankers and must switch over to tank water to continue operations until the tankers return. It is a must that you refill your apparatus tank each time you have a chance not just for the purpose of drafting, but for that extra water in case something else goes wrong as it always does. There is always a chance of having a dump tank failure or a tanker failure, which having a full apparatus tank will give you a few extra minutes when needed.
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Permalink Reply by Todd "Walt" Walton on
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Good point Kelly. Mentally I had filed this under "The Obvious" because that is what we do and what I have been trained to do.
Regardless of how the water is supplied, you always "thief" some water to the tank to get is full in case you lose your water supply. You could lose prime, your dump tank could run dry, the relay apparatus could shut down for whatever reason, a hose could get run over or burst or any other possible way Mr. Murphy decides to participate in your operation.
That tank of water gives you time to get the guys out. If you have one line flowing 125 gpm with a 600 gallon tank that team has 4 minutes of water. If you lose water supply and open the tank to pump to supply the operation (especially if interior) your hand goes straight from the TTP lever to either A) the radio to advise the IC you have lost water supply and/or B) the air horn button (in our case) to signal evacuation depending upon the situation. Give them all the time you can to get out.
Again, good point Kelly.
Walt
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Permalink Reply by John M. Scheibel on -
I am an Instructor with NY State. I like all the answers here, and only can add that an additional thing to add to your arsenal, is Wet Pumping, and utilizing a Small stream to vent air from the Pump Cavity.
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Permalink Reply by Todd "Walt" Walton on
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John, this may be a terminology thing but you have piqued my curiosity. What do you mean by Wet Pumping and utilizing a small stream to vent the air from the pump cavity?
I would assume that means to run the pump wet and when initiating a draft to open the discharge slowly to keep from losing the draft. Of course we all know what happens when you assume.
Please set me straight.
Thanks,
Walt.
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Permalink Reply by John M. Scheibel on
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Hi Walt;
Actually you must use a "Butterfly"Valve on your Intake..You bring water into the Pump Cavity, and start a Stream..Once the Stream is free of air, open the Butterfly valve slowly, one click (detente), at a time and using this, you create a "Venturi effect", much like a Bypass Foam Eductor, venting the air from the Suction Hose as the water passes through the cavity. Now understand, that this is used when one of the Fins is damaged in the primer pump. This does take some training, but can be used in one of those dire moments when you really can't get over the Hump.
Todd "Walt" Walton said:John, this may be a terminology thing but you have piqued my curiosity. What do you mean by Wet Pumping and utilizing a small stream to vent the air from the pump cavity?
I would assume that means to run the pump wet and when initiating a draft to open the discharge slowly to keep from losing the draft. Of course we all know what happens when you assume.
Please set me straight.
Thanks,
Walt.
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