Tank To Pump

[darook]

Howdy Folks!

Recently have taken on the responsibilities on getting into a driving rotation. In my initial pump training I was told to leave "tank to pump" valve open when running off a hydrant just in case we "lose the hydrant". Made sense to me at the time. Fast forward 3 yrs later I was doing my pump ops cert and was told not to leave the tank to pump valve open. I explained that I was taught to leave it open in case I lost the hydrant. Instructor noted that in his 20+ yrs hes never had a hydrant malfunction on him, (were in a large urban setting)

My question is does anyone know of any reasons why we would close the tank suction?

[ffmedcbk1]

the p.o. leave the t2p closed when on a source so that if the hydrant or water main craps out or a lessening of pressure occures due to other units getting supplies, you can identify and address the issue easily. using you basic senses of sight (on the intake residual gauge), feel (ldh gets soft) and sound (revving up of the motor) you can identify quickly, then get on tank water, notify the companies operating on you lines and command. then they can prep for withdrawl or they may have an under control and turn to mop ups. then you'll have a sense of the timeline of tank supply (knowing your tank gallons and flows occuring on the attack lines).

if you leave the t2p open then, you may not hear the change or know that you're on tank.

keeping it closed may give you a momentary lapse of water (potentially <2 seconds typically) but will give them and you the awareness and knowledge to make a safe and stratigic withdrawl.

i know that there will be varying opinions on it, but that is the way i see it and instruct too.

[BoxAlarm187]

In addition to what's posted above, if you leave your tank to pump open, you run the risk of starving the tank dry without realizing it.

Suppose you're on a weak hydrant at a working fire. You started off on tank water, but then got your sustained water supply established, and leave the tank to pump open. Meanwhile, the interior crews are placing additional lines in service. Eventually, they get to the point that they're using more water than the weak hydrant is giving you, so the pump does exactly what it does -- looks for more water. Finding more water in the tank, it starts to feed those additional lines with tank water until *poof* all the tank water is gone. I don't want to be on the end of the line when that happens!

You want that tank water to be your "reserve" in the case of hydrant failure, so by closing the tank-to-pump valve, you'll guarantee that it's there when you need it.

This is standard practice for my departments, and is part of our state's training curriculum.

I'm sure others will weigh in on this also...

[rm1524]

I can say that I have never heard of leaving the tank to pump open once a water supply is established other than on CAFS. Once water supply is established the tank to pump is closed and the tank is slowly refilled. The tank is your emergency supply if something happens to the water supply.

[Eng34FF]

I agree with most of the post here. leaving the tank-to-pump open may lead to bleeding water from the tank slowly wihout the operater noticing it.

I disagree slightly about the instructors comments regarding hydrant failure. While I have not seen a hydrant fail completely once it is flowing water, I have seen it not be able to supply the amout of water being demanded. As mentioned earlier, if the tank-to-pump is left open, you may not see the signs of this as soon and could drain the tank or have issues if more water is needed.

[Firetacoma1]

While I agree that it should not be left open, the reason given that you could be draining your tank and not realize it is bogus. Do you not have a gauge on your panel? Any operator worth anything should be monitoring his tank level and realize they're using more water than the single hydrant can provide!

[DeputyMarshal]

My question is does anyone know of any reasons why we would close the tank suction?

The first that comes to mind is that, once the tank has back-filled through the open tank-to-pump valve, you're going to be dumping some of your hydrant water from the overflowing tank onto the street instread of running it all through the pump where you want it to go...

[CCCFire09]

From NFPA 1901, 2009

"A.18.3.3 A check valve installed in the tank-to-pump line is the
most common method used to prevent water from backflowing
into the tank at an excessive rate if the pump is being supplied
from a hydrant or relay pumper and the tank-to-pump line valve
has been inadvertently left in the open position."

If it is a newer (1995 on?) pumper, it should have a check valve to prevent back flowing.

[DeputyMarshal]

From NFPA 1901, 2009

"A.18.3.3 A check valve installed in the tank-to-pump line is the
most common method used to prevent water from backflowing
into the tank at an excessive rate if the pump is being supplied
from a hydrant or relay pumper and the tank-to-pump line valve
has been inadvertently left in the open position."

If it is a newer (1995 on?) pumper, it should have a check valve to prevent back flowing.

"Should," not "Shall" and note also the phrase "to prevent water from backflowing into the tank at an excessive rate " -- not to prevent it altogether.*

The reference to the valve being "inadvertently" left open does, however, seem to reflect that the 1901 TC believes it should be closed. That addresses the original poster's question nicely.

-----
*18.3.3 requires an automatic means to prevent unintentional backfilling of the tank which is problematic because there is no practical mechanical means to determine if backfilling is intentional or not.

[Saltspringfire]

In addition to what's posted above, if you leave your tank to pump open, you run the risk of starving the tank dry without realizing it.

Suppose you're on a weak hydrant at a working fire. You started off on tank water, but then got your sustained water supply established, and leave the tank to pump open. Meanwhile, the interior crews are placing additional lines in service. Eventually, they get to the point that they're using more water than the weak hydrant is giving you, so the pump does exactly what it does -- looks for more water. Finding more water in the tank, it starts to feed those additional lines with tank water until *poof* all the tank water is gone. I don't want to be on the end of the line when that happens!

I'm sure others will weigh in on this also...

Most of the hydrants on our island are weak hydrants, so this is common for us. That is where you need to rely on a good operator to let IC and Attack crew where they stand on water supply.

Our standard is any truck with a governer the tank to pump is left open... since like stated you can hear the engine rev up, and you will see the visual of the water gauges going down and watching your intake gauges. Truck without governers the TP valve is shut unless IC is looking for a short burst of water to hit the fire hard.

[voyager9]

I'll chime in and say that once a water supply is established the choice to augment that supply with tank water should be a conscious one. Once you have a real supply, the tank is the emergency reserve.

That being said if the demand is outrunning the supply the operator should catch that right away whether the tank is open or not. Tank water won't effect the residual reading so the drop will be the same whether it is open or closed.

[mikeyboy411]

Open or Closed....?

I've always taught that the "Change-over" isn't complete until the Tank to Pump Valve/Handle is closed. My reasoning is the same as what's been stated here (the robbing of water from the Tank). As far as totally relying on the Tank Level Indicator on the Pump Panel, I discourage this also since something as simple and routine as "Batch Mixing" Class A Foam can send a false reading. What I teach is to open the top hatch and visually inspect the level. This always gives a correct/accurate water level.

Just some "food fer thought....."

[kuh shise]

darook: I've been teaching pump operations for just under 37 years, but that doesn't make me the expert on operating pumps. I've been driving fire apparatus for nearly 42 years, and that doesn't make me the expert either. Having sad this, I keep and open ear out for any logical reasons for changing how I teach or what I recommend.

First. in those 43 years I have seen rapid losses of hydrant and relay supplied water on numerous occasions. Rocks and stones in a poorly installed new main comes to mind at one item. A snuff can lid is about 2 - 9/16" diameter and does a heck of a job at sealing off a 2 1/2" intake. Try a plastic bag over the screen on a 6" steamer inlet. Screened coal drafted from a mine wash pond can plug the fine screen inlet in a 2 1/2" pony suction. The requirement by a water authority that the FD use a back flow preventer when using a hydrant resulted in the clapper valve coming apart and partially plugging the inlet of a 6" steamer. So.... in my experience, you better be prepared for the loss of supply.

Second, for a lot of the readers on here, the pump operator is often charged with throwing ladders while the attack crew is making entry. Thus he is not on the panel at a critical moment in the attack. It is a whole lot safer for the line to have an automatic source of additional water while the P.O. is otherwise occupied.

Third, If the pump operator doesn't know if there is a check valve in the tank-to-pump he's not a pump operator, or he hasn't been properly trained on that engine.

Pump discharge pressure is the total of pressure developed by the pump plus the incoming pressure from the hydrant. If the hydrant pressure goes to zero, the pressure governor will throttle up automatically. Any pump operator worth his salt will be listening for any changes in the engine rpm, and will immediately investigate any unusual engine operation.

An engine equipped with a pressure relief valve and properly set-up with the relief valve set just above the desired operating pressure, will bog down when an additional load is placed on the pump. So the operator, who is listening for engine changes will hear the shift to lower rpm and go to investigate.

Yes, if you run out of tank water there will be a rapid loss of line pressure, but it will occur several minutes after you loose water from the main. Hopefully, if you are doing your job, you will find it before it runs dry. The line would immediately loose water if the T to P wasn't open.

In my opinion, you were taught correctly when you received your initial pump training, and the current instructor needs to rethink his protocol.

[BoxAlarm187]

KuhShise,

I've always respected your postings, they're always very educational. While I understand your post and thoughts on this subject, I respectfully disagree.

Even in departments where the PO is expected to throw ladders (such as mine), I've yet to see where the PO has neglected his duties at the pump panel in order to do ancillary activities at the fireground. Perhaps it's a matter of training and expectations within different departments.

Based on your post, are you suggesting that the others on here that teach to close the tank-to-pump are teaching incorrectly?

Also, what are your thoughts on starving the tank with the additional demand for water on the hose lines?

[darook]

wow great responses guys, keep em coming