Tank To Pump
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?
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.
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...
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.
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.
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!
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...
Originally Posted by darook
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.*
Originally Posted by CCCFire09
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.
Originally Posted by BoxAlarm187
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.
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.
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....."
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.
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?
wow great responses guys, keep em coming
Without saying "always" and "never", for the most part, my guys stay at the pump panel if they are the chauffeur. The only time that changes is on multiple alarm fires where it's not necessarily the rig that's needed - but man power and tools.
We don't keep the tank to pump open once we've got an established water supply for a few reasons:
1) We lose the supply from another pump, hydrant, whatever, we've got 500 gallons of tank water to allow our crews one last hit, or plenty of protection as they make their way out.
2) We put an engine on the hydrant every time. The first due may nose into a hydrant right by the building, but the second due still picks up the hydrant behind them and pumps their line. If the water goes out, now not only do we have one 500 gallon tank, but two. 1000 gallons of tank water once your hose is filled is a good thing. Plenty of time for protection.
3) If we're flowing at a rate that requires more then our supply can handle, we call for another alarm or start bringing up the cover companies to the scene. More LDH, more supply pieces, perhaps even drafting to augment the city municipal water system.
Personally speaking, I'd rather know that if my supply fails, my pump op is right there anyways. Our pump operators rarely (can't say never..) throw ladders and get too far away from the piece except to make standpipe/hydrant/whatever connections to pump. If you can't "pump with your ears", then you don't belong behind the wheel of my fire trucks.
Box Alarm 187, I am suggesting that as a policy in my department, you normally run with the tank to pump open when supplied by a pressurized source. Particularly when starting out of the tank. In the initial stages of an operation, the P.O. has a lot of things going. We do not as a matter of course, have our pump operator throw ladders, but there are a number of other things that pull a driver away from the pump panel. Setting up a light tower or running extension cords & fans... (Truck Co. is 3rd or 4th due) Clearing the second attack line out of the bed. Aw, you know the routine when you are short handed. I'm not opposed to closing the T to P if you are chained to the panel so you can react to problems as they occur. With the T to P off and you loose water on the intake, the pressure governor will wind up to compensate for the drop in intake pressure. If you then open the tank to pump at the right time (just before the automatic shut down reacts) with the rpms wound up you will get a spike in pressure to the attack line. The other way around, you will get an increase in rpm that you investigate, find the intake is collapsed or the tank dropping, then you have time to radio the officer and withdraw the crew in the 2 to 5 minutes of water that remains in the tank. With the T to P closed and you loose water, the immediate result is no water to the attack crew, or worse. Just enough pressure in the line to stir up the thermal and you get the lower, oxygen rich air at the floor to mix with the hot stuff over the fire and whoooof, comes the ignition of the mix, with little or no water available.
Glad I went back and read your earlier post. One of the first things that needs to be done after establishing a pressurized supply, is to refill the tank to act as an emergency reserve, should the supply fail. So, no, I'm not in any way suggesting that an agressive interior attack be made without an adequate supply. I'm also not suggesting that a P.O. try to supply more lines than the hydrant or relay volume can handle. This goes back to the pump operator estimating the available water to his engine by comparing the static (if you get a chance to make the reading when nobody is taking water), with the residual and at a known volume being applied to the fire. You know, the old 5% drop = 3 more lines; 10% = 2 more and 25% or less 1 more line estimator.
I think you may be concerned with a situation where the hydrant supply is inadequate to supply the selected lines applying water to the fire. I agree, you won't immediately know that you are taking tank water to suppliment the fire flow, but you should realize that the intake is below zero. This would be an immediate indicator of an insuffient supply.
Personally, I look at the tank as an insurance policy if I were to lose the hydrant. As said before, if it were left open, a good operator would catch it and take the necessary actions from there... but you can blow through a lot of water in a hurry if you have multiple lines open. As for augmenting hydrant flow with tank water, I guess my theory is that you're going to run out of tank water at some point doing this, so then your contingency plan is gone, and you're going to have to refill the tank (hopefully not during the attack process).
I would prefer to get the instant warning of a problem (loss of incoming pressure), grab the tank to pump and sound the horns.
Personally, if I am inside a building and the pump operator is not within 6 feet of the panel, we are going to have some very harsh words. My life depends on him doing that job. I don't care how many govenors, relief valves, or anything else is in line with the pump; I want a live human with training on the pump when I am in a fire. I know that everyone is short handed (we only have about 10-15 really active members), but if we are going in, we have two people on the line, two outside that can go after them, and one on the pump regardless of what else has to be done.
We run with the T-P valve closed once we have water supply. You should be filling the tank once you get supply established while pumping. If I am inside and the line pressure fluctuates, I immediately make sure the other guy in with me knows, radio to see what is going on, and start on my way out. If you are pumping more water than the supply is giving, there should be communication going out to that effect so everyone knows that things cannot continue as they are going now.
We train that if you are running the pump you should be able to read the gauges and know what is going on based on that. We also train that if we cover any of those gauges that through the sound of the truck and the feel of the lines, you should also be able to tell what is happening. Then again, we do not have any trucks that have automatic pressure/RPM govenors.
If you're pumping from a draft, or working on the pump and don't want to loose all the booster tank water. Or, if the swing-check valve is malfunctioning.
Originally Posted by darook
Other than that, I never close mine.
BTW, if the swing-check valve is operating properly, and 99% of them do, then the tank-to-pump line is closed when you're hooked into a pressurized supply.
Instead of looking for a good reason to open it, I want good reason to close it.
We don't have hydrants.
Originally Posted by txgp17
When we are using pressure supply from another engine drafting or relay operation, we leave our T-P valves closed. Most of the engines around here do not have a check valve in the T-P line as most of them are 20+ years old.