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  1. #1
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    Question need help w/cafs problem

    Since the arrival of our new Quint 2 years ago we have been doing tons of training with this truck. The truck is a 75 foot quint with a single stage 2000gpm waterous pump with a class one pressure govenor. We are fortunate to have some really good hydrants in our area with hydrant pressures in the 130 to 150 and a few in the 180 range. When pitot the flow in excess of 1450 gpm. When trying to flow cafs threw 1 3/4" at 100 psi there is to much pressure coming in for the pressure govenor work. So what we have been doing is when the quint takes a hydrant when close the piston intake valve some to cut pressure. At calls where we can place a engine behind the quint we have them flow no more than 100 psi. so we can regulate pressure. Has anyone seen or have a pressure govenor and a relief valve with a cafs on the truck? Does it work? I was told that Hale makes one. I was also told that having both was not NFPA complaint. What are others doing? Waterous recomended that we pull the tank fill to bleed off pressure, we have done this but still have to much intake pressure. we are currently working with all of our mutal aid companies and training them to only pump 100 psi unless asked for more pressure. any suggestions. I have asked the manufacture for assistance and they are working with engineering on it, so does anyone have ideas I can take back to them?
    ASST.102
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  2. #2
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    We engineered a direct tank fill line on our CAFS truck (see http://www.willingtonfire.org/rescue113.htm). This way we are always drafting off the booster tank, allowing high enough rpm's to produce enough cfm, irregardless of incoming pressure (either from a hot hydrant or another truck).

    There is a Fire Research Inc. automatic tank fill controller installed on the electric tank fill valve. This automatically keeps the tank full without pump operator intervention

  3. #3
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    We have the same problem in our fire protection area - water system pressure ranges from 40 psi in some areas to 200 psi in others. We also run a Waterous CAFS system on our newest pumper and it wasn't too long before we figured out the problems with high intake pressure.

    Our solution is the Williams Pressure Reducing Valve from Williams Fire & Hazard Control (www.williamsfire.com). They have a portable version, or it can be permanently plumbed into the truck piping. We retrofitted one on the large diameter intake - it required a "shorty" pump intake flange to keep it from sticking out past the running board. Took a little work on our part, had to redo one side of the pump plumbing and enlarge pump panel holes to adjust for piping relocations with the new flange.

    If you go to the website, look under "Catalog" then under "Components for Fire Apparatus"; it's a few pages into the catalogue. The people we dealt with at Williams were very helpful throughout the process.

    On another note, to all the apparatus/pump reps out there; you need to be asking about what water pressures there are when a department specs CAFS. We thought we did our homework and knew CAFS pretty well during the spec process; we didn't know enough and nobody ever gave us a clue about the potential problem. In fact, when we talked to the reps and apparatus manufacturer about what we found out, they were not aware of the issue. The excellant trainer that Waterous sent out knew exactly what we were talking about and even brought a portable WPRV along for us to use during the training. Had we known up front that this would be a problem, we still would have gone with CAFS, but would have had the PRV built into the plumbing while the truck was being built.

  4. #4
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    Using a manual pressure relief valve as a backup to an electronic governor is certainly not against NFPA. In fact, due to the unreliability of electronic governors, NFPA should require a backup in their standards.


    On the CAFS issue...

    Although a manual PDV is a possible solution to your problem, I would not advocate an operation that, when working properly, dumps water all over the road (especially if you live in a climate that gets below freezing). Sister Bay/Liberty Grove, WI uses a Williams PRV for hydrant/CAFS operations with their pumper-tanker, and we are looking into doing the same for our new rigs.

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    We recently completed the spec work on a new rescue pumper that will have a Hale CAFSpro system. They stated that the problem you are having is a very common one so how they told us to build is to use a direct tank fill and only pump off of the tank. To combat the problem of having water dump all over the ground as soon as the tank is full, they have an air actuated valve that ties into the tank level guage. When the tank level goes below a certain level, the valve opens up. When Murphys law comes into play and the valve fails (hopefully never), you go into direct fill through the master intakes on the front or either side of the pump or just open up the rear intake manually and just dump water into the tank. If you would like, I can see if I can't track down the model number of the valve that Hale makes for this.

  6. #6
    dazed and confused Resq14's Avatar
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    Originally posted by Tallyho74
    They stated that the problem you are having is a very common one so how they told us to build is to use a direct tank fill and only pump off of the tank.
    This is true, and operating off the tank is the quick and easy solution.

    Fire304 will chime in here, I'm sure. But I'll just say we've had the same issue. So typically, we'll run off tank water and fill as needed. Granted, that's not the best plan since it's always ideal to have a full booster tank.

    The solutions presented here are interesting... definetly consider them, especially if it's "Spec Season" in your department.
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  7. #7
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    DING

    Last evolution we did with the CAFS truck we tried laying a 2.5" in addition to the 5"LDH to feed our CAFS pumper. We were getting horrible foam due to the low RPM's of the pumper when running off the LDH. By using the 2.5" feeder I was able to keep the RPM's up and still fill my tank every time it got below 3/4's.

    That said, I think the ultimate solution is a direct to tank fill, possibly off the steamer intake, that way you could keep the tank full but if things for the hell you can open the steamer up and flow big water.
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  8. #8
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    Here is the e-mail from the manufacture I just recieved about solutions for our problem. thought I would let everyone now what they are saying to do.


    If they have 125 psi hydrant pressure, then even with the engine at idle, which is what the pressure governor is going to do to attempt to control the pressure, they'll still have a high discharge pressure. That pressure may be as high as 150psi, since a pump with the engine at idle develops some pressure, usually at least 30 psi. In order to get lower discharge pressures, they have to limit or control the inlet pressure.



    other manufactures would have probably suggested one of two things. First, they would promote a relief system. The relief valve that dump to ground, to control the pressure. That would, or course, limit the pressure, but if the incoming line had a high volumetric capacity, you would need a life boat in order to get near vehicle for all the water coming out from under it. Second, they would promote a direct tank fill. Direct tank fill is highly successful with a CAF system. The water is brought into the vehicle's tank and then pumped back out. The inlet pressure is never seen by the pump.



    We use an automated direct tank fill on many CAF systems that is capable of tending to the tank supply by itself, freeing the operator. Direct tank fills are often a 2.5" connection. If a large diameter supply line has been laid, then an adaptor and short pony hose is used to make the connection. Most often times, the department terminates the LDH with a gate valve or wye, with the pony connected to it. If there is a need to change to LDH feeding the pump, the valve can be shut, an LDH pony connected to the valve and the pump, and the flow re-established.



    In one specific instance with the same problem, we set up a Direct Tank Fill / Valved Main Inlet for use with LDH on a Waterous pump. It was at Boulder Rural Fire District in Colorado. They have 150 to 160 psi on the water system(s). We used the flanges and butterfly valves of Waterous Monarch style system. The ports on the flanges that are normally for the intake relief valve were used as direct tank fill ports. Electric valves were used into the tank. The inlet relief that is upstream of the butterfly valve which is required, was accomplished by the customer's use of an intake elbow that has the relief. When the LDH is charged against the closed butterfly, water can be taken from the line by way of the ports, normally used for the intake relief valve(s), through the electric valve(s) and into the tank. That allows the operator to run the CAF system at a low discharge pressure, regardless of the intake pressure. If the operator needs to transition to more of a hydrant supply to the pump, he uses the electric butterfly valve(s) and begins to put water into the pump from the LDH.

    Here is the e-mail from the manufacture I just recieved about solutions for our problem. thought I would let everyone now what they are saying to do.
    ASST.102
    The few the proud the firefighters from 102

    I.A.C.O.J.

  9. #9
    Forum Member Fire304's Avatar
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    Originally posted by asst102
    but if the incoming line had a high volumetric capacity, you would need a life boat in order to get near vehicle
    LMAO!!! I think I've seen this a few times around here!

    We use an automated direct tank fill on many CAF systems that is capable of tending to the tank supply by itself, freeing the operator.
    Tony, take a note on this item!

    The ports on the flanges that are normally for the intake relief valve were used as direct tank fill ports.
    Brillant! There;s an engineer who's thinking right! As a further refinement the line from the relief port to the tank valve could have a "T" in it and the relief valve installed there eliminating the need for an external Jaffery's valve. 14, we need to remeber this for the E-3 replacement committee!

    asst102, which manufacturer did this?
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  10. #10
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    Fire304
    At the Harrisburg fire Expo I asked our Pierce sales rep from Glick for some help. He in turn refered me to Kelly there manager and he called Pierce with the problem. The Had one of the engineers e-mail me with these solutions.
    ASST.102
    The few the proud the firefighters from 102

    I.A.C.O.J.

  11. #11
    dazed and confused Resq14's Avatar
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    Thumbs up

    Good stuff here.

    Great thread.
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  12. #12
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    Wow! This stuff is brilliant - you can see one great idea that is picked up by somebody who makes it better, then passes it on to somebody else who incorporates it into another idea and makes it even better. This is great!

    THIS is the way fire apparatus needs to be designed! THIS is the kind of idea sharing and building that should take place for every fire apparatus design.

    Good work, guys! I would love to see more threads like this in the future.

  13. #13
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    Hi all,

    We have the same "HOT" hydrant issue with our CAFS operations. The plumbing connection prior to the LDH butterfly valve and utilizing the piping for the relief valve is the ticket. It is a great solution to this problem. I would also incorporate an "AUTO-TANK" fill on the plumbing to the booster tank. One less thing for the pump operator to have worry about. I would also incorporate an “INTAKE”” manifold so that all LDH intakes could be connected to the direct take fill valve.

    We do not use LDH in my department, so on our engine we utilized our 2 side 2.5" intakes and plumbed them into what I refer to as an "intake" manifold. From that "intake" manifold I have a 4" valved connection to my water pump. This valve is left normally closed. I then had a 3" line plumbed to my booster tank with an electric "auto-tank" fill control, controlling it. Our SOP's are to supply the side intakes first. If we are going to a water only operation, (which is rare) or relay pumping I open my 4" water valve and water goes directly into my pump.

    I do have a front suction intake on this truck, but when we built it in 1998 we didn't supply the "intake" manifold from it. However, we easily could have since there is already in place a 5" shutoff valve in that plumbing system. A 2" or 3" pipe could be tapped into the 5" line before the 5" valve and plumbed to the "intake" manifold. Our next CAFS engine will have it this way.

    As far as the Williams Valve goes. It works great too. It is a totally non-electric valve. It has a 3-position control for it, "OFF", "AUTO" and "BYPASS". The water makes it work. The valve comes in two sizes, 3” & 4”. The 3" valve has a MAXIMUM rated flow of 500gpm. This size works great for flows under 500gpm. If flows greater than 500gpm are required, than the 4" valve can be used. The 4" valve will only work when a minimum flow 140 gpm is achieved. Most single line 1 3/4" CAFS operations will flow around 100 gpm. This is not enough flow for the larger valve to work. I have used the 3" valve and it works just as the manufacturer states. I had the portable 3" valve connected to the side intake of a pumper with 180psi (residual pressure) feeding it from the hydrant and had 30 psi on my intake pressure on the engine, and still was able to flow it’s rated capacity. This valve reduced pressure without reducing flow.

    I'm glad that the issue of "HOT" hydrants is being discussed. It is a problem that can become a big logistics issue on the fire ground if not addressed prior to delivery of a CAFS unit.

    Hope this helps.

    Be Safe,

    Captain Lou
    "GOT FOAM"

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