1. #1
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    Default Fire Stream Troubleshooting

    You are going to test your nozzles and hose and are ready to make your connection to the hydrant.

    You flush the hydrant and make your connection with the flow meter on the intake side.

    You make sure your cooling line is closed, tank fill is closed, and tank to pump is closed. This ensures that the flowmeter will only be reading the water going out of the line you're testing.

    You install a pressure gauge in your preconnect and lay out your hose lay.

    You calibrate the flowmeter with smooth bore and pitot and you're now ready to start testing your nozzles.

    First test is with you fog nozzle which is a 95-gpm @ 100-psi nozzle fixed gallonage. You put a inline pressure gauge at the base of the nozzle and put it on the line.

    You bring your flow up to 95-gpm on the flowmeter and record your nozzle pressure which is 100-psi right on the money. No sooner than you record your numbers you see that the flow is dropping and nozzle pressure is going up.

    You assume the nozzle is clogged so you go to flush and back to SS. Flow and pressures are good and then again the flow starts to drop and nozzle pressure climbs.

    Thinking the nozzle is clogged again you shut down and take the nozzle off yet there is nothing in the nozzle blocking the flow. You reinstall the nozzle and the same problem is present.

    What do you think the problem is?

    Good Luck!
    Last edited by KirkAllen; 11-22-2002 at 05:17 PM.
    Kirk Allen
    First Strike Technologies, Inc

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    Some of you may remember when I posted several hyrdraulic questions last year. The feedback from those posts were very positive and informative for those interested in solving hydraulics related problems.

    After numerous requests to continue posting such questions I posted this latest scenario.

    Being blessed with the chance to flow water with virtually every type of apparatus, hose, nozzle and water supply system across the US and abroad I thought it would be good to share the many problems I have experienced over the years.

    That is the reason for this post and nothing more. Im sorry that a select few felt that I was trying to promote our product line. This post does not reflect a nozzle problem at all so NO I am not trying to promote a product. Thanks for your emails implying so but most who have read my posts know that I go to great lengths to be neutral.

    Many have viewed the problem but no input as of yet. Their could be many problems and the more feedback provided the more it will educate everyone.

    Good Luck.
    Kirk Allen
    First Strike Technologies, Inc

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    Wow, I do a lot of nozzle tests, that's kind of different. When I run into these problems I try to see if they're repeatable. 1st question is did you adjust the nozzle stream, that usually will mess up the gpm/pressure just like you mentioned. 2nd is when you pulled the nozzle off did you put the s/bore back on and re-pitot to see if it was the nozzle, or something else. 3rd Sometimes the gauges will have needle "creep", try another gauge if you have one. I'm glad to see someone else testing nozzles out there.

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    Well....any hints.

    I believe your intentions are pure...and would like to know the answer at some point.....

    Dave

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    Blacksheep:

    repeatable?
    Yes the problem repeated itself three times with the fog nozzle.

    >1st question is did you adjust the nozzle stream, that usually will mess up the gpm/pressure just like you mentioned.>

    If adjusting the stream changes your gpm/pressure then you have a nozzle that is not working properly unless its an old fog nozzle that will flow more in fog than in SS.

    The nozzle was put in flush and then back to SS. The flow and pressure corrected but only temporarily. After about 30 seconds the NP went up and the flow dropped.

    >2nd is when you pulled the nozzle off did you put the s/bore back on and re-pitot to see if it was the nozzle, or something else.

    Yes. The problem could not be duplicated with a smooth bore.

    >3rd Sometimes the gauges will have needle "creep", try another gauge if you have one.

    Good call, however three gauges tried and they all did the same thing.

    In fact, the very nozzle that was used on this situation was completly rebuilt thinking it was the nozzle. Nothing was found wrong with the nozzle when it was rebuilt and when it was removed from the line nothing was found in it.

    Keep the ideas coming!
    Last edited by KirkAllen; 11-24-2002 at 11:15 PM.
    Kirk Allen
    First Strike Technologies, Inc

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    Change the hose out and see if the problem comes up again.

    My guess is the hose is delaminating.

    Keep bringing this stuff to us, is keeps us thinking.

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    I would change nozzles first. If unable to duplicate the scenario with another nozzle then I would suspect that there was an incompatiblity problem with the gpm rating of the nozzle in question and the set up.

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    Well I would disagree with you on changing the stream/won't change the gpm. It's been my experience that quite a few nozzles actually change their gpm output when the nozzle stream is changed.

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    Actually, I'd check with the pump operator first. You gotta keep friction loss in mind also. If you have 100 psi going out from the pump, depending on how long your preconnect is, your gonna get that much friction loss which means you might be pumping 100 psi off the truck, but only getting 90 on the line. That still doesn't explain why the pressure keeps decreasing and increasing like in that scenario though..... I'd check the pump though.

    Export V.F.D.

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    Ok, I am a realitivly new pump operator but it seems there could be a problem at the engine. Is the Jake break off? What are we pumping with? Also you said the flow meter is on the intake side, shouldn't it be on the discharge?
    B Holmes

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    . Is the Jake break off?
    OK, I am not the most experienced at this, but my understanding is that the Jake brake only is in use when the engine is deaccelerating (if thats a word), and there for would not operate while maintaining an RPM in pumping. Also I think there are disabled when pumping, but that is another story.

    Dave

    The hose answer sounds interesting, did you try different line? Maybe there was expansion in the hoseline due to a defect...dunno

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    I doubt it could be the hose; the pressure gauge is mounted after the hose, right? Could the ball-valve on the nozzle be closing itself somehow? This would account for the higher pressure behind it and for the over-all reduction in flow. If the hose were causing it, wouldn't the flowing pressure be dropping, not rising?

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    ADSNWFLD:

    The hose was fine. Had no problems flowing water with the smooth bore.

    ARFF26:
    The nozzles were changed and none had the problem however this nozzle was brand new, inspected, and even rebuilt and the problem continues. With 1 3/4" hose and a 95gpm@100-psi nozzle there is no compatibility issues......other than 95-gpm is less than the minimum flow rate outlined in the NFPA standars for Fire Attack.....I know thats another thread


    Blacksheep:

    I didnt say its flow and pressure WOULDN'T change, I said it SHOULDN'T. I agree with you that many do however based on the testing guidlines outlined in the 1964 standard they should flow the same as what they are rated for regardless of pattern except for the automatic which has a 2% varience limit.

    FIREFIGHTER22JP:

    By using a flowmeter we are ensureing we get our flow first. Once flow is established we record the results. The pump discharge for this preconect was 120-psi. Our nozzle presssure was 100 so we had 20-psi of FL in the system.

    bkholmes: Jake Brake is not on.

    As far as the location of the flowmeter you will find in my first post why but I will try to simplify it.

    You can place it on the discharge side but then everytime you want to check another discharge you would have to move everything. By placing it on the intake side AND ensureing Tank Fill is closed, Tank to Pump is closed and our circulating line (Cooling Line) is closed then the water coming out of a discharge is being measured because it is only coming from one source, the intake. Now you can check any preconnect or discharge and not have to move the equipment.

    hfd66truck: The hose is fine and yes we tried a different line.


    ThNozzleman: You are correct that the ball valve closing could cause this problem however that was not the fix in this case.
    If the hose was the problem as flow gets choked off there is a creation of back pressure (Pressure increase). Thus, as flow decreases/ pressure increases, although when you kink a hose which restricts flow you will see a decrease in pressure at the nozzle.

    I think there is enough info to point us in the right direction but I will venture to say you will never believe what the problem was when you hear it.

    Any more takers?

    Good Luck
    Kirk Allen
    First Strike Technologies, Inc

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    I'm grasping at straws here, but now this has my attention.

    Is there any chance the bail is loose and the ball is closing slightly?

    Quit teasing us and tell us the answer, already....
    Omnis Cedo Domus

    www.hinckleyfd.org

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    Wait, I am confused, if the flow meter is on the intake before the pump then how can it gauge the discharge flow? Wouldn't the pump increase the gpm as the pressure was brought up?
    B Holmes

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    bkholmes wrote:
    Wait, I am confused, if the flow meter is on the intake before the pump then how can it gauge the discharge flow? Wouldn't the pump increase the gpm as the pressure was brought up?
    Ah, but if you take into account the conservation of matter. The pump merely boosts the pressure of the existing water. It does not make it. So if your tank full line is closed, and the engine cooler is closed and the tank to pump is closed then any water coming out the nozzle is going to come from the supply line with the flowmeter on it. You cant flow water you arent supplied from somewhere.The act of putting the flowmeter on the inlet keeps you from having to change the flowmeter each time you change discharges or nozzles.
    Shawn M. Cecula
    Firefighter
    IACOJ Division of Fire and EMS

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    Ok, I know this is not the thread topic but please bear with me. If I hook to the hydrant and insert a flow meter at the intake. Water now enters engine and say everything but discharge #1 is closed. The flow meter will tell me ....... wait it just clicked in my head. I get it now. with no other water moving what moves through the meter is the same GPM's as at the nozzle. As I was writing and thinking about it, it became clear, thanks Shawn.
    Kirk is there any water showing under the engine, drains leaking or the like?
    B Holmes

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    Are you pumping air? Creating a vaccum in the pump? Cavitation? I LOVE these teasers Kirk!

    Paul GRIMWOOD

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    Cool

    I would lean toward the pump operator. It has been my experience that this is usually the problem with flow rates. Are valves vibrating closed? Is he/she monitoring the pump panel guages? Does the pump have one of those new automatic operators? (Designed to cut one firefighter from the engine) Is the intake constant? i.e. is there a change from the water system?

    I hope Kirk lets us no the answer soon.
    Pete Sinclair
    Hartford, MI
    IACOJ (Retired Division)

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    bkholms:
    No water leaking under the engine. Good point though because if you are set up the way described and you have a leaking tank fill valve the tank will fill and overflow. This additional water going to the tank is measured thus causing accuracy problems.

    Paul:
    No, we are not cavitating or pumping air. We are hooked to a positive water supply. Thanks for joining in.

    Pete:
    Pump operator is doing everything right. All valves are working perfectly including the ball vavle on the nozzle. All gauges are woking and our intake pressure is constant as is our discharge pressure....other than it climbs at the same rate as our nozzle pressure.


    Great coomments! Keep them coming.
    Kirk Allen
    First Strike Technologies, Inc

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    WOW, lets review:
    1. Nozzle is not the problem
    2. Hose is not the problem
    3. Pump operator is not the problem
    4. No leaks or leaking valves
    5. All gauges are working correctly
    6. No air in system
    7. Water supply is not the promblem

    Your last post in your answer to Pete you say that "our intake pressure is constant as is our discharge pressure....other than it climbs at the same rate as our nozzle pressure." Is the problem with the hydrant pressure changing? Also how long is the preconnect? What are the elevations of the engine and the nozzle? You are killing me give us a hint!!!!
    B Holmes

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    bkholmes:
    The preconnect is 150 feet flat level ground.

    I think about every possible idea has been presented.

    OK hear it is

    During a recent fire the crew on the line charged the line and made entry. During the fire attack all was fine for the first 30 seconds or so and then the flow dropped noticeably. Thinking it was something with the pump operator they radioed for more pressure yet to no avail they did not get more water out of the nozzle.

    Note that I said after the nozzle was flushed things were fine, temporarily, and then flow would drop and pressure would climb.

    After removing the nozzle nothing was found to be clogged yet all indication was that the nozzle was the problem.

    If you can believe it, during that fire call a large amount of very small pebbles were sent from the hydrant (Dead End Hydrant that did not get flushed) to the pump. Now when I say small I mean that they were no more than 1/8” in size.

    What position do you hold a line when taking a nozzle off? If you hold the line vertically you will find that any debris in the nozzle simply SINKS back into the hose when its shut down, thus you don’t find anything wrong with the nozzle.

    Yes we tried different hose. Things were fine for about 30-seconds of flow and then the same problem would occur.

    Even after flowing with a smooth bore the problem continued with the 95-gpm nozzle.

    The main problem was a LARGE amount of debris was in the pump and only low flows were used so the debris would never get flushed out. After flowing 400+ gpm we tried the same nozzle and all was fine. Another solution would be to back flush the pump to remove the debris. More importantly, FLUSH the hydrant before making your connection.

    Now the reason you will see this with a 95-gpm @100-psi nozzle is because the orifice for this flow is so small that it does not take much debris to clog the nozzle. We tried other fog nozzles and had no problem and that is because they were 200-gpm nozzles, which let these small pebbles pass.

    Now I know several comments were that the nozzle was the problem but after being told the nozzle was brand new, inspected, and rebuilt with nothing found wrong it was hard to agree that the nozzle was the problem. Once we held the nozzle upside down (outlet down) and took it off the line we found over a cup of pebbles in the nozzle. Turned it over and they all fell out.

    If you would have been there during this experience it would have been evident that it was a nozzle related isshe yet it took us close to 30 minutes to discover that it was debris in the pump.

    Now I have seen debris in a pump but never so much of it that it had this type of problem for so long. It turned out this very nozzle was in service for several weeks with this problem because when it was taken out of service the nozzle would be tested in the shop with a different water source and found to be working properly. Once returned to service on the same engine, the same problem would show its ugly face at the next fire and again crews would take it off and send it back.

    During our testing with flow meters and pressure gauges we were able to isolate the problem because of the equipment. It is my opinion that if you don’t have inline pressure gauges and flow meters to test your equipment you may be surprised one day by what you are “really” flowing. Dont underestimate the value of test equipment!

    Thanks for all the great feedback.
    Kirk Allen
    First Strike Technologies, Inc

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    Very interesting, I did think about stones in the pump (we actually just fail a pump test due to stones), but you said the hydrant was flushed and with the changeing of nozzles and hose I just assumed all was well with debris. I guess I does not take much to clog those fog nozzles. We run with solid bore so we rarely use fogs. I will however keep this lesson in mind when we do use them. Thanks Kirk, can't wait for the next one!
    B Holmes

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    Quite often flow meters are put on the intake it knocks out some of the pressure surges. We're not talking about the type that are on the engine panel but rather an auxillary meter. From what I've seen, it would appear that the problem has been narrowed down to the nozzle. The problem is repeatable, When the suspect nozzle is removed, the problem goes away, you've used different gauges. It looks to me that possibly the nozzle has some slop in the bale and that the valve might be moving around. Would this happen to be an Elkhart with one of those Mickey Mouse cut out ball valves, or something simlar?
    Also did this turn out to be a gauge problem (or a test procedure problem), or an actual problem with the apparatus/nozzles/hose/etc.
    If not, how about an answer, this is giving me a headache.....

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    He gave the answer 2 posts ago!
    B Holmes

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