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Thread: NOS Bottle Pressure

  1. #1

    NOS Bottle Pressure

    I am new to the NOS deal, but I am very happy with it so far.

    I ran the bike for 3 qualifying passes out of one bottle, all good, ran a PB & within .03 on all 3 passes. Then I changed the bottle for racing & it all turns to crap !

    The second bottle I put in the bike blew the relief valve out of the pressure gauge & dumped all the NOS out.

    I had another full bottle in the trailer so it went in, pulled the busted gauge out & put a bung in, exactly the some problem again, but this time it blew out gas between the bottle & the -3 fitting, dumping the bottle again. Don't know how much pressure it has to reach, but blew it out anyway.

    My question is, has anyone had this problem before, or was it maybe because the 2 out of 3 bottles could have been overfilled, if that is possible ?

    Thanks

    Bob

  2. #2
    Administrator Wade Clark's Avatar
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    Bob,

    You need to know what each of your bottle weigh empty. I stamped the bottom of my bottles so I would know the weight of each one as they can vary 3-4 ounces from each other. If you put more in the bottle than it is rated at, like 2 lb bottle or 2.5lb bottle, or 5 lb etc. it can blow the burst disk. this are usually rated fairl high i think like 1800lbs and if you get that kind of pressure against the solenoids they will not function properly if they open up at all. You need to weigh the bottles and you also need to have a gauge on the bottles on hot days when they are sitting around so you can monitor pressure. Do you have a purge and a gauge mounted on the bike so you can leave the line each time with the same pressure? i alway like to leave the line with at least 950 lbs of pressure and I also would make sure each bottle weighed the same as the last pass for consistency. you can get a mail scale at a office supply store for about $40.00-$50.00 so that you can monitor the weight.

    As far as leaking by the fitting you either did not have the fitting tight enough or the line tight enough.

  3. #3
    Wade, the pressure in the 2nd bottle was 900psi when I checked after I swapped it. The strange thing was that when the when the gauge blew the needle was stuck on 1200psi, and still is.

    Seems like the bottle pressure went sky high just before or on the run. The 3rd bottle I didn't have the gauge on.

    Maybe I have to weigh the bottles empty as you say, and then tell the guy at the refill shop exactly how much to put in each

  4. #4
    Administrator Wade Clark's Avatar
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    If the bottles are packed (overfilled) it does not take long in the heat and sun for the pressure to get out of hand. You could take a pressure reading in the pits on a packed bottle and it might be at 950 psi, but then you go and sit in the staging lanes for a half hour and it could be at 1200psi in that short amount of time if they are overfilled. You have to monitor the pressure but you also need to weigh the bottles to make sure of a proper fill and to see how much you use each pass.

  5. #5
    Just had mine bust in the trailer over the weekend. Got it filled at the track and right away it felt overfilled. I sat it in the trailer and made a motor pass. Came back and the burst disk let loose. Total time maybe ten minutes in the heat with it overfilled. Never previously happened before. Lesson learned for me since I have a 2 pound bottle and a large mother bottle to refill it only.

  6. #6
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    Years ago when I didnt fill my own bottles, I would get bottles back from the speed shop that used to fill them for me that were as much as a half a pound over filled on a 2 pound bottle.

    My advise would be to buy a guage that you use in the pits prior to a run to monitor bottle pressure. Also weigh the bottle empty and again when it is full. The difference in weight is how much nitrous is in the bottle. If the bottle is overfilled when you weigh it, you can let some of the nitrous out by opening and closing the bottle valve quickly. Be extemely carefull when doing this that you point the fitting on the bottle downward and away from yourself, other people and animals. Smart move for you to wear gloves and safety goggles to be on the safe side. A few ounces overfilled won't cause a problem. In my experiences, the bottlles that were drastically overfilled usually pinned the gauge without heating the bottle or even leaving the bottle in the sun.
    ashes to ashes, dust to dust......

  7. #7
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    One more thing, don't be fooled by the gauge on your bike. The gauge on your bike isnt truely measuring bottle pressure while you are in the pits or staging lanes. The gauge is measuring the nitrous in your supply line up to your gauge. The pressure can read much higher on the gauge than what is truely your bottle pressure because the small amount of nitrous in the supply line can heat up quickly. If you don't already have a purge kit installed on our bike, get one. You can see the actual bottle pressure after you purge. This gets the "dead" nitrous out of your supply line and allows fresh nitrous to your gauge for proper readings of pressure.
    ashes to ashes, dust to dust......

  8. #8
    Senior Member jtodd5781's Avatar
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    Quote Originally Posted by Todd Meyer View Post
    One more thing, don't be fooled by the gauge on your bike. The gauge on your bike isnt truely measuring bottle pressure while you are in the pits or staging lanes. The gauge is measuring the nitrous in your supply line up to your gauge. The pressure can read much higher on the gauge than what is truely your bottle pressure because the small amount of nitrous in the supply line can heat up quickly.
    You can not have a difference in pressure in the supply line vs. the bottle. The pressure that is being felt in the line will be felt in the bottle too.
    JT

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    Jtodd5781, hey buddy I am not trying to start a range war with you, but be carefull giving incorect advice to racers that are new to using nitrous. A quick glance at the instruction sheet for a NOS purge kit supports my previous post that you took the liberty to correct me on. I have attached the instruction sheet for you and the the guy new to using nitrous that started this thread. Again I am not trying to start an argument with you or discredit you as a racer or tuner. I am simply trying to point someone new to nitrous in the right direction to avoid the mistakes that I made learning my way with the use of nitrous.

    The nitrous in the supply line can start to change state from a liquid to a gas prior to purging in hot weather. The nitrous gauge on your bike will read a higher pressure in this situation until you purge. I have experienced as much as 200psi bleed off my gauge within a fraction of a second of hitting the purge button. Please open the attached link.

    http://www.holley.com/data/Products/...A5155-SNOS.pdf
    Last edited by Todd Meyer; 05-08-2012 at 08:29 PM.
    ashes to ashes, dust to dust......

  10. #10
    Senior Member jtodd5781's Avatar
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    Hey Todd ole buddy, I am not giving incorrect information, I am just stating the facts. Yes, the nitrous may become a gaseous state when exposed to elevated temperatures, but the same pressure that's in the line will be felt in the bottle. The main purpose of a purge valve is to insure that you have liquid nitrous available at the solenoid valve and the secondard purpose is the bleed the pressure to the same level for consistant performance.
    JT

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