Todd157k

I had a question a few weeks back about the burst plate and the pressure it breaks at.. 3000 lbs. Now comes the new questions.
1. I am going to hook up the exhaust tube but I want to make sure the burst plate is AFTER the bottle valve. (ya, may be a stupid question but think of how stupid I'd feel when everyone tells me I should have put the tube on it before my bottle was full)
2. Has anyone ever experienced a burst plate breaking just from the car sitting in the sun? My tank pressure was pegged on 1500 while parked at work all day. I really don't want to come out to a 'fog filled' car at the end of the day.

Todd157k

dust clouds rolling through...

Warp Factor

I'm not sure I understandwhat you want to know, but I'll take a stab at it.
If you somehow put the burst plate after the bottle valve, the plate won't be able to perform it's safety function of releasing excess pressure.

The only time I've heard of burst plates going on a bottle inside a hot car was when the bottle was overfilled.

Anyone else?

Beer99C5@FastbirdPerf.com

Opposite side of the bottle nut that your Main line is attached to is where the ruture disk goes.

In the picture below there is a -8 blowdown line (Black 90° fitting).
The rupture disk goes under the fitting the Black 90° is attached to.

The close up shows that fitting saying
"3000
PSI"

DO NOT OVER TORQUE the fitting! It will weaken the ruture disk. I believe the fitting is torqued to about 15 Ft/Lbs, check with the manufacture of your bottle.

Likely causes of blowing the ruture disk is leaving the bottle heater on (no pressure switch/incorrectly hooked up pressure switch).

If you saw 1500 PSI and that was max i would say your good...

Is there a plug/cap in the bottle now? And you are going to put the ruture disk in when the bottle is empty? Or is it in already and you are just adding the blow down tube? I am guessing that its already installed and your just adding the blow down tube?

Todd157k

Yes there is a cap and disk there now. I want to remove the cap and put on the tube (with the disk) but I want to make sure that when I remove the cap my nitrous doesn't spew out. I assume that closing the main valve, there is no pressure on the burst disk.
If that is true, then the burst disk shouldn't pop at all if I don't open the valve when it's hotter than hell in my car and reading 1500+ psi.

Also, my guage only goes to 1500 psi and was pegged there so I have no idea how much pressure there really was. I just know it was over that. Lately, it's been over 100 deg. F here and the car get's pretty toasty inside.. even with the windows cracked down.

Warp Factor

No, at least in the systems I've had, the disk is before the shutoff.
Have fun running the bottle down, and then make you changes.

terry s

Closing the main valve will NOT take the pressure off of the burst disc. You need to use most of the nitrous up and then purge the rest or open the main valve a little to let all the pressure off. Then change the fitting and use a new burst disc. with the propper torque as Beer said.
Then have the bottle re-filled.

Beer99C5@FastbirdPerf.com

I agree with the others, as long as there is pressure on the bottle, the rupture disk has pressure on it regardless of the bottle valve being closed. It is made this way so that if it builds up pressure as you have noticed, it will rupture (at 3000psi) and flow the nitrous (into the car or through the blowdown to the outside if its hooked up) rather than let the bottle get to the point where it may fail (I believe bottles are tested to 5 times their working pressure).

I believe all you will need to do is attach your blowdown tube to the existing fitting (-8AN). Keep the new rupture disk you got with the kit as a spare.

Todd157k

Thanks guys. I really appreciate it. So does my wife cuz she won't have to take me to the hospital to remove the cap screw out of my forehead. It didn't make sense that the burst disk would be on the non pressure side of the valve but it also doesn't make sense because you'd have to take off the tube to go refill your bottle. If you take the tube off, then fill the bottle, you couldn't put the tub back on. Obviously, you must be leaving the tube on and remove the whole assembly.

Beer99C5@FastbirdPerf.com

The black 90° I have pictured (think of that as your Blow down Tube) is put on hand tight to the "Blow Down Fitting".

Remember the "Blow down fitting" is torqued to only 15 ft lb so do not over tighten your blow down tube to it.

When you take the bottle in for refill just unscrew the blowdown tube from the fitting (leaving the rupture disk in place), take your bottle accessories off (mainline, Heater, wires for the pressure switch, opener etc), and lift the bottle out.

Be careful when undoing the mainline, ensure the system is purged. When I disconnected my system a couple weeks ago I forgot to purge it and when I went to unscrew the mainline with the NX "Wingman" I caught some Nitrous to the hand...very cold...

creighton

on a side note, i've been one of the guys to over torque my rupture disc. what happens is when the bottle sits in the back under the rear windown in a coupe, it heats up real nice and then blows a hole in the rupture disc. the nitrous escapes threw the blow down tube/line and all is well. except everything is really cold for 5-10min in the back portion of the car. luckily i had a blow down tube attached, even though it isn't vented to atmosphere, and my luggage shade installed, so the explosion discharged the nitrous into the trunk compartment. i've seen the maxima pictures. i think the problem with that explosion was the owner did not have a blow down tube/line. therefore, the bottle brackets became the weak link in the system and when the pressure became too great, the bottle went flying. moral of the story, at the very minimum, install the supplied blow down tube fitting into the bottle. the bottle usually ships with a bolt in place of the blow down fitting. if you leave the bolt in and the bottle pressure becomes greater than the rupture disc pressure rating, then you have problems.