JMatlock88

I notice that the NX heater has built in thermostats to automaticly shutoff at critical N2O temp. Can anyone dream up for me a circut to control my compucar heater? Maybe of available radio shack parts? Is there a generic aftermarket thermostat/controler somewhere that I havent found? I'd like to flip the switch on and just not have to worry about it. At worse, I'll just have to purchase the NX heater, but it would be nice to be able to do this w/ our old heaters.
Correction: ZEX brand instead of NX
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[This message has been edited by JMatlock88 (edited December 09, 2001).]

IROCKZ4me

Just for the record,
the NX bottle heater control is not a temperature/thermostat controller.

It is a pressure transducer. Temperature has no bearing on it, only bottle pressure.

It turns the heater on when the bottle pressure drops below 950 PSI and turns the heater off when the pressure gets to 1050 PSI.

JMatlock88

oops...I meant to say ZEX brand. It is pictured and described on this ebay auction:

http://cgi.ebay.aol.com/ebaymotors/a...ndexURL=0&rd=1

An image of what I am talking about is here:
http://www.impactparts.com/Zex/media...-82006-001.gif
*picture loading*
I realize that phase is a function of pressure, temperature, and volume, but this method will work fairly well. It is probably much less expensive to configure than the pressure cut-off switch.





[This message has been edited by JMatlock88 (edited December 09, 2001).]

SteveSpohn

I wouldn't be messing with a bottle heater using radio shack parts.

Anyone remember the pics on the web like a year ago of that ***** who left his bottle heater on after he parked his car in the garage? It looked like his house got hit by a 2000# smart bomb, it was destroyed.

Steve

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JMatlock88

No worries about that...simply relay off of an existing circut that is powered only when ignition is on. In fact, this thermostat will make it even SAFER since it will cut off the heater at a given peak temp. Yes, i do remember the picture. That was just due to someone's ignorance. Anyone else?

B4Ctom1

i cannot enphasize this enough, do-not-nickel-and-dime-your-bottle-heater!!!!!! at the least you will pop your safety burst disk and pop out your windows, at the worst you could expirience first hand and up close death or serious bodily harm.

JMatlock88

To ALL: Please dont respond to this thread if you are going to "warn"us about the dangers of overheating a bottle. We are aware.

I am currently working with another engineer on a diagram and will post soon.

B4Ctom1

I am just curious, if both a thermostatic control devices (NOS), as well as pressure control devices (Nitrous Express) already exist, why arent they good enough to control your bottle heater? (p.s. I have a freind that uses a relay and a Nitrous Express transducer on a pair of "driving/fog lights" to heat his bottle. put your hand in front of one of those fog lamps when there on and see how hot they are.) but he is using an established safe control system. Im not trying to hack at you, please understand this. I can see that you are addressing bottle pressure safety by the fact that you dont want your bottle on all the time. the part # of the NX transducer is 15943 and should be used with a relay because the current draw from your heater is to high for it to handle. the -4 manifold that is female -4 on one end and -4 male on the other with a few 1/8" npt holes in it (one for the transducer [and one for a gauge?]) its part # is 15513 from NX or $27 at http://www.outlawperformance.com/d4manwitmulp.html the 15943 is about $100 from oulaw also.

JMatlock88

This relates to my first question as follows:

Thanks for the response! I think you hit the nail on the head...almost! The question I posted above was asking if any company made the TEMPERATURE based controller that will work with a plain jane bottle heater. I was aware that there exists a pressure transducer (which is actually the best method for automatic heater control!) that would work perfectly. The drawback is that it is $100+. What I'm looking for is a cost comprimise. Radio shack parts for a temperature based controller should not be NEARLY as expensive (say maybe $10-20 max) but will function similarly because of the following explanation:


By three dimensionally graphing the critical tempature/pressure/volume characteristics of N2O, we can map out when N2O is in liquid phase. Volume is constant, mass is not. N2O will be in liquid phase at the highest mass point (bottle just filled) and higest pressure point unless a huge ammout of heat is given to the bottle. On the opposite side, we can also realize that it will take the lowest temperature to create gas N2O when pressure is down and mass is down. At our minimum working pressure (for jets to work optimally) there is some X ammount of mass that needs to be in the bottle when the bottle is at the greatest temperature before N2O turns to gas. At this temperature will be the upper limit of the thermostat switch. This limit kicks off the heater. This will ensure that if the pressure is within the usable range, nitrous will always be in liquid phase. The converse is applied in order to figure out the lower limit of the thermosat enveolope.

Once we get these two critical temperatures for our temperature envelope, we construct the thermost to kick off the current to the heater and kick on the heater at these two temps. A relay is used to handle the current draw of the heater of course. A relay is also used so that no matter what the heater cannot be on when the key is not on.

Ta Da...you have something that will get you close to what the pressure transducer does. The drawback of this setup as compared to the pressure transducer is as follows: It is possible that if we need a higher temperature to get us into the optimal pressure range (when we have a low mass in the bottle...) than the lowest critical temperature, the heater will cut off a little early. You wont get to scavenge out that extra run when the bottle is low.

Simple? No, not really. That hurt my head and I left my thermo book at home. The positive side of this is that it only cost us < $20! Also, this is safer than just using your plain jane heater because the heater will cut off at unsafe temperatures. Hmm...good invention!

Someone feel free to correct me if I botched up the explanation!
I think that's pretty close...


Thanks for the explanation an part numbers, B4Ctom1