on-board air tank in engine compartment...

MadeInMaine

MadeInMaine

New member
Hey everyone,

A few of you keep your on-board air tanks in the engine compartment. Is anyone worried about the heat from engine? The heat will make the pressure in the tank rise....
a bit dangerous, no?


Thoughts?

Cheers
 
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MadeInMaine said:
Hey everyone,

A few of you keep your on-board air tanks in the engine compartment. Is anyone worried about the heat from engine? The heat will make the pressure in the tank rise....
a bit dangerous, no?


Thoughts?

Cheers
Click to expand...

I have one of these 200psi safety pop off valves on my tank New 1/4" ASME Safety relief Valve 200 PSI American made - Amazon.com and the tank is rated at 300psi.

I only had it open once,parked and idling in a Chick Filet parking lot in Phoenix at 115F out, a couple of years ago. Scared the bejesus out of me as it's really loud when it pops open!

I highly doubt it would get that hot and rise that much to damage a 300psi tank and no safety valve,as a line or a fitting is likely to blow before the actual tank IMO.I'm more worried that my 160psi shut off valve that controls the compressor might malfunction and my compressor would over charge the tank and system.
 
Like Harper7 I had my tank and compressor in the engine compartment for quite a while before I ended up moving it. Never had any problems. However, you definitely need to make sure you have a safety valve and a good margin of safety between safety valve and tank rating.
 
Jangoforhire mounted a 1 gallon tank behind the bumper on the driver side. That's where I'm putting mine when I get a Shrockworks bumper.

Although I'm pretty happy with the ARB dual compressor I'm running in terms of continuous flow and pressure.

Okki
 
My tank is only pressurized when I need it - which is rarely when the car is running. So I'm not worried about it getting too hot.
 
Safety valve sounds good.

Narkhelek.... where did you move yours to? and why?

Okki... I was just looking at Jango's setup, and I would be worried there about it exploding if there was a front end accident (rear end someone, head on collision, deer, etc). But i suppose only keeping it pressurize while using it would help.
 
This was a great question.

It seems that way too often people post information on a modification (with good intention), but for whatever reason fail to provide important details of how it works out.

I would have never guessed harper had blown the valve on his set up. I try to apply a "first due no harm" / KISS philosophy to my modifications, but it is hard to know what will work.

Similar situation: I would have never know the LED light some have used to replace the signal in the Shrockworks bumper causes the turn signal to blink fast due to the lower voltage pull. I only discovered the info by pm'ing someone about the light.

FYI: I finally ended up buying the fully engineered ARB compressor in a case solution.
 
MadeInMaine said:
Okki... I was just looking at Jango's setup, and I would be worried there about it exploding if there was a front end accident (rear end someone, head on collision, deer, etc). But i suppose only keeping it pressurize while using it would help.
Click to expand...

it's mounted behind the bumper brace, so I'm not to concerned about it being crushed. Also, if I'm in a collision that severe, I doubt a ruptured tank is going to be my main concern. Upon compression, the hose connections and/or valves will blow first because they are the easiest point of failure. with only 1 gallon of air, it will be a loud noise, but I'm seriously doubting any additional damage from that event by event by itself.

Beyond that, as Jangofohire already mentioned; not keeping the system pressurized unless you need it will remove that concern altogether.

It's everyone own decision in the long run, but I'm following Jango's lead in this case.

Okki
 
MadeInMaine said:
Good words....

hope others see this the thread.

Thanks a lot
Click to expand...

Guys, use this calculator Combined gas law calculator - Chemistry Online Education to determine what your pressure would be at a certain temperature.

The combined gas law (Boyle, Charles, Lussac) is a combination of laws that go through a lot of complicated derivations to get:

(P1V1)/T1=(P2V2)/T2.

P1 is your initial pressure
V1 is your initial volume
T1 is your initial air temp

P2 is your pressure after you heat it up with your engine
V2 is your final volume (should be the same as V1)
T2 is whatever your temp is at max engine heat

Solve for P2, or work it backwards and solve for P1. I did it and used 100 degrees F to start and 250 degrees F as max temp. I used a volume of 144 inches cubed and the pressure rise was like 32 psi or something. Make sure you convert the units to what you understand though lol.

I would worry about a valve malfunction before I would worry about engine heat raising pressure to a dangerous level.

Edit: I did not work this formula out by hand to make sure the calculator was correct but there is no reason why it wouldn't. It's a simple formula.

Google combined gas law for interesting reading.
 
Last edited:
1engineer said:
Guys, use this calculator Combined gas law calculator - Chemistry Online Education to determine what your pressure would be at a certain temperature.

The combined gas law (Boyle, Charles, Lussac) is a combination of laws that go through a lot of complicated derivations to get:

(P1V1)/T1=(P2V2)/T2.

P1 is your initial pressure
V1 is your initial volume
T1 is your initial air temp

P2 is your pressure after you heat it up with your engine
V2 is your final volume (should be the same as V1)
T2 is whatever your temp is at max engine heat

Solve for P2, or work it backwards and solve for P1. I did it and used 100 degrees F to start and 250 degrees F as max temp. I used a volume of 144 inches cubed and the pressure rise was like 32 psi or something. Make sure you convert the units to what you understand though lol.

I would worry about a valve malfunction before I would worry about engine heat raising pressure to a dangerous level.

Edit: I did not work this formula out by hand to make sure the calculator was correct but there is no reason why it wouldn't. It's a simple formula.

Google combined gas law for interesting reading.
Click to expand...

I think temperature has to be in degrees Kelvin for that formula to be accurate...

David
 
Canazes9 said:
I think temperature has to be in degrees Kelvin for that formula to be accurate...

David
Click to expand...

That's why I linked that calculator as it let's you choose units. I work it usually in SI units then convert final answer but with this you can use PSI, cubic inches or gallons and degree f so it makes it easy to understand.
 
1engineer said:
That's why I linked that calculator as it let's you choose units. I work it usually in SI units then convert final answer but with this you can use PSI, cubic inches or gallons and degree f so it makes it easy to understand.
Click to expand...

Whoops sorry, didn't click the calculator just commenting on the formula calculations and references to temps in F.

David
 
Now that I think about it for a second Rankine would work just fine also, just need a temperature scale without an artificial zero.

:bolt:

David
 
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