Summer Heat

[littlejohn]

With the summer heat here, just how hot dose a tank get in the trunk of a car?
The computer in my jeep will read up in the 115* range.
What happens to a HP steel filled to 3500psi when it is heated up to 120*?

 

[rcontrera]

When I was in California two years ago and it was 113 outside, the temperature in the trunk of my car hit at least 135 (the max on my instrumentation). That is hot enough to melt most suit glues.

 

[CamG]

Greetings from a warming Indiana littlejohn! I am glad you brought this up because it is a factor all of us who travel with full tanks in our vehicles need to consider. I have not personally saw the carnage from a ruptured burst disc in a car or truck but know those who have. Windows do not fair so well! HP tanks have a pretty tough burst disc but at extreme temperatures it is not uncommon to gain 200+psi. If tanks are already 3500 psi it is pushing it, if your running HP good idea to dive them soon or store them in a cooler environment. I personally try to at least get them in the shade and dive them asap. If your burst disc has not been inspected it might be a good idea, to replace it with a new one. I realize some people would say I am paranoid but I like to play it safe for everyone. The LDS who fills your tanks will appreciate the concern. I think it is interesting to watch your air gauge when you hit the water, lots of times you loose 200 psi immediately. Guess 50º water has that effect on compressed air! LOL! Have a great, safe dive season! CamG Keep diving....keep training....keep learning!

 

[ronbeau]

With the summer heat here, just how hot dose a tank get in the trunk of a car?
The computer in my jeep will read up in the 115* range.
What happens to a HP steel filled to 3500psi when it is heated up to 120*?

You can figure this out using the formula for the gas laws

(P₁ * V₁)/ T₁ = (P₂ * V₂)/T₂

Where

P = pressure in PSI
V = Volume in Cubic Feet
T = Temperature (Rankine scale - Farenheit temp + 460)

Using your example and assuming ambient temperature was 70 F before putting the tanks in the Jeep.

(3500 * 100) / 530 = (P₂ * 100) / 575

660.337 = 100P₂ / 575
660.337 * 575 = 100 * P₂
379,716.775 = 100 * P₂
3,797 PSI = P₂

At 115^o F the tanks would be about 3,797 PSI (assuming I didn't screw up doing the calculations).

Let me know if you have any questions.