HPA Tank in a Hot Car: Safe or Asking for Trouble?

Your gear lives in the trunk between games. An r/airsoft player in a dorm asked "Is it ok for the tank to sit in a car where it may get pretty hot?" Leaving an HPA tank in a hot car is unlikely to end in disaster, but players say bring it inside anyway.

Can you leave an HPA tank in a hot car?

Players say don't make a habit of it. Player report: one reply said "There's practically zero chance anything dangerous happens, but compressed air tanks should be sheltered from heat, moisture, and direct sunlight, particularly composite tanks." Another said he keeps his tank in the garage instead of his truck.

Why does heat matter?

Gas in a sealed tank pushes harder as it warms. That's Gay-Lussac's law: at fixed volume, pressure rises with absolute temperature. A full tank in a baking car sits above its fill pressure until it cools.

How much depends on how hot the car gets.

Could the burst disk go?

That's the safety valve doing its job. Player report: an r/airsoft post titled "PSA: Dont leave HPA Tanks in a hot garage (didnt explode)" reported losing 1000 psi. A reply there suggested a slow leak in the regulator instead, so heat may not have been the only cause. Either way, you lose your air before the game.

Does heat hurt the tank itself?

Player report: in a Hard Air Magazine forum thread on storing a filled tank in a vehicle, one user worried about repeated heat cycling and said sunlight breaks down the resin on carbon tanks.

That's one forum user's opinion, not a manufacturer spec.

Should I pull the regulator off?

Player report: one reply in the dorm thread said to remove the regulator after every use and purge it, to keep the seals from wearing.

Check your reg's manual before you take it off.

Does this change pistol pressure?

The tank regulator still sets the line. Our product pages say to run near 120 psi on a 0–140 psi low pressure regulator, and never over 140. If your line reads higher after the car sat in the sun, check the reg before you shoot.

Shade, a cool room, and an in-date tank go a long way. See HPA Tank Storage After a Game and our regulator creep post. Wikipedia's Gay-Lussac's law page has the physics.