I Is the hot weather causing bursting airbeams when camping?

[fella1973]

Im a keen camper and for my family tent I have been a long time convert to airbeam tents as opposed to poled tents. There is a lot of anecdotal evidence that the recent spate of hot weather has led to increase in burst airbeams due to the higher temperatures, but i find it hard to believe that a relatively small increase in temperature would put the pressure in the beams beyond the max acceptable limit of the beams. I've tried to figure it out myself but its a long time since i did any physics.

Here is what i know:

Beam Dimensions 12cm diameter by 6m length
Recommended air pressure at 7psi
Max recommended air pressure 9psi

if we assume normal temp is 20deg what would be the impact on the beam pressure at say 30deg C and 40 degc?

Cheers

 

[gleem]

For a closed /constant volume, the pressure of a gas is proportional to the absolute temperature (293° for 20°C and 313° at 40°C. The pressure increases at the same rate as the temperature. The percent increase in temperature from 20°C to 40°C is 6.8% so the pressure increases by 6.8%. So at 8 psi and 20°, this increases the pressure to 8.5 psi so no problem if the 9 psi max is reliable.

 

[berkeman]

but i find it hard to believe that a relatively small increase in temperature would put the pressure in the beams beyond the max acceptable limit of the beams.

If the increased incidence of failures is real, then more likely is a failure of the adhesive or welding procedure used to form the air chambers. Do you have any photos of such failures? Were they along seams or someplace else in the airbeam construction?

You list a max pressure specification, but what do the manufacturers list for max operating temperature? The temperature of the structure's fabric in the direct sunlight in hot weather will be a fair amount higher than the ambient air temperatiure...

Do airbeam tents with dark-colored fabric fail more often in hot weather compared to airbeam tents with light-colored fabric?

 

[dlgoff]

For reference, PV=nRT

 

[RichMacf]

For a closed /constant volume, the pressure of a gas is proportional to the absolute temperature (293° for 20°C and 313° at 40°C. The pressure increases at the same rate as the temperature. The percent increase in temperature from 20°C to 40°C is 6.8% so the pressure increases by 6.8%. So at 8 psi and 20°, this increases the pressure to 8.5 psi so no problem if the 9 psi max is reliable.

Not quite right. It’s the absolute pressure that increases, 8 psi + 14.7 is 22.7 absolute, which increases to 24.2 = 9.5 psi.
In reality, it’s probably a combination of higher pressure, and the softening of the plastic. Let it down a bit if it’s hot!