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Old Navy · 08-10-2010, 01:41 PM

What Sleep Number didn't tell us.

After replacing two bladders (at different times) in our queen size air bed, my spouse has become the "Pressure Checker". Our losses were aggravated by crossing the Rockies twice. Yes, air pressure decreases with elevation, which increases the pressure in the air bladders. They don't collapse -- just start leaking a little. And one morning you awaken surrounded by softened mattress.

Air bladder pressure changes with outside temperature as well. If located over a hot engine you can be sure the pressure will increase substantially. Likewise, cold outside air will deflate somewhat.

What to do? Deflate by half before hitting the road. Then reinflate before bed. When changing climates, adjust air pressure for your comfort level.

Here's to more comfortable sleep!

Elkhartjim · 08-10-2010, 04:51 PM

I just stopped in a Sleep Number store today and asked them if they had ever heard of pressure increasing and of course they had not...now I know why our bed sometimes increases in pressure. Its over the dang engine and it does get heat from the engine.

Ernie n Tara · 08-10-2010, 07:23 PM

The other reason is that it will change about 1 PSI (less any reduction due to stretch increasing the volume of the mattress) for each thousand feet increase in elevation due to reduced outside air pressure; you are actually measuring PSID (pounds per square inch difference) or the difference between inside air pressure and outside.
Ernie

frankdamp · 08-11-2010, 08:46 AM

During my time at Boeing, I went on a large number of customer acceptance test flights. The cafeteria provided "Flight Lunches" which included individual-size chips. One of the tests is a cabin depressurization test to demonstrate that the oxygen masks all drop out properly.

The first time I witnessed the test, I was sitting just aft of the first-class galley where all the boxed lunches were stacked. About the time the test director said the cabin was at 12,000 feet, I heard a series of small explosions in the galley. Nobody seemed to be worried.

I found out when lunch was passed out that the noises I'd heard were the chip bags blowing apart.

Your air mattress has the same issue. Sea level air in a container will expand at higher altitude to where the pressure differential can rupture the container. Nex time you're in a grocery store up in the mountains, take a look at the potato chip aisle. They need about 30% more shelf space at 5000 feet than they do at sea level for a similar number of bags.