So a 100 block of dry ice will sublimate much faster than a 10lb of dry ice, I guess it was calculated 1% sublimation vs 2% sublimation. As Borek mentions, the sublimation happens at the surface area of dry ice. The bigger the block, the slower the sublimation.Īirplane cabin pressure of 10.3psi has a very very insignificant impact on the sublimation. So in essence we are saying, its the size the dry ice comes in that is the most important factor for sublimation rate. In other words, should I be concerned about temperature and pressure?Īssuming i have 10lbs of dry ice in pellet form, the ambient outside temperature will have no effect on the sublimation? Whether its 100F or 50F ambient temp, the sublimation on a 10lbs pellet of dry ice will not differ? Ambient temperature has almost no effect on the sublimation. So if the sublimation rate of 2% has been given, does temperature and pressure have a very minimum effect on sublimation, like +-0.3%. That is what airlines use to calculate dry ice shipments (dry Ice limits are derived from the accepted method to calculate the mass of Dry Ice, provided in the FAA Advisory Circular 91.76A). The FAA's average sublimation rate of dry ice is 2% per hour. Does the lower cabin pressure increase sublimation of dry ice? At what ambient temperature does dry ice sublimate faster?Ģ. Atmospheric pressure is 14.7 psi and aircraft pressure is around 10.3 psi, maintains to an equivalent altitude of 8000 feet.ġ. Atmospheric pressure decreases with increasing elevation. The sublimation point of the dry ice is -109.3F. My question is regarding the "sublimation" during change of pressure and change of ambient temperature. The FAA restricts CO2 concentration thru 14 CFR §25.831(b)(2), which limits the maximum concentration of CO2 during flight at 0.5% by volume in compartments normally occupied by passengers or crewmembers. Dry ice sublimates and therefore releases CO2 in the airplane. I am doing some testing on dry ice shipments on airplanes, a special project my company assigned to me. Hello, this is my first post to this forum.
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