The Importance of an Air Pressure Seal on Standard Cell Enclosures with High Temperature Stability

The use of a pressure seal on standard cell still-air enclosures having high-temperature stability is discussed. The seal eliminates the effect of air pressdre variations on the temperature of the cells and the temperature monitor. It is calculated that a pressure change of 1 percent for air at normal temperature and pressure will change the air temperature 0.85 K under adiabatic conditions. While the conditions in a still-air enclosure are far from adiabatic, a measurement made on an oven under development gave an air inner chamber temperature change of 0.8 mK for this pressure change.