A: There are three valves located at the foot of the mattress. Each valve is labeled either “Head”, “Middle” or “Foot”. Each valve correlates to the air cell that it controls. If a nurse wants to release some of the air in the “Middle” section, he or she can turn the valve to the open position, and the air will release. After a few seconds, the nurse can then turn the valve to the off position to seal it.