because each of the two way valves are identical in construction the description of elements in two way valve 66 are equally applicable to two way valve 68 therefore for ease of understanding the description of two way valves 66 and 68 will only make reference to two way valve 66 as required and the same reference numerals will be used in the figures to identify identical elements in both valves table i______________________________________parameter requirement______________________________________valve rate inlet area of 1 1 u00d7 10 sup 5 square inch per psig of control pressure exhaust area of 3 3 u00d7 10 sup 5 square inch per psig of control pressurevalve range full open inlet area of 0 005 square inch at 400 r r is constant of proportionality in gas equation full open exhaust area of 0 015 square inch at 400 rleakage area to be relatively insignificant leakage area must be approximately 0 0001 square inch per poppetvalve seating forces as required for minimum leakage and proportional to environment accel eration and valve massmechanical rate spring mass system cannot resonate within environmental vibration 500 lb per in minimum deadband control pressure u00b1 3 5 psig maximumhysteresis control pressure u00b1 1 2 psig maximum______________________________________ housing 64 of actuator control device.