PRESTON PRESSURE PS-500 User And Maintenance Manual page 8

above 120 seconds nor under 30 seconds. Pressing the Units button will start the counter
and display the leakage.
 The front panel's Airspeed buttons function as follows:
The UNITS button is used to toggle between the various units of measurement available
from the pressure/airspeed section. (Airspeed – MPH, Knots, KPH, mBar, mmHg, inHg,
PSIA, EPR)
NOTICE! The Mach airspeed is only accurate at the altitude of 0 feet (sea level)!
The EXIT button is used to exit out of the leak check mode.
The LEAK CHECK button is functional only when in the Airspeed mode. Pressing this
button will begin a 120 second timer, and the display will also show the gain or loss of
airspeed experienced during the displayed time period. If the operator wishes to select a
different length of time, the Leak Check button may be pressed repeatedly, which will
cause a reduction in the timer counter in 30-second increments. The timer will not toggle
above 120 seconds nor under 30 seconds. Pressing the Units button will start the counter
and display the leakage.
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