UEi Test Instruments AK900SC - Manual (Page 14)

14
R-  / 
These keys select between available refrigerants. When the last
available refrigerant has been reached, the first one is shown again. If
the unit has been upgraded with additional refrigerants, they will be
shown following the original refrigerants. Refrigerants are labeled
according to their ASHRAE designations or trade numbers.
• To change between ASHRAE and trade number display, hold
R- while pressing PWR when turning the unit on.
ZERO
Depress this once to calibrate the unit. Regardless of what pressures
the low and high side are sampling at the time that this key is pressed,
these pressures will then be considered the “0” or atmospheric
pressure reference reading. For best accuracy, allow unit to reach
ambient temperature before pressing ZERO.
UNIT
This key toggles the pressure and the temperature readings through
the following combinations of pressure units in sequential order:
• kPa / ºC (atmospheric reference)
• BAR/ ºC (atmospheric reference)
• PSIA / ºC
• PSIG / ºC
• PSIA/ ºF
• PSIG/ ºF
Temperature units also apply to superheat and subcooling readings
when active.
NB To toggle the backlight on and off in the display, hold the UNIT
key down for 5 seconds.
1SEC / 5SEC / HOLD
This key selects the time between updates of the numeric pressure
reading and corresponding temperature displays.