As the figure on the left shows, moving the
pointer four
positions to the right (by pressing the
UP>
button four times)
switches the meter to operate in Ambient pressure mode.
In Dew point measurement mode,
will appear at the left of
the secondary readout to remind you that the value shown reflects
the dew point temperature, rather than the ambient temperature.
GENERAL CONTROLS
Changing measurement units
. By default, the RH650 uses Imperial units for all parametric
readouts.
To switch to metric units
, press the
UNIT
button. Ambient temperatures and dew points
will then be displayed as °C rather than °F; absolute humidity values will be stated in g/m
3
rather
than in mg/L; mixing ratios will be displayed in units of g/kg rather than GPP; and barometric
pressures and vapor pressures will be stated in KPa rather than mBAR.
Backlight
. The RH650 has a green backlight that automatically illuminates whenever any button
is pressed. It will remain on for 30 seconds and then extinguish to extend battery life.
Holding readings
.
Briefly
pressing the
ON/OFF HOLD
button freezes
both the primary and secondary readouts.
will appear on
the display to remind you that the readouts are frozen.
To release the hold, briefly press the
ON/OFF HOLD
button again.
Note: When the RH650 is in Hold mode, it takes two separate
presses of the
ON/OFF HOLD
button to power off the meter. The first
(brief) press (which is accompanied by a short beep) releases the
hold. The second press (and hold) initiates shutdown (which is announced by two short beeps).
Storing readings
. Pressing and holding the
STORE/ENTER
button for at least 2 seconds saves the
values shown on the primary and secondary readouts as a pair in the meter’s nonvolatile
memory. Each “save” automatically increases by one the Record number indicator—the number
above
MEM
at the lower left of the LCD. The readings remain in memory, available for recall, after
the meter powers off.
The next section of this manual contains instructions for recalling saved readings.
8
