3-3
TEST psi
-
The test pressure, P
t
, in pounds per square inch absolute, measured whenever
the test pressure transducer is plugged in. (Pressure units may be set to psi, bar,
or hPa. See section 3.3) Since test pressure is used in the determination of
Frost Point, Dew Point, and %RH, the test pressure transducer should be placed
as close as possible to, but downstream of, the device under test in order to
measure device pressure. When the test pressure transducer is not plugged in,
calculations of Frost Point, Dew Point, and %RH are referenced to the user
entered test pressure setpoint rather than any measured value. For accurate
humidity generation under these conditions, the absolute pressure at the device
under test should be entered as the test pressure setpoint.
TEST
o
C
-
The test temperature, T
t
, as measured by the test temperature probe whenever
the test temperature probe is plugged in. Since test temperature is used in the
calculation of %RH, the test temperature probe should be placed as close as
possible to either the temperature sensing element (for chilled mirror
hygrometers, etc.) or the humidity sensing element (for solid state humidity
sensors) of any device under test. When the test temperature probe is not
plugged in, calculations of %RH are referenced to the user entered test
temperature setpoint rather than any measured value. For accurate humidity
generation under these conditions, the temperature at the device under test
should be entered as the test temperature setpoint.
FLOW l/m
-
The mass flow rate, in standard liters per minute. Flow rate is not used in the
calculation of humidity and is only an indication of the amount of gas flowing
into the system. Since all gas flowing into the system also flows through and
out of the system, it is useful for setting the desired flow rate through a device
under test.
3.2.2.1 Changing the Display Contrast
To increase the display contrast press the <1> key on the numeric keypad. To decrease the
contrast, press the <0>. The new contrast setting is automatically remembered by the system.
