Vaisala HMT310 - Manual (Page 57)

Chapter 4 ________________________________________________________________ Operation
VAISALA _______________________________________________________________________ 57
NOTE When you enable this function, wait about 8 min after powerup before
taking measurements. The powerup chemical purge locks the output
values for the first operation minutes.
Chemical Purge Activated Manually
Chemical purge needs to be performed always before calibration (see
Chapter 7 Calibration and Adjustment on page 67) or whenever there is
reason to believe that the sensor has been exposed to an interfering
chemical. Make sure that the temperature of the sensor has come down to
normal before starting calibration.
Before starting chemical purge please note the following:
- The sensor is protected with a PPS grid with stainless steel netting, a
stainless steel sintered filter or with a membrane SST filter.
- The sensor temperature needs to be below 100 °C. At higher
temperatures the chemicals evaporate spontaneously from the sensor
and the chemical purge is not necessary.
Starting Manual Chemical Purge
Type PURGE via the serial line to activate chemical purge.
Syntax: PURGE
>purge
Purge started, press any key to abort.
>
The prompt ">" appears when the heating period is over. However, the
transmitter outputs are locked to values measured before chemical purge
until the settling time is over.
Sensor Heating
General
This function is optionally available only in transmitters with
HUMICAP
®
180RC sensor. It should be used only with the warmed
probe.