Stationary Photoionization Detector SPID2
User Manual
SPID2 - User Manual (en) - 1.11.docx
Analytical Control Instruments GmbH, Volmerstraße 9A, D-12489 BERLIN, Germany, www.aci-berlin.de
Version 1.11
Page 28 of 60
6.3.
Purge Mode
Under most environmental conditions, a pollution of the PID sensor can decrease the measurement
performance. Parts that are exposed to the sample gas like tubes, pump, valve, PID sensor and lamp
window surface can be polluted on its surface. This may lead to incorrect measuring values over time.
To provide the possibility of working under such hard conditions a purge mode is installed. The
principle of this mode is a periodic interchange between ambient air, which is filtered by the active
carbon filter and sample gas. The switching can be performed automatically by self-chosen time
intervals or by one time manual user input.
The
Automatic Purge
mode
is the default-operating mode for long-term measurements. Therefore,
two time intervals must be configured:
Purge Time
•
This parameter determines the purge time how long the device will be taken ambient air,
filtered by an active carbon filter. During this time, the last valid measurement value is retained
on the display. The purge time includes a recovery time fixed to 10 seconds at the end of each
cycle.
Meas Time
•
This parameter determines the measurement time how long the device will be taken sample
gas from the sample port. During this time, the measurement value is continuously updated
and shown on the display.
Tm
Measurement
Purging
t1
t2
t3
Tp
Tm
MEAS TIME
Tp
PURGE TIME ( including recovery time ( Tr ) )
Tr
Recovery time ( fixed to 10 seconds )
t4
Measurement
Tr
Auto purge timing
