GDS-68XP Operation & Maintenance Manual, Revision 3.4
Page 31
CALIBRATION PROCEDURE (STREAM SAMPLE)
In certain situations, calibration gas may not be available.
However in some cases the target gas value may be known,
either from lab tests, pull tubes or local analyzers. If the gas level
is known, the following procedure can be used to adjust the
output of the GDS-68XP to match the current level of target gas.
CALIBRATION PROCEDURE – STREAM SAMPLE
OBTAIN THE FOLLOWING ITEMS:
1) CURRENT VALUE OF TARGET GAS PRESENT IN THE STREAM, MEASURED INDEPENDENTLY
2) CYLINDER OF ‘ZERO AIR’ IF NECESSARY
SET CAL SPAN VALUE:
SET THE CHANNEL 1 CAL SPAN VALUE TO MATCH THE
PREDETERMINED LEVEL OF TARGET GAS IN THE GAS STREAM
THIS PROCEDURE IS ONLY RECOMMENDED IF
CERTIFIED CALIBRATION GAS IS UNAVAILABLE
ENTER CAL MODE:
WAIT UNTIL THE SEQUENCER IS IN PURGE/HOLD MODE
AS
INDICATED BY “L2” (GREEN) FLASH
PRESS THE “CAL” KEY FOLLOWED BY THE “EDIT” KEY
ATTEMPTING TO CALIBRATE THE GASMAX
DURING A SAMPLE SEQUENCE WILL RESULT IN
A CALIBRATION ERROR
THE “APPLY ZERO GAS” SCREEN WILL APPEAR; L2 WILL CHANGE TO SINGLE FLASH
PURGE AIR PUMP WILL TURN ON AND AMBIENT (“ZERO”) AIR WILL FLOW INTO THE SENSOR FLOW CELL
SET THE ZERO VALUE:
ALLOW THE READING TO STABILIZE AND
PRESS THE “EDIT” KEY TO
ACCEPT
THE CURRENT READING AS ‘ZERO’
IF THERE IS A POSSIBILITY THAT TARGET GAS
MAY BE PRESENT IN AMBIENT AIR, USE A
CYLINDER OF ZERO AIR IN PLACE OF PURGE AIR
IF ZERO READING IS WITHIN LIMITS, THE
ZERO CAL SUCCESS
SCREEN WILL MOMENTARILY APPEAR
THE “APPLY SPAN GAS” SCREEN WILL APPEAR
SET THE SPAN VALUE:
PRESS “BYPASS” ON THE SEQUENCER
AND VERIFY FLOW ON THE
FLOW METER. ALLOW THE READING TO STABILIZE AND
PRESS THE
“EDIT” KEY TO ACCEPT
THE CURRENT READING AS ‘SPAN’
PRESSING “BYPASS” ALLOWS TARGET GAS TO
FLOW THROUGH THE SEQUENCER.
ALLOW THE GAS TO FLOW FOR ABOUT AS
LONG AS IT DOES DURING A NORMAL
SEQUENCE, USUALLY BETWEEN THREE AND
FOUR MINUTES.
IF SPAN READING IS WITHIN LIMITS, THE
SPAN CAL SUCCESS
SCREEN WILL MOMENTARILY APPEAR
THE GASMAX DUAL SCREEN WILL REAPPEAR SHOWING CHANNEL 1 IN PURPLE (CAL DELAY)
COMPLETE CALIBRATION:
PRESS “RUN” ON THE SEQUENCER AND DISCONNECT THE SPAN
GAS CYLINDER
ONCE CAL PURGE DELAY IS COMPLETE, THE
SEQUENCER WILL RETURN TO THE
PURGE/HOLD MODE
Figure 7-3: Calibration Procedure (Sample Stream)