GDS-68XP Operation & Maintenance Manual, Revision 3.5
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)