Det-Tronics U9500 Infiniti Gas Transmitter - Manual (Page 25)

95-8444 23 10.1
Calibration Gas Sources
For optimum performance, only use Det-Tronics
calibration gases.
iMPOrTanT
The calibration gas concentration setting must
match the concentration of the gas used to
perform the calibration (printed on label of
calibration gas cylinder).
For PointWatch calibration, use only 50% LFL
concentration calibration gas of the same type as
selected by the PointWatch gas selection switch. Refer
to the PointWatch instruction manual for details.
For catalytic sensor calibration, most applications
require the use of 50% LFL calibration gas matching the
type of gas to be detected. If a matching calibration gas
type is not available, a conversion K-factor must be used.
Refer to the “Catalytic Sensor Calibration” section in this
manual for details.
For toxic gas sensor calibration, the calibration gas
type must match the sensor cell type. The calibration
gas concentration should be one half of the full scale
measurement range of the sensor in use.
For oxygen sensor calibration, normal ambient air may
be used for span calibration if it is known to be clean and
not depleted of O
2
(21% vol.). Compressed clean air is
available from Det-Tronics if required. It is not necessary
to utilize an O
2
free gas such as compressed nitrogen
to calibrate the O
2
sensor zero level. An electronic zero
switch is provided within the C7065E sensor housing for
this function. Refer to the O
2
sensor instruction manual
for details.
Important Calibration Notes
• Ensure that the transmitter is properly programmed
for the gas concentration being used for calibration.
(See the “Setup” section.)
• Ensure that only clean air is present at the sensor prior
to entering the calibration mode. If the possibility
of background gases exists, purge the sensor with
clean air to ensure accurate calibration.
• Ensure that the concentration of the calibration
gas matches the calibration gas setting. Typically,
calibration gas concentration equal to 50% full scale
is used.
• If the calibration procedure is not completed or
if the sensitivity of the sensor has deteriorated to
the extent that calibration cannot be successfully
completed, a fault will be generated and the system
will automatically revert back to the former calibration
settings (after 10 minutes or when the gas level drops
below the lowest setpoint). If a successful calibration
cannot be accomplished, replace the sensor and the
hydrophobic filter (if used) and re-calibrate.
Table 11—Recommended Sensor Calibration Methods
Sensor Type After 1 Hour Warm-up After 24 Hours After 1 Week Every 90 Days
PointWatch
*
Opt Opt Opt
Catalytic Req Req Req Req
H
2
S Electrochemical Req Opt Opt Opt
Chlorine Req Req NR Req
Oxygen Req Opt Opt Opt
Carbon Monoxide Req Opt Opt Opt
Sulfur Dioxide Req Opt Opt Opt
Req = Required
Opt = Optional
NR = Not Recommended
* = Optional for methane. Must be calibrated if gas selection setting other than methane is used.
Table 12—Recommended Frequency of Calibration for Det-Tronics Sensors
Sensor
Calibration
Method
Auto Manual
Combustible Catalytic (Ex) X
H
2
S X
CO X
PointWatch (HC) X only
O
2
X only
Cl
2
X only
SO
2
X only