Detcon 700 Series Remote Sensor/Alarm Relay Module With HART Interface - Manual (Page 23)

700 HART-RAM I.M.
Auto Zero
Auto Zero function is used to zero the sensor. Local ambient air can be used to zero most sensors as long as
there are no traces of target or interference gases. If this cannot be confirmed, then a zero air or N
2
should be
used. N
2
must be used for zero calibration of O
2
deficiency sensors.
Material Requirements:
• Handheld Communicator or PC and interface for HART-RAM.
• Detcon PN 613-120000-700 Model 700 Splash Guard with integral Cal Port. -OR-
Detcon PN 943-000006-132 Threaded Calibration Adapter
• Detcon PN 942-001123-000 Zero Air cal gas (or use ambient air if no target gas is present).
• Detcon P/N 942-640023-100 Nitrogen 99.99%
NOTE: Refer to appropriate sensor manual for the specific information on zero gas.
For DM, IR, and PI sensors, the zero gas source may be zero air or N
2
, but must be pure N
2
(99.99%) for O
2
deficiency sensors.
For FP sensors, zero air should be used. Zero Air should have a normal background of 20.89% O
2
. Pure
Nitrogen (N
2
) should not be used or errors may result.
Auto Zero consists of entering “Autozero Cal” and following the menu-displayed instructions.
1. If applicable install the Calibration Adapter or Splash Guard Adapter with integral Cal Port.
2. If applicable connect zero gas to the cal port.
3. Select “Autozero Cal” from the Sensor Calibration section of the screen.
4. Upon entering Auto Zero Calibration the procedure will prompt to begin Auto Zero Calibration. If zero
gas is to be applied to the sensor, apply the gas.
NOTE: Upon entering calibration the 4-20mA signal drops to 2mA and is held at this level until the
program returns to normal operation.
5. The procedure will prompt to verify that no gas is present, and the sensor will perform Auto Zero.
NOTE: The sensor will scroll “Zero Cal . . . Setting Zero . . . Zero Saved” twice.
6. After successfully setting Zero Cal the sensor and the HART Interface will return to Automatic Mode.
7. Remove the zero gas and calibration adapter if applicable.
Auto Span
The Auto Span function is used to calibrate the sensor. Unless otherwise specified by the associated sensor
manual, span calibration is recommended at 50% of range.
Material Requirements:
• Handheld Communicator or PC and interface for HART-RAM.
• Detcon PN 613-120000-700 Model 700 Splash Guard with integral Cal Port. -OR-
Detcon PN 943-000006-132 Threaded Calibration Adapter
• Detcon Span Gas (See Detcon for Ordering Information). Recommended span gas is 50% of range with
target gas. Other suitable span gas sources containing the target gas in air or N
2
balance may be
acceptable.
NOTE: Refer to the appropriate sensor manual for information regarding Span Gas, flow rates, cross
interference, or other sensor specific criteria.
700 HART-RAM I.M. Rev. 0.0 Page 19 of 24