ViewSmart 200/2050/2150 Controller User's Manual
Document: UM-1021
Revision Level B
13
2.2.6
CALIBRATE INPUT MENU
Calibration is the most important function for insuring correct operation of ViewSmart
200’s equipped with sensor inputs. The CAL MODE (flow chart shown in Figure 2.6) is
designed to make calibration quick, easy and error free. A successful ZERO and SPAN
calibration requires only five keystrokes. Optional 4-20mA outputs (if equipped)
transmit 1.5mA during CAL MODE and 4mA during the subsequent CAL PURGE delay
to prevent external alarms during calibration. Local ViewSmart 200 alarm relays are
inhibited during CAL MODE. Unintentional calibrations may be reset by the
Set
UNITY
menu item.
Set UNITY
resets
Cal OFFSET
to 0
&
Cal GAIN
to 1 which is
useful for returning the calibration to a known starting place. Sensor aging may be
monitored by recording zero and span readings at
Unity Gain
when the sensor is new,
and again later when degradation may have occurred. CAL MODE automatically exits if
no keystroke is detected after 5 minutes.
Follow these ViewSmart 200 sensor calibration guidelines:
Calibration accuracy is only as good as the calibration standard accuracy. R. C.
Systems recommends calibration standards with NIST (National Institute of
Standards and Technology) traceable accuracy to increase the validity of the
calibration.
Do not use a gas cylinder beyond its expiration date.
Calibrate a new sensor before use.
Allow the sensor to stabilize before starting calibration (approximately 5
minutes).
Calibrate on a regular schedule. (R. C. Systems recommends once every 3
months, depending on use and sensor exposure to poisons and contaminants.)
Calibrate only in a clean atmosphere free of background gas.
Use the following step-by-step procedure to perform ZERO and SPAN calibrations.
1.
To enter the CAL MODE from any data display, press the dual purpose DOWN /
CAL key and within 5 seconds press the EDIT key.
2.
Using the Cal-Cup and following the instructions on the screen, apply a clean
ZERO gas or be sure there is no background target gas in the monitored area.
After the reading is stable, (approximately 1 minute) press the EDIT key to
perform a ZERO calibration.
3.
If the ZERO calibration is successful, CAL MODE automatically proceeds to the
SPAN check.
4.
Apply the
correct
SPAN gas at .5 liters/min. After the reading is stable,
(approximately 1 minute) press the EDIT key to perform a SPAN calibration.
WARNING:
The SPAN gas used must match the value specified since this is
what the ViewSmart 200 will indicate after a successful SPAN calibration. The
Span Gas
value may be edited if it becomes necessary to apply a different gas
concentration (see
Span Gas
in section 2.2.5).
