10
A100g
JULY 2017
LED LOGIC
GAS SENSOR LED INDICATORS
LED OPERATIONS
RESULT
Green LED Flashing / Red LED off Warming up ≈ 5 min
Green LED on / Red LED off
Ready to detect gas
Green LED on / Red LED on
Gas level above gas
sensor trip point
Green LED off / Red LED on
Sensor element
failure or sensor
disconnected
Green LED off / Red LED flashing
Low supply voltage or
low supply current
TABLE 3
CALIBRATION PROCEDURES
Refer to Fig. 12 for calibration of Hansen sensors.
Equipment required:
Hansen calibration kit, stopwatch, hex wrench; 5/32˝,
long nose pliers, 24V AC/DC power supply, voltmeter,
2 minigrabber voltmeter leads and calibration gas for
the specific sensor.
Setup:
1. B e s u r e t h e s y s t e m i s m a d e s a f e d u r i n g
calibration. The 4-20mA output and internal relay
will be active during calibration.
2. Be sure the gas sensor has been powered up for a
minimum 24 hours to stabilize the sensing element.
3. Verify the green LED is illuminated and the red LED
is off.
4. Disable the internal horn by removing JP2 jumper.
Zero Calibration:
5. Set the voltmeter to the appropriate DC range. The
sensor element output is measured in DC volts;
zero volts equals zero PPM and 5 volts equals the
gas sensor PPM rating. (i.e. 100 PPM, 250 PPM).
Attach the voltmeter leads to the VS, (+) lead from
the voltmeter, V0, (-) lead of the voltmeter.
6. Be sure the ambient atmosphere around the gas
sensor is free of any background gases. To zero
CO2 sensors, pure nitrogen needs to be used to
ensure free ambient conditions.
7. Adjust the zero potentiometer (Z) until the voltage
reading on the voltmeter reads between zero volts
and +/- 0.030VDC.
Span Calibration:
1. Always perform the zero calibration before doing
the span calibration.
2. Place the boot over the sensor element. Use the
correct concentration of calibration gas for the
full range of the sensor. In other words, for a gas
sensor with a range of 0 to 250 PPM, use a 250 PPM
calibration gas when setting the span. If full range
calibration gas is not available, a calibration gas of
less than full range can be used then adjust to the
corresponding output voltage. This may result in
some loss of accuracy.
3a.
G a s s e n s o r s ( e x c e p t V e n t l i n e a n d
S e m i - c o n d u c t o r g a s s e n s o r s ) .
Start the flow of gas. Observe the output, it should
begin to increase after 5 seconds. Leave the gas
flow on and observe the voltage. The sensor voltage
will slowly climb toward 5VDC. When the voltage
does not change by more than +/- 0.010 volts per 15
seconds the sensor output voltage is considered to
be stable. Adjust the span potentiometer (S) so the
output voltage reads between 4.95 to 5.00 volts DC.
3b.
Vent line and Semi-conductor gas sensors
Start the flow of gas. Observe the output, it should
begin to increase after 5 seconds. Leave the gas
flow on and observe the voltage. The sensor voltage
will ramp up quickly. When the voltage does not
change by more than +/- 0.010 volts per 15 seconds
the sensor output is considered to be stable. Adjust
the span potentiometer (S) so the output voltage
reads between 4.95 to 5.00 volts DC.
4. Stop the flow of gas and remove the boot from the
sensor element. Verify the sensor voltage output
begins to decrease.
5. Do not attempt to re-adjust the zero or span
calibration until another 24 hours of powered
operation has passed.
6. Enable system. Verify proper operation.
7. Enable the internal horn by installing JP2 jumper.
Electrochemical Sensor Only (Zero Offset)
If the gas sensor is calibrated in the environment for
which it will be used a final zero adjustment will not be
necessary. If the gas sensor will be calibrated at one
temperature (70ºF, 21ºC) then moved to its operating
environment (-4ºF, -20ºC) a maximum zero offset of
2% will occur. If unacceptable, adjust the zero point as
described in section
Calibration Procedures, Zero
Calibration
. At (-40ºF, -40ºC), a maximum zero offset
of 12% will occur. If unacceptable, adjust the zero point
as described in section
Calibration Procedures, Zero
Calibration
.
CALIBRATION GAS CYLINDERS
Warning: Refer to Material Safety Sheet supplied with
gas cylinder and local safety precautions for proper
usage, handling and disposal.
Hansen calibration gas standards are traceable to NIST
(National Institute of Standards and Technology) and
analysis data is available on request.
A variety of calibration refrigerant gases and PPM ranges
are available, refer to Page 23. For special mixtures,
consult factory. Calibration gas should be stored in a
cool area, 65ºF/75ºF. Shelf life labeled on cylinder−one
year from date of manufacture.
Calibration gas must be shipped according to Department
of Transportation Hazardous Gas Regulations. Special
shipping charges will apply. Shipping only available in
the continental USA.
