Installation and Operation Guide | DGS Modbus
RS8HJ102 | 15
© Danfoss | ADAP-KOOL® | 2016.12
6.2 Bump Testing
After installation, the units should be bump tested. Expose the
sensors to test gas (R134A, CO2, etc.). The gas should put the
system into alarm and light the red LED. The delay prevents the
audible alarm from sounding, the relay from switching and the
alarm from activating on Modbus.
With a bump test you can see the functions of the sensor - the red
LED will light, the relay and audible alarm will function, and the
output (0 - 10V, for example) will show the gas level.
Ideally bump tests are conducted on site in a clean air atmosphere.
NOTE
: Prior to carrying out a bump test, check and adjust the zero
setting as described in the Calibration section.
NOTE
: Procedures for bump test and calibration vary depending
on the sensor technology used and the gas in question. The DGS
Modbus is available in two sensor versions: Semiconductor (SC)
and Infrared (IR).
NOTE
: Do not pressurise the sensor.
NOTE
: For semiconductor sensors, you MUST use calibration gas
in a balance of air (not N2).
IMPORTANT
: After a semiconductor sensor is exposed to a sub-
stantial gas leak, the sensor should be zero calibrated and bump
tested and replaced if necessary.
NOTE
: To test the audible alarm and/or relay function, check the
delay is set at zero and expose to gas. You can mute the audible
alarm by removing jumper J3.
Step Bump Testing Using Calibration Gas Cylinders
1
Remove the enclosure lid of the gas detector (not in an
exhaust area).
2
Connect a voltmeter to monitor sensor response. Moni-
tor response (0-5V) between pins 0V (TP3) and Vs (TP2).
3
Expose the sensor to gas from the cylinder. Use a plastic
hose/hood to direct gas to the sensor head. A response
of above 80% is acceptable.
NOTE
: Gas ampoules are not valid for calibration or accuracy
checks of the sensor. These require actual gas calibration, not
bump testing with ampoules.
Calibration Kit
Flow
Regulator
Typical Flow
0.3L/Min
Outlet 5/8’’
18 UNF
(C10)
Flexible nonabsorbant
tubing
Vented
Calibration
Hood
Cylinder
360mm high x 88mm diameter
440mm high with flow regulator
110L capacity of calibration gas
Weight 1.4 kg
Figure 6. Gas Cylinder and Test Hardware
Figure 7. Gas Ampoules for Bump Testing
Gas ampoules are convenient and inexpensive alternatives to
using gas cylinders for bump testing.
Sensor
adapter
M35 adapter
Gas ampoules
Test beaker
(M42 Thread)
