Bump Testing vs. Adjusting Detector Response
Functional Tests and Adjustments • 21
6.2.
Bump Testing vs.
Adjusting Detector
Response
There are two concepts that need to be differentiated:
• bump test
• gas detector response adjustment
A bump test exposes the gas detector to a gas. The
operator then observes the gas detector’s response to
the gas. The objectives are two-fold:
• establishes if the gas detector is reacting to the gas
• determines if all of the detector outputs are working
correctly
There are two types of bump test:
• quantified: A known concentration of gas is used.
• non-quantified: A gas of unknown concentration is
used.
Adjusting gas detector response exposes the gas
detector to a calibration gas as well (like a quantified
bump test), but additionally sets the actual gas
detector response level (via parameter
P.-17
) to
ensure that the gas detector activates at the specified
gas concentration.
Refer to the following sections for addition
information on bump testing and gas detector
response adjustment.
CAUTION: Before you carry out
the test or adjustment:
• Advise occupants, plant operators,
and supervisors.
• Check if the gas detector is connected to
external systems such as sprinkler systems,
plant shut down, external sirens and beacons,
ventilation, etc., and disconnect as instructed
by the customer.
• For bump test or calibration, the
MRLDS-250 should be powered up and fully
stabilized (see Section 4, Operation and
Stabilization).
6.3.
Bump Testing
WARNING: Notify others that
testing is underway. During bump
testing, the alarm outputs are active
and will trigger the intended
response. It is the operator’s
responsibility to ensure that such actions are
acceptable and can be performed safely.
After installation and parameter setup (see
Section 5,
Configure the Gas Detector
, the units should be bump
tested. Expose the gas detector to test gas. The gas
selected should be a high enough concentration to put
the system into alarm and light the LED display.
With a bump test you can see the functions of the gas
detector:
• the LED display will light and show the detected
PPM concentration once the alarm setpoint is reached.
• the relay and audible alarm will function as
configured including any delays set (ON or OFF).
• the output (0-10V, for example) will show the gas
level.
Ideally bump tests are conducted on-site in a clean air
atmosphere.
Table 6-1
- Bump Testing Using Calibration Gas
Cylinders
Step
Bump Testing Using Calibration
Gas Cylinders
1
Remove the Splash Guard accessory
if one is used.
2
Connect the regulator to the test gas
port using 3 mm or 1/8” inside
diameter tubing (see below).
3
Expose the gas detector to gas from
the cylinder. Monitor the LED
display reading. Refer to the
Section
1.5.,
Specifications
for acceptance
criteria.
