Honeywell Midas User Manual page 141

Applying gas at the end of the installed sample
line will test the full system including the whole
length of tubing. This will verify the integrity of the
tubing. Sample line integrity can also be checked
by performing a leak check (see section 8.5). Note
that there will be additional transport time due to the
tubing length and conditioning the gas-wet surfaces
(see table 4-1).
Bump tests are also used as an approximate means
to present a controlled gas release to the sensor
cartridge in order to verify that the transmitter does
respond accordingly. Bump testing is popular as
typical experiences show that a smaller list of easier
to handle gases can be used to provide functional
tests on a wider range of gas types. In the absence
of a formal calibration policy from the end user,
Honeywell Analytics would recommend a minimum
semi-annual schedule of at least one bump test
per sensor with the appropriate test gas (see details
below).
Bump testing may reduce sensor cartridge lifetime
and the accuracy of the calibration if applied
incorrectly or too frequently. Use only the target gas
or the recommended bump test gas.
Zero calibration is a recommended procedure
that should be performed periodically to improve
the performance of the sensor. This is particularly
important when the sensor is operating outside of
normal environmental conditions (20°C, 50% rH).
The tables in Appendix B
calibration or bump test gas for the Midas
cartridges:
Consult with your Honeywell Analytics Service
Representative for approved methods and materials
before commencing calibrations and bump tests. See
indicate the recommended
sensor
®
Midas
Tech Note 1998-0219 Protocol for Testing Toxic Gas
Detectors for additional information.
Bump the Testing Midas
A bump test is not intended to be an accurate
calibration, but is used as a confidence check to
ensure that the gas detection system is functional.
Since some of the target gases are difficult to handle,
bump testing often makes use of cross sensitivities
so that more convenient gases can be used. In bump
test mode, the Modbus/TCP outputs are not inhibited.
Only the 4-20 mA and alarm outputs are inhibited.
The bump gas test is a functional check only. Consult
local guidelines for recommended best practices.
Bump test concentrations are calculated to generate
a minimum first alarm level response.
Equipment
See Tech Note 1998-0219 Protocol for Testing Toxic
Gas Detectors for additional information. These items
are required:
• Test gas (see Appendix
• Special regulator for extractive use (if using field
calibration cylinder) or suitable sample bag (if not
sampling directly from cylinder)
• Tubing (suitable for gas being applied)
Preparation
Most of the test gases are highly toxic. It is essential
that personnel using these toxic gases be trained in
their use. Ensure that the test gas will be vented safely.
Applying test gas may cause alarm, fault or
17-3
Gas Detector
®
Gas Detector
®
B)