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checked by performing a leak check. Note that there will be additional transport time due to the
tubing length and conditioning the gas-wet surfaces.
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.
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 Gas Table indicates the recommended calibration or bump test gas for the Midas-M sensor
cartridges:
Consult with your Honeywell Analytics Service Representative for approved methods and
materials before commencing calibrations and bump tests.
Bump Test
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.
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 maintenance fault indications on the 4-20 mA loop,
relays or digital outputs. Before starting a test, ensure that suitable steps have been taken to
prevent these indications from triggering unwanted actions. The Midas-M gas detector has a
special mode for bump testing where the alarm outputs are inhibited.
Finishing
Wait for the gas reading to return to normal levels. This may take some time, especially if
concentrations above the recommended levels have been used or if the test gas has been
applied for an extended period of time.
Ensure that any latched faults or alarms that have been generated by the testing have been
cleared.
Midas-M
40
User Manual
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