13
Industrial Scientific further recommends that a full instru-
ment be performed using a certified concentration(s) of
calibration gas(es) monthly to ensure maximum accuracy.
If an instrument fails to operate properly following any
functional “bump” test, a full instrument calibration
should be performed prior to use.
Calibration will be most accurate when the instrument has
been in a stable temperature environment for at least one
hour prior to calibrating.
NOTE: Instrument zero and oxygen span calibration
should be performed in clean air containing
20.95% (21%) oxygen. If you are measuring a
known combustible gas, use a known %LEL
concentration of that gas for span calibration. For
general combustible gas measurement, Industrial
Scientific Corporation recommends calibrating to
pentane in the 15-50% LEL range.
The measured LEL concentration of gases other
than the calibration gas may not correspond on a
one-to-one basis with the monitor reading.
Calibration gas flow rate should be between 0.5
and 1.0 liters per minute. Apply CL
2
, at a 1.0 liter
per minute flow rate. Always use teflon or teflon
lined tubing when calibrating Cl
2
or NO
2
sensors.
The TMX412 utilizes a one-button calibration system.
When using multi-component gas cylinders, a full
instrument span calibration can be performed in a
single step. Multi-component calibration gas cylinders are
available for combustible gas/carbon monoxide/hydrogen
sulfide configurations.
To calibrate the TMX412:
• From the normal READING mode, press the MODE
switch to access the ZERO operating mode.
• Press the (E) key to start the instrument zeroing process.
The instrument display will indicate ZEROING.
• When zeroing is complete the instrument display will
indicate O2 CAL and will show the current full span
value of the oxygen sensor. The oxygen sensor will be
spanned to 21.0 in approximately 30 seconds. Oxygen
calibration may be aborted at this time by pressing the
MODE switch.
NOTE: Zeroing the instrument in clean air is preferred,
provided that there is no trace of toxic or
combustible gas that would cause the instrument
to respond. If the air purity is uncertain, use a
cylinder of zero grade air to zero the instrument
and span the oxygen sensor.
ZERO
PRESS
ZEROING
21.0
02 CAL
12
BATTERY
FAIL
To clear the combustible gas over-range alarm:
• Exit the hazardous area immediately.
• Press the enter (E) key in clean air.
NOTE: When the enter (E) key is pressed, the combustible
gas level must be less than 100% of LEL or 5%
CH
4
to clear the combustible gas over-range
condition.
4.5.5
LOW BATTERY WARNING
When approximately 1 hour of instrument operation
energy remains in the battery, the instrument emits a short
beep every 15 seconds. In addition, the battery indicator
will be replaced by a flashing “B” on the display.
NOTE: The length of warning time will increase when
there is no combustible gas sensor installed in the
instrument.
4.5.6
BATTERY FAILURE
When the battery has insufficient charge to operate the
instrument, “BATTERY FAIL” is displayed. The
instrument stops monitoring and emits a short beep once
every second.
When “BATTERY FAIL” appears, turn off the instrument
immediately. Recharge or replace the battery.
4.5.7
FAULT INDICATION
The TMX412 will emit a short beep approximately once a
second if a newly installed sensor does not agree with the
valid sensor type for that position when the instrument is
turned on. The corresponding display position will be
blank. This fault indication occurs when a toxic or
combustible sensor becomes disconnected or a
combustible fault is detected during normal operation.
Sensor types become valid only after a successful
calibration has been completed.
5.
C
ALIBRATING THE
TMX412
The TMX412 is a potential life saving device.
Recognizing this fact, Industrial Scientific Corporation
recommends that a functional (“bump”) test be performed
on every instrument prior to each days use. A functional
test is defined as a brief exposure of the monitor to a
known concentration of gas(es) for the purpose of
verifying sensor and alarm operation and is not intended to
be a measure of the accuracy of the instrument.
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