MAN0597 ISSUE 08 - 02/04
2302M5030
54
4.9 CALIBRATION
The accuracy of the Impact instrument must be functionally
checked with known concentration calibration gas before each
day’s use. If any sensor fails recalibrate the Impact before
using, or replace the cartridge. It is recommended that the
instrument be calibrated at least every 6 months.
The Impact instrument provides three methods of calibration,
offering flexibility for the user. Flow calibration is the traditional
method and can be performed, following instructions displayed
on the instrument itself (Section 4.9.2 Flow Calibration –
Instrument), or when the instrument is connected to a PC via
a basestation, on the PC display (See Section 4.9.3 Flow
Calibration – PC). An alternative method for instruments fitted
with a combination of oxygen, flammable, carbon monoxide
and hydrogen sulfide sensors only is to use the Enforcer
accessory. For all other gases the flow calibration method
must be used.
CAUTIONS
Use of non-standard calibration gas and/or calibration
components when calibrating the Impact can lead to
dangerously inaccurate readings.
The calibration should be carried out in a well-ventilated
area to avoid contaminants.
4.9.1 Contaminants
Oxygen sensors may be affected by prolonged exposure to
carbon dioxide, and it is recommended the Impact not be
subjected to use in atmospheres containing more than
25%v/v carbon dioxide (CO
2
). Oxygen sensors may read high
in the presence of carbon dioxide.
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