Page 27
8:
CALIBRATION
The Smokemeter calibration is automatically adjusted after every test
sequence. This is done by accurately measuring the light being received
by the detector. If the light level is too low the lenses require cleaning.
Since the smoke density measurement is directly related to the level of
light obscuration this process serves as an automatic re-calibration.
Should automatic recalibration not succeed it may indicate an electronic
failure or a failure to properly remove residual smoke after a test
sequence. In extreme cases, after extensive use with high smoke output
engines, there may be a build up of soot in the measurement tube
obscuring the light path.
See below for details of how to correct for these situations.
8:1 Calibration Verification
For regulatory emissions programmes some authorities still require that
calibration is regularly verified using neutral density filters.
The AUTO600 is currently unapproved (approval to UK standards
pending) and so is only intended for use in pre-compliance testing
situations.
With future approvals in mind the AUTO600 has been designed to allow
such calibration verification to be performed.
When required this can be achieved as follows:
CAUTION!
EXPOSED PARTS MAY BE HOT
Remove an End Cap as detailed below and then withdraw the air curtain
applicator. Insert a neutral density filter in place of the air curtain and run
a static test to confirm calibration.
Note:
The neutral density filter must be perfectly clean to give
repeatable results. You must also confirm the accuracy limits of
the filter and apply these as appropriate to local regulations