PCME QAL 181 X, User Manual, Page: 97 / 106

- PCME QAL 181 MANUAL: 97 -
Level 1 - Cleaning the Sample Volume prior to inserting an Audit Unit (as part of a PM
(Preventative Maintenance program)) or Linearity tests (as part of the Annual
Surveillance Test (AST)).
Contamination
- Typically the outer covers (Main and End Cap) and baffle faces can become
contaminated – this will not affect the readings, but could be disturbed during installation of
manual audit unit and so cause interference.
Symptom – None specific, for Routine Manual Testing purposes (the Span reading may have
fallen (drifted down)
Location - On the platform.
Level 2 - Cleaning the Span Element (when the Span reading has fallen)
Contamination – In addition to the outer covers (Main and End Cap) and baffle faces, the cone
in the exit baffle can become contaminated (the cone in the beam entry baffle is usually clean) as
can the face of the span material.
Symptom - The Span reading has fallen (drifted down).
Test – Self check value has dropped (or reading low), result of manual Audit Unit is correct, most
likely contamination is on the surface of the span element.
Location - On the platform or in the site workshop
Level 3 - Cleaning the Optical Elements (when the Span and the AST reading have
fallen)
Contamination – In addition to level 2 contamination, further contamination may have entered
the end cap and beam dump.
Symptom - The Span reading has fallen (drifted down) and the readings have drifted from
‘expected’/normal.
Test – Self check value has dropped (or reading low) and the result of manual Audit Unit is also
low, the most likely contamination is A) on the mirror of the beam dump B) on the surface of the
span element C) build up in the end cap (which can lead to contamination of the beam dump, end
of Quartz Rod and possible interference signal as floating dust).
Location - On the platform or in the site workshop
Level 4 - Cleaning the Optical Elements after an air purge failure (with ‘dry’ dust)
Contamination – When the air purge fails, contamination can enter into the probe assembly, end
cap and potentially coat all optics.
Symptom - The Span reading has dropped (likely to be failing), the readings have changed from
‘expected’/normal.
Test – Self check value is reading low and the result of manual Audit Unit is also low and a visual
inspection confirms contamination present within the end cap.
Location - In the site workshop (must be clean ie no dust) or at an off site workshop (PCME or
its distributors).
Notes -
•
If significant contamination has entered unit and it is not easily removed (sticky) it is
recommended that you return the unit to PCME for cleaning. Internal components may
have suffered due to contamination and may need replacing. Also some parts may move
during cleaning, requiring re setting. Some factory resetting may also be required.
•
If the sensor has been removed from the stack in order to carry out the following
procedures, then you can ignore the ‘air supply’ steps as long as working environment is
clean ie dust free and dry.