Page 29 - PPE GUIDELINE
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Guidelines on the Use of PPE Against Chemical Hazards
Maintenance
The employee should leave the respirator use area in the following situations:
1. To wash their faces and respirator face-pieces as necessary to prevent eye or
skin irritation associated with respirator use; or
2. If they detect vapour or gas breakthrough, changes in breathing resistance, or
leakage of the face-piece; or
3. To replace the respirator or the filter, cartridge or canister elements.
Replacement of Filters and Cartridges
The service life of a filter depends on filter/sorbent characteristics, contaminant
concentration, airflow rate and relative humidity. For cartridges, the sorbent type,
mesh size and quantity affect the ability for contaminant removal. Many sorbent beds
are designed to remove very specific chemical(s) and may not be effective for other
chemicals.
a. Particulate filter
The breathing resistance for particular filter will progressively increase as it traps
particles and eventually become so high that the filter must be replaced. The time for
this to occur varies according to the filter characteristics, the type and concentration of
the particles in the air. As a guide, the breathing resistance can be considered too high
when there is a perceived increase in breathing resistance. The resistance can also be
increased if the filter is used in a damp condition.
For powered air purifying respirators, clogging of the filters is normally signalled by a
fall in the airflow rate.
A filter should be replaced when it is very dirty or damage.
It is important to note that washing or cleaning clogged filters with compressed air is
not advisable as it may damage the filter.
b. Cartridges or canister
Cartridges or canister should be replaced on a regular basis, when an odour or taste is
perceived in the inhaled air or when the user experiences discomfort. The breathing
resistance normally does not increase during use. Some cartridges or canister may
have built-in end-of-service-life indicator.
Department of Occupational Safety & Health, Ministry of Human Resources, Malaysia October 2005 29
