ENMET PGD2 - Manual (Page 24)

ENMET Corporation PGD2
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11 H AZARDOUS A REA U SE
11.1 Areas of use
The PGD2 Portable Gas Detector is intended to be used for personnel protection and is specifically designed and certified to be safe
in the following areas: -
i) Confined spaces
that is, areas where normal atmospheric ventilation is not available,
e.g. sewers, tunnels, ducts, storage vessels etc.
ii) Hazardous areas
classified as follows: -
Zone 0 - Explosive gas/air mixture continuously present, or present for long periods.
Zone 1 - Explosive gas/air mixture is likely to occur in normal operation.
Zone 2 - Explosive gas/air mixture not likely to occur and, if it occurs, it will exist only for a short time.
11.2 Methods of use
The PGD2 can be utilized for: -
i) Personal protection
where the instrument is worn on the person as close to the breathing area as possible and switched on at all times.
ii) Group protection
used in a ‘Sentinel’ mode where the instrument is switched on and suspended at a suitable point in the working area, and the
360 degree visual and audible alarms are utilised.
11.3 Basic Precautions
The following basic precautions should be observed in order to ensure that the instrument provides the protection for which it is
intended: -
a)
Ensure that the instrument is of the correct Model for the gases to be detected.
b) Before use, check that the instrument is within its calibration period - see Section 6.8.
c) Before use, check that the instrument is not physically damaged and that all covers are intact.
d) Before use, establish that the instrument has been charged sufficiently.
e) When in use, ensure that the gas sensor inlets are not obstructed - the instrument must not be used whist in a pocket, bag or
other confined container.
f) When lowering the instrument into for example, a manhole, ensure that it is not lowered into water.
g) Use the instrument in its rubber boot at all times.
h) If an instrument fitted with dry cells is out of use for more than a week, or if the cells are exhausted, they should be removed to
prevent corrosion of the instrument due to leakage of the cell electrolyte.
11.4 Confined Space Pre-entry Checks
The area to be investigated prior to entry can be checked in two ways: -
i). Peak Reading Mode
With the instrument selected for this mode as described in Section 6.3, it can be lowered into the confined space. It should be
left there for a minimum period of 1 minute; upon withdrawal the display will show the maximum readings obtained for the
flammable and toxic sensors and the minimum reading for the oxygen sensor. If any of the sensors detect gas above or below
(in the case of oxygen) the pre-set alarm levels then the visual and audible alarm will be operating and reference should be
made to supervisory personnel.
ii). Aspiration
Having selected and fitted an aspirator appropriate to the duty (refer to Section 6.24), a sample can be drawn, either manually
or by use of the internal pump if fitted, from the confined space. Care should be taken to ensure that a representative sample
has been obtained from the area under investigation using the guidelines given in Section 6.24. If any of the sensors detect
gas above or below (in the case of oxygen) the pre-set alarm levels then the visual and audible alarm will be operating and
reference should be made to supervisory personnel.