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ML442 | v5k
Expo Technologies UK
T: +44 (0) 20 8398 8011
Expo Technologies US
T: +1 (440) 247 5314
Expo Technologies China
T: +86 532 8906 9858
Zone 2 Installations:
Alarm Only on pressure or flow failure with power being removed manually by turning off the air
supply to the MiniPurge
system if the failure persists for an unacceptable time.
Class I Division 1 Installations:
Alarm and Automatic Trip of Power. Note: NFPA 496 states power to the circuits shall be
permitted to be continued for a short period if immediate loss of power would result in a more
hazardous condition and if both audible and visual alarms are provided at a constantly attended
location.
Class I Division 2 Installations:
Where automatic timing is preferred, Alarm Only on pressure or flow failure with power being
removed manually by turning off the air supply to the MiniPurge
system if the failure persists
for an unacceptable time.
4.9 Internal Gas Release
If the PE contains an internal source of release of flammable gas or vapour, the procedures for
assessment of the release as given in NFPA 496 or IEC / EN 60079-2 should be used. Expo is
pleased to provide assistance or consultancy and advice on such matters.
The user must verify that the specifications of the Expo system e.g. pressure, continuous flow
(dilution) rate and type of protective gas are correct for the specific application.
4.10 Multiple Enclosures
More than one PE can be protected by a single system. Where PEs are connected and purged
in "series" e.g. "Daisy Chained", the RLV and when using a CF system, the SAU25 should be
fitted on the last enclosure with the Purge Inlet connected to the first enclosure. The bore and
length of the pipe or conduit used to interconnect the enclosures is critical and will determine
the maximum pressure experienced by the first enclosure in the series. Advice on sizing can be
obtained from the Expo sales office but in general terms when using RLV25 or SAU25, the pipe
bore size should not be less than 25mm (1”).
A common fault of installing small bore pipe leads to over pressurizing of all but the last
enclosure.
PEs should not be connected in parallel.
