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2. Application Suitability
Hoffman Purge/Pressurization Units are certified for use in Hazardous Areas, where the
Hazardous Area is non-mining (i.e. above ground) and the hazard is caused by flammable
gasses, vapors or dust.
Z-Purge Units may be used in IECEx, ATEX Zone 2(22) - Category 3 and NEC 500 Class I, Div
2.
Y-Purge Units may be used in IECEx, ATEX Zone 1(21) - Category 2 and NEC 500
Class I, Div 1.
Hoffman Purge/Pressurization Units may be used for hazards of any gas group. However,
apparatus associated with the Hoffman Purge/Pressurization Unit, such as Non-Incendive,
Intrinsically Safe signaling circuits and flameproof enclosures containing switching devices may
be limited in their gas group. The certification documentation supplied with any such devices
must be checked to ensure their suitability.
This unit is designed for use primarily with compressed air. Where other inert compressed
gasses are used (Nitrogen, for example) the user must take suitable precautions so that the
buildup of the inert gas does not present a hazard to health. Consult the Control of Substances
Hazardous to Health (COSHH) data sheet for the gas used. Where a risk of asphyxiation exists,
a warning label must be fitted to the Pressurized Enclosure.
The following materials are used in the construction of Hoffman Purge/Pressurization Units. If
substances that will adversely affect any of these materials are present in the surrounding
environment, please consult Hoffman for further guidance.
Materials of construction:
Stainless Steel
Mild (carbon) Steel
Brass
3. Installation, Operation and Maintenance for CF Units
This Hoffman Purge/Pressurization Unit is designed for use under normal industrial conditions
of ambient temperature, humidity and vibration. Please consult Hoffman before installing this
equipment in conditions that may cause stresses beyond normal industrial conditions.
The Hoffman Purge/Pressurization Unit shall be installed and operated in accordance with
relevant standards, such as IEC / EN 60079-14, NEC 500, NFPA 496 and any local codes of
practice that are in force.
For IEC / ATEX applications, references to the NFPA 496 within this instruction manual, should
be replaced by the equivalent clause in IEC / EN 60079-2.
For IEC / ATEX applications, the "Example calculations:" in section 1.1.4 within this instruction
manual, should read:
If the PE external dimensions indicate a volume of 0.5 m
0.5 m3 (or 17.7 ft
0.225 m
Aluminum
Acrylic
Nylon
Silicone Rubber
Polyurethane
Neoprene
3
) enclosure volume x 5 volume changes = 12 minutes purge time
3
/min (or 8 scfm purge flow rate
3
3
(17.7 Ft
) then,
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