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5.1.5 Corrosion resistance
The effect of corrosion on DX enclosures is negligible.
5.1.6 Flammability rating
The flammable properties of the materials used in the construction of the enclosures are well
understood by manufacturers and ratings have been established to a number of standards. One of
the better known standards is the Underwriter's Laboratory standard UL 94 and the ratings for the
enclosure materials are given as:
Materials UL94 rating
Polycarbonate (all lids) V2/V0
Polycarbonate with glass reinforcement (DX070 base) V1/V0
Polyester with glass reinforcement (DX170 & DX430 bases) V0
Items made from similar materials are well established as suitable for use in process I/O marshalling
areas.
5.1.7 Impact resistance
The enclosure designs have been tested to an impact resistance of greater than 2 Joules which
exceeds the BS EN 61010-1 requirements of 0.5 Joules.
5.1.8 Chemical resistance
The overall chemical resistance of the enclosures is limited by the resistance of the transparent
polycarbonate lid. The glass-reinforced polycarbonate/polyester (GRP) bases have a higher resistance
than plain polycarbonate. Table 5.5 lists qualitative evaluations of resistance to a variety of chemical
agents.
Table 5.5: Qualitative evaluations of resistance to various chemical agents
Chemical agents Qualitative
evaluation
of resistance
Salt water; neutral salts; acids (low concentrations); hydraulic oil Excellent
Alcohols Very good
Acids (high concentrations); alkalis (low concentrations); petrol; cooling fluids Good
Alkalis (high concentrations); solvents. Poor
5.2 Mounting
5.2.1 General
These instructions are concerned solely with mounting the DX enclosures. Instructions for
wiring and testing individual modules within the enclosures are provided in Section 6.
Sufficient space is provided within the enclosures to accommodate tagging and earth-rail
accessories but this is at the expense of a reduction in the number of modules that can be
fitted.
5.2.2 Location and orientation
5.2.2.1 Location
The DX enclosures are intended for safe (non-hazardous) area use.
The enclosures are rated NEMA 4X; consequently, in N. America or Canada, assuming the
modules have the required approvals, they can be used in Class 1, Division 2 (gases) location,
but check with local requirements and ensure all cable entries also conform. In this case, an
additional warning label will be required on or near the enclosure warning that the MTL5500
interfaces must not be removed unless the area is known to be non-hazardous. The enclosures
are NOT suitable for Class II or III, Division 2 hazardous locations.
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