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Installation, operation & maintenance instructions
IP152, Rev AD
April
2012
P4, P8, H4, H8 Switch Mechanisms - Simple Apparatus
These Switch Mechanisms in a standard switch housing are classified as “Simple Apparatus” when used in Intrinsically Safe
circuits. They comply with the requirements of EN60079-0, General Requirements and EN60079-11, clause 5.7 ‘Simple
Apparatus’ and are not considered as a potential source of ignition for an explosive atmosphere.
They do not fulfill the definition of equipment in Article 1 (3) of Directive 94/9/EC (Equipment Explosive Atmospheres (ATEX)
and are therefore outside the scope this Directive and do not have a Declaration of Conformity or CE mark related to this
Directive.
When used as “Simple apparatus” within a hazardous atmosphere the following should be noted:
1. The product should be installed by suitably trained personnel, in accordance with the applicable code of practice.
2. As the product has no source of internal heating, the temperature classification is dependent on the ambient air temperature
and the temperature of the process vessel to which it is attached.
3. Materials of construction: Refer to product catalogue or customer drawing for actual material of level switch concerned.
Housing and Cover: Carbon Steel, or Stainless Steel 316 type, or Aluminium Alloy LM25 or LM24 or
B85 grd 360, or Cast Iron grd 250, or Gunmetal LG2
Pressure Tube & Union: Stainless Steel types 316, 321 or 304, or Carbon Steel 220M07, or Alloy NA18,
or Alloy C-276 (UNS N10276) or Alloy 625 UNS N06625, or Alloy 825 UNS N08825
If the equipment is likely to come into contact with aggressive substances, it is the responsibility of the user to take suitable
precautions that prevent it from being adversely affected, thus ensuring that the type of protection is not compromised.
Aggressive substances
: e.g. acidic liquids or gases that may attack metals or solvents that may affect polymeric materials.
Suitable precautions: e.g. regular checks as part of routine inspections or establishing from the material’s data sheet that it
is resistant to specific chemicals.
Note: The metallic alloy used for the enclosure material may be at the accessible surface of this equipment; in the event of
rare accidents, ignition sources due to impact and friction sparks could occur. This shall be considered when the switch is
being installed in locations that specifically require group II, category 1G equipment.
4. It is the responsibility of the user to ensure:
a. The joint requirements between the switch housing and vessel are compatible with the process media.
b. The joint tightness is correct for the joint material used.
c. That suitable temperature rated cable is used. Note: The cable entry temperature may exceed 70°C
d. The float is protected from impact or friction, or static electrical build-up from fast flowing non-conductive
fluids, that could generate an ignition source.