Intrinsic Safety – Auto-Switches & Pressure Switches for Hazardous Area Applications

• ... According to clause 3.5.4 of AS/NZS60079.14:2009...

... If connected into an Intrinsic Safety circuit, a 'Simple Device' such as a 'contacts only' switch may be applied exempt from certification.

Simple Device = 'Contacts Only' Switch with no Energy Storage capacity (E.g.: without indicator lights, internal circuits or inductors for surge suppression, etc.).
Refer clause 5.7 of AS/NZS60079.11:2011 for defined examples of 'Simple Apparatus'.

• Auto Switch:
  
  With regards 'Reed Switch' models definitive as 'Simple Device' classification:
  Please refer "Reed Auto Switches" Circuit Diagram No.4” page 9/10
  https://www.smcworld.com/upfiles/pl/M-03-3C-04-E.pdf

2-wire Reed Switches as 'Simple Devices' (all spec'd without indicator light) & again wired into an Intrinsic Safety circuit:

• D-C80, D-C80C
• D-A90, D-A90V
• D-A80, D-A80H, D-A80C
• D-A67,
• D-Z80,
• D-E80A

Note: we cannot apply 'Contacts Protection Box' accessories (E.g.: CD-P11, CD-P12) as those would provide energy storage potential & nullify the 'Simple Apparatus' stature.

• Pressure Switch: We could thus apply 'IS10-01S-6*' as a 'Simple Device' if wired into Intrinsic Safety circuit,