93. Non-Electrical side

Non-Electrical Equipment in Hazardous Area

ISO/IEC Reference:

ISO 80079-36:2016

Explosive atmospheres — Part 36: Non-electrical equipment for explosive atmospheres — Basic method and requirements

This standard was last reviewed and confirmed in 2021. Therefore this version remains current.

ISO 80079-37:2016

Explosive atmospheres — Part 37: Non-electrical equipment for explosive atmospheres —

This standard was last reviewed and confirmed in 2021. Therefore this version remains current.

The following Non-Elelctrical types of protection techniques are considered :-

• constructional safety ‘c’,
• control of ignition source ‘b’,
• liquid immersion ‘k’

ISO 80079-36 specifies the following marking format :

(Symbol) Ex + (letter) h

(Any level of protection is NOT applied to letter ‘h’ )

Types of protection ’c, b and k’ will not be marked on the product, because of possible user mis-interpretation with levels of protection ’c and b’.

Manufacturers shall indicate Ex h only and have to define the specific used method(s) in the user installation instructions

Main	Details (this has to be specified in the user installation instructions)	Basic Principle	Equipment	Standard
		This standard specifies the general requirements for explosion-protected electrical equipment and also details equipment marking		ISO 80079-36
h	constructional safety “c”	Proven technical principles are applied to equipment types which do not have any ignition source in normal operation, so that the risk of mechanical faults causing incendive temperatures and sparks is reduced to anegligible degree.	couplings, pumps, gear drives, chain drives,belt drives,conveyor belts	ISO 80079-36 ISO 80079-37
h	control of ignition sources “b”	Sensors are integrated into the equipment to detect imminent hazardous conditions and adopt countermeasures at an early stage before potential ignition sources become effective. The measures can be initiated automatically by means of a direct connection between the sensors and the ignition protection system or manually by issuing a warning to the operator of the equipment .	pumps, belt drives,conveyor belts	ISO 80079-37
h	liquid immersion “k”	Ignition sources are rendered ineffective by immersion in a protective liquid or by constant moistening with a liquid film.	gears, Submerged pumps	ISO 80079-37
	Additional protection concepts for non-electrical equipment
	Flameproof enclosures “d”	Parts that can ignite an explosive atmosphere are housed in an enclosure which withstands the pressure of an explosive mixture exploding inside the enclosure and prevents transmission of the explosion to the atmosphere around the enclosure.	brakes, couplings	IEC 60079-1
	pressurized enclosure “p”	The formation of an explosive atmosphere inside an enclosure is prevented by maintaining a positive internal pressure of inert gas in relation to the surrounding atmosphere and, where necessary, by supplying the inside of the enclosure with a constant flow of inert gas to dilute combustible mixture.	pumps	IEC 60079-2
	protection by enclosure “t”	Due to its tightness, dust cannot penetrate the enclosure or reduces it to a negligible degree. Ignitable apparatus can now be mounted in the enclosure. The enclosure temperature must not be sufficient to ignite the surrounding atmosphere	equipment for explosive dust atmospheres	IEC 60079-31

With reference to Annexure G ( ISO 80079-36):

Protection concepts of types of protection :

• d
• p
• t

are acceptable for non-electrical equipment. With due consideration to all technical requirements of IEC 60079-1, 2 and 31 .

IEC SC 31M : Non-electrical equipment and protective systems for explosive atmospheres

Scope  of SC 31M

To prepare and maintain international standards relating to non-electrical equipment and protective systems for use where there is a hazard due to the possible presence of explosive atmospheres of gases, vapours, mists or combustible dusts

Note: For the purposes of this sub-committee non-electrical equipment is defined as “equipment which can achieve its intended function mechanically”. For the purposes of this sub-committee, ‘Protective system’ is defined as devices other than components of the equipment which are intended to halt incipient explosions immediately and/or to limit the effective range of an explosion.  (IEC )

Interesting History of SC 31M (By  JIM MUNRO, CHAIRMAN, IEC COMMITTEE TC 31)

In 2007 it was jointly agreed by ISO(International Organization for Standardization) ‘s Technical Management Board  and IEC (International Electrotechnical Commission )’s Standardization Management Board  to establish IEC Subcommittee SC 31M within IEC TC 31 instead of establishing a separate committee in ISO.  It was agreed that IEC SC 31M would produce IEC/ISO double logo standards as either double prefix ISO/IEC, or single prefix ISO and IEC standards.  The secretariat would be held by ISO/DIN/ in Germany.

Thus SC 31M was formed as a unique approach to joint development of standards between IEC and ISO.

The following are types of standards that can be developed by IEC SC 31M:
* ISO/IEC double logo with ISO prefix
* ISO/IEC double logo with ISO/IEC (preferred) or IEC prefix

The first double logo standard produced by SC 31M was published in April 2011.

 It is ISO/IEC 80079-34: Explosive atmospheres – Part 34: Application of quality systems for equipment manufacture

There are more new ISO/IEC double logo standards that are under active development.  Two of these are:
ISO 80079-36 Explosive atmospheres – Part 36: Non-electrical equipment for explosive atmospheres — Basic method and requirements;

and
ISO 80079-37 Explosive atmospheres – Part 37: Non-electrical equipment for explosive atmospheres — Non-electrical type of protection constructional safety “hc”, control of  ignition source “hb”, liquid immersion “hk”

These cover protection technique requirements relevant for non-electrical equipment.  Part 36 complements and refers to IEC 60079-0, the general requirements, and introduces ignition hazard assessment.  Part 37 introduces explosion protection techniques not covered by current standards.  It will also be possible to apply appropriate current techniques (e.g. Ex d) to non-electrical equipment.  The above standards are ISO standards because they contain requirements only relevant for non-electrical equipment.   (END)

The presently published standards are as follows:

ISO 10807:1994 Pipework — Corrugated flexible metallic hose assemblies for the protection of electrical cables in explosive atmospheres

ISO/IEC 80079-34:2011 Explosive atmospheres — Part 34: Application of quality systems for equipment manufacture

ISO 80079-36:2016 Explosive atmospheres — Part 36: Non-electrical equipment for explosive atmospheres — Basic method and requirements

ISO 80079-37:2016 Explosive atmospheres — Part 37: Non-electrical equipment for explosive atmospheres — Non-electrical type of protection constructional safety ”c”, control of ignition sources ”b”, liquid immersion ”k”

ISO/IEC 80079-38:2016 Explosive atmospheres — Part 38: Equipment and components in explosive atmospheres in underground mines

ISO/IEC 80079-20-2:2016 Explosive atmospheres — Part 20-2: Material characteristics — Combustible dusts test methods

(Source : ISO )