Gas Compressors, Gas Boosters, Air Blowers And Vacuum Pumps For Hazardous Locations

Utile Engineering is a leading manufacturer of gas compressors, gas boosters air blowers and vacuum pumps for the global industrial market. Our products are used in almost every industrial activity including waste water treatment, building services, general processing and manufacturing.

We have 90 years of technical and design experience in this most specialised market and are able to ensure the correct selection of compressor for any application, taking into account the two most important factors to be considered – safety and economy.

Atex Directive 2014/34/EU

General

A potentially explosive atmosphere is one which could become explosive under certain conditions (the danger is a potential one).

An explosive atmosphere is one where a mixture with air, under atmospheric conditions of flammable substances in the form of gas, vapour, mist or dusts exist in such proportions that they can be ignited by excessive temperature, arcs or sparks (the danger is a real one).

ATEX

ATEX (ATmosphères EXplosibles) is the European Directive 2014/34/EU. It applies to all equipment either electrical or mechanical used in hazardous atmospheres containing both dust and/or gas. ATEX Directive 2014/34/EU was introduced to replace the pervious ATEX Directive 94/9/EC. All new equipment manufactured, or equipment commissioned after 20th April 2016 to be situated in an explosive or potentially explosive must comply with ATEX Directive 2014/34/EU.

The main purpose is to remove barriers to trade throughout the European Community. It also lays down specific requirements for users of such equipment.

The essential elements of ATEX involve: Notified Bodies, Standards, Conformity Assessment, Marking and Documentation.

The ATEX Directive is complementary to other directives such as Machinery Directive, Low Voltage Directive and Electromagnetic Directive. To show compliance with any of these directives, equipment is CE-marked accordingly. The ‘USE’ Directive (1999/92/EC) which sets down the requirements for safety and health protection of workers potentially at risk from explosive atmospheres further complements it.

Notified Bodies

These were previously referred to as Testing Authorities. The notified body provides approval and certification to the appropriate standard. This is mandatory for category 1 and category 2 electrical equipment, though category 2 mechanical equipment and category 3 only need to be subject to internal control.

Standards

Standards must be current. This may mean, as with dust, entirely new standards. In the case of others, the standards have remained the same in substance, the latest editions contain only small detail changes.

Equipment Categories

Equipment Categories are another change, which has been introduced. Equipment will now have a category number appropriate to the zone for which it is intended to operate (see table in machine data plate).

Zones remain the same as previously for gas but in the case of dust, a new system using zones 20, 21 and 22, has been introduced.

Certification

Certification by a Notified Body is only mandatory for equipment category 1. For categories 2 and 3 equipment manufacturers are allowed to issue their own certificate of compliance.

Documentation

Specific installation and maintenance instructions must be supplied for ATEX equipment.

Marking

This is the area of greatest visible change and is detailed below.

Atex Directive 2014/34/EU: Concept

Flashpoint Vs Auto Ignition Temperature

Auto Ignition Temperature is the temperature at which a gas, vapour or mist will ignite without the presence of a spark or flame. The temperature at which ignition occurs due to a spark or flame is known as the Flashpoint – see examples on the right. Machine selection must therefore ensure that the maximum surface temperature class must not exceed the Auto Ignition Temperature of the explosive mixture.

Temperature Considerations

The minimum temperature at which a gas, vapour or mist ignites spontaneously, at atmospheric pressure, is known as the Auto Ignition Temperature. To avoid the risk of explosion, the temperature of any part or surface of the compressor or booster exposed to the surrounding atmosphere must always remain below the Auto Ignition Temperature of the mixture. The classification of the maximum surface temperature is detailed on the right.

Groups

Equipment for potentially explosive atmospheres is divided into: –

Group I – Mines
Group II – All potentially explosive atmospheres other than mines

Categories and zones

The degree of danger varies from extreme to rare. Hazardous areas are classified into three Categories and six Zones as follows: –

Category 1

  • Zone 0 is which an explosive gas/air mixture is continuously present or present for long periods
  • Zone 20 is which a combustible dust/air mixture is continuously present or present for long periods

Category 2

  • Zone 1 is which an explosive gas/air mixture is likely to occur in normal operation
  • Zone 21 is which a combustible dust/air mixture is likely to be present in normal operation

Category 3

  • Zone 2 is which an explosive gas/air mixture is not likely to occur in normal operation and if it occurs it will only exist for a short time
  • Zone 22 is which a combustible dust/air mixture is not likely to occur in normal operation, but if it is present it will only exist for a short time

By implication, an area that is not classified Zone 0, 1, 2, 20, 21 or 22 is deemed to be a non-hazardous or safe area.

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