Motors for Hazardous Areas

 
TYPES OF MOTORS 
The following are the main groups of motors used in hazardous locations, but not all situations are covered. Should you have an application not covered by the following, please refer to one of our sales offices.
- Ex d flameproof motors for industrial use
- Ex e increased safety motors
- Ex n non-sparking motors
- D.I.P. dust ignition proof motors 
 
COMPLIANCE TO STANDARDS 
All motors suitable for use in hazardous areas are manufactured/modified in strict accordance with the conditions required by the relevant standards and the issued< Certificate of Compliance, and are fully tested prior to despatch by the manufacturer. 
 
SELECTION OF MOTORS FOR USE IN HAZARDOUS AREAS 
There are a number of defined hazardous areas covering gases and dusts. It istherefore strongly recommended that all relevant SABS 0108 Standard be consultedprior to final selection of the motor.
 
HAZARDOUS AREAS 
Many gases, vapours and dusts which are generated, processed, handled and stored in industry are combustible. When ignited they may burn rapidly and with considerable explosive force if mixed with air in the appropriate proportions.
Areas where gases, vapours, dusts and fibres occur in dangerous quantities are classified as HAZARDOUS. Classification of areas are:-
- gases, vapours, mists - Class I
- dusts - Class II
Gas groupings are further defined for either:-
- coal mining (methane) - Group I
- other industries - Group II
With Group II gases, they are further subdivided into sub-groups IIA, IIB, IIC, depending upon the ignition point of the gas.
ZONAL CLASSIFICATION is also required where explosive gas atmospheres are present and they indicate the probability of the presence of a flammable, combustible or explosive material, the extent, dimension and shape of the hazardous areas, together with the volume in which the hazardous material can be expected. There are three zones:-
- ZONE 0 - An area in which an explosive gas atmosphere is continuously present or is present for long periods of time.
- ZONE 1 - An area in which an explosive gas atmosphere is likely to occur in normal operation.
- ZONE 2 - An area in which a gas atmosphere is not likely to occur in normal operation and if it does occur, it will exist for a short period only. 
 
TEMPERATURE CLASSIFICATION 
Hot surfaces can cause ignition of gases, vapours and dust, therefore it is necessary to ensure that the maximum surface temperature of equipment introduced into a hazardous area does not exceed the ignition temperature for the gas, vapour or dust in the hazardous area.
Group I Gases - Maximum Surface Temperature 150°C
Group II gases and Class II dusts are given a Temperature Class (T) based on the maximum surface temperature of the equipment.
Temperature Classes are:-
T1 - 450°C
T2 - 300°C
T3 - 200°C
T4 - 135°C
T5 - 100°C
T6 - 85°C
Note: For Ex d flameproof apparatus the external surface is the measured surface. For other types of protection (e.g. Ex e) internal surfaces are of equal importance if the explosive atmosphere has access to them.  
 
 
EXPLOSION PROOF MOTORS Ex e, INCREASED SAFETY 
Standard three-phase motors
These motors are certified to Ex e and can fit a wide range of products as shown throughout the catalogue. These motors are certified to Ex e Class 1, Zone 1 protection.
The certificate covers gas groups IIA, IIB and IIC, temperature classification T3 and enclosure protection IP66.
The Standard complied with is AS2380.1:1989. This Standard means the motors are also suitable for Ex n and DIP applications.
 
ELECTRICAL AND MECHANICAL SPECIFICATION 
Voltage: Up to 500 Volts
Insulation: Class ‘F’
Enclosure: Totally enclosed, fan-cooled
Degree of Protection: Up to IP66
Frequency: 50 or 60 Hz 
 
LIMITING TEMPERATURE 
The temperature of an external or internal surface to which the surrounding atmosphere has access, shall not exceed the LIMITING TEMPERATURE specified. 
 
RANGE 
It is possible variations will arise in the kW/frame size/rpm, from one manufacturer to another from that normally referred to in normal motor standards. 
 
FANS FOR Ex d AND Ex e APPLICATIONS 
Fans for Ex d and Ex e applications, or indeed any hazardous application, can be constructed of special materials and incorporate special features.
Anti-static impellers and earthing leads are just some of the features we can provide. 
 
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