The basics of dust-explosion protection - STAHL - #29

29

Cable Glands

The requirements for the entries into dust explosion protected equipment from Categories 1D and 2D are almost identical with those for a gas explosion protected glands, type of protection "Increased safety". Both must be in compliance with AnnexB of EN 50014.

The only differences are in the degree of protection and in approval:

> Dust-Ex: IP6X, certification for Zone 20 and/or Zone 21

> EEx e: IP54, certification for Zone 1 and Zone2

Cable glands must be assembled and mounted so that they do not compromise the equipment's dust tightness. They can also be permanently connected to the equipment, in which case they are certified together with the equipment.

8.3 Documentation

EN 50281-1-2,10.3:

"Plans of each site shall be maintained to show the following:

> The classification and extent of the hazardous areas; the information shall include the zoning and maximum layer thickness, if greater than 5mm.

> Records of the types and marking details of protected apparatus and sufficient information to enable them to be maintained properly.

> Types, routes and details of wiring system."

This task is in conformity with the requirement of the Directive 99/92/EC, which obligates the employer to draw up an explosion protection document. The content of the document should indicate:

> The explosion risk have been determined and assessed.

> Adequate measures will be taken.

> Work equipment and warning device are design, operated and maintained with due regard for safety.

> Provisions to ensure that the equipment is used correctly.

8.2 Maintenance and Servicing

In addition to the protective measures already taken, an organisational plan must be drawn up for the installation.

> Cleaning, removal of dust deposits.

> Inspection and maintenance of equipment and protective systems.

> Testing of earthing, especially for the parts of the equipment that could become electrostatically charged.

These measures serve firstly to reduce the risk of explosion and secondly to ensure the effective­ness of the constructional protective measures.

"The inspection and maintenance of electrical apparatus for use in combustible dust shall only be carried out by personnel who are familiar with the concept of protection."(EN 50281-1-2:1998,12.1)

R.STAHL Explosion protection