Flameproof Exd Flashcards
What is Flameproof Exd?
An enclosure containing electrical apparatus or circuits that is capable of withstanding an internal explosion.
Prevent internal combustion communicating with external gas/vapour
What is a flame path and why is it needed?
Needed as not possible to machine faces of covers/enclosures for the perfect join.
A small joint or gap in an enclosure through which air, gas or the products of an internal explosion may pass
What is the maximum flange gap for each gas group?
2A - 0.15mm
2B - 0.15mm
2C - 0.1mm
What are the ‘rules’ for Exd?
6 Rules
Suitable for Zones 1 and 2
Live maintenance is not permitted
Components cannot be removed or modified
No unauthorised mods to a certificated enclosure
All bolts to be spanner tight
Adding components should never take place
What are flameproof obstructions and the minimum distance for each gas group?
2A - 10mm
2B - 30mm
2C - 40mm
Obstructions include: Steel work, walls, guards, mounting brackets, pipes
Flameproof Sealing tape for each Apparatus group
2A - a single wrap of non-setting denso tape
2B - consultation with technical authority required
2C - not permitted
Use of grease for flameproof equipment
Only non-hardening grease can be used. Silicone based are generally suitable but should not be used on seals of gas detectors.
What are adaptors?
Used when the thread size of the cable gland/connection device is larger than or same size as the entry to the enclosure.
Only ONE thread adaptor to be used per entry
What are reducers?
Used when the thread size of cable gland is smaller than the entry thread of the enclosure.
Only ONE thread reducer per entry.
Do not fit blanks into a reducer
What are reducers?
Used when the thread size of cable gland is smaller than the entry thread of the enclosure.
Only ONE thread reducer per entry.
Do not fit blanks into a reducer
