5
1
Introduction
1.1
Revision Status
This operator manuel describes the following revision status of the equipment:
Rev. 2.9 of the EEx-p controller F-351
Rev. 1.0 of the parametrizing software
1.2 General Information on the Types of Protection
In hazardous areas of Zones 1 and 2, only certified electrical equipment with the types of
protection EEx-d (flameproof), EEx-e (increased safety), EEx-i (intrinsically safe) and EEx-p
(pressurized apparatus) shall be used. For some types of electrical equipment, the type of
protection EEx-p is the simplest and most economical, and in certain cases it is only possibility.
1.3 Pressurized Apparatus
In the case of pressurized apparatus, a distinction is made between two modes, namely (a)
operation with compensation for leakage losses, and (b) operation purge (a continuous flow of
protective gas). In both cases, the enclosure should have at least. IP 65 protection.
1.3.1 Operation with Compensation for Leakage Losses
Is this mode, after an initial purging (which removes the potentially explosive gas mixture of the
surrounding atmosphere from the enclosure) has been performed, a sufficient flow of compressed
air or inert gas is introduced to compensate for the leakage of the enclosure and to maintain a
minimum overpressure in relation to the surrounding atmosphere.
During the purging, a pressure difference of the least 4mbar is built up, whilst during normal
operation the difference is at least 1 to 2 mbar (can be adjusted to other values).
1.3.2 Operation with Constant Purge
In this mode, the enclosure is purged continuously with compressed air or inert gas, e.g. in order
to dissipate the heat generated in the enclosure. The air outlet of the control unit can end in the
hazardous location; it is certified for this purpose.
During the purge process and also normal operation, a pressure difference of at least 4 mbar is
maintained.