Protecting a water treatment plant

Dec 11, 2011 | Electrical & electronics

Rotterdam’s Dokhaven waste water treatment plant from waterschap Hollandse Delta treats around 5,500 cubic metres of waste water every hour. With the potential for chemical reactions, potentially causing an explosive atmosphere, gas detectors have been installed here.

Ex-de explosion-protected gas detectors are used during the first biological treatment stage, when oxygen is added to the waste water. They are protected to IP 66/67 and have a three-pole connection, 24V DC at 3.5W and a 4-20mA signal output. To ensure that the 12 gas detectors are fully operational at all times, Cooper Crouse-Hinds has suppliedeXLink plug-in connectors, which enable the detectors to be replaced and serviced by a maintenance engineer without requiring a ‘Hot Work Permit’. eXLink is a range of connectors that enable the connection and disconnection of electrical apparatus in potentially explosive gas (or dust) atmospheres without the use of tools and without an engineer having to isolate the apparatus from the mains or disconnect the terminals.

This plug-in version of the gas detector has several advantages. In the event that an LEL meter is contaminated or faulty, the detector can be isolated electrically and replaced within a very short time – even in a potentially explosive atmosphere, by the eXLink’s simple disconnection procedure.

In the event of a fault with a gas detector and to enable their maintenance to be carried out quickly, the detectors use plug-in connections – a connection cable with an explosion-protected eXLink coupler, four-pole plus PE, is fitted via an M20 Ex-e cable gland. The counterpart to this is a socket with an eXLink inlet, four-pole plus PE, which is mounted directly adjacent to the gas detector. The detector can be connected and disconnected at any time thanks to this IP66/68 protected EX-e plug and socket connection. These compact connectors have an M20 thread of the inlet whereby, similar to a cable gland, the latter can be integrated into any type of enclosure.

By using eXLink connectors, the LEL meters are fully functional at all times, which is an essential basic requirement for the safe operation of the plant.


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