Castell safeguards concrete production at T5

A concrete mixing plant used in construction projects at Heathrow Terminal 5 has been fitted with a trapped-key interlocking system from Castell, based on proven reliability in dusty environments

A concrete mixing plant used in construction projects at Heathrow Terminal 5 has been fitted with a trapped-key interlocking system from Castell.

Compactors Belgium, which is based in Herentals, near Antwerp, has supplied a twin plant for the production of paving-quality concrete for the Terminal 5 runways and taxiways.

Compactors decided to rely on a mechanical means of granting access to the plant after many of the tongue switches previously fitted to its equipment seized up as a result of prolonged exposure to dirt or cement dust.

"Given that this is such a prestigious project, we didn't want to run into the same problems that tongue switches had caused us in the past", explains Eric Broes, Compactor Technical Manager, who was responsible for overseeing the plant installation.

The plant features two solenoid-controlled KSSE20 electrical switches and four AI access interlocks.

"This system is rigid and reliable," continues Eric, "We have been so impressed with its durability and simplicity that we now fit one to every mixing plant that we produce".

Whenever an operator wishes to carry out cleaning or maintenance work on the plant, they first switch off the main power supply.

Depressing the KSSE20 push button then energises the switch solenoid and illuminates an LED to confirm that either one or both of its trapped keys can be removed.

Rotation and removal of one or both keys changes the machine electrical supply to a safe condition, while also granting access to one or both sides of the mixing plant.

The plant access doors can only be opened once the electrical supply has been switched into a safe condition.

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