Sensors protect gensets from water leaks

Edited by the Engineeringtalk editorial team Dec 9, 2002

Gems Sensors' electro-optic technology is providing environmental protection for a major international trading bank, using diesel engine generator sets for emergency shutdown power.

Gems Sensors' electro-optic technology is providing environmental protection for a major international trading bank, using diesel engine generator sets for emergency shutdown power.

The electro-optic sensors were specified by Power Plan - a company that specialises in the planning, installation and servicing of all types of secondary power systems to commerce and industry - from small mobile generators to complete multiple megawatt generator UPS systems with load and set shedding.

The sensors were chosen to form the basis of a leak detection solution for a number of generator sets that had been installed below the water table in London.

There was a potential risk that the generator sets could cause contamination to ground water in the event of a diesel leak, so five electro-optic sensors were mounted on the engines to provide an early warning.

This was combined with the added protection of bunding, to capture any fluid that may escape.

Small display panels provide constant monitoring, while the system is linked to an alarm, connected to a building management system.

This ensures a rapid response from an engineer, should an incident occur.

One solution initially considered was an electronic cable, laid across the floor and designed to react if the diesel makes contact.

This solution was considered to be more difficult to test and install than the electro optic sensors.

Testing would require immersion of the cable, but the subsequent cleaning and drying was believed to be too complex and time consuming.

Testing of the electro-optic sensor is extremely simple as the unit is simply dipped in diesel and wiped clean.

It also offers a faster response time to potential leaks and requires no moving parts - which was a significant factor affecting Power Plan's final choice.

This ensures low maintenance and increased reliability though out the sensor's lifetime.

Unlike competing optic sensors, Gems Sensors' units use a strong, glass prism - fused to a nickel-plated carbon steel housing.

This deflects the troublesome build-up of droplets associated with conventional 'dome-type' sensors.

The glass prism works in conjunction with infrared LED and TTL/CMOS-compatible solid-state circuitry to provide accurate liquid level or leak detection.

With no liquid present, light from the LED is reflected within the tip to the receiver.

When the tip is immersed into liquid, the light is refracted out into the liquid, leaving insufficient light to reach the receiver.

Sensing this change, the receiver actuates electronic switching within the unit, which operates an external alarm - thereby giving an early warning.

Commenting on the selection of the electro-optic sensors, Chris Taylor at Power Plan said: "I've been impressed with the reliability and quality of Gems Sensors' products.

The sensors, combined with the bunding, ensure complete environmental protection, which is vital to maintaining our client's world class reputation".