One of the largest passively-cooled instrumentation shelters ever constructed is being supplied by Intertec to house remote control and instrumentation equipment required for a new natural gas collection project in the Middle East. Without any electricity, the cooling system reduces interior shelter temperatures by some 20?C - to enable the instrumentation to operate at its desert location.

Intertec is supplying three shelters for the project. Two employ active cooling and were delivered at the end of 2013. The third shelter, which will house solar-powered instrumentation and uses innovative passive cooling technology, is currently nearing completion.

The shelters are designed to protect supervisory control and data acquisition (SCADA) systems - comprising remote terminal units (RTUs), telemetry network equipment and associated electronics ?- for the control infrastructure of a new gas pipeline that is being constructed on the coast of the Persian Gulf. At present, much of the gas from oilfields in this part of the world is burnt off as waste at the point of extraction. This project is designed to improve resource management by collecting and using the gas to power seawater desalination plants that are currently fuelled by oil.

Environmental conditions at the site are severe. The coastal location means that the atmosphere contains corrosive salt and chlorine, as well as sulphur from the natural gas. During the summer months, additional factors include extremely high levels of UV radiation and daytime temperatures that can reach 55?C in the shade. Protecting field instrumentation for long life-cycle applications under such extreme conditions requires specialist knowledge and materials.

Intertec has constructed all three shelters using the techniques and composite materials that it uses for its high performance ARCTIC range. In this instance, 85 mm thick walls are employed - with 4 mm inner and outer skins of GRP sheeting (glass reinforced polyester) sandwiching a 77 mm layer of insulating foam. The GRP material layers are inherently inert and virtually immune to the corrosive effects of salt and aggressive chemicals. Intertec's passively-cooled shelter comprises two adjacent walk-in rooms with their own entry doors. One room contains the rechargeable batteries, while the second room houses all the system instrumentation and electronics including a PLC, computer network, power inverters and a controller for the external photovoltaic generator. The overall dimensions of the contained area are 5.2 metres x 9.1 metres, with a floor-to-ceiling height of 3 metres; the entire roof area is covered by a heat exchanger and sunshade combination.

The passive cooling technology Intertec employs for this project is based on thermo-siphoning using water - which is cooled and heated by the natural swing of day and night temperatures. The rear of the equipment room houses an 8,000 litre thermally stratified water tank connected to two closed-loop thermo-siphon systems formed by internal wall-mounted and external roof-mounted heat exchangers. The water circulates entirely due to natural convection. No pumps are involved and the process operates entirely automatically to provide highly reliable, safe and energy-efficient cooling.

Intertec Instrumentation Pvt Ltd, B535 New Friends Colony, New Delhi 110 065. Tel: 011-41628183. Email: india@intertec.info