What makes it different from the conventional cooler are the cellulose pads which are used in them. They are manufactured by two or three companies in the world, and all such pads used in rigid media systems are imported. The pads are made of corrugated sheets. The surface contact material is specifically engineered for direct evaporative cooling and humidification.

Manufactured from special cellulose paper impregnated with rotproof compounds, it contains stiffening saturants and wetting agents. The paper has high water-retention properties. The sheets have a patented angle arrangement to direct water flow towards the air inlet side which is where most of theevaporation occurs. The air, passing through the channels formed by the corrugation, evaporates the water present in them, resulting in highly effective and efficient cooling. It is also designed to flush away atmospheric dust.

The most important thing about cellulose pads is glueing. "Glueing holds the key to success. If it is not strong enough and gets washed by water, the entire system becomes useless. We import glued pads," says Richie Mittal of Roots Air Systems Pvt. Ltd.

Rajeev Saxena, director, Roots Cooling Systems Pvt. Ltd., also insists that imported glued pads give a better performance. "The chemical composition of the glue is important and it is a trade secret of Munters, a Swedish company." The brand name of Munters' product is CELdek.

This is not correct, counters Deepak Sood of Ambassador Coolers Private Limited. "We glue pads here, but they are used only after they are certified by Munters. We do that because we have volumes, the technology, and the capability to do that. There is nocompromise on quality simply because Indian hands glue the pads. Had our product been of inferior quality, we would not have had 70 to 80 per cent of the market in our hands."

Another manufacturer of cellulose pads is Glacier which is based at Phoenix, US. Roots Air Systems has a tie up with it.

Sood, who claims to be a pioneer in the line of rigid media cooling systems, rarely sells directly to the end-users. "We don't take contracts except in the agriculture segment of our business," says Sood. "We supply pads to other groups including Symphony and Videocon."

Rigid media evaporative cooling systems are fast becoming popular. Roots Air Systems' clients include Bennett, Coleman & Co Ltd., Eicher Tractors Ltd., BPL, Hero Honda, DCL Polyester Ltd., Rajiv Gandhi Cancer Institute and Vam Organics. Roots Cooling have installed systems at the premises of Shriram Piston & Rings Ltd, Ballarpur Industries Ltd., Daewoo, Visakapatnam Steel Ltd., Castrol India Ltd., Punjab Tractor Ltd., JK Tyres Ltd., RelianceIndustries Ltd., Claridges Hotel and Telco.

People in the rigid media cooling industry claim that this is a cheaper, energy-efficient method of cooling air by evaporating water. "It costs 20- 25 per cent as compared to airconditioners," says Saxena.Rigid media coolers take only 40 per cent of space as required by conventional coolers. They require no masonry work and can be located inside or outside a building. The cooling unit becomes more compact, can be fitted in tight places, and works effectively even where only one side of the unit is exposed to the atmosphere. The pads do not require annual change as in conventional systems.

Power consumption, too, is negligible. According to Saxena, rigid media coolers consume one tenth of that consumed by ACs. Besides, the noise level is only 65 decibels near machines. They can be customised, the availability varying in depths. They are also compatible with other airconditioning components.

All these features make rigid media evaporative systems apt for officebuilding, canteens, commercial kitchens, banks, theatres, auditoriums, schools, libraries, museums, general shop floor cooling and ventilation, textile mills humidification, printing presses humidification and ventilation, laundries and dry-cleaning establishments, generator rooms, warehouses and stores, poultry and livestock confinement buildings, greenhouse set-ups, hatcheries, egg rooms, etc.

However, rigid media evaporative cooling systems are not very popular in domestic use. The most important reason being its price which is on the higher side. Sood says that such systems are being sold by Symphony and Videocon in Gujarat and Maharashtra. He is also trying to sell the concept and is awaiting the market response. "So far, the response has been positive."

Concept selling is something everybody has to do in the rigid media cooling business. "It is an important part of marketing," points out Saxena.

Prospects for growth are bright in this sector. People in the rigid media business feel that thegovernment would do well by allowing 100 per cent depreciation in income-tax.