Sidwal Refrigeration Industries, an ISO 9001 certified company, is a pioneer in indigenously developed roof mounted air conditioning units for rail coaches. It has supplied over 4500 AC units for various trains including the Palace on Wheels, and is the largest supplier of roof mounted AC units to Indian Railways. The company is also a supplier of AC units for Delhi Metro coaches. The units manufactured under stringent quality assurance standards are made from the best raw materials. Its sleek, roof mounted bus air conditioners (170 mm in height) are available in a wide range to meet any requirement of mini, midi and large buses. These are specially designed to operate in 50°C and are approved by TELCO and Swaraj Mazda as OEM parts. The roof mounted unit is designed in a manner that it can be mounted outside the body of the bus without disturbing the interiors and since it is very sleek, it allows the bus to be parked in a garage with a low ceiling. The company offers a single roof mounted air-conditioning unit for large buses, Model SR-30S. Specifications: type – roof mounted (35-45 seater); cooling capacity – 28,000 (kcal/h); engine – M&M; compressor – open type reciprocating 575 cc; condenser – fin and tube, fan – axial flow; evaporator – fin and tube, motor – centrifugal; refrigerant – R-134a; and total current – 85 A, 24 V. Salient features: high cooling capacity for large sized buses; compact design is realised by employing a corrugated fin and tube heat exchanger; large evaporator section for optimum air distribution; and heating available at main engine at extra cost.