A cold storage facility keeps its cooling systems running at peak operating efficiency despite a warm climate.

Cooling table grapes from South Africa's famous Hex River Valley for storage and worldwide shipping is the name of the game for Hexkoel Beperk, a large cold storage operation located 93 miles from Cape Town. The company cools more than 16 million cartons of grapes annually-1.5 million weekly during the peak harvest period between February and March. Ensuring that the compressors used in the cooling process run at peak operating efficiency in the region's warm climate, while meeting strict food safety requirements, is a vital part of the process.

However, when maintenance personnel at Hexkoel Beperk inspected the cooling systems, they discovered excessive wear of the control valves as well as frequently clogged filters and strainers. "Our compressor oil was circulating with the ammonia gas in the cooling system," says Johan Muller, technical manager with the firm. "This resulted in significant wax build-up on compressor components. The wax was clogging up our filters, which in turn allowed dirt and metal chips through. The problem was compounded because wax had also built up on the control valves, trapping dirt and metal chips. This acted like sandpaper between the moving parts."

Hexkoel Beperk's oil distributor, Cool Lubricants, suggested trying Petro-Canada's REFLO 68A compressor fluid, which is designed to lubricate compressors in ammonia refrigeration systems. Muller decided to test it in one of Hexkoel Beperk's Sullair compressors. The company operates nine screw compressors to cool grapes to 32