... Sigma, Lean Production and Management Air to Water Swimming Pool Heater Horizontal SeriesModelPASRW012015020030035040040S050SHeating CapacitykW6.87.39.714.016.019.021.025 ... , is held biannually in Guangzhou every spring and autumn, with a history of 55 years since 1957. The Fair is ... a comprehensive one with the longest history, the highest level, the largest scale, ...