NES Type CLS Vacuum Heating Pumps are some of the most efficient and reliable systems on the market today. Designed and engineered by the company that has been building the most reliable vacuum systems since 1915, the CLS line of vacuum condensate units are engineered to precisely match the requirements of your vacuum steam system. NES Engineered vacuum units are built with liquid ring vacuum pumps which are up to twice as efficient when compared to water jet type pumps. Liquid ring technology uses contactless liquid compress to produce a vacuum which due to the reduction in mechanical wear offers superior reliability.