The product is a kind of middle and large double suction double screw pump with two construction forms i.e.With inbuilt bearing or bearing,and with two outfit types i.e.With or without heating chamer and safety valve.The bearing bore and pump bore of external bearing type are separated by mechanical seal and skeleton oil seal.Type and of good seal tightness.The product possesses large flux.good self suction performance,low noise and long service life.