In recent years, water cooled screw pumps and the multi-stage Roots pumps described in the following section have been replacing more and more the previously dominating oil-lubricated rotary vane pump in the high pumping speed segment (100 – 600 m³ · h-1).
Advantages of screw pumps include:
- No lubricant in the gas displacement area
- No contamination of the medium to be pumped
- No operating fluid disposal problems
- Higher efficiency due to internal compression
- Virtually constant pumping speed between 1 and 1,000 hPa.
- Good liquid and dust tolerance
- Ideal backing pump for Roots pumps
This makes HeptaDry screw pumps very well suited for chemical applications or processes that generate dust, e. g. for crystal growing or if significant volumes of condensate are produced.
In thermostatic cooling, the water flow volume will depend on the following parameters: inlet pressure, gas type, rotation speed and pump size. Due to the waterflow cooling, virtually no heat is dissipated to the atmosphere. This reduce the heat load on any existing air conditioning systems and reduce their energy consumption.
Overview of primary screw pump applications:
- Drying, freeze-drying
- Electron beam welding
- Load locks
- Chemical applications
Figure 4.8: HeptaDry with connections and accessories