Dry vacuum pump technology – especially variable pitch screw chemical dry pumps – offer clear, measurable advantages in a wide variety of essential applications. A properly designed dry screw vacuum pump ensures the processing needs are accomplished with a safe, reliable, and cost-effective solution.
Dry screw vacuum pumps require no water or oil for sealing or lubrication in the vacuum stages. Consequently, these dry vacuum systems eliminate effluent generation, pollution, and high treatment costs.
Thermal management is essential for the reliable operation of chemical dry screw vacuum pumps.
In a pump that is too cool for a given process, aggressive vapors may condense, leading to corrosion, the dilution of lubricants, and the swelling of seals. This damage is serious but can only happen if the vapor is allowed to condense into the liquid phase.
Conversely, if the operating temperatures in the pump are too high for a given process, unwanted reactions such as polymerization or auto-ignition are possible, with the addition of high bearing temperatures or thermal seizure.
The effects mentioned above can be mitigated slightly by internal coatings but this is something that should never be relied on. Coatings work great to protect the pump during initial storage and system commissioning but they can only survive so long at the temperatures and vacuum levels where the pumps spend most of their time.
The key is to ensure that the process vapors stay in the vapor phase [Green area] in the figure below. A few strategies to ensure this occurs include temperature/flow control of the pump coolant, use of nitrogen purge to change process dew point, and the use of inlet condensers to remove the vapor upstream of the pump.
To further improve reliability where system challenges are always present, additional features can be added to the pump system to help guarantee reliability. One example is a solvent flush system to keep the pumping mechanism free and clean. Another being knock-out pots (KOPs) and filters to capture liquid or powder slugs when unable to prevent them.
NASH dry screw vacuum pumps are remarkably simple, yet sophisticated, reliable, and highly efficient. The dry and contact-free operation requires no lubrication in the pumping chamber. This translates into major advantages: no process contamination and no pollution caused by the pump operation. NASH dry vacuum pumps can safely and reliably handle corrosives, organics, inorganics, and solvents because of their oil-free, non-contacting screw design. Key applications include: