Liquid ring and dry screw vacuum pumps are both pumps that use the principle of positive displacement but have some differences. A liquid ring pump uses fluids to create the needed vacuum, while a dry vacuum pump does not.Get more news about 2022 Dry Screw Vacuum Pump,you can vist our website!

The vacuum in dry screw pumps is created through two parallel-arranged screw rotors that rotate in opposite directions. These rotors trap the gas coming in through the inlet and deliver it to the gas discharge or pressure side. As the gas is getting compressed, there is no contact between the rotors. This does away with any need for the compression chamber to have any operating fluids or lubrication, and this is the reason for the nomenclature "dry" technology.

There is, however, an internal gearbox in dry screw pumps that does need to be lubricated. This lubricant can find its way into the pumping chamber during operations over time, and in a way making false the claim of a "dry" technology.

Liquid ring pumps have cylindrical housing that is filled partially with a sealing liquid and a shaft that has a multi-blade impeller that is placed eccentrically inside the housing. The centrifugal force created by the rotating impeller creates a liquid ring.

It is this force that causes the liquid ring to be forced up against the walls on the inside of the pumping chamber.

Because of the eccentric location of the impeller in the pumping chamber, there is a constant increase and decrease of its blades depth of entry. This helps to create an increase in impeller cell volume on the side of the inlet port, thus forming a vacuum. What happens on the discharge side, is that the blades move further into the ring of liquid, causing an increase in pressure that causes the discharge through the discharge port.

The design inherent in the liquid ring pump permits the use of various liquids to act as a sealant, and this can be oil, solvents, water, or any other liquids that are compatible with the process. Liquids remain in contact with the vapors or gases that are needed to be compressed, and as a result, the compression of the gas is almost isothermal. Depending on the conditions, discharge temperatures can be between 45 and 150 degrees Fahrenheit and remain typically controlled in any process applications. As discharge temperatures are controlled in liquid ring pumps, gases of all kinds can be passed through or condensed, and this offers a great degree of flexibility.

Screw vacuum pumps can have a constant-pitch design, that allows transportation of gas at a constant volume of discharge where the major part of the compression occurs or can have progressive pitch design, in which the vapor or gas gets compressed while it is being transported to the discharge port. In both cases, the compression is adiabatic, and no heat leaves or enters the process, and discharge temperatures can be as high as 450 degrees Fahrenheit. These high temperatures in the use of this technology lead to concerns for safety.