Dry Pumps: Screw, Roots, Hook & Claw

Dry Pumps: Screw, Roots, Hook & Claw

May 15, 2020

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by Katy Manning

Industrial dry pumps are a critical to maintain load-locks, support abatement systems, and provide vacuum for production in many industries including Semiconductor, Aerospace, Chemical Processing, and more. Dry pumps provide fast, clean vacuum in a typically compact and isolated containment system that helps to knock down noise. The three most popular design-types to generate dry vacuum are dry roots, dry hook and claw, and dry screw technologies.

Dry Screw

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 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.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. Popular dry screw vacuum pumps include the Kinney/Tuthill KSV and SDV series, Leybold SP series.

 

Dry Roots

Roots pumps, or Roots blowers, are rotary displacement dry-running rotary vacuum pumps, and they can be either single- or multi-stage.

 

A Roots pump has two counter-rotating rotors that function synchronously and without contact, all within a single housing. The rotors are set up and configured in a figure-eight, and a small gap separates them. The rotor shafts have between 4 and 6 pairs of rotors. The rotor cavities are separated from each other by a stator disk containing a gas orifice. The gas that passes through is pumped from the inlet port and is pumped out of the outlet port.

 

With regards to the shafts, one is driven by a motor, while the other synchronizes with a timing gear within the gearbox. Only the gearbox and the encapsulated high pressure and low-pressure bearings are lubricated. The shaft seals closes the bearings off from the suction chamber.

 

The lack of friction in the suction chambers allows the Roots pump to operate at extremely high rotational speeds, even up to 6,000 rpm. Moreover, the rotor mass is symmetrically distributed around the shaft axis. This gives the pump perfect dynamic balance, resulting in extremely quiet running, even at very high speeds.

 
Popular dry roots pumps include Pfeiffer ACP, A series,  Ebara A and ESR series.

 

Hook & Claw

Dry hook and claw vacuum pumps have two or more claw-shaped rotors that turn in opposite direction. The claws do not make contact which each other during operation, although are designed with very close tolerances to optimize compression and vacuum production.

Popular dry hook & claw pumps include Edwards QDP, IQDP, and IH series, Busch Mink, Leybold Clawvac series.

 

To view our collection of dry pumps for sale, click here https://www.provac.com/collections/dry-pumps

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