Three-screw pumps AS-ЗV

  • Series description
  • Technical characteristics
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The unit is intended for use in the oil systems of the main circulating pump (GCN) at the nuclear power stations.

The unit is not designed for installing in explosion-and-fire hazard productions.

The unit is designed for operation at the attended premises (location category 3), and is manufactured in climatic version U as per GOST 15150-69; it is intended for operation in the atmosphere of II type as per GOST 15150-69.

Three-screw pump AS-ЗV 8/25 being part of the electric pump unit is related to the items of specific purpose (IKN), item aspect I (repairable) as per GOST 27.003-90.

The unit is of aseismic design. Earthquake stability category II in conformity with NP-031-01.

The unit maintains its strength, air-tightness and serviceability during and after PZ - 7 points earthquake as per MSK-64 scale at the mark minus 5,0 m.


Electric pump unit consists of three-screw pump, connecting piece, coupling and electric motor.

As to the principle of operation the three-screw pump – is a positive displacement machine.

Pump consists of the following main details and subassemblies: pump casing, shell, one driving and two driven screws, end-face seal.

The thread of screws is made with a special profile ensuring their mutual conjugation, the thread is of the double-start type, left-hand on the drive screw and right-hand on the driven screws.

During rotation of screws a rarefaction is created in the pump suction chamber, as a result the pumped liquid is fed to the screw thread hollows mutually closed during rotation of the screws. The liquid volume closed in the screw thread moves in the shell rectilinearly without mixing, and then it is forced into the discharge chamber.


  • on the Nuclear Power Plant for systems of bearings and end-face seals of pumps GCN lubricating

Features /Advantages

  • high reliability - simple design and precision manufacturing provide high reliability and 50 years of operational life
  • easy operation - virtually no need in maintenance to significantly lower downtime and servicing cost
  • safety - pumps are certified for application in nuclear power, in in earthquake-resistant design, I or II seismic category, 2 or 3 safety class. Single mechanical seals of our own manufacturing provide protection from leakages along the shaft.
  • casing material is carbon steel
  • material selection for pump parts according from requirements of nuclear power.. Additional quality control of materials and component is carried out s.

Technical parameters

Pump models Pump power input (max.), kW Rotation speed, c˜¹ Rotation speed (rang), rpm Pump inlet pressure, kgf/sm², max Pump outlet pressure, kgf/sm², max Full overflow pressure, MPa Efficiency,% Voltage, V Frequency, Hz Kinematic viscosity of pumped liquid (calculated), ° VU Allowable vacuum suction, m
AS-3V 8/25-11/10A 5 48 2900 2.5 10 1.5 72 220/380 50 10 5

Pump type key

For example АS-ЗV 8/25-11/10А-UЗ , where :

  • AS – version of the pump for nuclear power station
  • ЗV 8/25 – standard size designation as per GOST 20883-88
  • 11 – rounded-off capacity of the pump when coupled with motor, m³/h
  • 10 – outlet pressure of the pump when coupled with motor, kgf/сm²
  • А – conventional material designation of the base members - steel 25
  • – climatic version and location category as per GOST 15150-69