Three screw pumps of 3V type are intended for pumping nonaggressive liquids possessing lubricating power (mineral oil, residual fuel oil, oil, diesel fuel ), without abrasive mechanical admixtures, at a viscosity of up to 1500 sSt and temperature of up to 100°С. At the Client's request certain pump models may be fabricated for pumping liquids with temperature of up to 150°С. The lower limit of viscosity is restricted by lubricating ability of the pumped liquid, the upper one – by rating of an engine and suction capacity of a pump.
While placing purchase order do not fail to agree the liquid to be pumped, viscosity limits and working temperature.
Pumps of 3V type are manufactured in climatic version ОМЗ for installing at the marine ships and river craft vessels (with acceptance of Russian Maritime Register of Shipping and/or River Register).
Electric pump unit consists of three-screw pump and motor, connecting piece, coupling, safety valve.
As to the principle of operation the three-screw pump – is a positive displacement machine.
Pump consists of the following main parts and subassemblies: hydraulic part, casing with covers, end-face seal, safety and ball valves.
The casing houses a shell with three cylindrical bores incorporating one driving screw and two driven screws packing the driving screw.
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. Ingress of air into operative parts of the pump is inadmissible.
An end-face seal is arranged within the gland cap cavity at the outlet of the driving screw.
|Series||3V, 3V*2 (for ships)|
|Flow, m³/h, least||75|
|Rotation speed, rpm||730|
|Rotation speed, c˜¹||12|
|Pump outlet pressure, kgf/sm², max||4|
|Full overflow pressure, MPa||0.6|
|Type of current||AC|
|Kinematic viscosity of pumped liquid (calculated), ° VU||10|
|Allowable vacuum suction, m||5|
For example А1 3V х2 500/10-400/4B ОМ3,TU 26-06-1547-89, where: