TVC types have been designed as piston cooing and LO pump for B&W engine.The motor bed is mounted on the top of LO tanks and the pump is suspended to the bed by discharge pipe.They are used in the submerged state below the oil level of the LO tank.
Compared with gear or screw pump used in general for LO these pumps have the following features giving much benefit to the user.
1.Suction side needs no suction pipe,valve and strainer so weight,installation space and price can be reduced.
2.Since the pump is submerged in oil, no priming is needed at starting.
3.The control of capacity and head is very easy.
4.The casing is of special consideration is given so that radial thrust on the impeller becomes minimum.
5.The impeller is of single suction and in order to improve suction performance francis vanes are adopted. For large sized pumps, thrust load acting on the upper ball bearing is reduced by changing the upper and lower diameters of impeller mouth soas to turn fliud thrust upward. Moreover, by providing balance holes at the impeller inlet, downward thrust is reduced and at the same time air olck is prevented.
6.Because of high LO viscosity at cold startup, capacity decreases and at the same time shaft horsepower increase. Accordingly,Motor output is determined by multiplying normal shaft horsepower by correction facter so that the motor is not overloaded at cold startup.
7.For the line bearing material, HLBC is adopted