|
|
|
|
Innovative
Mag-Drive TB Mag Series |
 The
TB-mag pumps create three distinct pressure regions around the
impeller. These regions are the suction pressure in the impeller
eye, the discharge pressure in the volute and the balance pressure
behind the impeller. In operation, the balance pressure is approximately
one quarter to one third of the discharge pressure.
The discharge pressure is created by the routine pumping action
of the impeller while the balance pressure is controlled by the
combined action of a fixed orifice and a variable orifice. The
fixed orifice is created by a set of clearance rings behind the
impeller. These rings limit the leakage flow behind the impeller
to a relatively constant rate.
The leakage then flows around the magnets, past the bushing to
the thrust control valve. This thrust control valve combined with
the front of the shaft defines the variable orifice. Because the
impeller is free to slide axially the variable orifice changes
size. As conditions of service change for the pump the impeller
will automatically compensate for the pressure change and remain
thrust balanced.
If the impeller moves forward, the valve is opened to a greater
degree and the balance chamber pressure is reduced. This causes
the impeller to react with a net force towards the motor. However,
the valve is now closing and the balance chamber pressure increasing.
This moves the impeller towards the suction. The net result is
a very stable axial position for the impeller. There are no axial
bearings and the radial bearings always operate in a pressurized
fluid environment.
|
|
