Back plate
Used in some centrifugal pumps to position the stuffing box and
provide an impeller wear surface.
Back pull out pump
A design that allows the wet end of the pump to be left on the
piping when the power end and adapter are removed. A.N.S.I. pumps
are designed this way.
Back to back double seal
The rotating seal faces are facing in opposite directions. The
worst possible configuration. In the past this term was used to
describe a higher barrier fluid pressure between dual mechanical
seals.
Balanced seal
A design in which the seal face closing area is reduced to lower
the closing force, and reduce the heat generation between the
faces.
Balance Ratio
A 70/30 balance ratio means that 70% of the seal face closing
area is seeing the stuffing box pressure and 30% is not seeing
the pressure.
Ball bearing
Consists of an inner race, an outer race, and a series of balls
between them. Often called a precision or anti friction bearing.
Bar
Metric term for one atmosphere of pressure.
Barrier fluid
The high pressure fluid that is circulated between two mechanical
seals. The fluid should enter the bottom and leave the top to
prevent air pockets.
Base plate
The pump and motor mount on this unit. The pump and motor feet
closest to the coupling should be doweled to the base plate.
Bayonet
The mechanical seal drive lugs wear into the drive slots and
prevent the seal faces from moving forward to compensate for wear.
Bearing
Supports the rotating shaft and allows it to turn with a minimum
amount of friction. Could be either sleeve or anti-friction type
Bellows
Can be manufactured from metal or non metallic materials to eliminate
flexing, rolling or sliding elastomers in mechanical seal designs.
Bellows plate
A thin, stamped disc. Two are welded together to form a convolution.
Bernoulli's law
A moving stream of liquid or gas exerts less sideways pressure
than if it were at rest. The result is that things seem to be
drawn into the stream, but they are really being pushed in by
the higher pressure from outside.
B.E.P.
The best efficiency point. It is the point where the power coming
out of the pump (water horse power) is the closest to the power
coming into the pump (brake horse power) from the driver. This
is also the point where there is no radial deflection of the shaft
cause by unequal hydraulic forces acting on the impeller.
B.H.P.
Brake horse power. The actual amount of horsepower being consumed
by the pump as measured on a pony brake or dynamometer.
Body bound bolts
The bolt has an interference fit with the bolt hole.
Brinnell hardness
A method of measuring the hardness of metal parts and hard seal
faces. Above 350 the standard machining operations of turning,
boring, drilling, and tapping become uneconomical.
Buffer fluid
The low pressure fluid that is circulated between dual mechanical
seals.
Buna N
Some times called Nitrile. A common elastomer used in the sealing
of oil or water. Sensitive to Ozone attack and therefore has a
short shelf life.
Bushing
A close fitting support device used to restrict flow between
two liquids, thermally isolate a hot liquid, support the rotating
shaft, break down pressure etc. Commonly made of carbon or Teflon.
Bypass line
Used to either re-circulate fluid from the pump discharge to
the stuffing box, the stuffing box to the pump suction, or the
pump discharge to a lower pressure point in the system.