- 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
- A design in which the seal face closing area is reduced to
lower the closing force, and reduce the heat generation between
- 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.
- Consists of an inner race, an outer race, and a series of
balls between them. Often called a precision or anti friction
- Metric term for one atmosphere of pressure.
- 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.
- The pump and motor mount on this unit. The pump and motor
feet closest to the coupling should be doweled to the base
- The mechanical seal drive lugs wear into the drive slots
and prevent the seal faces from moving forward to compensate for
- Supports the rotating shaft and allows it to turn with a
minimum amount of friction. Could be either sleeve or
- Can be manufactured from metal or non metallic materials to
eliminate flexing, rolling or sliding elastomers in mechanical
- A thin, stamped disc. Two are welded together to form a
- 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.
- 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
- Brake horse power. The actual amount of horsepower being
consumed by the pump as measured on a pony brake or
Body bound bolts
- The bolt has an interference fit with the bolt
- 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
- The low pressure fluid that is circulated between dual
- 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.
- 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
- 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.
For information about my CD
with over 600 Seal & Pump Subjects
Link to Mc Nally home page