- The materials chosen for the lapped seal faces. Usually a
grade of carbon graphite running on a hard face material.
Face to face seals
- Two seals running against a common seal face. The barrier
fluid pressure is always lower than stuffing box pressure.
- Measured by an optical flat and a monochromatic light. The
measurement is read in helium light bands (.0000116 inches or 0,3
- The fluid or vapor that sometimes exists between lapped
mechanical seal faces.
- The sum of all the loads on the seal face including the spring
load, hydraulic load and shaft axial thrust, divided by the area
of the seal face. This face load is reduced by friction between
the sliding elastomer and the shaft or sleeve.
- Contains organic or inorganic materials that might be
sensitive to temperature, or be attacked by the fluid you are
sealing. Usually a low cost carbon.
- A devise used to remove solid particles from liquid. It
removes smaller paricles than a strainer.
Finite element analysis
- A computer generated method of predicting seal face
- A rapid change in liquid state from a liquid to a gas.
- Measured by Helium light bands (0.0000116" or 0,3 microns) as
opposed to surface finish that is measured by R.M.S. or
- Same as L3/D4 Used to predict shaft
- The portion of the seal containing the springs or
- A shaft with an operating speed higher than its first critical
- The material assumes the shape of its container. It could be
either a liquid or a gas.
- Genetic term for the elastomer called Viton®. Viton is a
Dupont Dow elastomer product.
- Putting an outside liquid into the stuffing box of the pump at
a pressure higher than stuffing box pressure. All of this liquid
mixes with and dilutes the pumped fluid.
- Supports the wet and power end of the pump and attaches it to
the base plate.
- Created whenever pressure works on an area. The units are
pounds. (F = P x A)
Formed metal bellows
- Manufactured by stretching and compressing the metal bellows
material. Not usually used in mechanical seals because of its high
- Feet per minute. When used in the context of seals it is
measured at the center of the seal face.
Francis vane impeller
- The most popular impeller shape with a specific speed between
1500 and 4000.
- The uncompressed axial length of a seal.
Frett or fretting
- Damage or grooving caused by the removal of the protective
oxide that is formed on most corrosion resistant metals. It
happens when a softer material (rubber) rubs against a hard shaft
or sleeve. A common problem with low cost O.E.M. mechanical seals
and bearing grease or lip seals.
- The government has designated certain chemicals as hazardous
to the environment. If any of these chemicals is released to the
atmosphere they are called fugitive emissions.
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with over 600 Seal & Pump Subjects
Link to Mc Nally home page