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Vacuum Pump Terms
– The process involving the penetration
of a gas or vapor beyond the surface of a solid or liquid, usually by
some kind of diffusion and its subsequent binding or capture.
– The sum of atmospheric and gauge pressures,
it is the total force per unit area exerted by a fluid and the pressure
above a perfect vacuum (zero pressure) in vacuum systems. U.S. units
for absolute pressure are pounds per square inch absolute (psia).
– Gas or vapor bonding on, or “sticking” to,
a solid or liquid surface.
– Device installed at the intake port of a compressor
or vacuum pump that is used to capture insoluble contaminants from a
fluid with porous material.
– A vacuum heat treatment process in which a material is
relaxed and uneven or heterogeneous regions of a substrate, which result
from the application of internal stress, are homogenized.
– Unit of pressure that will sustain a column of mercury
of 29.92” at 0°C, sea level. Actual daily atmospheric pressure
fluctuates about this value.
– Pressure exerted by the atmosphere in all
directions, equal at sea level to about 14.7 psi. Also the force exerted
on a unit area by the weight of the atmosphere.
– Resistance to flow in the system.
– The movement of the vapor of the operational fluid
of a pump in the direction of the area being depleted.
– A system of cold surfaces placed between the inlet of
a pump and the area on which it is pumping to condense backstreaming
vapor and return it to the pump.
– The heating of vacuum system components during the pumping
process for the purpose of degassing. The bake-out process increases
the evolution of adsorbed and absorbed gases.
– Mechanism for calculating
atmospheric pressure, given in inches of mercury (in. Hg) at a precise
point.
– A plate that supports a belljar along with its enclosed
materials or components subjected to a vacuum, providing mechanical,
electrical and other connections to components within the vacuum system.
– A cylindrical vacuum compartment with a detachable seal
supported by a baseplate.
– The negative electrode
in an electron device. A cathode is the most negative electrode in an
ion pump, which can discharge electrons and accumulate positive ions.
– A two-way directional
valve that allows free flow in one direction and blocks flow in the other
direction. Check valves can act as either directional or pressure control
apparatuses. (http://www.check-valves.net)
– The process of a vapor becoming a liquid or solid.
– Under steady-state
conservative conditions, the ration of throughput to the pressure differential
between two specified cross sections inside a pumping system.
– The pressure at which pumping is transferred
from one pump to another, providing a higher speed and/or a lower pressure.
– The deliberate removal of gas from a material, usually
done by heating the material under vacuum.
– An absorption material that eliminates moisture
from air.
–
Switch with a low-pressure and high-pressure adjustment. Fluid pressure
activates an electric switch to perform work. (http://www.pressure-switches.net)
– The process of particles moving from an area of higher
concentration to one of lower concentration.
– Meaningful only
in positive displacement compressors, the entire volume that is swept
by the repetitive motion of the
pumping element. Displacement per revolution depends on the size of the
pumping chamber or chambers, and displacement per minute is determined
by compressor speeds.
– Also known as “pass-through,” it is a
device used to transmit electrical current, fluids or mechanical motion
through the walls of a vacuum system.
– A measurement of the amount of fluid at a point per
unit of time, commonly represented by cubic feet per minute (cfm).
– Energy controlled and transmitted through utilization
of a pressurized fluid within an enclosed circuit.
– A measurement of the force per area applied
by a fluid with atmospheric pressure as the zero reference.
– Often used to indicate gauge pressure, this is energy per
pound produced by pressure, elevation or velocity. Expressed in linear
units, it is the height of a column or body of fluid above a given point.
– The exertion of pressure in all directions
equally at points within an enclosed gas or liquid at rest.
– A process that
occurs by adding or removing electrons to or from an atom or molecule,
resulting in the formation of ions.
– Expansion or compression of a gas at a constant temperature.
Practically, this is a slow process because of the time required to replace
heat absorbed by expansion or to remove heat generated by compression.
– Energy due to motion that is added to a fluid
either by rotating it at a high speed or by providing a catalyst in a
direction of flow.
– Gas flow of adequate velocity so the gas will flow
efficiently over surface obstructions and defects.
– Pneumatic component that lubricates through the injection
atomized oil into the air stream.
– An instrument used to measure the pressure of vapors
and gases.
– Highest
level of vacuum recommended for a vacuum pump.
– The average distance a gas molecule moves without
interacting with a surface or another molecule.
– Also called “gauge vacuum” or “vacuum
level,” it is the pressure drop that results from the system emptying,
measured in inches of mercury (in. Hg.). Negative gauge pressure is a
term that must be carefully used, because absolute negative pressure
does not exist.
– A vacuum gauge intended to be inserted into a vacuum
system that does not have its own envelope.
– The volume of air exhausted per minute, expressed
in cfm, when there is no pressure or vacuum load on the pump.
– The process of evaporation that substances, such as
oil and dirt, undergo after being placed in a low-pressure or vacuum
environment.
– The movement of gas through a solid. The process always
involves diffusion through the solid and may involve surface phenomena
such as dissociation, sorption, desorption and migration.
– The energy that is controlled and transmitted
within an enclosed circuit by use of a pressurized fluid.
– The difference in pressure above atmospheric
pressure.
– Force per unit area impacting a surface, typically expressed
in pounds per square inch (psi) or in MegaPascals (Mpa).
– An electrical switch controlled by fluid pressure.
– Pressure measured from a state of complete absence of air.
–
Pressure above or below (vacuum) atmospheric pressure.
– A valve
that releases air directly to the atmosphere, bypassing the directional
valve, which reduces backpressure
resistance.
– Container in
which gas is stored under pressure or vacuum as a source of pneumatic
fluid power. Receiver tanks accommodate sudden or unusually high system
demands, prevent frequent on/off cycling of an
air compressor or vacuum pump and absorb pulsations.
– Also referred to as a “partial pressure
analyzer” or “partial pressure gauge,” it is a device
for measuring the amounts and species of various gases present in a vacuum
chamber.
– Gas remaining in the vacuum chamber after pump-down.
– A valve that opens to its full capacity to provide
a rapid and large reduction in pressure when a predetermined value is
exceeded.
– Holes covered with the glass through which the inside
of a vacuum system may be observed.
– Any element that controls current without moving
parts, heated filaments or vacuum gaps.
– A generic term used to describe the uptake of a gas
or vapor by a solid without distinction as to whether the process occurs
by adsorption and/or absorption.
– Air at a temperature
of 68°F, a pressure of 14.7 psia and a relative humidity of 36%.
– Also referred to as “standard operating conditions,”
it is a term referring to the temperature and pressure to which all values
are referenced for comparison. STP is generally 760 mm Hg (1 atm), 25°C.
– The physical changes of a surface structure to states
of less regularity or symmetry, or the chemical changes in its composition.
– A unit of pressure equal
to 1/760th of a standard atmosphere.
– A device used to capture and retain vapors and gases on
cold and/or adsorbent surfaces.
– Gas flow that is not laminar at high pressures
and velocities.
– A space of air or other gas that is less than atmospheric
pressure, expressed in inches of mercury (in. Hg).
– The enclosure or container that is evacuated and
in which the process or experiment is performed.
– An instrument for determining gas pressure below
atmospheric pressure.
– The cfm of free air exhausted by a vacuum
pump at rated speed. Usually given for vacuums ranging from 0 in. Hg
to the maximum vacuum rating.
– A valve
that operates to provide a modulated flow of atmospheric air into the
system to control vacuum level of the
system.
– A total assembly,
comprised of vacuum pumps, valves, chambers, lines and monitoring instruments,
used to conduct a vacuum process
or experiment.
– A fixed value that typically refers to the saturated
vapor pressure at a specific temperature for all substances.
– The resistance to flow of a fluid when subjected to
pressure.
– The flow of gas, which may be turbulent or laminar,
through a channel under conditions such that the mean free path is very
small in comparison with the smallest dimension of a transverse section
of the channel. At these pressures, the flow characteristics are determined
mainly by collisions between the gas molecules.
– Also
known as “volumetric ratio,” it
is the ratio of the actual delivery of a pump to its calculated delivery
multiplied by 100%.
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