Vacuum Pumps

About Vacuum Pumps and Vacuum Pump Manufacturers Including: Air Pumps, Dry Vacuum Pumps, Industrial Vacuum Pumps, Liquid Ring Vacuum Pumps & Rotary Vane Vacuum Pumps.

Vacuum pumps are basically devices used to create a vacuum. The vacuum pump changes the mechanical force of a rotating shaft to pneumatic force by removing air and other gases and releasing them into the atmosphere or holding them on surfaces within the pump. The amount of energy created depends on the force for all vacuum applications. Vacuum pumps are produced by vacuum pump manufacturers as either positive displacement or non-positive displacement. A positive displacement pump pulls a constant volume of air despite variations in the vacuum levels. Nonpositive displacement vacuum pumps use changes in kinetic energy to remove air from a system. The most important advantage of this design is its ability to supply very high volume flow rates that are much higher than possible with any of the positive displacement designs. Both types of pumps mentioned could be either oil lubricated or oil-free. The oil lubricated types have advantages in that they are able to provide a higher level of vacuum because the oil provides a greater seal between moving parts. Oil-free pumps are useful for pumps that will be mounted in inaccessible or remote locations. They are also used in the food and pharmaceutical industries where it is necessary to keep the product free from contaminants.
 
The standard types of positive displacement pumps produced by vacuum pump manufacturers are the piston, diaphragm, rocking piston, rotary vane, lobed rotor and rotor screw designs. Piston pumps consist of rotating pistons of varying stroke lengths that pump fluids through check valves. Diaphragm pumps consist of one or two flexible diaphragms that pulsate to displace fluid, while check valves control the direction of the fluid flow. Rocking piston pumps are basically a combination of diaphragm and piston pumps. Rotary vane pumps have an impeller made of rigid material and are useful for high-pressure or low-shear applications. Lobed rotor pumps have lobe-shaped rotors that gently fill with and dispense fluids containing soft particles, solids and highly viscous fluids. Rotary screw pumps have capabilities that are similar to the piston pumps in terms of vacuum, but air removal is pulse-free.
 
The standard type of nonpositive displacement vacuum pumps are the centrifugal, axial-flow and regenerative designs. Centrifugal pumps have a rotating vanned disk that is attached to a drive shaft. As it spins, the drive shaft moves fluid without pulsation. The outlet can be restricted without damaging the pump. Axial-flow pumps are designed to have a fluid flow parallel to an axis of rotation, similar to a turbine. Regenerative nonpositive displacement pumps consist of a series of pumps joined together to increase and maintain pressure.
 
All of us benefit from vacuum technology, whether wearing a pair of glasses, watching TV, listening to music, using a PC or driving a car. The manufacturing of semiconductors, CDs and DVDs, eyeglasses and the coating of heavy-duty mechanical tools are a few examples in which vacuum technology is applied. Vacuum pumps are used for vacuum distillation and the processing of food and in devices such as vacuum tubes, vacuum bottles, barometers and research equipment. Industries in which vacuum pumps and vacuum generators are commonly used include chemical and corrosive gas, food processing, manufacturing processing, medical and laboratory, packaging, power generation, pharmaceutical/sanitary and semiconductor manufacturing industries. Vacuum pumps are also used to improve the efficiency of steam heating systems. Different types of pumps are created by vacuum pump manufacturers and are used for industrial gripping and chucking, laboratory degassing and purification in the fields of chemical and semiconductor processing.

Vacuum Pumps and Vacuum Pump Manufacturers Image Provided by Vacuubrand, Inc.

Vacuum Pumps and Vacuum Pump Manufacturers Image Provided by Dekker Vacuum Technologies, Inc.	Vacuum Pumps and Vacuum Pump Manufacturers Image Provided by Varian, Inc.	Vacuum Pumps and Vacuum Pump Manufacturers Image Provided by Varian, Inc.

Types of Vacuum Pumps

• Air pumps cause a gas to flow against a pressure, converting mechanical force and motion into pneumatic fluid power.
  
• Cryogenic pumps, also called “cryopumps,” are gas binding vacuum pumps that work by the condensation and/or sorption of gas at surfaces maintained at temperatures, kept low enough through refrigeration, for the vapor pressures of the condensed gases to be insignificant. Cryogenic pumps, which are vacuum pumps working in a range below 120° Kelvin, cause the vapor pressures to be lower then the vacuum pressure.
  
• Diffusion pumps are vacuum pumps in which heated oil or another substance is pushed through jets as a vapor that collides with gas molecules and carries them out of the compartment being evacuated.
  
• Dry vacuum pumps operate without fluids, such as steam or water, eliminating environmental worries and the cost of contaminant disposal. Dry vacuum pumps, which can be configured to operate either hot or cool depending on the application, reduce emissions and ease solvent recovery.
  
• Ejector pumps are vapor pumps in which the vapor streams primarily under viscous flow conditions.
  
• Heavy duty vacuum pumps have the ability to operate under the most difficult conditions, such as when highly saturated vapors form in or solid particles get into the inlet stream.
  
• Industrial vacuum pumps are heavy-duty pumps used in to create a vacuum in industrial settings.
  
• Ion pumps are “capture and hold” pumps in which ionization removes gas at a significant rate.
  
• Liquid ring vacuum pumps, used in many industries for the evacuation of both dry and wet gases, have the capability to deal with condensable vapors or even small slugs of liquid entrained in the incoming gas. The condensing effect, occurring at the liquid ring as the incoming gas makes contact with it, can greatly enhance the upstream capacity of the pump.
  
• Mechanical pumps have moving parts such as pistons, rotating vanes or eccentric rotary members used for pumping vapor or gas.
  
• Nonpositive displacement pumps utilize kinetic energy to produce pressure gradients (slopes) for air in motion.
  
• Positive displacement pumps move an exact volume of air for every cycle of operation.
  
• Rotary piston vacuum pumps are reliable industrial-grade, heavy-duty pumps that are used in high contaminate applications.
  
• Rotary vane vacuum pumps are oil-sealed, air-cooled, direct-drive pumps with a small footprint that are used for pumping clean, dry, non-reactive gases. With regular oil and vane/filter changes, the reliability of rotary vane vacuum pumps, as far as maintaining maximum up-time, is moderate
  
• Side channel pumps consist of many circular hollow rings, half of which are in the upper and lower side of the pump housing and the other half in either side of the impeller, which has scoops on both sides. Side channel pumps generate very low pulse suction air, making them ideal for a wide variety of industrial applications that require precisely defined functions.
  
• Turbo molecular pumps are axial-flow turbines designed for operation in the molecular flow range. Turbo molecular pumps consist of a series of alternate circular rotor and stator disks, both of which have inclined blades designed to impart momentum change to gas molecules in a preferential direction from the pump inlet to the outlet.

Vacuum Pump Terms

Absorption – 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.
 
Absolute Pressure – 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).
 
Adsorption – Gas or vapor bonding on, or “sticking” to, a solid or liquid surface.
 
Air Intake Filter – 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.
 
Anneal – 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.
 
Atmosphere – 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.
 
Atmospheric Pressure – 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.
 
Back Pressure – Resistance to flow in the system.
 
Backstreaming – The movement of the vapor of the operational fluid of a pump in the direction of the area being depleted.
 
Baffle – 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.
 
Bake-out – 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.
 
Barometer – Mechanism for calculating atmospheric pressure, given in inches of mercury (in. Hg) at a precise point.
 
Baseplate – 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.
 
Belljar – A cylindrical vacuum compartment with a detachable seal supported by a baseplate.
 
Cathode – 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.
 
Check Valve – 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.iqsdirectory.com/check-valves/)
 
Condensation – The process of a vapor becoming a liquid or solid.
 
Conductance – Under steady-state conservative conditions, the ration of throughput to the pressure differential between two specified cross sections inside a pumping system.
 
Cross-over Pressure – The pressure at which pumping is transferred from one pump to another, providing a higher speed and/or a lower pressure.
 
Degassing – The deliberate removal of gas from a material, usually done by heating the material under vacuum.
 
Dessicant Dryer – An absorption material that eliminates moisture from air.
 
Differential Pressure Switch – Switch with a low-pressure and high-pressure adjustment. Fluid pressure activates an electric switch to perform work. (http://www.iqsdirectory.com/pressure-switches/)
 
Diffusion – The process of particles moving from an area of higher concentration to one of lower concentration.
 
Displacement – 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.
 
Feedthrough – 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.
 
Flow Rate – A measurement of the amount of fluid at a point per unit of time, commonly represented by cubic feet per minute (cfm).
 
Fluid Power – Energy controlled and transmitted through utilization of a pressurized fluid within an enclosed circuit.
 
Gauge Pressure (psig) – A measurement of the force per area applied by a fluid with atmospheric pressure as the zero reference.
 
Head – 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.
 
Hydrostatic Pressure – The exertion of pressure in all directions equally at points within an enclosed gas or liquid at rest.
 
Ionization – A process that occurs by adding or removing electrons to or from an atom or molecule, resulting in the formation of ions.
 
Isothermal – 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.
 
Kinetic Energy – 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.
 
Laminar Flow – Gas flow of adequate velocity so the gas will flow efficiently over surface obstructions and defects.
 
Lubricator – Pneumatic component that lubricates through the injection atomized oil into the air stream.
 
Manometer – An instrument used to measure the pressure of vapors and gases.
 
Maximum Vacuum Rating – Highest level of vacuum recommended for a vacuum pump.
 
Mean Free Path – The average distance a gas molecule moves without interacting with a surface or another molecule.
 
Negative Gauge Pressure – 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.
 
Nude Gauge – A vacuum gauge intended to be inserted into a vacuum system that does not have its own envelope.
 
Open Capacity – The volume of air exhausted per minute, expressed in cfm, when there is no pressure or vacuum load on the pump.
 
Outgassing – The process of evaporation that substances, such as oil and dirt, undergo after being placed in a low-pressure or vacuum environment.
 
Permeation – 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.
 
Pneumatic Fluid Power – The energy that is controlled and transmitted within an enclosed circuit by use of a pressurized fluid.
 
Positive Gauge Pressure – The difference in pressure above atmospheric pressure.
 
Pressure – Force per unit area impacting a surface, typically expressed in pounds per square inch (psi) or in MegaPascals (Mpa).
 
Pressure Switch – An electrical switch controlled by fluid pressure.
 
Psia (Pounds per Square Inch Absolute) – Pressure measured from a state of complete absence of air.
 
Psig (Pounds per Square Inch Gauge) – Pressure above or below (vacuum) atmospheric pressure.
 
Quick Exhaust Valve – A valve that releases air directly to the atmosphere, bypassing the directional valve, which reduces backpressure resistance.
 
Receiver Tank – 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.
 
Residual Gas Analyzer – 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.
 
Residual Gas – Gas remaining in the vacuum chamber after pump-down.
 
Safety Valve – A valve that opens to its full capacity to provide a rapid and large reduction in pressure when a predetermined value is exceeded.
 
Sight Ports – Holes covered with the glass through which the inside of a vacuum system may be observed.
 
Solid-state – Any element that controls current without moving parts, heated filaments or vacuum gaps.
 
Sorption – 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.
 
Standard Air – Air at a temperature of 68°F, a pressure of 14.7 psia and a relative humidity of 36%.
 
Standard Temperature and Pressure (STP) – 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.
 
Surface Damage – The physical changes of a surface structure to states of less regularity or symmetry, or the chemical changes in its composition.
 
Torr – A unit of pressure equal to 1/760th of a standard atmosphere.
 
Trap – A device used to capture and retain vapors and gases on cold and/or adsorbent surfaces.
 
Turbulent Flow – Gas flow that is not laminar at high pressures and velocities.
 
Vacuum – A space of air or other gas that is less than atmospheric pressure, expressed in inches of mercury (in. Hg).
 
Vacuum Chamber – The enclosure or container that is evacuated and in which the process or experiment is performed.
 
Vacuum Gauge – An instrument for determining gas pressure below atmospheric pressure.
 
Vacuum Rated Capacity – 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.
 
Vacuum Relief Valve – A valve that operates to provide a modulated flow of atmospheric air into the system to control vacuum level of the system.
 
Vacuum System – A total assembly, comprised of vacuum pumps, valves, chambers, lines and monitoring instruments, used to conduct a vacuum process or experiment.
 
Vapor Pressure – A fixed value that typically refers to the saturated vapor pressure at a specific temperature for all substances.
 
Viscosity – The resistance to flow of a fluid when subjected to pressure.
 
Viscous Flow – 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.
 
Volumetric Efficiency – Also known as “volumetric ratio,” it is the ratio of the actual delivery of a pump to its calculated delivery multiplied by 100%.