VACUU·LAN® Local Area Vacuum Network:

Vacuubrand, Inc.

VACUU·LAN® vacuum networks make it possible to supply several different applications with one vacuum pump; this is a money- and space-saving solution when a lot of users are working with vacuum in one laboratory. This also avoids the numerous drawbacks of a central ("house") vacuum supply. These very versatile modules for single workplaces can be subsequently upgraded. All of the components are available for new laboratory furnishings or for installation in existing or renovated laboratories. All of the subassemblies are very resistant to chemicals and have built-in check valves to ensure that adjacent applications do not contaminate or interfere with one another.

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There are many contexts throughout industry and commerce in which the creation of a vacuum is necessary. Laboratory vacuum pumps create carefully controlled environments for electron microscopy and other tests and experiments. Medical vacuum pumps are used for suction during surgical procedures and for radiotherapy. Vacuum forming, eyeglass lens fabrication, light bulb manufacturing, plastic molding, lamination, hard coating, safety glass fabrication, photolithography and a host of other processes make use of vacuum pumps. Chemical and corrosive gas suppliers, food processors, manufacturers, packagers and many other companies need vacuum pumps for their operations. Vacuum pump systems are designed in varying configurations; liquid ring pumps, dry pumps, oilless pumps and rotary vane pumps are just a few possibilities. All vacuum pumps are air pumps; they work by directing air out of an enclosure and preventing it from re-entering.

Different vacuum pumps direct airflow in different ways, and three main categories of pump systems account for most of those methods: positive displacement pumps, momentum pumps and entrapment pumps. Positive displacement pumps create a vacuum by repeatedly expanding and exhausting a closed cavity; rotary vane pumps, scroll pumps, piston pumps, diaphragm pumps and liquid ring vacuum pumps are all positive displacement pumps. Most positive displacement pumps feature simple designs and are used to create low-intensity vacuums. Momentum transfer pumps expel air molecules from a sealed vacuum pump by accelerating the molecules using high speed gas jets or fans. Diffusion pumps and turbomolecular pumps are examples of momentum vacuum pumps and can be used to create very low-pressure vacuums. Entrapment pumps trap gasses using a heating or cooling process that makes them easier to catch. Some vacuum pumps are not easily categorized. A piston vacuum pump, which is a type of regenerative pump, consists of rotating pistons of varying stroke lengths that pump fluids through check valves. Diaphragm pumps feature one or two flexible diaphragms that pulsate to displace fluid, while check valves control fluid flow direction.

Though vacuum pump system configurations can vary wildly, the concept of vacuum creation is the same in every design and application. Vacuums can only be created in enclosed spaces. The first artificially created vacuums were intended for use in demonstrations and research. Their enclosures were usually glass and were not much larger than a large glass jar. The glass enclosure would be placed upside-down on a surface after its edges had been coated with some kind of liquid sealant. Air would then be removed by an air pump through an outlet in the surface. The first vacuum pumps were simple, low-capacity fans. Every time a fan blade spun near the vacuum enclosure's outlet, it would push air away from the outlet and through an exhaust port located elsewhere in the pump, creating a small vacuum. Air pressure imbalances correct themselves naturally, so some of the air from the enclosure would flow out to correct the imbalance. This air would be pushed away by the spinning fan, and the process would repeat itself until much of the air from the enclosure had been evacuated. Today, many pump systems still resemble this model, though great improvements in vacuum pump efficiency and effectiveness have been made since then. Many options are available to the great diversity of industries and processes for which the use of vacuum pumps is necessary.

All vacuum pump systems can be categorized as either wet or dry. Wet systems are any vacuum pumps that make use of a liquid at any point in a pumping process. Wet systems can make use of oil as a lubricant or sealant. Liquid seal vacuums use liquids within their mechanical enclosures to create air-tight compression seals. Dry systems are the opposite; at no point during a dry vacuum pumping process is any liquid used. Different applications call for either dry or wet vacuum systems. Oil-sealed vacuums are used when high-intensity vacuums are needed because oil provides a good seal between moving parts. When oil-seals are used, a downstream oil separator must be employed to ensure that neither the enclosure nor the exhaust areas are contaminated with oil. Dry vacuum pumps eliminate this problem, but they do so at the cost of effectiveness. Wet vacuum pumps generally achieve lower vacuum pressures, but they also require more frequent maintenance and can cripple operations if they fail. In applications like aircraft instrumentation in which long-term, failure-free performance is absolutely critical, dry vacuum pumps are almost always preferred over wet pumps. Industry professionals are careful to consider the potential costs and benefits of choosing a wet or dry vacuum pump.

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Vacuum Pumps Types

• 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.
• High vacuum pumps are devices that remove air particles from a sealed volume, resulting in a vacuum with a pressure between 10-2 and 10-8 Torr. The vacuum pump changes the mechanical force of a rotating part into pneumatic force as gas is removed from the volume, creating pneumatic or hydraulic flow and suction.
• 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.
• Laboratory vacuum pumps are devices that remove gas molecules from a sealed volume, creating a vacuum that is used for medical and scientific applications. Laboratory vacuum pumps have special features that make them suitable for use with tight spaces, delicate equipment, sanitary conditions and a variety of substances.
• 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.
• Medical vacuum pumps remove air molecules from a volume by creating a vacuum within a sealed device and have been adapted for the medical field.
• Nonpositive displacement pumps utilize kinetic energy to produce pressure gradients (slopes) for air in motion.
• Oilless vacuum pumps are devices used to create a vacuum by removing gas molecules from a sealed volume without the use of oil for lubrication.
• 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.
• Small vacuum pumps are modest-sized devices used to create a vacuum by removing gas molecules from a sealed chamber. They are the opposite of industrial vacuum pumps in terms of size and dimensions but are otherwise quite similar.
• 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.
• Vac pumps, also known as vacuum pumps, are devices that remove gas molecules from a sealed space, creating a vacuum.
• Vacuum pump systems are composed of one or more vacuum pumps combined with the parts and accessories necessary to successful remove gas molecules from a sealed chamber, resulting in suction, pneumatic or hydraulic flow and a vacuum.

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.
 
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.
 
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%.