TABLE OF CONTENT

CONTENT PAGE

1. Introduction

2. Types of vacuum pump

3. Advantages

4. Application in industry

5. Conclusion

6. References

7. Appendices

1
INTRODUCTION

A vacuum pump is a device that removes gas molecules from a sealed volume in order to leave a
partial vacuum inside it. Usually a vacuum pump takes in gas at very low pressure and normally
discharged at atmospheric pressure thus making its pressure ratio high. [2]

A vacuum pump is a machine that can create a vacuum in a chamber by pumping gas molecules
out of the chamber. Vacuum pumps are used in a wide variety of scientific and industrial
applications, either as part of a larger process or in the testing of other products. Vacuum pumps
have been available in some form for approximately 400 years, although contemporary pumps
are much more reliable and effective. Vacuum pumps function under one of three principles and
different pumps have varying levels of efficiency, speed and “throughput,” (which refers to the
effectiveness of a pump on a gas volume). [4]

THEORY

The most basic principle of vacuum pump functionality is positive displacement. The method
involves creating a vacuum by expanding one part of a chamber, closing it off, exhausting it, and
then repeating the process. Basically, when a chamber expands, it creates a natural vacuum and
sucks more gas into its interior. This is how lungs work—the lungs expand and air is pulled into
them through the nose or mouth. However, in a chamber, this expansion would need to grow
infinitely in order to create a vacuum. By sectioning the chamber so that the expanding section
can be closed off, this “infinite” expansion can be achieved. A sectioned chamber could expand
one side, drawing gas into its interior, and then close off the vacuum part of the chamber. Then,
the gas in the expanded side is expelled, or exhausted, and the sections reconnect. The chamber
expands again, creating a stronger vacuum in the vacuum side of the chamber, and the process
continues. [4]

A simple example of a vacuum pump in action is a manual water pump. When one works the
pump action, one side of a chamber expands and pulls air from the other side into its interior.
The chamber then closes and that air is exhausted. The vacuum section of the chamber is sealed
off by water. Because of the creation of a vacuum in the chamber, the water level begins to rise
as it is no longer affected by downward pushing pressure. [4]

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Momentum Transfer

Momentum transfer is the governing principle in both diffusion and turbomolecular pumps. In
momentum transfer, a chamber has two sides: a vacuum side and an exhaust side. The vacuum
side is where the vacuum is created and the exhaust side is where the gas molecules are expelled
from the chamber. Momentum transfer involves the creation of a positive displacement pump to
create a mild vacuum in the chamber. When this occurs, the gas molecules are pushed to the
sides of the chamber. In a diffusion pump, jets of oil or mercury are blown at these isolated gas
molecules to force them towards the exhaust end of the pump.

A turbomolecular pump uses several high-speed fans to force the gas molecules to the exhaust
side. When these pumps force the gas molecules to the exhaust, a high vacuum is created in the
chamber. However, the seal is not closed, so backstreaming, or leakage, can occur, limiting the
effectiveness of the vacuum. To counteract this leakage, the blowing speed of the oil, mercury or
fans, called molecular pumping, must be operated at a very high speed. [4]

Entrapment

Entrapment covers the principle used by a variety of pumps that capture gas in a non-gaseous
state, that is, in a solid or adsorbed state. The basic principle involves converting gas into a solid
or forcing it to adsorb (when the gas molecules collect together on the surface of a substrate) and
then using a device to exhaust the gas molecules from the vacuum chamber.

A cryopump uses entrapment to create a vacuum in a pump chamber. In a cryopump, gas is

cooled by helium, dry ice, or liquid nitrogen until the gas molecules collect on the bottom of a
chamber. As long as the chamber remains cold, the gas molecules will remain on the cold
surface, creating a mild-to-high vacuum in the rest of the chamber. In order to turn off the
vacuum and “regenerate” the cryopump, the chamber is heated up and the gas molecules
eventually become excited again, ending the vacuum effect. [4]

3
TYPES OF VACUUM PUMP

1. Liquid ring vacuum pump

It is made from a bronze or a stainless steel impeller. Other than that, it is also made up from
stainless steel shaft and other contact parts in cast iron.

The features of this vacuum pump are silent and considerably free running. Other than that, it is
also being modified to be use as a compressor and it has mechanical shaft seals on either end of
the shaft.

Usually this type of vacuum pump is being used in drying, filtering, distillation, crystallization
and other field in industry due to its outstanding features.

2. Rotary high vacuum pump

For this type of vacuum pump, it is a rotary sliding vane and oil immersed type. It is made from
high nickel content cast iron and very ideal for handling dry and clean air. It is also provided
with gas ballast and belt guard.

It consists of exhaust valve to eliminate the noise from this vacuum pump and their unique
constructions remove the sucking air through the shaft seal.

4
 3. Vacuum/pressure pump

It is divided into two types of vacuum/pressure pump:

i) Series LVN
ii) Series LV

Series LVN Series LV

Features Rotary sliding vane, oil Rotary sliding vane, oil
lubricated belt driven type. lubricated
Compact, light weight and can Have duo functions which are
be placed inside original to give the pressure and
equipment. vacuum at the same time.
Advantages Vibration free Have duo functions

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Rotary Vane Pumps [3]

Rotary Vane Pumps

Vacuum Level: Coarse Vacuum or Rough Vacuum (design dependent)

Gas Removal Method: Gas Transfer
Pump Design: Oil-Sealed (wet)

There are two different types of rotary vane pumps—those for coarse vacuum applications and
those for rough vacuum applications. The major distinctions between the rotary vane mechanism
for coarse pumps and rough pumps are the number of vanes, their tolerances, and the trapping of
exhaust oil vapors.

In all rotary vane pumps, gas from the chamber enters the inlet port and is trapped between the
rotor vanes and the pump body. The eccentrically mounted rotor compresses the gas and sweeps
it toward the discharge port. When gas pressure exceeds atmospheric, the exhaust valve opens
and gas is expelled. Oil is used as a lubricant, coolant, and gas sealant for the vanes. Single-stage
rough rotary vane pumps have ultimate pressures around 10-2 Torr range while two-stage rough
vane pumps reach 10-3 Torr. Pumping speeds vary from 1–650 cfm, depending on whether the
pump is a coarse vane or rough vane pump.

Rough vane pumps are used primarily as backing pumps for roots or high-vacuum gas transfer
pumps such as turbomolecular and diffusion in all vacuum applications. Coarse vane pumps are

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used in freeze drying, vacuum filtering, vacuum impregnation, materials handling, meat packing,
and "house" vacuum systems.

Diaphragm Pumps [3]

Diaphragm Pumps

Vacuum Level: Rough Vacuum

Gas Removal Method: Gas Transfer
Pump Design: Dry

A flexible metal or polymeric diaphragm seals a small volume at one end. At the other end are
two spring-loaded valves, one opening when the volume's pressure falls below the "outside"
pressure, the other opening when the volume's pressure exceeds the "outside" pressure. A cam on
a motor shaft rapidly flexes the diaphragm, causing gas transfer in one valve and out the other.

Diaphragm pumps often have two stages in series—to produce a lower vacuum, or in parallel, to
produce a higher pumping speed. In general, diaphragm pumps have low pumping speeds (<10
cfm) and produce a poor ultimate vacuum (1 Torr to 10 Torr). However, they do exhaust into the
atmosphere and their low costs make them attractive roughing pumps. In part, hybrid pumps
were developed to accept the poor foreline pressure diaphragm pumps produce. Diaphragm
pumps are also used for simple vacuum filtration, thin film evaporation, distillation, gel drying
applications, and as sample movers for gas analyzers, membrane filtration, and sample
extraction.

7
.

Reciprocating Piston Pumps [3]

Reciprocating Piston Pumps

Vacuum Level: Rough Vacuum

Gas Removal Method: Gas Transfer
Pump Design: Dry

The mechanism, patented by CSIRO Australia, moves a reciprocating piston in a metal cylinder
lined with a composite PTFE wall honed to a 3-micron finish. A combination of poppet and slide
valves, similar in concept to those of the 4-stroke and 2-stroke internal combustion engines,
directs gas flow to and from the cylinder. The pumps are built with up to 4 stages, often
connected in parallel or series to achieve an ultimate vacuum of 2 x 10-2 Torr or pumping speeds
from 6—32 cfm while exhausting at atmospheric pressure. They are used in clean, dry
applications that do not contain aggressive gases, water vapor, or dust. A typical application is
roughing load locks in MBE and UHV processing systems. [3]

8
Scroll Pumps [3]

Scroll Pumps

Vacuum Level: Rough Vacuum

Gas Removal Method: Gas Transfer
Pump Design: Dry

Two open spiral metal strips are nested together. One spiral is fixed while the other "orbits"—its
center point describes a small circle but the spiral does not rotate. As the moving spiral orbits, it
touches the stationary spiral at everchanging positions. The shape of the spirals means at one
orbital point there is an open (crescent-shaped) volume connected to the inlet. A little later in the
orbit, the connection with the inlet closes, trapping a volume of gas. Continuing the orbit causes
this volume to decrease, compressing the gas until it reaches a minimum volume and maximum
pressure at the spirals' center, where the outlet is located. In this orbital position, the inlet is again
connected to the large open volume. Typically, two such nested spiral stages are mounted in
series, producing an ultimate vacuum in the 10-2 Torr range and pumping speed of roughly 12–25
cfm while exhausting at atmospheric pressure. Scroll pumps are used in clean, dry processes and
as dry backing pumps for high vacuum pumps. They should not be used outside an ambient
temperature range of 5–40º C. [3]

9
Screw Pumps [3]

Screw Pumps

Vacuum Level:Rough Vacuum

Gas Removal Method: Gas Transfer
Pump Design: Dry

Two contra-rotating, left- and right-handed "screws" mesh with each other but do not touch.
When the screws are rotated at a modest speed (3,600 rpm), gas is transferred from one end of
the structure to the other. The mechanism produces an ultimate pressure in the 10-3 Torr range,
yet can operate with the inlet at atmospheric pressure. Pumping speeds from 30–318 cfm are
available. The construction materials are chosen to enable the screw pump to operate in the harsh
environments of aggressive gases and particulates found in semiconductor etching and CVD
processes. They are also used for roughing dry, high vacuum transfer pumps or initial pumpdown
for capture pumps.

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Rotary Piston Pumps [3]

Rotary Piston

Vacuum Level: Rough Vacuum

Gas Removal Method: Gas Transfer
Pump Design: Oil-Sealed (wet)

This mechanism is best at pumping high gas loads at pressures lower than 0.1 Torr. The
mechanism is complex, but also rugged and can withstand much abuse. Gas from the chamber
enters the pump body through a sliding sleeve valve. An eccentrically mounted cylinder rocks
(orbits) around the inside of the pump body without rotating. It compresses the gas out through
the exhaust valve into the atmosphere. Rotary pistons are used extensively for backing large
roots pumps and/or diffusion pumps attached to production-sized vacuum furnaces.

11
Diffusion Pumps [3]

Diffusion Pumps

Vacuum Level: High Vacuum

Gas Removal Method: Gas Transfer
Pump Design: Oil-Sealed (wet)

Diffusion pumps were the first high vacuum pumps in operation. Diffusion pumps operate by
boiling a low vapor pressure, high molecular weight, nonreactive fluid and forcing a dense vapor
stream up a central column and out as a conical vapor curtain, through jets that are angled
downward. Gas molecules from the chamber randomly enter the curtain and are pushed toward
the boiler by momentum transfer from the fluid molecules. When the vapor curtain reaches the
cold wall, the temperature change of perhaps 200–250º C immediately returns it to liquid form at
a low vapor pressure. Small (1") and large (36") diameter pumps give ultimate vacuums in the
10-4 Torr range. Mid-sized pumps, with an LN2 trap, reach the 10-7 Torr range. Pumping speeds
range from perhaps 30 L/s to 50,000 L/s.

Diffusion pumps tolerate operating conditions (e.g., excess particles or reactive gases) that would
destroy other high vacuum pumps. They have high pumping speeds for a relatively low cost, and
are vibration- and noise-free. Unfortunately, they continuously backstream oil vapor and
instantly turn a simple operating error into a major system disaster with oil everywhere. For this
reason, diffusion pumps have decreased in popularity but are still seen in applications requiring
huge pumping speeds such as molecular beam systems, large scale vacuum furnace processing,
and space simulation chambers.

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Turbomolecular Pumps [3]

Vacuum Level: High Vacuum & Ultra High Vacuum (design dependent)
Gas Removal Method: Gas Transfer
Pump Design: Dry

Turbo pumps, as they are commonly called, resemble jet engines. A stack of rotors, each having
multiple, angled blades, rotate at very high speeds between a stack of stators. Gas molecules
randomly entering the mechanism and colliding with the underside of the spinning rotor blade
are given momentum toward the pump's exhaust. The compression ratio for N2 across the pump
may exceed 108. That is, if the partial pressure in the foreline is 10-4 Torr, the chamber partial
pressure may be 10-12 Torr, 108 times lower. (The actual partial pressure depends on many
factors not related to compression ratio.) Compression ratios for H2 and He are much lower,
sometimes less than 103, which suggests the turbo mechanism alone is not good at producing
low chamber pressures when H2 or He is present.

The ultimate vacuum of most turbos lies between 10-7 Torr and 10-10 Torr. However, UHV
pressures are achieved by backing a large turbo by a small turbo (which, in turn, is backed by a
mechanical pump). Turbo pumping speeds range from 50 L/s to 3,500 L/s for normal
commercial pumps. Correctly operated and vented, the turbo mechanism prevents vapor
backstreaming from the greased rotor bearings. For truly dry chambers, a turbo with
magnetically levitated bearings backed by a dry mechanical pump are used. With proper venting,
the turbo mechanism stops in less than a minute, which may mean chamber venting is
accomplished without the need for a valve separating pump and chamber. Also, a separate
roughing line is usually unnecessary because the chamber can be roughed through the stationary
or accelerating turbo.

Turbo pumps are used in all vacuum applications between 10-4 and 10-10 Torr and are replacing
diffusion pumps as general workhorses. Turbo pumps are not used on dusty processes or those
for which small high frequency vibration might be a problem. However, some turbo pumps are
built to resist corrosion from reactive gases.

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 A (stylized) combination of turbomolecular and
molecular drag mechanisms mounted on one
shaft to form a hybrid turbo pump

Turbo-Drag Hybrid Pumps [3]

Vacuum Level: High Vacuum & Ultra High Vacuum (design dependent)
Gas Removal Method: Gas Transfer
Pump Design: Dry

The hybrid pump (also called a combination pump or sometimes just turbo pump) combines the
input stage of a standard turbo pump with the output stage of a drag pump. The resulting hybrid
has a much higher pumping speed than a molecular drag pump yet operates at high foreline
pressures often requiring only a diaphragm pump. The compression ratio for hybrid pumps can
reach 1,010 for N2 and more than 104 for H2. Their ultimate pressure is 10-11 Torr when backed
by a pump giving a low foreline pressure and pumping speed ranges from 50 L/s to 3,200 L/s.

The hybrid pump appears to be rapidly replacing the regular turbo for all R&D applications
requiring 10-9 Torr, and the cryopump in process applications for which the cryopump’s
regeneration time is unacceptable. Hybrid pumps with magnetically levitated bearings are truly
dry and their lack of lubricated "physical" bearing surfaces enables their adaptation to fairly
corrosive environments. [3]

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Ion Pumps [3]

Ion Pumps

Vacuum Level: Ultra High Vacuum

Gas Removal Method: Gas Capture
Pump Design: Dry

Ion pumps are the primary choice for all true UHV chambers. They are clean, bakeable,
vibration-free, operate from 10-6 Torr to 10-11 Torr with low power consumption, and have long
operating lives. All ion pumps have the same basic components: a parallel array of short,
stainless steel tubes, two plates (Ti or Ta) spaced a short distance from the open ends of the
tubes, and a strong magnetic field parallel to the tubes' axes.

Electrons from the (cathodic) plates move along tight helical trajectories in the magnetic field
through the (anodic) tubes. When a gas molecule is ionized by an electron in a tube, it is strongly
attracted to a cathode that it strikes with force sufficient to sputter titanium. The sputtered Ti
coats everything: tubes, plates, and pump casing. Several pumping mechanisms are possible,
including chemical reaction (getter action), ion burial, and neutral burial (the last two accounting
for the pump's ability to pump inert gases).

The ion pump's characteristics are determined by the plate material, its physical form, and the
voltage supplied. In the "diode" pump, the Ti plates are grounded and the tubes have a high
positive voltage.
The diode has high pumping speed for H2, O2, N2, CO2, CO, and other getterable gases. The
"noble diode" pump has the same electrical supply as the diode, but Ta is substituted for one Ti
plate. This reduces the pump's H2 pumping speed, but enables higher pumping speed and greater
stability for Ar and He. In the "triode" pump, the plates are slotted or penetrated in some manner
and connected to a high negative voltage. Both the tubes and the pump casing (acting as a third
electrode) are grounded. Sputtering from the slotted plates deposits Ti not only on the tubes and

15
plates but also on the pump casing. Inert gases and methane burial on the casing are less
susceptible to later ion bombardment, even at high pressures when plates are heavily bombarded.

ADVANTAGES [6]

 Energy-efficient : optimal exploitation of the compressed air by means of the multi-step-

principle

 High vacuum output : The pump can reach an end vacuum of over 90%

 Economical consumption : Energy is only consumed when you need vacuum (pulsing)

 Speedy reaction : Quick generation of the vacuum when needed due to its high suction
performance

 Operation safety : The vacuum pumps do not have any rotating wear parts. As energy you
only need clean compressed air.

 Low noise

 Easy installation

 Low maintenance

 Installation possible in nearly any position

 Compact design

 Light weight

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APPLICATION IN INDUSTRY

1. Pharmaceuticals
2. Packing
3. Environmental
4. Health and medical
5. Food conservation
6. Composite Plastic moulding processes (VRTM)[2]
7. Driving some of the flight instruments in most aircraft. [2]
8. The production of most types of electric lamps, vacuum tubes, and CRTs where the
device is either left evacuated or re-filled with a specific gas or gas mixture. [2]
9. Semiconductor processing, notably ion implantation, dry etch and PVD, ALD, PECVD
and CVD deposition and soon in photolithography. [2]
10. Electron microscopy. [2]
11. Medical processes that require suction . [2]
12. Medical applications such as such Radiotherapy, Radiosurgery, Radiopharmacy . [2]
13. Analytical instrumentation to analyse gas, liquid, solid, surface and bio materials. [2]
14. Mass spectrometers to create an ultra high vacuum between the ion source and the
detector. [2]
15. Vacuum Coating for decoration, for durability, for energy saving. [2]
16. Glass coating for low e glass. [2]
17. Hard coating for engine (as in Formula One). [2]
18. Ophthalmic coating. [2]
19. Air conditioning service - removing all contaminants from the system before charging
with refrigerant. [2]
20. Trash compactor. [2]
21. Vacuum engineering. [2]
22. Sewage systems (see EN1091:1997 standards). [2]
23. Freeze Drying. [2]
24. As the main source of vacuum in dairy shed plant. [2]

Vacuum may be used to power, or provide assistance to mechanical devices. In diesel engined
motor vehicles, a pump fitted on the engine (usually on the camshaft) is used to produce vacuum.

17
In petrol engines, instead, vacuum is obtained as a side-effect of the operation of the engine and
the flow restriction created by the throttle plate. This vacuum may then be used to power.

In an aircraft, the vacuum source is often used to power gyroscopes in the various flight
instruments. To prevent the complete loss of instrumentation in the event of an electrical failure,
the instrument panel is deliberately designed with certain instruments powered by electricity and
other instruments powered by the vacuum source. [2]

18
CONCLUSION

19
REFERENCES

1. http://www.buzzle.com/articles/erectile-dysfunction-vacuum-pump-therapy-seven-
advantages.html
2. http://en.wikipedia.org/wiki/Vacuum_pump
3. http://www.lesker.com/newweb/Vacuum_Pumps/vacuumpumps_technicalnotes_1.cfm
4. http://www.thomasnet.com/articles/pumps-valves-accessories/vacuum-pump-principles
5. http://www.pfeiffer-vacuum.de/en/tec2.6.1/technology.do
6. http://pneumatics-en.timmer-pneumatik.de/vakuumtechnik/vakuumpumpen.html

APPENDICES

[5]

20