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Topic: Diffusion pump

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	High Vacuum Diffusion Pump - SPI Supplies
		Pump and jet designs have evolved over the years and synthetic fluids have advanced, enabling higher levels of vacuum to be achieved.
		Since the diffusion pump cannot exhaust directly to atmospheric pressure, the forepump is used to maintain proper discharge pressure conditions.
		When a vacuum diffusion pump is slower than normal in pumping down to the desired vacuum level, the reason is likely to be either outgassing of moisture on internal surfaces of plastics or other volatile substances, or a leak.
	www.2spi.com /catalog/vac/santovac-5-diffusion-pump-fluid-technical-paper.html (1873 words)

	Diffusion vacuum pump manufacturers in vacuum-guide.com
		In a diffusion pump, a suitable fluid is vaporised in the boiler of the pump at 200-250oC and the vapour is sprayed into the pump through high velocity jets incorporated in the interior of the pump.
		Diffusion pumps are a type of vacuum pump designed to achieve higher vacuum (lower pressure) than possible by use of mechanical pumps alone.
		The pumped gases continue flowing to the base of the pump at increased pressure, flowing out through the diffusion pump outlet, where the pressure is increased to ambient, and exhausted by the secondary mechanical "rough pump".
	www.vacuum-guide.com /high_vacuum_pump/diffusion/diffusion_pump_europe.htm (783 words)

	DIFFUSION PUMP
		The prototype pump of this design was intended for use as a visual display for
		Further testing of the pump revealed that the pump was functional and the pumping
		pumps have advertised pumping speeds of 7 to 30 liters per second.
	www.public.asu.edu /~aomdw/GLASS/DIFFUSION_PUMP.html (251 words)

	how does a diffusion pump work
		Diffusion pumps will operate only if the pressure is less than a few tenths of a millimeter of mercury, and they operate best with a "backing pressure" of a few hundredths of a millimeter of mercury.
		Where N is evacuated by an auxiliary diffusion pump instead of the mechanical pump, pressures of 10^-7 mm of mercury or lower can be obtained in a tight glass apparatus connected to M (provided mercury vapor is removed with a liquid air trap).
		With oil diffusion pumps it is not uncommon to have pumping speeds of some tens or hundreds of liters per second, whereas with mercury diffusion pumps the speeds are ordinarily only a fraction of a liter per second up to a few liters per second.
	www.absolute-vacuum.com /resources_howdoesdiffwork.php (1823 words)

	TECHNIQUE OF HIGH VACUUM, PART THREE
		Where N is evacuated by an auxiliary diffusion pump instead of the mechanical pump, pressures of 10^-7 mm of mercury or lower can be obtained in a tight glass apparatus connected to M (provided mercury vapor is removed with a liquid air trap).
		With oil pumps it is not uncommon to have pumping speeds of some tens or hundreds of liters per second, whereas with mercury diffusion pumps the speeds are ordinarily only a fraction of a liter per second up to a few liters per second.
		The vapor pressure of the vacuum pump oils used in roughing pumps, according to Dushman, is 10^-3 to 10^-4 mm at ordinary temperatures, 1/5 of this value at 0 C., and negligibly small at the temperature of dry ice or liquid air.
	www.tau.ac.il /~phchlab/experiments/vacuum/Techniques_of_high_vacuum/Vacuum3.html (2811 words)

	Kids.Net.Au - Encyclopedia > Diffusion pump (Site not responding. Last check: )
		Diffusion pumps use a high speed jet of fluid to direct residual gas molecules in the pump throat down into the bottom of the pump and out the exhaust.
		Diffusion pumps cannot discharge directly into the atmosphere, so a mechanical forepump is typically used to maintain an outlet pressure around 0.1 torr.
		Due to backstreaming, diffusion pumps are not suitable for use with highly sensitive analytical equipment or other applications which require an extremely clean vacuum environment.
	www.kids.net.au /encyclopedia-wiki/di/Diffusion_pump (222 words)

	Electron Microprobe Notes: Vacuum System
		The diffusion pump is used to produce and maintain low pressures in the electron column, spectrometers, and sample chamber.
		Diffusion pumps are so named because rather than actively "pull" air molecules out of a volume, they wait for the molecules to diffuse into the active part of the pump where they are then trapped and removed.
		A diffusion pump operates by boiling oil at the base of the pump that rises as a hot vapor.
	www4.nau.edu /microanalysis/Microprobe/Vacuum-DiffPump.html (351 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal (Site not responding. Last check: )
		Diffusion pumps are a type of vacuum pump designed to achieve higher vacuum (lower pressure) than possible by use of mechanical pumps alone.
		The pumped gases continue flowing to the base of the pump at increased pressure, flowing out through the diffusion pump outlet, where the pressure is increased to ambient, and exhausted by the secondary mechanical "rough pump".
		Diffusion pumps cannot discharge directly into the atmosphere, so a mechanical forepump is typically used to maintain an outlet pressure around 10 pascals.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=diffusion_pump (427 words)

	Silicone diffusion pump fluids - Patent 4289891 (Site not responding. Last check: )
		The diffusion pump fluid is vaporized and the vapor is forced through a jet in the center of an outer chamber containing the gas molecules to be removed.
		It would be desirable to be able to change diffusion pump fluid in a particular diffusion pump as the vacuum became better, that is, to insert at that point a diffusion pump fluid which would have the capacity to adsorb a further amount of the light gases, but in practice this is not possible.
		For the most preferred silicone diffusion pump fluid it is desirable to mix in the reaction pot at least two moles of the alkoxylated phenyl chlorosilane with at least 4 moles of the trimethylchlorosilane with one mole of diphenyldichlorosilane.
	www.freepatentsonline.com /4289891.html (8105 words)

	EE143: Description of a Basic Vacuum System
		The rotor is eccentric to the pump cavity.
		Fast pumping action is achieved through the use of high speed jets of oil vapor which collide with gas molecules and compress them in the direction of the mechanical pump (see Figure 3).
		The foreline valve and the hi-vac valve (Figure 1) serve to isolate the diffusion pump, the baffle and cold trap from the object being roughed.
	microlab.berkeley.edu /ee143/Vacuum_System (1080 words)

	Diffusion Pump Fluids at Clearco Products
		Synonyms: diffusion pump fluid, silicone diffusion pump fluid, silcone diffusion pump oil, diffusion pump oil, high vacuum diffusion pump fluid, 10-8 diffusion pump fluid, Dow Corning® 704 diffusion pump fluid, DC 704 diffusion pump fluid, CAS 3982-92-9, Tetraphenyltetramethyltrisiloxane, single component diffusion pump fluid
		Clearco DPF-7040 is a single-component fluid for high vacuums of 10-7 to 10-8 torr (untrapped) and to 10-11 torr (trapped).
		Synonyms: diffusion pump fluid, silicone diffusion pump fluid, silcone diffusion pump oil, diffusion pump oil, high vacuum diffusion pump fluid, 10-8 diffusion pump fluid, Dow Corning® 705 diffusion pump fluid, DC 705 diffusion pump fluid, CAS 3982-92-9, Tetraphenyltetramethyltrisiloxane, DC705 fluid single component diffusion pump fluid
	www.clearcoproducts.com /diffusion_pump_fluids.html (475 words)

	Silicone Diffusion Pump Fluid, Silicone Diffusion Pump Fluid Importer, Silicone Diffusion Pump Fluid Wholesale, ... (Site not responding. Last check: )
		The efficiency and the lifetime of oil diffusion pumps related to vacuum value of ventilation etc. highly dependent upon the mechanical system of the pumps and the kinds of fluids used.
		Diffusion pump fluids widely and commonly used at present are mainly those of petroleum series and ester series of fatty acids.
		Therefore, the following troubles may be avoided by the use of silicone diffusion pump fluids; the decrease of thermal conductivity of heater parts, the closure of nozzle parts,the corrosion of the apparatus, the decrease of high vacuum, etc., due to thermal oxidation of fluids.
	www.deltasilicones.com /sil_difus.htm (770 words)

	ontspiegeling
		Ultimate pressures attainable are limited by leakage between the high and low-pressure sides of the pump (due mainly to carry over of gases and vapors dissolved in the sealing oil that flash off when exposed to the low inlet pressure) and decomposition of the oil exposed to high temperature spots generated by friction.
		Vapor Diffusion Pump This pump is mainly used on equipment for the study of clean surfaces and in radio frequency sputtering.
		The active gasses are pumped by chemical combination with the sputtered titanium, the inert gasses by ionization and burial in the cathode, and the light gasses by diffusion into the cathode.
	optochemicals.nl /ontspiegeling.htm (1120 words)

	A Short History of Vacuum--SOUTHERN PVD Co., Ltd (Site not responding. Last check: )
		One is a two-bladed pump in which the rotor is eccentric to the stator, forming a crescent-shaped volume swept by the blades through the outlet valve.
		The diffusion pump is initially evacuated by an oil-sealed rotary pump to a pressure of about 0.1 torr or less.
		The active gasses are pumped by chemical combination with the sputtered titanium, the inert gasses by ionization and burial in the cathode, and the light gasses by diffusion into the cathode.
	www.southern-pvd.com /vk/evksh02.htm (2417 words)

	Provac Ltd. Vacuum Technology, Wexford, Ireland, Irish experts for vacuum design projects, leybold, stainless steel ...
		In the case of diffusion pumps a pump fluid contained in a boiler is heated to such an extent that it is vaporized.
		pumping action of diffusion pumps and fluid entrainment pumps in general is based on the transporting capacity of the vapor jet.
		Compared to other fluid entrainment pumps the density of the vapor in the boiler and in the vapor jet is fairly low so that the gas molecules may almost completely diffuse into the vapor jet.
	www.provac.ie /pump_products/dip_oil_diffusion_pumps.htm (700 words)

	RTFTechnologies Particle Accelerator
		The diffusion pump has 3 bolt holes in the top of the flange adapter where two aluminum mounting plates are attached for mounting the pump.
		The flange adapter is mounted to the diffusion pump flange with 6 bolts and is sealed with an aluminum/rubber o-ring.
		The welch pump initially pumps the beam line down to 20 torr at which point the diffusion pump is turned on and pumps the system down to 1.5E-5 torr.
	www.rtftechnologies.org /physics/linac.htm (1696 words)

	Feature Guide
		The pump oil in the oil sump is heated to where it has an appreciable vapor pressure and the heavy-molecular-weight oil vapor is directed toward the foreline by the vapor-jet elements of the diffusion pump.
		The pump housing is generally water-cooled and the temperature gradient of the pump housing is important.
		Diffusion pumps are built in many sizes, ranging from as small as a 2-inch-diameter inlet throat to greater than 48 inches.
	www.svc.org /EP/EP_FeatureGuide.html (1355 words)

	Diffusion Pump Notes (Site not responding. Last check: )
		Diffusion pumps operate by boiling a fluid, often a hydrocarbon oil, and forcing the dense vapor stream through central jets angled downward to give a conical curtain of vapor.
		Water cooled diffusion pumps have coils through which cooling water circulates during operation.
		As the first high vacuum pump ever developed, the diffusion pump has been used in probably every type of vacuum application on earth (literally, since experiments on other planets have not used diffusion pumps).
	www.lesker.com /newweb/Vacuum_Pumps/Individual_Pumps/Diffusion_Pumps/TechNotes.cfm?CFID=985840&CFTOKEN=54376526§ion=diffpumps&init=skip (346 words)

	Myers-Vacuum
		The pump has no moving parts which may be corroded by the acidic nature of the material being pumped.
		The KSM-2000 is a three stage vapor pump whose diffusion and ejector nozzles are supplied from a common electrically heated boiler.
		The compressed gas is then passed on to the ejector stage in the horizontal convergent divergent arm of the pump.
	www.myers-vacuum.com /ksm2000.shtml (414 words)

	varian vacuum pump (Site not responding. Last check: )
		Includes the new Smart Pumps, operating from atmosphere to 2 x 10-3 mbar, Varian’s rotary vane pump is designed and manufactured to meet the demanding requirements of various industrial and scientific applications, Varian’s reliable Rotary Vane Pumps ensure high pumping stability for light gases, low noise, minimal oil back-streaming, and a long operating life.
		As the worldwide diffusion pump market leader, Varian produces the most comprehensive high performance family of diffusion pumps, ranging from 2” to 35” in diameter and operating from 10-1 to 10-8 mbar.
		Ion pump is an ultra-high vacuum pumps in diode, noble diode, and StarCell® versions, operating from 10-4 to 10-11 mbar.
	www.tawada-ndt.com /content/products/VARIAN/vacuumpump.htm (426 words)

	control Backstreaming
		On electron microscopes traps are found between the sample chamber and sometimes between the diffusion pump and on the foreline to the rotary pump.
		Backstreaming in the foreline of the diffusion pump is the result of the pressure in the foreline being so low that molecular flow is possible for the oil molecules against the flow of the pumped gasses.
		The diffusion pump is them able to reach a pressure limited by the pressure of the diffusion pump oil vapor pressure alone.
	www.evactron.com /backstreaming.html (3246 words)

	The Oil Diffusion Pump (ODP) (Site not responding. Last check: )
		The air or other gas in the high vacuum part of the pump (6) is forced to move along with the high speed oil vapour in the different cascade levels and leaves the pump on the low-vacuum side of the pump (8).
		Since the heating is basis of the ODP pumping operation, if the pump is still cold some time after it having been switches on (~ 10 minutes) the pump is not working.
		A classical accident with the ODP is the backflow of air through the pump (from the low vacuum side (8)) that may then lead to a massive oil contamination of the high-vacuum side (6) of the equipment, in our case, the electron microscope.
	www.cbem.ic.ac.uk /EM_Faculty/Equipment/Oil_Diffusion_Pump.htm (337 words)

	Myers-Vacuum
		Torr range) vapor pump designed for heavy gas load applications such as in vacuum distillation, evaporation, vacuum arc melting, freeze drying, impregnation and casting of metals.
		The compressed gas is then passed on to the ejector stage in the forearm of the pump.
		Pump has four (4) 500-watt cartridge immersion heaters which insert into wells for simplified maintenance.
	www.myers-vacuum.com /pump.shtml (274 words)

	Chapter 7 Writing Rate Laws for Translocation Processes
		Diffusion is a special case of passive movement in a chemical field.
		To apply Fick's law to diffusion through a cell membrane of finite thickness one must satisfy two assumptions: 1) that the membrane thickness is small and 2) that the inside and outside compartments are well mixed.
		The term pump is generally restricted to those membrane proteins that carry out active transport (that is, transport against a concentration gradient) and which do so at the direct expense of ATP or some other high energy phosphate.
	www.bioinformaticsservices.com /bis/resources/cybertext/chapter7.html (2297 words)

	Vacuum Pump Oils & Vacuum Pump Fluids - TMC Industries Inc.
		The grades for rotary vane pumps are 1506, 1514 and 1525.
		Grades are H-190, having the higher viscosity for rotary piston pumps, and H-100, a lower viscosity for rotary vane pumps.
		This fluid is designed for use in all types of mechanical vacuum pumps and is classified as a general purpose mechanical pump fluid.
	www.tmcindustries.com /vac.html (439 words)

	Changing Diffusion Pump Oil
		Caution: Be certain diffusion pump is not hot or under vacuum 1.
		Support pump so that when only one nut is left you do not torque it.
		Remount the pump to the evaporator and reconnect water and electrical.
	mitghmr.spd.louisville.edu /lutz/resources/sops/sop32.html (498 words)

	Diffusion Pump offers half-power energy-saving mode., BOC Edwards
		The pump has a machined cast aluminium interior for exceptional stability during operation, and a stainless steel body to prevent corrosion and ensure cleanliness.
		The new pump also features a sight glass as standard equipment which enables operators to easily check the oil level of the pump without disturbing the integrity of the vacuum system.
		BOC Edwards invented the concept of the oil-free 'dry' vacuum pump and now markets a range of dry pumps using claw, roots, scroll and combined mechanisms for a wide range of vacuum and pressure applications.
	news.thomasnet.com /fullstory/485768/45 (1094 words)

	Oops, pump oil backed up into the diffusion pump.
		I don't have a stop cock between the diffusion pump and mechanical pump, only the main stopcock which I closed before shutting down.
		It was fun to watch the diffusion pump outgass and watch the guage jump a bit when a bubble would work out of the oil and the little boiling fits it had.
		One thing, the mechanical pump was pretty noisy when I first started it but as the pump warmed and the vacuum droped below 20 microns, the pump ran very quietly.
	www.neonshop.com /neontech/index.cgi?noframes;read=13960 (610 words)

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