Oil Diffusion Vacuum Pump concept

• Industry News
• 24 Nov, 2023

The diffusion pump uses a high-speed steam direct injection pump to decompose the gas at the throat of the throat. In 1915, hosted by Wolfgang Gade and using mercury vapors, they were high vacuum free molecular flows in which the movement of gaseous molecules could be better understood than conventional hydrodynamic diffusion, regimes operated pumps of the first kind. Gaid used the name Diffusion Pump because he was discovering that gas could not diffuse on the basis of steam flow, but would carry on with it the exhaust gas. However, the working principle may describe the jet pump more accurately, because diffusion plays an important role, and in other high vacuum pumps. In modern textbooks, diffusion pumps are classified as momentum transfer pumps. Diffusion pumps are widely used in industrial and research applications. Most modern diffusion pumps are used as working medium. Cecil repot discovered the possibility of silicone oil used in 1928.

KT Series Oil Diffusion Pump

Technical parameters:

Item		KT-100	KT-160		KT-200		KT-250		KT-300		KT-320		KT-400		KT-500
Ultimate pressure (Pa)		5×10-5
Pumping Capacity (L/S)		550	1800		2800		3500		4600		5000		8500		12000
Critical fore-pump pressure (Pa)		40
Backflow rate mg/(cm2·min)		≤3×10-2
Heating time ( min)		≤30	≤35				≤40						≤45
Heating Power (kw)		0.8-1	1.4-1.6		1.6-1.8		2.2-2.4		2.4-3		4~5		4~5		6~8
Electric Voltage (AC)V		220									380
Pump Oil Model		KS-3
Pump Oil Volume ( L)		0.15	0.45	0.55		1-1.4		1-1.6		1.4-1.8		3~4		4
Cooling water consumption (L/H)		180	250	300		350		400		420		500		600
Inlet dimension (mm)		100	160	200		250		300		320		400		500
Outlet dimension (mm)		32	50	65		65		80		80		100		100
Recommended forepump speed (L/s)		4	8	15		15		30		30		70		150
Dimension (mm)	L(Length)	320	420	530		473		695		725		885		1010
	B(Width)	260	315	390		450		505		525		665		815
	H(Height)	365	505	575		650		726		830		925		1165
Net weight (kg)		14	31	39		48		89		100		175		185

 

The operation of the oil diffusion pump is a low vapor pressure oil. The aim is to achieve higher vacuum (low pressure) by using positive displacement pumps than is possible. Although its use is mainly related to the use of high vacuum range (down to 10-9 millibars), today’s diffusion pump produces pressures close to 10-10 millibars when appropriate with modern fluids and accessories. To make diffusion pumps high, ultrahigh vacuum attractive is its high pumping of all gases and pumping speed per unit of low cost, speed than other types of pumps used in the same vacuum range. Diffusion pumps can not be directly discharged into the atmosphere, so the front-stage mechanical pump is usually used to maintain about 0.1 MB outlet pressure.

The high speed jet produces boiling liquid and guides the assembly by injecting steam. Inside the nozzle, the laminar flow changes to supersonic and molecular. The usual fighters are used to strengthen pumping operations. The diffusion pump uses external cooling or air flow or waterline. Due to the effect of steam jet cooling outside the diffusion pump housing, the working fluid is concentrated, recovered, and instructed to return to the boiler. Pumping gas continues to flow into the pump at increased pressure, the pump base, where the flow through the diffusion pump outlet compresses the auxiliary front-stage mechanical pump and the exhausted ambient pressure.

With the turbo molecular pump and cryogenic pump, the diffusion pump has no moving parts, so it is quite durable and reliable. They can operate in a pressure range of 10-10 to 10-2 mbar. They can only be driven by convection, resulting in very low energy efficiency.

A major drawback of the diffusion pump is the tendency to enter the vacuum chamber. The oil can contaminate the surface or interior of the rear chamber with hot wire or discharge contact may lead to carbon and silicon deposits. Due to reflux, the oil diffusion pump is not suitable for use with highly sensitive analytical equipment or other applications requiring a very clean vacuum environment, but the mercury diffusion pump may be deposited in a super-case high vacuum chamber with mercury. Usually cold traps and baffles are used to minimize reflux, although in some cases the pumping capacity is lost as a result.

The common mistake of an oil diffusion pump operation is in the hot oil contact atmosphere. If this happens, the oil will be burned and replaced. A system should always be cooled to the atmosphere before contact at room temperature.

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