Oil diffusion vacuum pump

What is oil diffusion vacuum pump:

The oil diffusion vacuum pump is a vacuum pump with low pressure, high speed and directional flow of oil vapor jet. The principle is that under the condition of molecular flow, gas molecules continue to diffuse into the steam flow, and the steam is taken to the pump outlet step by step to be compressed and then removed by the front pump. The pump works in high vacuum area. The oil diffusion pump has the advantages of simple structure, convenient operation and low cost per unit pumping speed. The oil diffusion pump has no mechanical moving parts, long service life, high reliability and convenient maintenance.

KT Series Oil Diffusion Pump

KT Series Oil Diffusion Pump

Oil diffusion vacuum pump is especially suitable for the process that requires rapid evacuation of large working vessels and rapid removal of large amounts of gases from treated materials during treatment. For example, vacuum metallurgy and vacuum heat treatment equipment.

Oil diffusion vacuum pump principle:

A vacuum pump that transfers gas by means of the momentum of a high-speed oil vapor jet from a nozzle. In this sense, it should be called a steam jet pump, but the inventor’s cap emphasized the process of gas diffusion into the steam flow and named the diffusion pump, has been used so far. Oil vapor is called oil diffusion pump, and mercury is called vapor diffusion pump. Because Mercury operation is troublesome and harmful to human body, it is not practical now.

When the oil vapor is ejected from the umbrella nozzle (such as stage I nozzle) at supersonic speed, the velocity increases gradually, the pressure and density decrease gradually. The exhausted gas A on the upper part of the jet diffuses into the steam jet due to the density difference and is carried to the water-cooled pump wall B by the jet. The oil pan is recycled, and the exhausted gas accumulates and compresses at B. Finally, it is carried away by the lower jet to achieve progressive compression, and finally is pumped away by the front pump.

The diffusion pump is formed by injecting oil with three stage nozzles, The oil in the diffusion pump oil pan is heated in vacuum to the boiling temperature (about 200 C), producing a large amount of oil vapor. The oil vapor is directionally and rapidly ejected from various nozzles through the diversion pipe. Because the partial pressure of the exhausted gas near the inlet of the diffusion pump is higher than that of the vapor flow, the molecule of the exhausted gas is continuously diffused into the vapor flow. Oil vapor impingement on the extracted gas molecules is driven by gas molecules moving along the direction of the vapor stream. The gas molecule touches the pump wall and reflects back, and then encounters the collision of the steam flow and re-flows along the direction of the steam flow to the pump wall. After several collisions, the gas molecule is compressed to the low vacuum end, and then the vapor stream from the lower nozzles is compressed in multiple stages, and finally pumped out by the front stage pump. The oil vapor is condensed on the cooling pump wall and then returned to the oil pan to be reheated, thus circulating.

Oil diffusion vacuum pump classification:

The new national recommended standards will be divided into K series oil diffusion pump (straight cavity pump), KT series (convex cavity pump) two series, mainly based on the shape of the pump to distinguish. In fact, the existing products on the market include KA series (straight cavity low pump), KTD series (convex cavity low return pump), KC series (wide area pump) and so on. According to the number of nozzles, there are 5, 4 and 3 grades.

Technical parameters:

Item KT-600 KT-630 KT-800 KT-900 KT-1000 KT-1200 KT-1400 KT-1600
Ultimate pressure(Pa) 5×10-5
Pumping Capacity (L/S) 17500 20000 30000 40000 50000 60000 90000 130000
Critical fore-pump pressure(Pa) 40
Backflow ratemg/(cm2·min) ≤3×10-2
Heating time( min) ≤50 ≤60 ≤65 ≤70 ≤80 ≤90
Heating Power(kw) 8~9 9~11 13-13.5 14-16 17-20 28-30 38-40 48-50
Electric Voltage(AC)V 380
Pump Oil Model KS-3
Pump Oil Volume( L) 6~7 7~8 12~14 14-15 15-16 22 38 50
Cooling water consumption(L/H) 800 850 1200 1350 1500 2600 3400 4300
Inlet dimension( mm) 600 630 800 900 1000 1200 1400 1600
Outlet dimension(mm) 150 160 200 200 300 300 320 320
Recommended forepump speed (L/s) 300 600 600 600 1200 1200 1200 2500
L(Length) 1145 1170 1520 1843 1990 2235 2556 2900
B(Width) 975 1010 1275 1283 1290 1750 1950 2100
H(Height) 1444 1275 1870 1950 2220 2465 2950 3355
Net weight (kg) 375 420 670 830 990 1500 2150 2500


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