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
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.
|Pumping Capacity (L/S)||17500||20000||30000||40000||50000||60000||90000||130000|
|Critical fore-pump pressure(Pa)||40|
|Heating time( min)||≤50||≤60||≤65||≤70||≤80||≤90|
|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|
|Recommended forepump speed (L/s)||300||600||600||600||1200||1200||1200||2500|
|Net weight (kg)||375||420||670||830||990||1500||2150||2500|