Preventive Measures of Diffusion Pump
Specific measures for eliminating oil vapor reflux in the system
(1) Increase the starting power of the diffusion pump to shorten the pressure transition zone when the mechanical pump and the diffusion pump switch.
(2) Avoiding the dangerous area of backflow (switching the transition zone) by changing the operation process of the system and using valves. For example, a high vacuum valve which can be opened at a predetermined speed can be gradually opened to ensure that the gas flow into the diffusion pump is lower than its larger exhaust volume, and that the mechanical pump pumping speed can ensure the pressure of the diffusion pump front stage, so that the diffusion pump can set up work. In this way, the transition zone can be avoided.
(3) Improve the operation technology, and adjust the heating power of the diffusion pump to a better power to avoid the phenomenon of pump oil explosion and boiling; in general, the peak value of reflux will appear during the beginning and closing of the heating process of the diffusion pump, so the high vacuum valve at the pump mouth can be used to control the avoidance of reflux.
(4) Adding liquid hydrogen cold trap or adsorption trap at the entrance of diffusion pump to capture reflux oil vapor.
(5) Selection of high-quality diffusion pump working fluid.
| 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 |
