Cause and solutions of mutual contamination of operation oil of oil diffusion pump and oil rotary pump
1. The oil of oil diffusion pump enters into the oil rotary pump
2. The oil of oil rotary pump enters into the oil diffusion pump
1. The oil of oil diffusion pump enters into the oil rotary pump
| Causes | Solutions and Result | ||
|---|---|---|---|
| Location | Trouble | Reason | |
| Pump main unit | ・Leakage in the boiler part | ・Operation while the cooling water is insufficient ・Operation while the oil is insufficient ・Partial oil shortage in the fractional distillation plate due to a contaminant |
・Repair leakage points |
| Cooling water system | ・Not enough Cooling water ・Wrong flow of cooling water |
・Increase in pump wall temperature ・Increase the reevaporation of oil vapor |
・Manage Cooling water |
| Load side | ・Too much gas load | ・Occurrence of leakage ・The main valve cannot be fully closed |
・Repair leakage points |
2. The oil of oil rotary pump enters into the oil diffusion pump
| Causes | Solutions and Result | ||
|---|---|---|---|
| Location | Trouble | Reason | |
| Fore pump side | Forget to vent atmospheric pressure when the oil rotary vacuum pump is stopped | The oil of the oil rotary pump moves to the oil diffusion pump side due to the pressure difference | Introduce atmosphere when the oil rotary pump is stopped |
| Continuous operation of oil rotary pump at 40Pa or less | Operation in the pressure range that oil backflow occurs frequently | Install a trap between the oil rotary pump and the oil diffusion pump | |
Causes and solutions of oil backflow and contamination of the oil diffusion pump
| Causes | Solutions and Result | ||
|---|---|---|---|
| Location | Trouble | Reason | |
| Pump main unit | ・Jet setting failure ・The oil is not fractionated |
・Deformation, Inadequate Gap | ・Correct gaps or replace heads |
| ・Too much oil | ・Reduce the amount of oil until it reaches the proper level | ||
| Baffle ・ Trap Shape |
・Not uniformly cooled due to the structure | ・Oil cannot be trapped due to uneven temperature | ・Review the structure of the baffle |
| ・Not optically blocked | ・Temperature rises due to heat inflow and oil reevaporates | ||
| Cooling trap | ・Trap temperature is not stable ・The trap is not cold ・Wrong cooling period |
・Insufficient cooling ・Heat inflow from the load side ・Not cooled when there is much backflow |
・Refill Refrigerant ・Cool the oil diffusion pump for a while after starting and stopping |
| Load side | ・Too much gas load ・High Intake pressure |
・Load exceeding the maximum pumping capacity (Leakage or outgas) |
・Eliminate the excessive gas load |
| ・The oil diffusion pump started pumping when roughing is not enough by the oil rotary pump | ・Exhaust the vacuum chamber to 40Pa, and then pump with an oil diffusion pump | ||
| Cooling water | ・Water temperature is not appropriate ・Not enough water |
・Insufficient cooling of oil diffusion pump wall | ・Set the appropriate water temperature ・Add water until an appropriate amount |
| ・Wrong flow | ・Set the inlet of cooling water the inlet side and the outlet on the exhaust side | ||
| Fore pump side | ・Not operating | ・The pressure cannot decrease below critical back pressure | ・ Ensure that the condition of the fore pump is kept below the critical back pressure |
| ・Exhaust while operating gas ballast | ・The pressure increase over critical back pressure | ・Ensure that the condition of the fore pump is kept below the critical back pressure | |