Troubleshooting a Leaking Vacuum Rig¶
General Information¶
If the vacuum rig is not pulling below 100 mT, there could be a leak or moisture in the equipment being evacuated, there could be a leak in the test rig, the vacuum pump may have excess moisture, the vacuum pump may be low in oil, or the vacuum transducer may be out of calibration.
Troubleshooting the Manifold¶
Before you , ensure the manifold has been verified (See Vacuum Rig Verification).
If the manifold passes the verification, proceed with troubleshooting the part for a leak or moisture.
If the manifold does not pass the verification and nothing has been disconnected from the manifold, such as fittings or KF clamps, it is very likely that there is moisture in the manifold. The moisture will likely be in the Supply Helium Line or the Return Helium Line. You can isolate the lines with their corresponding valves to see if the vacuum level drops, allowing you to identify which line has moisture. To remove the moisture, pull a vacuum on the manifold with the ballast open on the vacuum pump. Removing the moisture can take a few hours, but you will see the vacuum level drop slowly on the bullseye. If the manifold does not continue to drop, there might be a leak somewhere.
If a component, such as the pressure transducer, was recently removed, it is likely that there is a leak. Ensure that all fittings and KF clamps were tightened. You can also close the Vacuum Transducer Isolation Valve and the Main Vacuum Valve, to protect the pressure transducer and the vacuum pump, and pressurize the manifold with helium and use the hand held sniffer to look for leaks.
Troubleshooting a Leak¶
If a component (heat exchanger or oil separator) was recently replaced, ensure that all connections were tightened. One can also install aeroquip caps to ensure the aeroquips are not leaking. If you see the vacuum level start to drop, then you have found your leak.
If nothing was replaced recently, pressurize the part to 300 PSI or 0.5 MPa and leak check the part at all the common leak points. If no leaks are found, then leak check all fittings and brazing joints. Check the heat exchangers water lines to ensure it is not breached.
If the leak is found, fix and evacuate the unit again. If no leak is found, then there is likely moisture in the part.
Troubleshooting Moisture¶
Moisture tends to be an issue when parts are left open to the atmosphere and oil absorbs the moisture. It is also an issue if a component was just replaced and it came from a unit that had a breached headexchanger or was left exposed to the atmosphere.
Leave the part pulling vacuum with the balast open on the vacuum pump. If there is moisture in the part, you will see the vacuum slowly drop and sometimes jump up and down as moisture evaporates and is removed. Removing moisture from parts can take a long time. Taking hours to pull down. If a component was replaced and it introduced moisture, it is sometimes best to replace the component again.
It is critical that the unit is leak-checked first to prevent damage to the vacuum pump from pulling vacuum on a leaking part.