Vacuum Technology and Vacuum Design Handbook for Accelerator ...

option. This is where add on vacuum equipment doesn’t change the original base vacuum of the
system it is connected to.
3.14 Inspection
All parts should be cleaned prior to inspection. This doesn’t need to be the final clean but enough to
ensure all welds and surfaces can be clearly inspected. Welds must be checked for pits and
alignment along the weld lines and seals must be checked for surface finishes. All crucial
dimensional must be checked. It is recommended that any non-complying findings are
photographed and documented in the project file. All non-complying parts should be reworked
rather than patched up.
3.15 Certification
As most vacuum vessels and equipment in the accelerator area fall within Hazard Level E of AS
4343-2005, certification is a local process. For large measurement vacuum vessels, results from the
inspection and leak testing will be recorded on the engineering drawing and registered in the local
accelerator register and/or ANSTO drawing register as appropriate.
3.16 Documentation
For all large measurement chambers requiring any level of design calculations, design documents
must be kept with project files.
3.17 Maintaining
Vacuum chambers and beam lines do not require high levels of maintenance other than a general
periodic clean and occasional seal replacement. Vacuum fittings and devices will have their own
level of maintenance so access to these components must not be difficult.
The design must be easy to maintain especially moving parts, sliding or rotating seal and other parts
in the vacuum space that may wear. Also vacuum pumping systems that may be mounted under or
near the vacuum chambers. Generally any part that will require any level of routine maintenance
must be accessible without the need for a major disassembly.
Vacuum pumping systems other than oil free systems, connected onto beam lines and chambers
must include suitable oil traps between the backing and high vacuum pumps and where mist filters
on all exhausts.
Some high vacuum gauges will require periodic cleaning. On ANTARES high vacuum cold cathode
gauges are scheduled for cleaning every 12-18 months or max 3 years for difficult to service or less
crucial instrument locations. Otherwise gauges will be cleaned on demand within the periods.
4. Performance and Operations
4.1 Ultimate Vacuum
The ultimate vacuum is the maximum vacuum or lowest pressure the vacuum equipment typically
reached after 3-5 days of uninterrupted pumping. This is a benchmark value which is used to assess
the long term quality of the vacuum system. It is sometimes referred to as the base vacuum or static
vacuum.
Generally, vacuums in the beam lines and chambers are well within the high vacuum range.
Vacuums lower than this range will indicate a higher than normal gas load, a failing seal or a pump
malfunction. On the accelerators the two main types of high vacuum pumps are turbomolecular and
cryogenic pumps. For a system designed for high vacuum or better with no leaks and low
outgassing then vacuums better than 4 x 10 -6 Pa should be readily achieved.
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