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Equipment/High Vacuum Station: Difference between revisions
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Updated information on diffusion pump specification and fluid options
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===Diffusion pump=== | ===Diffusion pump=== | ||
The diffusion pump | The diffusion pump donated by James Collings is an Edwards E04. It's ultimate vacuum capacity is 5x10^-7 mbar (0.0000005mbar) with a pumping speed of air of ISO 600l/s^-1 (hydrogen: ISO 800l/s^-1). It has a maximum starting pressure of 300 mbar and requires a backing pump capable of keeping the backing pressure at about 1mbar (assuming DC704EU pump fluid). | ||
Recommended backing pumps are the Edwards RV8 or RV12. The RV8 has a displacement of 9.7m^3h^-1 and an ultimate pressure of 2x10^-3. The RV12 is advised for fast roughing, has a displacement of 14.2m^3/h^-1 and an ultimate pressure of 2x10^-3 mbar. | |||
The diff pump operates by boiling a special silicone oil to vapour and forcing it out through special baffles onto a water-cooled jacket. There the oil re-condenses and trickles down along with any air molecules it grabbed on the way. It sets up a pressure differential across the pump, where at its exist it should be at a high enough pressure the backing pump will be able to pump it away. | The diff pump operates by boiling a special silicone oil to vapour and forcing it out through special baffles onto a water-cooled jacket. There the oil re-condenses and trickles down along with any air molecules it grabbed on the way. It sets up a pressure differential across the pump, where at its exist it should be at a high enough pressure the backing pump will be able to pump it away. | ||
Current prices for the compatible fluids (as of October 6th, 2011, direct from Edwards Vacuum) are; | |||
* DC702 fluid - £117, 500ml (critical backing pressure 1.3 mbar, ultimate pressure 5x10^-6 mbar) | |||
* DC704EU fluid - £134.10, 500ml (critical backing pressure 1.0 mbar, ultimate pressure 5x10^-7 mbar) | |||
* DC705 fluid - £211.50, 500ml (critical backing pressure 0.9 mbar, ultimate pressure 5x10^-7 mbar) | |||
* Santovac 5 fluid - £852.30, 500ml (critical backing pressure 0.8 mbar, ultimate pressure 5x10^-7 mbar) | |||
* Edwards L9 fluid - Unknown price, possibly discontinued (critical backing pressure 0.9 mbar, ultimate pressure 5x10^-7 mbar) | |||
On this I would recommend DC704EU fluid. For £17 extra you can achieve a magnitude better vacuum than the absolute cheapest. The spec sheet also describes it as a good durable and general-purpose fluid. | |||
====Cold baffle==== | ====Cold baffle==== | ||
