Gas locks and seal-off fittings

In many cases it is desirable not only to be able to seal off gas-filled or evacuated vessels, but also to be in a position to check the pressure or the vacuum in these vessels at some later time and to post-evacuate or supplement or exchange the gas filling. 

The pressures measured in vacuum technology today cover a range from 1013 mbar to 10 mbar, i.e. over 15 orders of magnitude. The enormous dynamics involved here can be shown through an analogy analysis of vacuum pressure measurement and length measurement, as depicted in Table 3.1. 

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