From Inches of Hg

• to Atmospheres multiply by 0.0334211
• to Bars multiply by 0.0338639
• to mm of Hg multiply by 25.4 (Torrs=1mmHg)
• to Grams/sq. cm multiply by 34.5316
• to pounds/sq. ft multiply by 70.7262

       
From Atmospheres

• to Bars multiply by 1.01325
• to mm of Hg multiply by 760
• to Grams/sq. cm multiply by 1033.23
• to Pounds/sq. inch multiply by 14.6960
• to Torrs multiply by 760
• to Ft of H2O multiply by 33.8995

All performance specifications stated, including but not limited to, pump-down rates and vacuum levels make the following assumptions:

• The Vacuum Chamber is empty.
• The Vacuum Chamber and other system components are clean and dry.
• The System is being operated at Sea Level
• The ambient temperature is 18°C +/- 2°C
• All system components, including those not supplied by Abbess, are appropriate for the system and are functioning properly.
• The specifications are not impacted by the properties of your product.

If you require performance specifications for conditions other than those listed above, it is vital that you make this known to Abbess Instruments in writing.  Generally Abbess Instruments recommends choosing chamber and pumping system qualities capable of achieving a theoretical vacuum at least an order of magnitude better than the desired operational vacuum. 

It is to be noted that a specification described as '10-5 Torr' is a range, and means the clean, empty, dry chamber system is capable of reaching some undetermined value between 1.0x10-5 and 9.9x10-5 Torr: The (clean, empty, dry) chamber is deemed compliant whether its As-Built base vacuum is 1.0x10-5 Torr or 9.9x10-5 Torr. It does not mean that the chamber is guaranteed to reach every level within that range.