From: roger@hayter.org   
      
   On 29 May 2024 at 18:56:33 BST, "peter@easthope.ca"  wrote:   
      
   > In article , ehsjr   
   >  wrote:   
   >> The only difference I can see is the SH-12 is for nitrogen, the   
   >> SH-16 is for air.   
   >   
   > Understood.  One is marked "Air" and the other "N2".   
   >   
   > A few microns or thousands of an inch can block interchangeability.   
   > Obvious when fitting parts; not in photographs. Fitting a UNC nut to a   
   > UNF screw is a more extreme example.   
   >   
   > Thx,                    ... P.   
      
   One reason for labelling them and keeping them separate is that the oxygen one   
   has to be kept free of inflammable lubricants etc.   
      
   --   
      
   Roger Hayter   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)