Lenore:
 
Thank you for sharing your question with the bulletin board.   It is a common misconception that the pipeline has to be disconnected as part of the FDA pre-use check.  The O2 pipeline only needs to be disconnected if the O2 cylinder pressure gauge is already reading a pressure of 1,000 psig or more before starting the pre-use check.  
 
Remember that in the 1993 FDA pre-use check the purpose of disconnecting the O2 pipeline is to depressurize the O2 cylinder pressure gauge.  As an extreme example, if the O2 cylinder pressure gauge is already reading zero when starting the pre-use check, it is a waste of time and effort to disconnect the O2 pipeline to bleed down the O2 cylinder pressure gauge because it is already depressurized.  
 
Another misconception is that the non-O2 tanks have to be checked.  In the 1993 FDA pre-use check, only the O2 tank pressure has to be checked to be above 1,000 psig.  
 
See http://vam.anest.ufl.edu/FDApreusecheck.pdf for the official version of the 1993 FDA pre-use check.  
 
A version of the 1993 FDA pre-use check that incorporates my edits/comments is available at http://vam.anest.ufl.edu/fdacheckout.html  
 
Hope this helps,
Sem Lampotang

Lenore:
 
Step 2a of the 1993 FDA checklist states:
"Open O2 cylinder and verify at least half full (1000 psi)"
 
Two comments on the technique you were taught:  "disconnect hoses from the pipeline source, open and close the tanks on the machine, and then "bleed" the tanks by turning up the flows until the tank gauges read zero."  
 
1.  It seems to imply that the air and N2O tanks also need to be checked.  That is not the case - Step 2a makes reference to checking only the O2 cylinder.  
 
2.  The technique you mentioned also assumes that the previous person who used the machine followed the prescribed technique and that therefore the O2 cylinder pressure gauge already reads zero.  What happens if the previous person (a) did not follow the same technique or (b) did not check the machine or (c) used the cylinder all of which could result in the O2 cylinder pressure gauge reading a non-zero value?  
 
In the technique you describe, it would be safer to bleed the O2 cylinder pressure gauge down to zero BEFORE opening and closing the tank and then bleed them again to zero afterwards as a COURTESY to the next person who will use the machine.  Let me illustrate by the following scenario.
 
a.  The O2 cylinder gauge is not depressurized after it has been opened for a pre-use check and reads 2,000 psi.  
b.  The O2 cylinder from the machine is borrowed and when returned it has only 200 psi left in it.  Using the technique you describe, if there is no O2 outflow with the O2 pipeline disconnected, the O2 cylinder pressure gauge will incorrectly continue to read 2,000 psig instead of the actual pressure in the O2 cylinder.  
 
I realize this is confusing and dependent on the practice at each institution.  Please let me know if you have further questions.  I'll be happy to answer them.  Thanks.
 
Sem
 
 
 

Thank you, Dr. Lampotang!