Expert: Kenton Scott - 5/20/2007

Question
I recently purchased a 1977 Claude Gordon Benge (sn 22840)  The valves do not have the serial number stamped on them, and I was wondering why, since some of the older models do have them stamped.  Is it because of the change to monel pistons?  It does have "CG" stamped on the second valve.  

Answer
I don't know specifically in Benge's case, why they would have changed that convention.  When manufacturing was less automated, the makers would mark the parts of the valve simply to keep the parts together.  They were hand fitted and they didn't want them to get mixed up.  

The valves were made by one department and were then sent, often in long strings to the assembly department with 2 digit numbers on the individual valves.  Consequently, you will occasionally see an instrument with valves that are out of sequence because one in the set was bad, so they just took a valve from the next set.

In Benge's case, it may be that they moved to a more automated production method and found the numbering unnecessary.   . . . or it may have something else . . .