Today I discovered that Lauter-Humana evidently decided to use copper inserts for the trackerbar tubing where it passes through the valve board. This board, which is 1-1/16" hardwood, is devilishly evil to lead tubing. Although I'm no chemist, I believe the acids in the wood, coupled with the air passing through the tubes, 'oxidized' them fairly rapidly (comparatively speaking). Every Lauter I've ever worked on has weak or completely deteriorated tubing at this particular point. Sadly speaking, the rest of the lead tubing is usually in really good shape, and it's kind of a shame that the best way to remedy the situation is to replace all of the tubing.
In this particular unit, one inch pieces of copper tubing were 'soldered' to the end of each lead tube. The then copper/lead piece was secured (glued) into the valve board such that 3/4" of copper tubing stuck out the 'valve block' side. It's interesting to note that about 60% of the nipples were still intact after removing the existing valve tubing. However, a previous technician (or perhaps even the factory) had used thick clear (or maybe yellow) vinyl tubing, and verdigris (chemical corrosion) had taken it's toll. Many of the copper pieces either came loose from the lead or broke at the board when the vinyl tubing (which was rock hard) was removed.
In the picture which I've sent along, you can also see that as the years passed, the corrosion got so advanced that the end of each tube is almost completely closed. Surely, this played a major part in the deteriorating performance of this machine. Although it's not surprising to me, the valves and pneumatics are still in very good working order, and they are original. Further, I can't disagree with the owner, who has chosen not to have them rebuilt at this time.
Another thing I want to report is that I found a very quick way to remove the lead tubing at the trackerbar. As many of you know, the manufacture typically used a sealer (or an adhesive) that is rock hard. Having tried chipping and dissolving (with chemicals), today I tried heat. After scoring each lead tube, where it's connected to the brass nipple, I focused a two-inch flame (from a standard propane torch) on the central portion of the sealer... like in the middle of the stuff. While I did that, I tugged on the lead tubing firmly. Within seconds, the sealer softened and the tube came right off. Moving rapidly onward because the sealer next to the one just removed was still fairly soft, I was able to remove all of the tubes on one side in less than three minutes.
Naturally, I had the trackerbar secured in a vice with rubber covers. And fearing I might damage the rubber, I couldn't do all 44 tubes in one shot. However, the far end was cool enough by the time I got 'down to the bottom' that I simply flipped the bar over and finished the first side. The second side went even faster because the sealer was still a little soft. Total time to 'strip the bar clean' was 5 minutes -- a record time for me! (And substantially less time than it's taken to write this posting... ;-)
While I was removing the tubing, I took a series of pictures which I'll eventually use in yet another web page about retubing the Lauter-Humana trackerbar. I'll also be taking more pictures when I install the new tubing because it's going to be a little tricky due to all the 'bends' at the valve board.