Think & Tinker Instrument Prototyping

Think & Tinker, Ltd.
P.O. Box 1606, Palmer Lake, CO 80133
Tel: (719) 488-9640, Fax: (866) 453-8473
Sales: Sales@thinktink.com, Support: Support@thinktink.com

Think
&
Tinker
Ltd.

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Peroxy-Sulfuric Etching Module
Maintenance/Leaky Connection

Maintenance
There is not a lot that can go wrong with the etching cell or mounting cart. Sounds like famous last words to me.

Fixing a leaky connection
Based on past experience, it is very unlikely that you will ever have to repair a leak in this system. All of the joints and fittings are sealed with a specially formulated liquid vinyl (Liquid Duct Tape®, LDT®) that stays flexible and resists the corrosive effects of the etchant. Nonetheless, it is beneficial to take a look at how each threaded connection is made so that you can repair or replace a fitting if necessary.

For the sake of demonstration, assume that one of the threaded connections has sprung a leak. Put on your safety glasses and chemical resistant gloves.

Applying LDT to a female fitting
Fig. 6

If necessary, drain the tank into clean carboys (or a single drum large enough to hold the entire bath).
Disassemble the leaking connection and clean off any old LDT that might be clinging to the threads.
Apply a liberal bead of LDT® around the top 2 or 3 female threads in the coupling.
If you are repairing a fitting that is molded to the tank (referred to as a molded boss connection), make sure that the stainless steel screw clamp is initially only finger tight. This will allow the boss to expand as the male part is threaded into place and the LDT® to flow into any irregularities in the threads that might have caused the leak.

Assembled welded boss-fitting
Fig. 7

Now, apply a liberal bead of LDT® to the starting threads of the male fitting.
Thread the fittings together and tighten hand tight.
Using a spanner (crescent wrench), tighten the fittings 1 full turn.
If working on a molded tank fitting, tighten the screw clamp until it is pressing firmly against the wall of the molded boss. This will keep the molded coupling from spreading or distorting over time, and will help maintain a tight, leak-proof seal.
Let the seal set for at least 2 hours to allow the liquid vinyl to dry.
After the exterior vinyl is dry, the fitting is ready to be returned to service.

"What the heck", you might ask "is this all about?" Well, I´m glad you asked.

When you thread the two fittings together, the two bands of LDT® (one in the female threads, one on the male side) will be pushed ahead of the threads (inside and outside of the fitting) and form rings of vinyl on either end of the seal. Meanwhile, some of the LDT® is smeared along the entire length of the threads inside the sealed area to fill in any pits or scratches. When the LDT® dries, you end up with a VERY secure seal that can be easily taken apart later if modifications or further repairs are necessary. Experience has shown that threaded couplings sealed using this technique will provide many years of leak-free service.

Established 1990

On the web since 1994