These connectors, with pin counts from two up to several dozen, are ubiquitous in aviation and other industries - notably their increasing use for automotive, truck other transportation and heavy machinery. Computerized systems and other electric systems are becoming more complex, especially in the Electric Vehicle industry.

 

Cannon plugs with fluorosilicone elastomer O-ring seals are vulnerable to swelling due to solvents, including isopropanol. A connector which is sealed immediately after treating with Stabilant 22A would retain enough isopropyl alcohol to swell the seal, up to 6%. Reassembly would then put extra force on the seal, distorting it. Once the solvent dissipates and the elastomer shrinks, leaks can result.

 

The need to avoid this suggests that Stabilant 22 concentrate is preferred when reassembly of connectors must be done on a tight schedule – not allowing the drying time required (30+ minutes). This time vs. convenience trade-off also applies when alcohol is used for initial cleaning of the connectors.

 

In order to provide a solution that avoids this, testing was done to determine a level of isopropanol dilution which would not cause a swelling problem, while retaining the application convenience of a thinned mixture.

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It was determined that a 7% by volume dilution was satisfactory. This can be achieved by adding 7 parts of isopropanol (99% isopropyl alcohol is readily available) to 93 parts of Stabilant 22 concentrate. There is sufficient air space in a bottle of the concentrate to permit this. For example, if you have a 15mL bottle of Stabilant 22 on hand, just add 1.1mL of the isopropanol and mix well.

 

Alternately, by special order, we can supply a 7% isopropanol-diluted material under the designation Stabilant 22P. The Safety Data Sheets for Stabilant 22 & 22A will cover this type of material with regard to applicable precautions. Data such as viscosity and specific gravity naturally vary with the dilution as well as temperature, and users should conduct their own tests for all such products.

 

Please note that when doing this in-house, the bottle should be over-labelled as containing 7% isopropanol. Service departments, whether in aviation, auto service, or other industries, will need to adhere to their own set of regulations and manufacturers’ specifications for the equipment at hand