stopcock outside not turning off

[JohnD]

you want air to get into the test jar

you are trying to produce conditions that encourage rust

if the inhibitor prevents it, then you know it is working.

 

[steved101]

Corrosion inhibitor only protects against electrolytic corrosion though doesn't it, as you said metals rusting metals, ie steel being rusted. - not against affects of air being drawn down the vent (air getting in) or fresh water constantly getting in (pumping over)???

 

[JohnD]

you can buy an inhibitor-strength test kit

but before they were invented, the makers of inhibitor chemicals used to recommend the nail-in-the-jar technique.,

It's cheap and easy.