Q = What is the diameter of the 2 outer (electrode) glass tubes?
A = The internal diameter (ID) of the 2 outer glass tubes is 14.5mm. The outer diameter (OD) of the tubes is 17mm. They will accept both 13mm and 15mm bungs but bear in mind that a stopper with an electrode in may have a slightly wider diameter.
Q = What are the dimensions of the Hoffman Voltameter?
A = Total length (height) 62cm. Gas collection tubes (electrode tubes) 50ml capacity each.