Radice RMTA shaft seal vent hose ID

[MagicalArmchair]

Hello all, I’ve fitted the Radice dripless shaft seal last weekend, all I need to do is fit the vent pipe. Does anyone know what the vent pipes internal diameter should be?

 

[MagicalArmchair]

If anyone happens to come this way looking for the answer to the above, I used a pipe with a 10mm ID and whilst it was a tight fit, it wiggled on there nicely!