Wooden taps suitable for use in barrels. 
 
These barrel taps are  tapered along their length. They are fitted by simply drilling a  suitably sized hole in the barrel and hammering the tap in. If the seal  is not initially completely watertight it will become so after soaking.  
 
By filling the barrel with water to just above the tap level, the tap  and the barrel wood around it will swell and form a seal. This may take  several hours.
A hole diameter of 25mm to 32mm is suitable for fitting the 7" tap  and 30mm to 34mm is suitable for 8" wooden taps. A 38mm to 44mm diameter  hole is suitable for fitting a 10" tap.