I stole this from a thread from probrewer.com.
Here is the info on the stainless steel nail in the barrel head acting as a poor man’s MacGyver sample port:
We drill a hole using a 7/64 drill bit on the barrel head of each barrel. The hole can be drilled while the barrel is empty or even with beer in it. You just have to be ready with the nail if you are doing it with the barrel full. The hole is so small that there is no problem with losing too much beer at this point.
I have two sizes of stainless steel nails that I purchase from McMaster Carr.
1–½” 4d smooth common nail – 316 stainless steel McMaster Carr # 97990A102 2” 6d smooth common nail -316 stainless steel McMaster Carr # 97990A104
I use the smaller nail, but, I keep the larger ones around just in case a hole gets boarded out to large, it hasn’t happened yet, but, I’m just playing it safe.
I do use barrel wax sometimes (www.barrelbuilders.com) around the nail after I have pulled a sample. We have never had a nail blow out due to pressure; they are pretty snug in there.
You can pull a sample and actually have the flow stop coming out of the small hole in the head of the barrel because the barrel is not vented, but, there is no issue. It is such a small hole that you can’t harm the barrel. If anything, it makes it easier because you can control the flow by removing the bung and putting it back into place. I usually drill the hole about half way up on the barrel head.
Recently we've started to drill the barrel out after the barrel has beer in it as opposed to before. Sometimes you don't get the small hole drilled out all the way. You won't know that this is the case until there is beer in the barrel and you see that you don't even have a small stream of beer coming out of the hole.
I've also taken to the practice of having a backup nail in my pocket when I'm pulling samples just in case you drop the nail on the floor on accident.
The hole at the bottom of the head of the barrel (six o’clock if you are looking at the head of the barrel straight on) for removing beer with fruit in it is a 15/16” hole, the tubing that you use to remove the liquid and fruit is also from McMaster Carr. A Belgian beer bottle cork like we cork with fits in the 15/16” hole. Here is the part number from McMaster for the tubing:
15/16” OD tubing, McMaster Carr # 5231K944
It takes a little practice but you can removing the cork quickly and push the 15/16” tubing in the cork hole. The tubing is than run down to some sort of strainer that you would need to fashion and from the strainer it is pumped to a tank.
Vinnie Cilurzo Brewer / Owner Russian River Brewing Company 725 4th St. Santa Rosa, CA 95404