A typical small chemical hand warmer packet [that employs an oxidation process] absorbs about 1.25 grams of O². (This was calculated from weighing on a lab scale.)
So at 32 grams per mole for O² or 22.4 liters at standard temperature and pressure that is 32/22.4=1.4286 grams of O² per liter.
Assuming O² in the air at 20%, a 5 gallon bucket (18.92 liters) would contain 1.4286 x 18.92 x 20% = 5.4 grams of O²
It would take roughly 4 packets to absorb the O² in a 5 gallon HDPE bucket at 1.25 grams per packet if the bucket contained only air.
Therefore, using 1 or 2 packets to a 5 gallon pail filled with wheat, they should absorb all of the O² in the bucket. Note a typical HDPE plastic bucket will [gradually] pass some O² so ideally a heat-sealed Mylar bucket liner should also be used. Regards, – Jeff H.
JWR Replies: I describe mylar bucket liners and both the O² absorbing packet method and the dry ice (CO2 displacement) method of packing food grade buckets in the Rawles Gets You Ready Preparedness Course. This course would be a good gift to put in the hands of any relatives or friends who are interested in prepping. It is now priced at less than $20.