The AFFF concentrate is then poured into the bottle. As you can see I have on safety gloves. Firecharger recommends gloves and eye protection because the AFFF concentrate can cause permanent eye damage. Once the bottle is filled to the top we attached the discharge hose and head assembly onto the bottle. Since there is an O-ring seal on the head assembly, Firecharger recommends torqueing the head to between 15 and 30 pounds, although additional torque may be required to get the plumbing to line up.