A carbon dioxide fobber.

Weaver, R.L., Murphy, G.A. and McInnis, T.R.

Abstract
Fobbing is induced in bottles between filling and crowning to expel air. This has been done by bottle knockers, by transducers which are vibrating plates contacting the bottles and by water jetting. The transducers alone have been retained in conjunction with carbon dioxide fobbers. The carbon dioxide fobber is a curved stainless steel tube 6 in long, of 1/2 in diam. pierced with 11 holes of 0.0465 in. This protrudes as far as possible under the crowners. It is supplied with carbon dioxide at 6 psi controlled by a valve when the filler stops and has been used with the transducer at lower output so that the foam just reaches the crown ring. The carbon dioxide jets break the top of the foam, release any air in the bubbles and replace it by carbon dioxide. This method of fobbing has been used on lines running at 450 and 700 bottles per minute. Air content of 12 oz bottles has been decreased by 0.1 to 0.2 ml and the fill height increased by 0.025 oz with less variation between bottles. Since the bottle knockers have been removed breakage is reduced and this combined with the more accurate fobbing by carbon dioxide has reduced beer loss by 10%.
Keywords: air carbon dioxide equipment filling fobbing headspace