Better-Bottle DryTrap air locks, are precision check valves made of an incredibly tough, proprietary PET that does not stain or impart flavors and is easily cleaned and sanitized. A polished ceramic ball rests in a tapered seat to create a one-way seal. Fermentation gases can escape easily by pushing the ball up, but air is blocked from flowing in the reverse direction.
Better-Bottle DryTraps simply plug into a Better-Bottle O-ring closures as well as standard stoppers (snugly) and DryTraps are easy to clean and reassemble.
DryTraps should not be installed until foaming has settled away from the neck of a carboy. Prior to that point, the rate at which carbon dioxide is being produced should be so rapid that a blow hose will suffice. Once fermentation has slowed and a DryTrap is installed, the rate of carbon dioxide production can be easily monitored by listening to the gentle buzz of the valve as it opens.
Alternatively, a hose can be connected to the outlet of the DryTrap and the free end occasionally submerged in container of water to observe the rate of bubbling.
To quickly assess the fermentation rate in large numbers of bottles at a glance, consider hanging a zipper, sandwich bag, filled with some water, on each dry trap. Pierce a hole through the edge of a bag, just below the zipper and push the outlet of the DryTraps through the hole. The zipper makes it easy to position, fill, and close a bag.