A laboratory with a facility located nearly a mile and a half above sea level recently reported that the utility of the funnelcock is compromised at his altitude. Quote "On a side note, I did find that the universal funnelcock does not work at our altitude. There is just not enough atmospheric pressure at 7400 feet to support the column of water in the bottle. Once the bottles are turned over, the water keeps flowing out of the bottle and overflows the funnelcock. It may still work with shorter bottles, however."
There have been no issues with the use of the funnelcock at lower altitudes and all equipment may be returned and refunded within 90 days without question.