Jokari Fizz-Keeper Pump Cap

Approximately how many times do you have to pump these? I removed the ring on the 2 ltr bottle, and after 30 pumps, still no pressure. defective?

The pump only seems to pump air at the very end of the stroke—like the last 3mm. Is this normal?

Is it good for the internal part of the cap to be in contact with the liquid inside the bottle? Like when you store the bottle horizontally.

Why is there a warning label that says it contains chemicals that have been known to cause cancer? Which chemical is in this device?