I bought a keg valve with the floating pin that is designed to let you switch between 8g bulbs and S30 cylinders. When I tried injecting 8g bulbs the gas leaked past the 'O'-ring that seals the bulb. I tried three times. I moved the floating pin to a different S30 valve (brass) and the same thing happened. I recommend biting the bullet and buying a proper pin valve. I returned the dual-purpose one for a full refund. Another supplier told me he had given up selling the valves with floating pin because they were so unreliable. The bulb does not go far enough into the valve for the 'O'-ring to seal and all the gas escapes through the bulb holder.