A carbon dioxide cartridge is triggered when a lance with a piercing tip punctures its burst disc. The cartridge has a cap that has an outlet and a passage for the lance and puncturing tip to travel. The lance is pushed into the burst disc when a heat expanding substance which is stored hermetically the cap in such a way that the only direction to expand is to displace and push the lance right into the burst disc. Once the burst disc is pierced, the cartridge empties its contents quickly out the outlet. In at least one embodiment the cartridge and the cap are attached by screw threads.