A failsafe system for a medical fluid procedure, comprising a medical fluid processing apparatus comprising a sealer and a programmable controller driven by software, wherein the programmable controller is programmed to recognize a failure event from input from hardware components of the medical fluid processing apparatus. The system also comprises a disposable fluid circuit configured to associate with the medical fluid processing apparatus and comprising a tubing segment configured to fit within the sealer. The programmable controller is configured to seal the tubing segment by activating the sealer surrounding the tubing segment in response to an occurrence of the failure event.