Continuous positive airway (CPAP) machines are allowed for airline travel, but the device will need to pass through the security checkpoint. Following the right procedure will help you keep your device safe and sanitary, and board the aeroplane on time.
Pack your CPAP in a separate carrying case; do not put it in your checked luggage.
Consult your airline about how early you should arrive at the airport. Tell them that you will be bringing a CPAP.
Remove the CPAP from its case and put it in the clear plastic bag when you get in the security checkpoint line. The plastic bag will keep your device clean when you put it in the bin. You can leave the face mask and tubing in the carrying case.
Place the CPAP in the bin for x-ray screening.
Tell the security agent that you have a CPAP.
In addition to x-ray screening, the agent will have to do a visual inspection and explosive trace detection (ETD) sampling. The agent will change gloves before removing your device from the bag for visual inspection if you request it. The agent will also clean the table where the ETD is done and change the ETD media before testing your CPAP at your request. These steps can help keep your device clean and hygienic.
Security is taken very seriously at airports, so don't make any "jokes" about the purpose of your device.