"Open flame" refers to a fire that is not enclosed or contained. It is when a fire is burning in an area where it is not covered or protected, and can potentially spread easily. Full definition
Roast a jalapeno over open flame, then chop into little bits to include the seeds. (101cookbooks.com)
Do not use or store in or near open flame or heat. (vetdepot.com)
For the aerosol, also be sure to keep away from open flame, and to hold several inches from your face, eight to ten inches seems to be the general comfort zone. (thefashionablehousewife.com)