Flammable liquids shall be drawn from or transferred into vessels, containers, or portable tanks within a building:
- only through a closed piping system,
- from safety cans,
- by means of a device drawing through the top, or
- from a container or portable tanks by gravity through an approved self-closing valve.
Transferring by means of air pressure on the container or portable tanks shall be prohibited.
So what is approved self-closing valve?