Symbol 0029 from ISO 7000 - Title/Meaning: Draining; emptying 
Function/description: To indicate the emptying of any vessel, or container of liquid or produce (for example, draining of oil tanks, draining ink reservoirs, emptying grain hoppers).
Own work using: iso.org/obp/graphics/grs/a119c574-52d1-479f-ad07-2c947b867b5d 200.png
Vectorization:  Mrmw