The Sprinkler Stop Valve (ZF6) safety sign has a red stop valve on the square shaped safety sign.
 
The sign indicates where the sprinkler stop valve can be located and is often used in conjunction with one of the following safety signs:
Location Of Fire Fighting Sign
Location Of Fire Fighting Sign (Diagonal)
The sprinkler stop valve safety sign is also available as a Photoluminescent (glow in the dark) sign as a single safety sign or as a combination of more than one safety sign.
Refer to the Photoluminescent section for various combination options. 
SABS standard safety sign