The Fire Hydrant (ZF 4) safety sign has a red fire hydrant on the square shaped safety sign.
 
The fire hydrant indicates where specific fire-fighting equipment can be located and is often used in conjunction with one or a combination of the following safety signs:
Location Of Fire Fighting Sign
Location Of Fire Fighting Sign (Diagonal)
The fire hydrant 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