law: Petroleum Act, 1934
  6. Receptacles of dangerous petroleum to show a warning
  All receptacles containing 17[petroleum Class A] shall have a
  
  stamped, embossed, painted or printed warning, either on the receptacle itself
  
  or, where that is impracticable, displayed near the receptacle, exhibiting in
  
  conspicuous characters the words "Petrol" or "Motor
  
  Spirit", or an equivalent warning of the dangerous nature of the
  
  petroleum:
  Provided that this section shall not apply to-
  (a) any securely stopped glass, stoneware or metal receptacle of
  
  less than 18[ten liters] capacity containing 17[petroleum Class A] which is not
  
  for sale, or 
  (b) a tank incorporated in motor conveyance, or attached to an
  
  internal combustion engine, and containing petroleum intended to be used to
  
  generate motive power for the motor conveyance or engine, or 
  (c) a pipe-line for the transport of petroleum, or 
  (d) any tank which is wholly underground, or 
  (e) any class of receptacles which the Central Government may,
  
  by notification in the Official Gazette, exempt from the operation of this
  
  section.