§ 7  TYPE OF PROTECTION REQUIRED.
   (A)   The type of protection required under § 6 of this appendix shall depend on the degree of hazard which exists as follows:
      (1)   An approved fixed proper air gap separation shall be installed where the public water supply system may be contaminated with substances that could cause a severe health hazard.
      (2)   An approved fixed proper air gap separation or an approved reduced pressure principle backflow prevention device shall be installed where the public water supply system may be contaminated with a substance that could cause a system or health hazard.
      (3)   An approved fixed proper air gap separation or an approved reduced pressure principle backflow prevention device shall be installed where the public water supply system may be polluted with substances that could cause a pollution hazard not dangerous to health.
   (B)   The type of protection required under § 6(B)(4) of this appendix shall be an approved fixed proper air gap separation or an approved reduced pressure principle backflow prevention device.
   (C)   Where a public water supply or an auxiliary water supply is used for a fire protection system, reduced pressure principle backflow preventers shall be installed on fire safety systems connected to the public water supply when:
      (1)   The fire safety system contains antifreeze, fire retardant or other chemicals.
      (2)   Water is pumped into the system from another source.
      (3)   Water flows by gravity from a non-potable source, or water can be pumped into the fire safety system from any other source.
      (4)   There is a connection whereby another source can be connected to the fire safety system.