Existing Class I and III wells authorized by rule.

Maximum injection pressure. The owner or operator shall limit injection pressure to the lessor of: (a) A value which will not exceed the operating requirements of § 144.28(f)(3) (i) or (ii) as applicable; or (b) A value for well head pressure calculated by using the following formula: Pm = (0.800-0.433 Sg)d where: Pm = injection pressure at the wellhead in pounds per square inch Sg = specific gravity of injected fluid (unitless) d = injection depth in feet. [49 FR 20197, May 11, 1984, as amended at 56 FR 41072, Aug. 19, 1991]