The owner or operator shall limit injection pressure to the lesser of:

(a) A value which will not exceed the operating requirements of § 144.28(f)(3)(i); or

(b) A value for well head pressure calculated by using the following formula:

Pm = (0.8 ? 0.433 Sg) dwhere:Pm = injection pressure at the well head in pounds per square inchSg = specific gravity of injected fluid (unitless)d = injection depth in feet.[49 FR 45308, Nov. 15, 1984]