Maximum injection pressure. The owner or operator shall limit injection pressure to the lesser of:
(a) A value which will not exceed the operating requirements of Sec. 144.28(f)(3) (i) or (ii) as applicable or
(b) A value for well head pressure calculated by using the following formula: Pm=(0.733 - 0.433 Sg)d where: Pm=injection pressure at the well head in pounds per square inchSg=specific gravity of inject fluid (unitless)d=injection depth in feet.