147.753—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
    
    
    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.