The bit currently in use has three 1%2-in. nozzles. The driller has recorded that when the 10-lbm/gal mud is pumped at a rate of 500 gal/min, a pump pressure of 3,000 psig is observed, and when the pump is slowed to a rate of 250 gal/min, a pump pressure of 800 psi is observed. The pump is rated at 1,000 hp and has an overall efficiency of 0.9. The minimum flow rate to lift the cuttings is 240 gal/min. The maximum allowable surface pressure is 3,000 psi. a. Determine the proper pump operating condi- tions and bit nozzle sizes for maximum bit horsepower for the next bit run. Answer: q=514 gal/min; A, 0.345. b. What bit horsepower will be obtained at the conditions selected? Answer: 611 hp. c. What impact force will be obtained at the con- ditions selected? Answer: 1,270 lbf. d. What nozzle velocity will be obtained at the conditions selected? Answer: 477 ft/s.