The system contains a fixed displacement pump with a pressure relief valve set at 1000psi. The system operates 20 hours per day for 250 days per year. The cylinder is stalled in its fully extended position 70% of the time. When the cylinder is fully extended, 1.0 gpm leaks past its piston.
a. If the electric motor driving the pump has an efficiency of 85% and the cost of electricity is $0.10 per kW hour, find annual cost of electricity powering the system.
b. It is being considered to replace the fixed displacement pump with a pressure-compensated pump (compensator set at 1000psi) that costs $2,500 more. How long will it take for the pressure-compensted pump to pay for itself if its overall efficiency is the same as the fixed displacement pump?