AIR AND GAS COMPRESSORS AND VACUUM SYSTEMS Estimating the Cost of Air Leaks in Compressed-Air Systems Selecting an Air Motor for a Known Application Air-Compressor Cooling-System Choice for Maximum Coolant Economy Economics of Air-Compressor Inlet Location Power Input Required by Centrifugal Compressor Compressor Selection for CompressedAir Systems Sizing Compressed-Air System Components Compressed-Air Receiver Size and Pump-Up Time Vacuum-System Pump-Down Time. | Source HANDBOOK OF MECHANICAL ENGINEERING CALCULATIONS __SECTION 9 AIR AND GAS COMPRESSORS AND VACUUM SYSTEMS Estimating the Cost of Air Leaks in Compressed-Air Systems Selecting an Air Motor for a Known Application Air-Compressor Cooling-System Choice for Maximum Coolant Economy Economics of Air-Compressor Inlet Location Power Input Required by Centrifugal Compressor Compressor Selection for Compressed-Air Systems Sizing Compressed-Air System Components Compressed-Air Receiver Size and Pump-Up Time Vacuum-System Pump-Down Time Vacuum-Pump Selection for High- Vacuum Systems Vacuum-System Pumping Speed and Pipe Size Determining Air Leakage in Vacuum Systems by Calculation Checking the Vacuum Rating of a Storage Vessel Sizing Rupture Disks for Gases and Liquids Determining Airflow in Pipes Valves and Fittings System Economics and Design Strategies ESTIMATING THE COST OF AIR LEAKS IN COMPRESSED-AIR SYSTEMS 1 Find the cost of compressed air leaking through a diameter hole in a pipe main of a typical industrial air piping system Fig. 1 to the atmosphere at sea level when the air pressure in the pipe is 10 lb in2 gage kPa the plant Fig. 2 operates 7500 h yr air temperature is 70 F C and the cost of compressed air is per 1000 ft3 m3 . What is the cost of the leaking air when the pipe pressure is 50 lb in2 gage kPa and the other variables are the same as given above Calculation Procedure 1. Find the volume of air discharged to the atmosphere Air flowing through an orifice or nozzle attains a critical pressure of times the inlet or initial pressure. This reduced pressure occurs at the throat or vena contracta which is the point of minimum stream diameter on the outlet side of the air flow. If the outlet or back pressure exceeds the critical pressure then the vena contracta Downloaded from Digital Engineering Library @ McGraw-Hill .
