Answer the following questions
1. Using the nomogram and charts (FIGURES 1 and 2) on pages 4 and 5, determine the diameter of a suitable air main for the distribution of 6 m3 min–1 FAD. System pressure is 6 bar, the length of the pipe run is 175 metres, and a maximum pressure drop of 0.3 bar is allowed. The distribution main must also include the following : • 4 bends (r = 2d) • 2 elbow fittings • 6 tee connectors • 2 diaphragm valves.
2. Describe the relevant advantages and disadvantages of using steel, copper or plastic pipe for a distribution main.
3. What problems may occur if a pipe is specified : • larger • smaller than the optimum value?
4. A compressor delivers 300 s–1 of free air into a pipe at a pressure of 6 bar gauge. Using the pressure drop formula: calculate the minimum diameter of pipe if the pressure drop in a system is to be limited to 0.3 bar when is delivered through a pipe of equivalent length 160 m . pressure drop = 800 2 5 31 lQ Rd . 2 Teesside University Open Learning (Engineering) © Teesside University 2011 5. 5. Explain the difference in operation between a ‘macro’ and a ‘micro’ oil mist lubricator. State where you would use a ‘micro’ in preference to a ‘macro’ lubricator.
6. List four possible causes of overheating on a multi-stage reciprocating compressor.
7. Produce a system monitoring chart that could be used by a machine operator to maintain a daily record of hydraulic system performance details. 8. State the precautions to be taken when changing the fluid in a hydraulic system from a mineral oil based hydraulic fluid to a fire resistant fluid. 3 Teesside University Open Learning (Engineering) © Teesside University 2011