Research purposes all calculations to be shown please
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 l s-1 of free air into a pipe at a pressure of 6 bar gauge. Using the pressure drop formula:
pressure drop = 800lQ2/Rd5.31
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.
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.
| Types of fittiing |
Equivalent pipe length in in. |
| Inner pipe diameter in mm. |
| 25 |
40 |
50 |
80 |
100 |
125 |
150 |
| Seat valve |
3-6 |
5-10 |
7-15 |
10-25 |
15-30 |
20-50 |
25-60 |
| Diaphragm valve |
1.2 |
2 |
3 |
4.5 |
6 |
8 |
10 |
| Gate valve |
0.3 |
0.5 |
0.7 |
1 |
1.5 |
2 |
25 |
| Elbow |
1.5 |
2.5 |
3.5 |
5 |
7 |
10 |
15 |
| Bend r=d |
0.3 |
0.5 |
0.6 |
1 |
1.5 |
2 |
2.5 |
| Bend r=2d |
0.15 |
0.25 |
0.3 |
0.5 |
0.8 |
1 |
1.5 |
| Hose connction T-piece |
2 |
3 |
4 |
7 |
10 |
15 |
20 |
| Reducer |
0.5 |
0.7 |
1 |
2 |
2.5 |
3.5 |
4 |
FIG. Table of equivalent pipe lengths for valves and fittings as used on air distribution systems