136
THE HONGKONG GOVERNMENT GAZETTE, MARCH 11, 1910.
47.
Scum cocks and pipes; how are they arranged? Where are they placed ? At what height in the boiler? When are they used? When must they be shut ? Neglect of these
cocks lead to what dangers?
Of what does scale consist? How is its formation prevented?
48.
Where is it most objectionable? How is it removed? What evil effects are produced by it?
49.
What is a Salinometer? Of what does it consist? How does it act? How is it graduated? Can it be used at any temperature indiscriminately?
50.
What harm may be done through the check valve of one of a set of boilers being de- fective while under way ? How would you work to avoid this harm?
51.
How is the leak from a split tube stopped in a boiler at sea? Describe the operation.
52.
What is the use of dampers? Where are they fitted? When should they be used ?
53.
When there are no dampers fitted what is used instead? What evil to the boiler is sometimes attributed to this? When the heating surfaces are clean does this occur ?
54.
Describe the piston of a steam cylinder, with its different rings and their uses. There are generally round pieces let in flush on one side of a piston; what are they? How are these pieces fixed?
55.
Cylinder drain cocks; what is their use? There is sometimes a valve upon each cock; what purpose does it serve?
56.
How regulated?
Cylinder escape valves; of what do they consist? How protected ? When are they most needed? To what danger do they expose the engineer? precaution is sometimes used to obviate this danger?
57.
What
What is a compound engine? What different kinds are there for screw steamers, in respect to the number and arrangement of their cranks and cylinders? What is a triple expansion engine?
58.
What is link motion ? What are some of its advantages? In modern engines for the screw propeller, when there is no link motion, what takes its place?
59.
What is a separate expansion valve? Why is it not fitted to all engines? What effect has an expansion valve upon the starting and upon the reversing of the engine?
60.
What arrangement is applied to reduce the friction of a slide valve? To what is the friction due ?
61.
Describe a loose eccentric; how does it act ? In what engines are the loose eccentrics still employed?
62.
What is the travel of the eccentric rod ? How is it measured on the eccentric?
What
is the travel of the slide valve when the link motion is in mid gear, and the engine still moving?
What are
،،
63.
double beat valves"? What objections are there to their use ?
64.
What is a circulating pump? Is it always worked by the main engine? Give an example from your last steamer of the three water temperatures generally noted by careful engineers.
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