THE HONGKONG GOVERNMENT GAZETTE, MARCH 11, 1910.
135
30.
Where are angle irons sometimes used in the construction of a boiler, and where are flanged plates used ?
31.
Priming; to what causes is it attributed? What means are applied to prevent it? What evils may be produced by it?
32.
Funnel draught; what makes it? What checks it ?
33.
Flame sometimes is seen at the top of the funnel; what causes this appearance? Is it beneficial or is it detrimental? Why so?
34.
A blast pipe; what is its construction? Where is it placed? For what is it used?
35.
How many bottom blow-off cocks are generally fitted to each boiler, and why are they so fitted ?
36.
Blow-off cocks are sometimes fitted with a spanner guard; for what purpose is this? Describe how the guard is formed.
37.
Water-gauge test-cocks; where are they placed? At what heights? Must the cocks themselves be at those heights? What provision is made for cleaning these cocks should they ever become choked? When there are no test cocks how is the height of the water
ascertained?
38.
What is a dead-weight safety valve? Of what are the rubbing surfaces formed? How is a lock-up-valve arranged to admit of lifting it or of turning it round, and to prevent adding to the weight?
39.
What is the
About what area of safety valve is now required by the Board of Trade ? effect of suddenly opening a safety valve when steam is up? To about what extent do safety valves rise when blowing off without being eased by hand ?
40
Spring-loaded safety valves; what advantages have they that are not possessed by dead-weight valves? What are the disadvantages, if any, as compared with dead-weight valves?
41.
Of what pieces does a glass water gauge mounting consists? is it placed? At what height? Is it liable to derangement?
42.
How does it act? Where How is its working tested?
Glass water gauges have sometimes pipe connections top and bottom; what is the object of this arrangement? Should there be cocks at the extremities of these pipes ? Why? or why not?
43.
Describe a Bourdon steam gauge. Some gauges have an inverted syphon pipe below them; what is its use?
41.
Why is a small cock sometimes put on the pipe leading to a steam gauge? Where should it be placed, and what error might be made by omitting to use it?
45.
Do steam gauges indicate the total pressure of the steam, or only a portion of that pressure? What is the pressure measured from ?
46.
What is meant by the salting of the boiler? How is this prevented? What is the density of ordinary sea water? How is the density ascertained? What is the difference between the formation of scale and the salting of the boilers? What is the maximum density at which boilers should be worked at sea ? In the event of condenser tubes leaking, what is the minimum density at which boilers should be worked? Give your reasons.
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