5. Describe briefly the working principles of a regulator and illustrate with a simple sketch.
6. Explain the difference between high and low-pressure regulators.
7. (a) Can acetylene regulators be interchanged with oxygen regulators with perfect safety? Explain why.
(b) How is it possible, in majority of cases, to distinguish in a very simple manner, between oxygen and acetylene regulators, when no gauges are attached?
(c) Why does this difference exist?
8. (a) Why should all tension upon diaphragm springs be removed before admitting gas under pressure to the regulator?
(b) Can a regulator which has been abused in this manner be repaired?
(c) What can be employed as a fitting substitute for gallilith?
9. Explain why the high-pressure gauge on the acetylene regulator cannot be used as an index to the contents of the attached cylinder of gas in exactly the same manner as the oxygen high-pressure gauge.
10. Why is glycerine used as a substitute for oil when regrinding torch valve-seats with emery powder, and with lead-oxide in the caulking of leaky joints along the line?