Diving Equipment

Question 1

92. What construction material are the following cylinders made from

Answer 1

(a) AS 1777 Aluminium
(b) HOAL4 Aluminium
(c) DOT 3AA Steel
(d) 3AL Aluminium

Question 2

93. If the test pressure of a cylinder was known, how would you work out the fill pressure

Answer 2

Fill pressure equals 3/5 of the test pressure

Answer 3

yearly

Question 4

95. Describe the difference between a J valve and a K valve

Answer 4

J valve has a reserve mechanism that will withhold 50 bar of air until a mechanical lever is pulled.
K valve is a simple on/off tap.

Question 5

96. Regulator first stages are commonly described as being balanced or unbalanced. Describe the difference between the two.

Answer 5

Balanced regulators operate independently of the cylinder pressure, i.e. opening and closing forces are independent cylinder pressure

Question 6

97. List three advantages of a balanced 1st stage regulator

Answer 6

(a) Bigger orifices, so allow for higher air flow
(b) Constant line pressure independent of cylinder pressure or depth
(c) Balanced valves can cope with higher cylinder pressures
Also acceptable: Less maintenance, as cylinder pressure doesn’t act directly on seats.

Question 7

99. List four safety systems fitted to submersible pressure gauges.

Answer 7

(a) Pressure relief plug
(b) Pressure restrictor in HP hose swivel
(c) Pressure restrictor in HP port of 1st stage regulator
(d) Pressure relief holes in HP hose