3. (a) Sketch diagrammatically the arrangements to control lubricating oil temperature at cooler outlet by either of the following means: (i) diaphragm actuated control valve as part of a closed loop system or (ii) self-operated valve of wax element type.
(b) Describe how the selected arrangement operates.
(c) Define, with reasons, where a control valve of the wax element type should be positioned to be effective.
4. With respect to shipboard control equipments, state the following:
(a) Where is an electronic system essential?
(b) What are the advantages of the electronic system over the other systems?
(c) What are the disadvantages of the electronic system?
Class 2
1. Complete the following:
a. Sketch a diaphragm operated control valve of any design.
b. State how flow changes are sensed.
c. State how command signals are transmitted to actuators.
d. Explain why a pneumatic control system requires clean, dry air. Explain how the following pollutants are dealt with: water, oil, dust and dirt.
e. Describe, with sketch, a bridge/engine room telegraph interconnecting gear.
f. Explain how the system may operate a ‘wrong way’ alarm.
2. Describe, with sketches, instruments used for measuring the ambient temperature in the following spaces:
a. Refrigerated compartment
b. Main machinery exhaust gas uptakes
Class 3
1. Describe the start up sequence of an automatic auxiliary boiler.
2. Describe a device which would automatically activate an alarm when the lubricating oil supply to an engine fails.
3. Explain the principle of operation of a pneumatic diaphragm activator.
4. List three automatically controlled controlled systems in a ship’s machinery space which need to be provided with alarms. State the consequences of an alarm failure in each system.