Theory 1 Flashcards
(51 cards)
What is the definition of a system?
A system is a series of interconnecting pipes and components that will deliver a substance from one point to another.
What are the two types of systems?
- Open loop
- Closed loop
What is an open loop?
The working fluid is consumed e.g. Fuel, domestic fresh water
What is a closed loop?
The working fluid is re-sued e.g. lub oil system, fresh water cooling system
Name 3 types of tanks? And what their purpose is?
- Header Tank- Reservoir to top up a system.
- Service tank- supply of clean, water free fuel.
- Drain tank- collects oil returning from a system.
Name 3 types of tank gauges? And what their purpose is?
- Contents gauge- (clock/dial) How much fluid is in a tank.
- Gauge glass- Visual indication to tank level (press the button to read)
- Sounding tube- Used to measure the depth of liquid in a tank (Dip tape)
What is a Strainer?
Removes large course particles, usually metal plates with holes in or a wire basket.
What are the benefits of a strainer?
Usually washable and re-useable
What dose the type of pipework depend on?
- service being supplied (the fluid)
- operating temperatures and pressures
- other types of material used within the system(what the pipework might fit into)
Name the different types of pipework and the services they do?
- Phosphor bronze- High pressure salt water
- Copper - Domestic Fresh water
- Copper Nickel- Lub Oil
- Brass- Castings (valves, couplings, junctions, taps)
- Plastic- Sewage/waste systems and pre-wet
What dose the type of seal used depend on?
pressure
fluid being used
temperatures involved
Name the types of seals used? And a discription?
- Gaskets – Create a seal between two flat surfaces, can be made from various materials including Non Asbestos Fibre (NAF) – Paper – Leather – Cork – Copper - Rubber
- Mechanical Seals – Used on rotating components such as pump shafts
- Keeler Ring Couplings – Used on High Pressure Air system pipework connections
- Gland packing – Silicone, wool, wax – dependent on fluid type, pressure and temp
What is the purpose of valves?
To provide a method of controlling flow or pressure of a fluid or to provide a means of isolating various systems or components.
Name the different types of valves?
globe valve
gate valve
flap valve
Saunders valve
Ball seated cock
Relief Valve
Reducing Valve
Non-return Valve
Pressure Control valve
ROV (remote operation valve)
What is a relief valve?
Prevents over pressurisation
What is a reducing valve?
Reduces pressure for a part of a system
What is a non-return valve?
Prevents reverse flow
What is a pressure control valve?
Maintains pressure in a system at a set level, monitors the outlet pressure from the vavle.
What is an ROV (remote operation valve)?
Rod gearing to manually open or close a valve from another location or automated
What are the two types of pumps used on ship?
Positive displacement
Dynamic Displacement
Benefits of positive displacement pumps?
Less flow, increases pressure.
Benefits of dynamic displacement pumps?
Large flow, low pressure
What is a motor?
Converts electrical energy into mechanical motion to drive a pump.
How does a Bourdon Tube work?
tube extends as pressure increases moving a needle round a dial.
