Theory 4 Flashcards
Explain the pressure volume relationship and it’s effect on boiling point
The higher the pressure the lower the boiling point
Explain heat transfer
Heat always transfers from hot to cold
Explain latent heat
Latent heat refers to a constant temperature required to changing the state of a substance
Explain sensible heat
Sensible heat is applied to heat a substance whilst still remaining the same state
Explain super heat
Super heat is maintaining a temperature above a substances boiling point
What are the hydraulic rings made from, what temperature do they retain their elastic properties and what happens if they burn
O-rings made from fluorocarbon elastomers retains properties Untill 300 degrees at which point they give off toxic gases called hydrogen fluoride
What are the two categories oh hydraulic cell
Petrolium based abs synthetic based
What type of oil is used on, stating number and why?
Submarines:OX30-red-synthetic
Type 23 and type 45: OX40-green-synthetic
Type 22, type 42 and cvs:yellow/orange-petrolium
What are the desirables properties of hydraulic cell
Flow easily through lines
Practically incompressible
Lubricating
Cooling
What does demusibility mean
Ability of a fluid to separate out from water
Why are anti oxidants added to oil
Reduces likely hood of sludge/gum occurring in the oil
List 6 hydraulic pumps that are commonly used
External gear type pump Internal gear type pump Vane pump Love pump Piston type pump(single) Piston/plunger type pump(multi)
Briefly explain axial piston pump operation
Cylinder 1, plunger at highest point, no axial movement suction and delivery valve shut
Cylinder 2, plunger on inlet stroke,suction valve just opening,delivery valve shut
Cylinder 3, plunger near end of inlet stroke,suction valve closing ,delivery valve shut
Cylinder 4, plunger starting delivery stroke, suction valve shut,delivery valve just opening
Cylinder 5, plunger at maximum part of delivery stroke, suction valve shut, delivery valve fully open
What does an actuator do and what types are available
Covert energy(system pressure) into mechanical motion
What is the purpose oil drain leg
Allows oil that’s been specifically used for cooling sealing the acuator/motor to return to the tank
What are the advantages of a hydraulic system over an electric system
Reliable Simple/easy to understand Infinite speed range Easily reversed Ability to withstand overload No spank risk High torque at low speed 1/12 size of electric motor
Use of fresh water on board
Drinking, washing,cooking,cleaning
Briefly explain reverse osmosis
The transfer of water from salt water through a semi perable membrane into pure water, creating fresh water
What TDS and what does it measure
Total dissolved solids and it is measures the purity of the water
What is the TDS levels in concentrate, sea water permeate
Concentrate 56,000ppm
Sea water 34,000ppm
Permeate 250-300ppm
How much salt water is rejected
80% salt water rejected
What how of filters are fitted in an RO plant and what level do they filter to
Pre filters down to 50 microns
Briefly explain the RO plant pump
It’s a HP pump which operates at 10-65 bar. It’s a positive displacement pump three cylinder position type. Incline pulsation dampeners are fitted to smoothen out suction pulsations
Briefly explain the CCV function
CCV are fitted to the discharge lines and when closed down, they increase back pressure, ensuring the salt water pump is pushed through the membrane, allowing for osmosis to take place. A flow meter indicates the produced permeate
