Hydraulics Flashcards
What is the definition of fluid
A substance that will readily take the shape of its container
It is capable of transmitting power
It can be a liquid or gas
Hydraulic multiplication:
A =
F =
P =
A = AREA of piston face F = FORCE acting on a piston P = PRESSURE exerted on the system fluid
Explain the equation triangle for hydraulic multiplication
F/AxP
Name 8 advantages of hydraulics over electric motors
It is reliable
Simple and easy to understand
Infinite speed range
Easily reversed
Ability to withstand overload
No spark risks
High torque at low speeds
1/12 of equivalent electric motor
Name four disadvantages of hydraulics
Fire risk with mineral oil systems
Noise
Risk of contamination
Less efficient (85-95%)
Densi steel working mastic and pvc self adhesive tapes give off toxic gases when ignited. Where is the only place it should be used and where should it be stored?
On the upper deck and in the flammable store.
What temperature do fluorocarbon elastomer 0-rings give off toxic gases?
Above 300°C
What toxic gases are produced when fluorocarbon elastomer 0-rings are at extreme temperatures?
Hydrogen fluoride
What PPE must be worn when working with fluorocarbon elastomers?
Pvc gauntlets
Rubber boots
Pvc coveralls
Full face visor
Name two types of hydraulic fluid and what they are made from
Petroleum based - petroleum based oils are general purpose mineral oils.
Synthetic based - man made for specific purposes
The 3 oils in use are what colours, and used in what submarines/ships?
What are they called?
OX30 - red in colour, a synthetic oil used in hydraulic systems on board submarines
OM33 - this is yellow/orange in colour. A general purpose petroleum based hydraulic oil used in Older generation ships (T42, T22 and CVS)
OX40 - this is green in colour. A synthetic oil used in hydraulic systems on board T23s, T45s and all future projects
What is hydraulic fluid replaced with to prevent corrosion during upkeep periods when hydraulic oil has been removed from the system?
Rust Veto
List 6 requirements of a hydraulic fluid
The transmission of power (main requirement)
Fluid must flow easily through lines
It must be incompressible
Lubrication is an important requirement
Sealing properties
Cooling
Name 5 common causes of contamination in hydraulic oil
Airborne particles and moisture
Construction dirt
Dirt in new fluid
Dirt produced by wearing in new system
Dirt from human sources
What methods are used to reduce contamination
Good system design
Filtration and filter maintenance
Operation of filter and clogging indicators
Good working practices
Use guardian filter pack
Caps should be fitted to open pipework
Clean working area
The hydraulic system will generally have what three sets of pipework
Pressure supply, Return and drain.
The drain leg returns oil that has been used for cooling, sealing and lubricating
Name 6 types of positive displacement pumps used for hydraulic systems
Internal gearwheel External gearwheel Vane Lobe Radial piston type Axial piston pump (using a swash plate)
What are axial piston pumps used on?
Stabilizer systems
CPP systems
Steering systems
Define an actuator
Actuators convert hydraulic energy into mechanical motion.
The two types consist of linear and rotary.
Linears can be either single or double acting.
Define an accumulator
An accumulator is a device in which potential energy is held under pressure. They are useful in fluid power systems to store energy and smooth out pulsations.
Name four uses for fresh water
Drinking
Washing
Cooking
Cleaning
Services provided by the fresh water system include
The laundry
The galley
Shower and sinks
Water heaters
Medical use
Bridge window washers
Fresh water hose reels
Machinery cooling
Define reverse osmosis
The transfer of water from salt water through a semi permeable membrane into pure water
What is the TDS of sea water
34,000ppm
What is the TDS of water after desalination
250-300ppm
What percentage of the water is ejected whilst purifying water
80%
What is the desalinated water called
Permeate - made water
What is the waste water called after desalination
Concentrate
The reverse osmosis plant has two filtration stages. What does the first stage compromise of
A bag filter that filters down to 60 microns
The reverse osmosis plant has two filtration stages. What does the second stage compromise of
A bank of two cartridge filters that filter down to 10 microns
What type of pump does the RO plant have?
High pressure 3 piston positive displacement pump. (65 bar)
How are the cushion membranes edges held together
Ultrasonically welded edges
The anti scalant that is added called hypersperse is added at what rate?
5ppm
Concentration control valve controls the back pressure of sea water acting on the membrane cushions. By closing the valve the back pressure is …… And the amount of permeate is ……
Back pressure is increased and permeate is increased
What level is chlorine added in fresh water tanks after the membranes and when is it checked?
0.2ppm and daily and before embarkation.
When will desalination not continue and where?
If the water is contaminated such as harbour or estuary waters
Name the three fresh water tests
Chemets
Visual
Taste
What do we use to heat up water on board ship?
Calorifiers
Name the symptom of air in the fresh water system
“water hammer” a loud banging inside the pipes
What colour are fresh water hoses
Blue
What unit if used to measure the F in the hydraulics triangle
KG
What unit if used to measure the A in the hydraulics triangle
Cm2
What unit if used to measure the P in the hydraulics triangle
Kg/cm2
