Basic systems Flashcards
Definition of a system
A series of interconnecting pipes and components that deliver a substance from one point to another.
Types of system
Open loop and closed loop
Open loop system
The working fluid is consumed e.g. fuel system
Closed loop system
The working fluid is reused e.g. fresh water cooling system
Types of tank
Header tanks, service tanks and drain tanks
Header tank
Used as a reservoir to top up a tank or system.
Service tank
Used as a reservoir for clean, water-free supply of fuel.
Drain tank
Used to collect oil from a system.
Types of tank gauges
Contents gauge, sounding tube, gauge glass
Contents gauge
Used to indicate how much liquid remains in a tank
Sounding tube
Used to allow us to measure the depth of liquid in a tank
Gauge glass
Gives a visual indication of how much liquid is left in the tank
Dip tape
Used to find the height level of the liquid in the tank
Strainers
A metal plate with 3 holes in, used to remove large coarse particles
The material used for pipes depends on:
Fluid
Temperature and pressure
Other types of material used within the system
Materials used for pipes
Phosphor bronze Copper Copper nickel Brass Plastic
Phosphor bronze
High pressure salt water
Copper
Domestic fresh water
Copper nickel
Lub oil
Brass
Castings e.g. taps, valve bodies
Plastic
Sewage and pre-wet
Plastic
Sewage and pre-wet
Type of seal used depends on:
Pressure
Fluid
Temperature
Gaskets can be made from
Non asbestos fibre Paper Leather Cork Copper Rubber
Examples of seals
Mechanical seals
Keeler ring couplings
Gland packing
Purpose of valves
Valves and cocks provide a method of controlling flow or pressure of a liquid or gas and as a means of isolating a system.
Types of valve
Globe valve Gate valve Flap valve Saunders valve Pressure relief valve Ball seated cock Reducing valve Non-return valve
Globe valve
Can be altered to provide a variety of services such as being a non-return valve or two way flow
Gate valve
Used mostly on large bore systems such as ventilation.
Flap valve
Simple type of non-return valve
Saunders valve
Valve fitted with a rubber diaphragm, used in water and fuel systems
Ball seated cock
Has a hole through it so that when the valve is turned 90 degrees it lines up with the flow
Pressure relief valve
Valve is kept shut by a pressurised spring, if the pressure exceeds that of the spring it will be forced open and allow the excess pressure to escape.
Reducing valve
Accepts a high pressure fluid or gas to enter it, the substance expands thereby reducing pressure
Non-return valve
If the flow of the substance reverses the valve will be forced shut thereby preventing any reversal. Types include flap valve and globe valve
Types of pumps
Positive displacement pumps
dynamic displacement pumps
Methods of displacing fluid
Reciprocating(up and down) e.g. piston
Rotary(round and round) e.g. gear
Types of positive displacement pump
Gearwheel pump
Types of dynamic displacement pump
Axial pump
Centrifugal pump
Bernoulli’s principle
As the speed of a moving fluid increases the pressure within the fluid decreases
Motors
Electric motors convert energy into mechanical motion
Pressure and vacuum gauge
Fitted to monitor pressure and vacuum, normally bourdon tube gauge
Gauge cock
Allows a gauge to be isolated from a system
Manometers
Gives a visual representation of pressure or vacuum, as pressure increases fluids are forced apart, as it reduces fluid levels equalise.
Tachometers
For measuring the speed of a moving body such as a rotating shaft. It is used to measure the speed of fuel moving through the system which allows you to calculate flow rate and fuel consumption.
Types of thermometers
Fixed brass(sheathed or cased) Standard pocket/oblong Clock/dial face
Thermometer pockets
A plug which is screwed into a pipe or machine, the thermometer it made of either standard or fixed brass, it is inserted into the plug.
Sheathed or cased thermometers
Used in pockets, painted with yellow and black warning stripes
Thermometer: Transfer of heat
Thermometers are filled with transmission fluid to aid the transfer of heat. Reading it from eye level.
Voltage meter
Used to measure the potential difference in an electrical circuit
Types of filter
Metallic
Absorbent
Metallic filters
Made from wire wool, thin steel plates,
Used to remove coarser particles
When they become blocked they are removed, cleaned and returned
Absorbent filters
Made from paper, cloth, felt or yarn
remove finer particles
When they are serviced they are replaced and disposed of correctly.
If a filter becomes blocked the pressure will decrease on the discharge side of the filter.
Pressure control valves
Maintains system pressure at designated set levels
Rod gearing
Allows valves to be manually shut from a remote location if the location of the valve is inaccessible. It is important to maintain them as they are needed in emergency’s.
Pressure relief valve
Protects the system from over pressurisation
Accumulators
Holds potential energy which is exerted upon relatively incompressible fluid to dispense it.
Types of accumulators
Bladder type
Piston type
