15.9 Lubricants and fuels Flashcards
(24 cards)
What are the four functions of fuel?
- lubricate to reduce friction
- clean by suspending contaminants
- protect against corrosion
- cool
What are the main types of oil?
Mineral
Synthetic
Why was synthetic oil developed?
Miners oils lacked stability and suffered from excessive volatility and thermal degradation at high temps
What is the disadvantage if synthetic oil?
More expensive
What are the three types of synthetic oil?
Type I older engines, limited performance
Type II standard for most modern engines
Type III Hugh stability for extreme conditions
What is viscosity?
Resistance to flow
Decreases at high temps
What’s viscosity index?
Shows how viscocity changes w temp
What’s pour point?
Lowest temp at which oil still flows
What’s the pour and flash point of type II synthetic oil
Pour point -57c
Flash point >250c
What’s flash point?
Temp at which vapour can ignite
What is volatility?
Resistance to evaporation
What are jet fuels derived from?
Kerosene
What’s the general composition of fuel?
84% carbon
16% hydrogen
And impurities
What are the four main types of fuel?
Jet A1 – Most common in Europe (same as JP-1A).
Jet A – US version (same as JP-1).
Jet B – Cold-weather use (mainly in Canada), highly flammable.
JP-5 – Military use on aircraft carriers, high flash point (65°C), safe.
What’s the freezing point of JP 5?
-48c
How does water exist in fuel?
Dissolved (invisible)
Suspended (visible droplets)
What problems dies water in fuel present?
Ice
Corrosion
Flameouts
Microbial growth
How are additives added to fuel?
Mixed in small quantities measured in ppm
Strictly control and approved by the fuel manufacturer
What additive is added to bulk fuel or fuel tanks for anti icing?
Diethylene glycol solutions e.g Prist
Where do microbes live?
Where fuel and water meet so tank bottoms or in stagnant fuel
What additive prevents gum formation?
Anti oxidants
Which additive reduces static build up during fuel transfer?
Static dissipatoes
Which additive protects ferrous metals from corrosion?
Corrosion inhibitors
Which additive neutralises the catalytic effect of metals like copper that speed up oxidation?
Metal deactivators
