Aviation Turbine Fuel (ATF) is a blend of refined hydrocarbons that must meet strict specifications. It consists of kerosene or wide cut fuel with a distillation range of 150-300°C. Key properties include acidity, aromatics, olefins, sulfur and smoke point content. ATF composition and properties like flash point, freezing point, viscosity and thermal stability are tightly controlled for safety and engine performance. Contaminants such as water, particulates and microbiological growth can cause issues. Tests are used to check properties and ensure ATF meets specifications for use in aircraft.

1. 1
Aviation Turbine fuel (ATF)
its physico-chemical
properties and significance
BY
S.K.CHHIBBER

2. 2
Aviation Turbine fuel (ATF)
 Shall consists of Blend of refined
hydrocarbons.
ATF are of 3 type
 Kerosine type jet fuel having disi-tllation
rang 150 -300˚C
 High flash point jet fuel normally falls
between 175-300˚C
 Wide cut jet fuel, composed from kerosine
& naphtha fractions boiling between 30-
300˚C & flash point below 38˚C

3. 3
Composition of ATF ,
Characteristics.
Paraffin and Cyloparaffine
 Chemically stable
 Good storage stability under thermal
stress.
 High calorific value.
 Clean burning.

4. 4
Contd.
Aromatics
 low heat content
 Poor combustion
 Higher solvent and swelling effect on
rubbers, sealants and insulators.
 Poly nuclear aromatics burns with
illuminous flame.

5. 5
Contd.
Olefins
 Chemically unstable, gum forming
tendencies.
 Nearly clean burning
 Intermediate specific gravity and
calorific value

6. 6
Typical hydrocarbon type
composition
Content % Weight I % Weight II
Paraffin 57 26
Naphthalene 26 52
Aromatics 17 20
Olefin <1 2
Ultimate
Analysis
Hydrogen 14.1 13.3
Carbon 85.8 86.5

7. 7
IS 1571 Specification of ATF – Kerosene
Type
Characteristics Requirement Method
Appearance Clear, Bright Visual
Colour Particulate, mg/l Report
Map 1.0
D 156
D 5452
Composition
a) Acidity mgKOH/g, max
b) Aromatics, % vol, max
c) Olefins, % vol, max
d) Sulphur, %wt, max
e) Sulphur Mercaptan, % mass,
max
OR
Doctor Test
0.015
22
5.0
0.30
0.003
Negative
P:113
P:23
P23
P34
P109
P19
Volatility
a) Distillation
10% vol, at °C, max
50% vol, at °C,
90% vol, at °C
FBP, ºC, % vol, max
Loss, % vol, max
b) Flash Point, °C max
c) Density, 15°C, kg/m3
205
report
report
300
1.5
1.5
38
775-840
P:18
P;20 (Abel)
P:16
Fludity
a) Freezing Pt., C max (-) 47 P:11

8. 8
Characteristics Requirement Method
Combustion
a) Specific Energy Mj/Kg, min
OR
Product of API grav. * Aniline Pt.
Min
b) Smoke Pt. mm, min
OR
Smoke Pt, mm, min
And
Naphthalene cont. % vol max
c) Hydrogen content, % by mass
42.8
4800
25
19
3.0
report
P:6
P:3
IP 57/95
P118
ASTM D 3701
Corrosion
a) Copper strip Corro. 2 hrs., 100
C, max
b) Silver Strip Corro. max
1
0/1 (refinery / delivery
(def), 1 (civ)
P:15
IP 227
Stability
Stability (JFTOT)
a) Filter Pressure Differential,
mmHg, max
b) Tube rating, Vis.
25
<3 No Peacock (P)
No Abnormal colour
deposit
P:97

9. 9
Characteristics Requirement Method
Contaminants
a) Existent Gum, mg/100, max
b) Water Reaction
i. Interface rating, max
ii. Separation rating, max
c) MSEP
(Without SDA)
With SDA
7
1b
Sharp separation
85
70
P:29
Steam jet
P:42
P:142
Conductivity
Electrical Cond.
ps/m (delivery Pt.)
50 min
450 max
IP 274/82
Lubricity
Wear scan dia, mm 0.88 max D 5001
To be reported
1. Refining components at the point of manufacture
2. Hydro processed components
3. Severely Hydro processed components

10. 10
Physico Chemical
Characteristics
Appearance (Visual )
Product should be free from suspended
impurities and water.
 May clog the filter.
 May cause fuel pump failure.
 May cause engine wear.
 May cause corrosion.

11. 11
Acidity P:113
Should be free from inorganic/ organic
acids.
 Corrode storage tanks.
 Transport containers
 Aircraft tanks
 Fuel delivery system.

12. 12
Suphur P:34
Total sulphur limits as well as H2S and RHS
are limited due to their corrosiveness and
effects on elastomers.
 Total Sulphur Mercaptans by doctor
test.P:19
 To a sample, sodium plum bide & small
amount of S is added. It is
shaked,decloration of sulphur floating at
the oil water interface is indicative of
positive test

13. 13
Copper Strip corrosionP:15
Shows corrosiveness to copper and is
carried out at 100ºC for 2 hours.
 Silver strip which is very sensitive
test to determine qualitative
corrosion of Sulphur is carried out.
4 hours @ 50ºC
16 hours @ 45ºC

14. 14
Silver Rating IP 227
 No tarnish
 Slight tarnish
 Moderate tarnish
 Slight Blacking
 Total Black
This test mainly detects corrosive action
of H2S 0.5 ppm of H2S present in the
fuel is sufficient to cause Silver rating 4.
i.e. total black.

15. 15
Contd.
H2S may come in fuel during storage
and transportation by the presence
of Sulphate reducing bacteria known
as anerobic bacteria.

16. 16
Water Content in Traces
Water which can result in clogging is
undesirable even in ppm level and is
determined by Karl Fisher titration.
 H2S and RHS interfere because of
oxidation by I2 in KF.
 1 ppm sulphur as RHS causes error
of 0.2ppm water.

17. 17
Water Seprometer Index
Water Separation P:137
Test methods provides a measure of the
presence of surfactant.
Ability of fuel to release entrain emulsified
water when passed through coalescing
medium. (water fuel sample emulsion is
created using high speed mixture)
 High seprometer index indicates good water
separation..( Water rejection is observed by
light transmission through the photocell is
measured.)
 Low value indicated poor water separation
which is caused by the presence of
surfactant. (Certain additives can also have
adverse effect on rating)

18. 18
Conductivity ASTM – D2624/IP274
 Conductivity of aviation fuel are generally
low.
 Can be increased by incorporating static
dissipater additives.
 It acts quick dissipation of electrical
charge.
 Conductivity of untreated fuel is normally
less than 10 Cu.
 Voltage is applied across the electrodes
immersed in fuel & resulting current is
expressed as conductivity value

19. 19
Contd.
 Properly treated fuel ranges between
50 and 450 Cu
 Signifies the ability of fuel to become
electrically charged & to dissipate
this charge ,during operation
,controlled by its content species, as
measured electrically conductivity
(PISCO, Siemen/Meter known as
conductivity units)

20. 20
Static Electricity ASTM – D4865
 Pumping, filtering and tank filling can
cause generation and accumulation
of electrostatic charge which can
result in spark causing fire and
explosive.

21. 21
Distillation P:18
 20% point control front end volatility
that fuel will readily vaporize from
cold starting and yet will not be too
volatile give rise to high evaporation
loss at high altitude.
 90% point control the amount of
high boiling point material could
effect overall engine performance
 Flash point is another volatility
criteria of safety.

22. 22
Freezing Point P:11
 Temperature encountered at
high altitude is very low
 Temperature between 30000 to
80000 feet high is of the order of
-30ºC. The safe limit is -47ºC .

23. 23

24. 24
Kinematics Viscosity P:25
 It is closely related to pump ability
over the temperature range and
consistency of nozzle spray pattern.
 At low temperature increase in
viscosity causes poor pumpabitity at
higher altitude. Viscosity increases 5
to 6 times than at ambient ground
temperature.
Limits are fixed at -20ºC (Max 8 Cst)
and viscosity is to be reported at -
35ºC.

25. 25
Calorific Value
 It is direct measure of fuel energy
content.
 Heat energy is directly proportional
to useful work produced therefore
this is an important property for the
selection of fuel.
 In the absence of the calorific value
a minimum value of product of
Aniline point and API gravity is also
applicable.
 Correlation methods are available i.e.

26. 26
Contd.
 Calorific value 10225 Cal/g(net)
minimum or product of API gravity
and aniline point 4800 min.

27. 27
Smoke point P:31
 Fuel with higher smoke point should have
lesser aromatics and poly aromatics and
thus should have better burning
characteristics.
 Smoke point minimum 20mm.
Naphthalene Content
 Luminous flame
 Causes metal fatigue and increase in
engine deposits, limit maximum 3%wt &
luminometer number 45 min.

28. 28
Existent GumP:29
 It is a result of polymerization and
condensation of Olefins.
 Large quantity of gum is indicative of
contamination of fuel by higher
boiling point.

29. 29
Thermal Oxidation Stability
(JFTOT) P:97
 On high speed the fuel is also used
as a heat sink for air conditioning
system and control of Cabin air
temperature.
 Related to use of fuel as coolant in
supersonic flights.
 At the speed 1500 mph the skin
temperature is 100ºC while at 2300
mph the skin temperature is 315ºC.
Continued exposure reduces the
strength of alloy.

30. 30
Contd.
 Fuel should be thermally stable
under such condition and should not
produce varnish like materials
otherwise effect the efficiency of
heat exchanger

31. 31
OUTLINES OF THE METHOD
 600ml.test fuel is passed through
aluminum preheated tube and then
passed through17um porosity filter
in 2 hrs.30 mts.
 Preheated tube is rated for deposits
 Pressure across the filter is
measured

32. 32
Flash point P:20
 It is a temperature at which an oil on
heating under prescribed conditions
gives off sufficient vapour to form a
mixture with air, ignite on
introduction of the test flame from
the standard apparatus. It is
determined by Abel's method
 Signifies storage handling & safety

33. 33
Fuel effects on Turbine
performance
Poor Combustion
 Low luminometer number.
 Low smoke point
 High aromatics
 Heavier fuel contaminants

34. 34
Contd.
Excess Linear Blade deposit
 High fuel viscosity
 Low hydrogen content
 High sulphur/ hetro atoms.
 High aromatics
 Soluble metals

35. 35
Contd.
Nozzle plugging/ wear
 High particulate contamination.
 Soluble metals.
 Heavy end impurities
 Poor thermal stability.
 High sulphur content

36. 36
Fuel Effect On Turbine
Performance
Fuel control system malfunctions.
 High sulphur
 Heavy end contaminants.
 Thermally reactive hydrocarbons
 Low fuel viscosity
 Poor lubricity

37. 37
Contd.
Filter Plugging.
 Water contaminants
 Surfactant contaminations.
 Microbiological growth.
 Improper freezing point.
 Thermally reactive hydrocarbons.

38. 38
Test procedure in brief
on
Manual/Automatic Apparatus

39. 39
Distillation P:18
1. Take 100ml of sample in 125 ml distillation flask
2. Fit IP 5/6 C thermometer in the flask in such a way that
bulb of the thermometer is in the center of the neck
3. Fit the flask into the distillation apparatus having
requisite dia. of the flask support
4. Apply heat in such a manner that 1st drop falls from the
condenser in measuring cylinder with in 5-10 min. It is
IBP
5. Note temp. after every 10% recovery
6. Do not change rate of heating during till 90% is
recovered, At this point give max. heat to get FBP
7. FBP is the highest temp. reached during the experiment
& then fall in temp. takes place due to cracking
8. Record the residue left in the flask & evaporation loss

40. 40
Flash point P:20
1. Fill the sample in the brass cup to the inside
mark of the cup
2. Put the cup in a heating bath
3. Fit the cover having test flame device
4. Insert the proper thermometer in sample &
water bath
5. Heat the sample at a slow uniform rate
6. Test flame is directed into the cup at a regular
interval say a rise of 1˚C
7. Note down the temp. at which momentary flash
occurs on the introduction of test flame
8. This is the flash point of the sample

41. 41
Copper strip corrosion P:15
1. Surface finishing followed by polishing of the
copper strip having dimention75mm L ,12.5
mm W ,1.5-3.0 T
2. Wash it with solvent, dry it with filter paper ,
use foresep , should not be hold by finger
3. Take 30 ml of sample in clean test tube
4. Slide copper tube in to the tube & stopper tube
with vent corck
5. Keep it in water bath at 50 & 45˚C for 4 & 16
hrs. as per requirement
6. Take out the strip ,wash with iso-octane
7. Dry it on the pad of filter paper, examine for
tarnish/ corrosion by comparing with ASTM
copper strip corrosion std. & report

42. 42
Acidity P:2
1. Take 10 gm sample in titrating flask
2. Add 120 ml titrating solvent (T.S 500ml
toluene+495 ml IPA +5 ml water ) +methyl
orange indicator
3. Titrate with N/10 alcoholic KOH or by
potetiometrically to pH 11.
Calculate Acidity mg, KOH / gm of sample=
Vol. of KOH used x N x 56.1
Wt. of sample

43. 43
Viscosity kinematic P:25
1. Charge the capillary viscometer with the sample
2. Keep this viscometer in thermostatic bath maintained at
the temp. at which the viscosity is to be determined
3. Allow to leave the viscometer long enough to attain the
temp.
4. Use suction to raise the head level of the test sample 5
mm ahead the mark on the viscometer
5. Allow the sample flow under gravity, start the stop watch
when it crosses the upper mark of the capillary, stop the
watch when it crosses the lower mark on the capillary
6. To get viscosity in cSt Multiply the time of flow in seconds
with constant of the viscometer
7. Report viscosity in cSt

44. 44
Existent gum P:29
1. 50 ml of sample is taken in weight evaporating beaker
2. Place the beaker in an evaporating bath
maintained at 150±5˚C
3. Place an other empty weight beaker in other well of the
apparatus
4. Assemble the hot air jet so that air is spread in whole of
the beaker
5. Flow rate of hot air is kept 1000±150 ml / sec.
6. Allow the sample to evaporate for 30 minutes
7. After the test transfer the beaker to cooling vessel
8. Weigh the beaker & find out the increase in wt. ----A
9. Also find out the increase in wt. of empty beaker----B
10. Calculate existent gum in 100ml of sample =( A-B )x2
11. Since gasoline contain dye, n-heptane wash with 25 ml is
given by swirl to drive off it . Decant & discard n-
heptane, give three washing
12. Keep both beakers in an oven at 150˚C
13. Take out the beaker , cool them, weigh them &

45. 45
Smoke point P:31
1. Introduce 20 ml of dry sample in dry oil container
2. Wick minimum 125mm to be soaked in oil sample &
insert in wick holder
3. Cut the wick smoothly & project it 6mm from the holder
4. Place the wick holder in the container
5. Insert into lamp & light it
6. Adjust the flame to 10 mm height & allow to burn for 5
min.
7. Raise the wick until Smokey flame is produced, lower it
until smoke tail just disappear, note down the height at
which oil burns without smoke.
8. It is smoke point

46. 46
Conductivity D2624
1. Voltage is applied across the two electrodes in a
fuel cell, the resulting current is expressed as
conductivity
2. If conductivity is high, charges dissipate fast
enough to prevent their accumulation
3. See that sample container & measuring cell
have been thoroughly cleaned
4. Rinse the conductivity cell with fuel under test
5. Transfer the fuel in the measuring cell & record
the conductivity of fuel using procedure
applicable to particular apparatus
6. Report the conductivity & temp. at which
measurements made

47. 47
Static electricity D4865
1. It describe how static electricity may be
generated in the petroleum fuel systems
2. Pumping , filtering & tank filling of
petroleum products can cause generation
& accumulation of electrostatic charges
which could cause fire & explosion

48. 48
Silver strip corrosion IP 227
1. Clean the strip with 240 grade silicon carbide cloth
2. immerse the strip in iso- octane
3. Remove from solvent dry it with filter paper & polish it
wit carborundum powder using cotton.
4. Immerse again in iso- octane
5. Take it from it with the help of foresep , dry it with ought
touching with fingers ,suspend the polished from the
hook on the condenser by mean of glass cradle
6. Carefully lower the strip & condenser into the sample.
7. Maintain temp. at 50 ±1˚C for 4 hrs.
8. During test run water in the condenser
9. At the end take out the strip , wash with solvent & dry
using filter paper, inspect for evidence
10. Report the result as explained earlier

49. 49

50. 50
Freezing point P:- 11
1. Transfer 25 ml sample to clean, dry jacked tube
2. Close tube tightly with cork holding IP14C thermometer &
stirrer. Thermometer bulb should be in the center of the
sample
3. Clamp the jacket in the cooling medium containing
acetone & solid CO2
4. Stir the sample continuously & vigorously except when
making observations
5. Record the temp. at which crystal of hydrocarbon appears
6. Remove the tube from the coolant & allow the Temp. to
rise ,stir continuously
7. Record temp. at which HCs crystals disappears
8. If difference between the formation & disappearance is
greater than 3, repeat cooling & warming
9. Report this temprature

51. 51
Calorific value P:6
1. Calibrate the bomb calorimeter with benzoic acid tablet to
find out the water equivalents of the calorimeter
2. Weigh the calorimeter bucket, fill the desired amount of water in it &
weigh again to find out the weight of water
3. Place the bucket in the jacket of the bomb calorimeter
4. Assemble the bomb, attach nicrome wire to the electrodes of the bomb
, tie the thread to this wire
5. Weigh the benzoic acid tablet in an enconal crucible & place in the ring
attached to one of its electrode, tide the thread to tablet
6. Assemble the bomb , tighten the cover securely
7. Fill the bomb with 100 PSI oxygen
8. Dip the bomb in jacket which contains known quantity of water
9. Make electric connections , turn on the equipment, fire the sample
10. There will be rise in temp. which can be read on Beckmen thermometer
11. Note down reading after every min. till highest reading is obtained
Determine the bomb calorimeter water equivalent
Water equivalent = Wt. of sample x calorific value ob benzoic acid
Rise in temprature
Similarly carry out experiment to find out calorific value of the sample

52. 52

53. 53