MAPUA INSTITUTE OF TECHNOLOGY

SCHOOL OF MECHANICAL AND MANUFACTURING ENGINEERING

EXPERIMENT NO. 2

FLASH AND FIRE POINTS AND GREASE DROP TEST

19 Pedroso, Aldrich John E.

2010110455 Date Performed: January 28, 2014

ME139L A1 Date Submitted: February 13, 2014

Group No. 3

SCORE

Engr. Teodulo A. Valle

Instructor

TABLE OF CONTENTS

OBJECTIVES 1

THEORY/HYPOTHESIS 1

LIST OF APPARATUS 2

PROCEDURE 2

SET-UP 3

FINAL DATA SHEET 5

TEST DATA ANALYSIS 6

DISCUSSION 7

QUESTIONS AND ANSWERS 9

CONCLUSION 10

REFERENCES 11

*PDS

OBJECTIVES:

1. To determine the flash and fire points of lubricating oils by open cup method. 2. To determine the melting point of grease.

THEORY/HYPOTHESIS:

The flash point is the lowest temperature to which a lubricant must be heated before its

vapour, when mixed with air, will ignite but not continue to burn. The fire point is the

temperature at which the lubricant combustion will be sustained. The flash and fire points are

useful in determining a lubricants volatility and fire resistance. The flash point can be used to

determine the transportation and storage temperature requirements for lubricants. Lubricant

producers can also use the flash point to detect potential product contamination. A lubricant

exhibiting a flash point significantly lower than normal will be suspected of contamination with a

volatile product. Products with a flash point less than 38 C (100F) will usually require special

precautions for safe handling. The fire point for a lubricant is usually 8 to 10 percent above flash

point. The flash point and fire point should not be confused with the auto-ignition temperature of

a lubricant, which is the temperature at which a lubricant will ignite spontaneously without an

external ignition source.

Since lubricating oil can be oxidize, so can the base oil in grease. When the grease

oxidizes, it usually darkens; there is a build-up of acidic oxidation products, just as in other

lubrications. These products can have a destructive effect on the thickener, causing softening, oil

bleeding, and leakage. Because grease does not conduct heat easily, serious oxidation can begin

at a hot point and spread slowly through the grease. This produces carbonization and progressive

hardening or crust formation. All things considered the effects of oxidation are more harmful in

grease than in oil.

The rate of oxidation is mainly dependent on the temperature. Here it is good to

understand that if soap-based grease is heated, its penetration increases only very slowly until a

certain critical temperature is reached. At this point the gel structure breaks down, and the whole

grease becomes liquid. This critical temperature is called the drop point.

Grease, when heated above its drop point and then allowed to cool it usually does not

fully regain its grease-like consistency, and its performance subsequently will be unsatisfactory.

Therefore, it follows that at no time should the drop point be exceeded. The problem with multi-

purpose greases is that at least one of the agents will exceed its drop point thus adversely

affecting the saponification process. Grease has a maximum temperature at which it can safely

be used. Therefore, it follows that it must also have a minimum temperature. This minimum

temperature is the point where the grease becomes too hard for the bearing, or other greased

component, to be used. Again, the base oil of the grease determines the minimum temperature.

Obviously, the base oil of the grease for low-temperature service must be made from oils having

a low viscosity at that temperature.

LIST OF APPARATUS:

1. Open Cup Tester 2. Bunsen Burner 3. Thermometer 4. Graduated Cylinder 5. Tripod 6. Test Tube 7. Grease Cup 8. Beaker 9. Test Tube Holder 10. Wire Gauze

PROCEDURE:

Flash and Fire Point of Lubricating Oils (SAE 10, SAE 30)

1. Place the oil (70mL of SAE 30) to be tested inside the cup. 2. Heat the sample. 3. Pass a flame of about half an inch over the oil. 4. Wait until the greenish vapors are emitted. 5. Once again, pass a flame over the oil. 6. When it sparks, get the temperature and record it as the flash point. 7. Continue heating the sample until the sample burns. Get the temperature when it starts to

burn and record this as the fire point.

Grease Drop Test (Multi-purpose Grease)

1. Place the grease in the metal cup. Make sure it is totally filled by grease. 2. Place the metal cup inside the test tube. 3. Place the cork and thermometer inside the test tube. 4. Place the test tube sample inside the beaker, the test tube sample must be partially

submerged in the cooking oil.

5. Place the beaker on the tripod with the wire gauze. 6. Set up the Bunsen Burner. 7. Heat the beaker containing the sample and the cooking oil. 8. When the grease melts, record the temperature from the thermometer inside the test tube

and record as the melting point.

SET-UP OF APPARATUS

a. Flash and Fire Points of Lubricating Oils

Figure 1. Open Cup Method Set-up

In the open cup method, sample oil was poured in a cup and a thermometer was placed

and clamped in the manner shown in figure 1. The oil was heated through the use of a Bunsen

burner. The temperature for the flash and fire point were then recorded.

b. Grease Drop Test

Figure 2. Set-up of Grease Drop Test

In the grease drop test, a sample was first poured in a test tube and a thermometer was

inserted in the tube in a manner shown in figure 2. The grease was heated through the use of a

Bunsen burner as shown in figure 3. When it melted, the temperature was recorded.

FINAL DATA SHEET

FLASH AND FIRE POINTS OF LUBRICATING OILS

TRIAL Volume

SAE 10 SAE 30

FLASH FIRE FLASH FIRE

Temp/time Temp/time Temp/time Temp/time

1 70 mL 162C

3mins. 17secs.

170C

3mins. 42secs.

252C

6mins. 22secs.

254C

6mins. 33secs.

GREASE DROP TEST

TYPE OF GREASE MELTING POINT

temperature time

MULTI-PURPOSE 92C 17mins. 59secs.

TYPICAL

FLASH FIRE POUR

C (F) C (F) C (F)

SAE 10W 264 (507) 278 (532) -53 (-63)

SAE 30 258 (496) 274 (525) -48 (-54)

SAE 40 264 (507) 276 (529) -45 (-49)

TEST DATA ANALYSIS

The volume of oil poured in the cup has something to do with the flash and fire points of

oil itself. For this experiment, we use 70mL of oil. More oil means more time to consume in

heating it compared to just a small amount. It was notable that given SAE 10 values were far

from the experimental values. On the other hand, for SAE 30, the values were closer. This may

be due to dilution of the substances, additives on the lube and the thermometer touching the cup.

The refining process of the oil can also affect the flash point, if it is not refined properly, lower

flash points can be observed.

The thermometer touching the cup shouldnt be a problem since thermometer was

clamped accurately. Since it was performed only once, due to time constraint, the observed

results may not be compared to other trials and the performers may have had guidelines not

observed resulting to errors. On the grease drop test, it was obvious that even though there is

only a small amount of grease to be melted, the time needed to reach the melting point was quite

long. This is due to the viscosity and the poor heat conduction of grease. It was also seen that the

test tube deformed, this may be due to the fact the test tube was touching the beaker which has a

higher temperature than the water bath. It is known that the destructive oxidation effects in

grease are more harmful than that of oil. For that matter, this experiment is significant. The poor

heat conductance of grease can be seen through the results, it reached a temperature lower than

the flash and fire points though the time passed was long.

Lastly, the significance of knowing the flash and fire points of oils and the melting point

of grease had given us knowledge on safety in storing and shipping oils that the temperatures

must be controlled to avoid oxidation of such substances.

DISCUSSION

The first part of the experiment is about the determination of flash and fire points of

lubricating oils. The samples used are SAE 10 and SAE 40. The flash point was measured when

a greenish vapour are emitted once a flame was passed over the sample. While, the fire point was

measured when it starts to burn once a flame was passed over it. This was shown in figure 4. The

time for the sample to reach these two points were also recorded.Figure 5 shows some of the

apparatus and the samples used.

Figure 4.Determination of Flash and Fire Point

From the data obtained in the experiment, it can be noticed that for SAE 10, the flash and

fire points recorded are very low compared to the standardized or typical flash and fire point

values. This only means that there is presence of impurities in the sample used which resulted to

dilution. A contamination of even small amounts of volatile substances in the sample oil will

affect its flash and fire points.

Another possible cause of the different flash and fire points obtained is the rate of heating

applied. Since a Bunsen burner was used in the experiment, the size of the flame maybe was not

that large to give the proper rate of heating. Due to this, the time available for the vapour to

diffuse into air was affected. This affected the flash and fire points of the lubricating oil. For

SAE40, the values of the flash and fire points obtained are slightly near to the typical values. The

manner of placing the thermometer in the whole set-up and the presence of impurities may have

affected it.

Figure 6. Grease Drop Test

The second part of the experiment is about the determination of the melting point of

grease using the grease drop test as shown in figure 6. The melting point is important to know

since when it is exceeded, the oil once cooled will not fully regain its same characteristics and

properties as before. For the MARFAC which is a type of grease used as sample, the melting

point is quite high and a long period of time is needed for it to reach this point. This only means

that this kind of grease does not conduct heat easily. For the multi-purpose grease, the melting

point obtained is low and a slightly small time is required for it to become liquid. This is maybe

due to the agents dissolved on it.

QUESTIONS AND ANSWERS

1. Distinguish between flash and fire points of a lubricating oil.

Flash point is the lowest temperature of lubricant at which the fluid gives off

sufficient vapour that ignites for a moment, when flame is brought near it. While on the

other hand, fire point is the lowest temperature if lubricant which the fluid gives off

sufficient vapor that burn or ignites continuously for at least five seconds, when a flame

is brought nears it.

2. Why is it necessary to correct for temperature variations in the specific gravity test?

Specific gravity must always be referenced to a particular temperature reading

because it is temperature dependent. The specific gravity of fluid increases when its

temperature is lowered or decreases when its temperature rises.

3. Define the term pour point.

Pour point is the lowest temperature at which a lubricating oil or fluid will flow

under standardized conditions.

4. Define the term cloud point.

Cloud point is the temperature of a fluid at which soluble substances or solutes

that are dissolved become no longer soluble. They precipitate which results to a cloudy

appearance of the fluid.

5. Based on the PSME code, what type of lubricants when used will have a flash point

which will give an indication of dilution?

When the flash point of a known lubricant is different from the standard

conditions, this indicates that the fluid is diluted.

CONCLUSION

Experiment no. 2 deals with the flash and fire points of lubricating oils and the melting

point of grease which are its objectives. Flash point is defined as the lowest temperature at

which the fluid can form a mixture that ignites with oxygen. While on the other hand, fire point

is the lowest temperature at which the vapor continues to burn after being ignited. The drop point

of grease is the critical temperature where it becomes a liquid under specified conditions.

The first objective of the experiment was achieved by measuring the flash and fire points

of the sample oil using the open cup method and comparing it to the typical values. The

concentration of impurities present in the sample and the rate of heating had affected the flash

and fire points obtained. Through knowing the flash point and fire point of lubricating oil, one

can check the fire hazard involved in using and storing these lubricating oils.

The second objective of the experiment was achieved by using the grease drop test to

determine the melting point of grease. The melting or drop point plays an important role in

grease since once it is exceeded, the oil when allowed to be cooled, can no longer regain its

original characteristics or properties. The presence of substances or different agents in grease

will have an effect in its melting point. Through knowing the melting point of grease, one may

become aware of the best oil to use in particular applications and if the grease is already unable

to perform satisfactory.

REFERENCES

o Mechanical Engineering Laboratory Manual 1

o http://www.engineersedge.com/lubrication/flash_point_fire_point.htm

o http://books.google.com.ph/books?id=Tcamwv6JcvwC&pg=PA179&dq=flash+and+fire

+points+of+lubricating+oil&hl=en&sa=X&ei=AjL_UOXoIMf3rQe5sYH4Cg&redir_es

c=y#v=onepage&q=flash%20and%20fire%20points%20of%20lubricating%20oil&f=fal

se

o http://books.google.com.ph/books?id=xtlQx2-

Zgf4C&pg=PA110&dq=pour+point+of+lubricating+oil&hl=en&sa=X&ei=kjT_ULeG

O8aHrAfPmIAY&redir_esc=y#v=onepage&q=pour%20point%20of%20lubricating%20

oil&f=false