Practical No. 13: Flash and Fire Point by Cleveland’s Open Cup Apparatus
XIII. Interpretation of Results
Flash point and fire point of lubricating oil were successfully determined. Oil showed distinct flash at flash point, followed by continuous burning at fire point. Values indicate oil’s volatility and fire resistance.
XIV. Conclusions and Recommendations
- Conclusion: The lubricating oil can be safely used up to its flash point temperature.
- Recommendation: Conduct test in draft-free area, avoid breathing over oil, and heat at 3-5°C per minute for accurate results.
XV. Practical Related Questions & Answers
Q1. Write the precautions should be taken while performing the practical.
- Answer: Precautions include:
- (i) Perform the test in a draft-free laboratory space.
- (ii) Avoid breathing directly over the open oil surface to prevent inhalation of vapours.
- (iii) Maintain an accurate heating rate of 3 to 5°C per minute.
- (iv) Introduce the test flame from the standard specified distance.
- (v) Use the correct temperature range thermometer.
- (vi) Fill the oil cup exactly up to the filling mark.
- (vii) Ensure the test flame is kept at a standard bead size.
- (viii) Note the temperature carefully the exact moment the first flash appears.
Q2. For which type of oil Cleveland open cup apparatus is used to determine flash point.
- Answer: Cleveland open cup apparatus is generally used for the determination of flash points of fuel oils and other heavy oils having flash points above 79°C. It is highly suitable for oils with higher flash points and is commonly used for industrial lubricating oils, heavy petroleum products, and other high-viscosity industrial fluids. It is not suitable for volatile oils with very low flash points.
Q3. Explain the procedure to mount thermometer in the oil cup.
- Answer: The thermometer is mounted vertically by means of a firm laboratory clamp in such a way that the bottom of the bulb is about 1 cm above the absolute bottom of the cup. The thermometer should be positioned centrally and must not touch the metallic sides of the cup. The bulb should be completely immersed in the oil sample without touching the container to ensure accurate measurement of oil temperature.
Q4. State the heating rate of oil in this experiment.
- Answer: The oil should be heated at a steady rate of about 3 to 5°C per minute during the general determination of flash and fire points using Cleveland’s open cup apparatus. As the temperature approaches the expected flash point, the heating rate is carefully controlled, and the test flame is introduced periodically after every degree rise in temperature.
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