Practical No. 14: Flash Point by Abel’s Closed Cup Apparatus
XIII Interpretation of Results
Flash point of lubricating oil was successfully determined using Abel’s closed cup apparatus. Closed cup method gave lower flash point values compared to open cup method due to confined vapours.
XIV Conclusions and Recommendations
- Conclusion: Closed cup method is more suitable for oils with low flash points (below 49°C).
- Recommendation: Use correct thermometer, maintain 1-1.5°C per minute heating, and conduct test in dark room for better visibility.
XV Practical Related Questions
1. Write the precautions while performing the practical.
- Answer: Precautions include:
- (i) Fill oil carefully to avoid bubbles and ensure oil is not above the filling mark,
- (ii) Conduct test in a dark room for better visibility of flash,
- (iii) Use correct range of thermometer,
- (iv) Maintain temperature increase at 1 to 1.5°C per minute,
- (v) Stir oil continuously except during introduction of test flame,
- (vi) Ensure sliding shutter operates smoothly,
- (vii) Standard test flame should be of prescribed size.
2. Give the limitations of Abel’s close cup apparatus.
- Answer: Limitations include:
- (i) Suitable only for oils with flash point below 49°C,
- (ii) Not suitable for viscous oils,
- (iii) Closed cup method may not reflect actual fire hazard in open conditions,
- (iv) Results may vary if the apparatus is not cleaned properly,
- (v) Requires careful temperature control and dark room conditions for accurate results.
3. Explain the significance of fire & flash point.
- Answer: Flash point indicates the minimum temperature at which oil gives sufficient vapours to ignite momentarily, helping determine storage and transport temperature limits. Fire point indicates the temperature at which oil burns continuously for at least 5 seconds. Both parameters are crucial for fire safety, detecting volatile contaminants, identifying oils, and selecting appropriate lubricants for specific working temperatures.
4. Name the apparatus used for flash point & fire point determination.
- Answer: Apparatus used:
- (i) Cleveland Open Cup Apparatus – for flash and fire point of high flash point oils,
- (ii) Abel’s Closed Cup Apparatus – for flash point of oils below 49°C,
- (iii) Pensky-Martens Closed Cup Apparatus – for flash point of oils,
- (iv) Tagliabue Open Cup Apparatus – for flash and fire point, and
- (v) Koehler Open Flash Tester.
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