1. Acetylene gas production: Effect of carbide granule size on overall burn time in miners’ cap lamps

2. Question -
What size of calcium carbide granule would result in the longest overall burn time in a carbide miner’s lamp?

3. Hypothesis –
In the reaction of calcium carbide and water, decreasing the granule size of calcium carbide will increase the reaction rate due to an increased total surface area.

4. Background Information-
Total surface area increases as granule size decreases
Manipulation of reaction is generally done only through control of water flow
Various sizes of calcium carbide is available
Very little information available – (antiquated)
Calcium carbide and water are flammable and explosive
“Carbide cannons” use powdered calcium carbide

5. Reaction -
Text and images for this page provided by Marcos & Jonathan Perez-Blanco, © 2004

6. Initial Model-

7. Assumptions –
Heat of reaction and its effects on burn time are negligible
Calcium carbide samples are consistent quality
Water flow does not vary in lamp
Variation of water volume at initiation of combustion has negligible effect on overall burn time

8. Calcium Carbide

9. Calcium carbide(CaC2) was classified by size and weighed into 20 gram samples

10. Equipment Used- Cross-section of lamp Carbide Miner’s Lamp
Diagram Source:
Cross-section of lamp
Carbide Miner’s Lamp

11. Procedures- Lamp was loaded with weighed and screened sample
Lamp was filled with water
Water flow setting was set at a constant
Lamp was lit and allowed to burn until flame was extinguished
Each sample size was tested twice and burn time was averaged
Flame length was measure at 30 minutes

12. Safety consideration –
Due to safety concerns, the finest granule size 2-3mm was not tested
Lamp was loaded with the sample and reacted without combustion
Gas production was instantaneous and profuse
Results most likely would have been short burn time and extreme flame length, aka. EXPLOSION!!!!!

13. Trend of average burn time -

14. Flame Length -

15. Culminating Argument-
Claim - Decreasing CaC2 granule size reduces the overall burn time in carbide lamp by increasing the reaction rate.
Support - As successively finer sizes of carbide were reacted in lamp, the burn time in minutes effectively decreased. Flame length was also measured and graphed to indicate reaction rate.

16. Revised Model -

17. Final Thoughts -
Based on the sizes of calcium carbide granules tested, the ideal size which would maximize overall burn time would be 12mm.
Further testing of granule sizes above 12mm would indicate if larger granule sizes work in this type of lamp.