Term
| 1. What elements make up all hydrocarbons? |
|
Definition
|
|
Term
| 2. What are the separate parts that make up an oxyacetylene flame? |
|
Definition
| Primary combustion where carbon monoxide (CO) and free hydrogen (H) are produced, and the secondary combustion where water vapor (H2O) and carbon dioxide (CO2) are formed. |
|
|
Term
| 4. Approximately how long would it take a 50/50 mixture of oxygen and acetylene to flashback through a 21-foot-long hose? |
|
Definition
| Approximately one second (22.7 feet per second). |
|
|
Term
| 6. How is acetylene produced? |
|
Definition
| By mixing calcium carbide (carbide) with water. |
|
|
Term
| 7. Why is it not safe to use acetylene above 15psig? |
|
Definition
| Acetylene is unstable above this pressure and may explode as a result of rapid changes in temperature, electrical shock, or extreme physical shock. |
|
|
Term
| 9. Where is the highest temperature and where is the greatest heat produced in a neutral oxyacetylene flame? |
|
Definition
| The highest temperature is at the end of the inner cone and the outer envelope produces the greatest quantity of heat. |
|
|
Term
| 11. What are methylacetylene-propadiene fuel gases used for? |
|
Definition
| Cutting, heating, brazing, metalizing, and limited welding. |
|
|
Term
| 13. Which fuel gas has the strongest odor and is easiest to detect? |
|
Definition
|
|
Term
| 14. What is the major advantage of using propane or natural gas? |
|
Definition
| For heating, and natural gas does not have cylinders. |
|
|
Term
| 16. What two major safety problems does hydrogen present? |
|
Definition
| Hydrogen has no smell, which makes it difficult to detect leaks, and because the hydrogen molecule is so small it leaks easily. |
|
|
Term
| 17. Why should coat hangers not be used as gas welding filler metal? |
|
Definition
| The burning paint from the coat-hanger may produce hazardous fumes. Their chemical composition varies greatly, and weld deposits are often porous because of unacceptable levels of phosphorous and sulphur. Some wires may be cadium plated which will vaporize into poisonous fumes. |
|
|
Term
| 18. Explain the significance of the AWS filler metal classification RG-45. |
|
Definition
| R – Rod, G – to be used with gas welding, 45 – 45,000 psi tensile strength of the weld. |
|
|
