Question

The value of CO / O\(_2\) deficiency ratio 2% indicates

• A. Normal condition
• B. Existence of spontaneous heating
• C. Heating in advance stage
• D. Active fire

Hint:

For Graham's Ratio, remember these key thresholds:
- Below 0.5% is okay.
- Above 1% is a confirmed problem.
- Above 2% is a serious, advanced problem.
The higher the ratio, the more CO is being produced relative to the oxygen being consumed, indicating a higher temperature of oxidation.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the interpretation of a Graham's Ratio (CO/O\(_2\) deficiency) value of 2

Step 2: Detailed Explanation:

Graham's Ratio is a critical indicator used to detect and assess the severity of spontaneous heating (self-heating) of coal.
It is defined as the ratio of the volume of carbon monoxide (CO) produced to the volume of oxygen (O\(_2\)) consumed by the oxidation process, expressed as a percentage.
\[ \text{Graham's Ratio} = \frac{[\text{CO}]}{[\text{O}_2 \text{ deficiency}]} \times 100\% \] The interpretation of the ratio's value is generally standardized:
-

Less than 0.5%: Indicates normal conditions and slow oxidation of coal at ambient temperature.
-

0.5% to 1%: Suggests the possible onset or existence of spontaneous heating.
-

1% to 2%: Confirms the definite existence of heating, which is becoming more active.
-

Greater than 2% or 3%: Indicates that the heating is in an

advanced stage and there is a high risk of an active fire developing or already being present.
A value of 2

Step 3: Final Answer:
A CO/O\(_2\) deficiency ratio of 2 This corresponds to option (C).