Easy Pea-C | Global CIH & CSP Prep

Topic: Fire & Explosion

Q1. Which of the following properties determines the lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture with air near its surface?

A. Vapor Pressure

B. Boiling Point

C. Flash Point

D. Autoignition Temperature

Correct Answer: C (Flash Point)

💡 Explanation:
The Flash Point is the lowest temperature at which a liquid produces sufficient vapor to form an ignitable mixture with air near its surface. Crucially, it requires an external ignition source (like a spark or flame) to ignite.

❌ Distractor Analysis:
• Vapor Pressure: Measures a liquid's volatility, not its lowest ignitable temperature threshold.
• Autoignition Temperature: The minimum temperature at which a substance will spontaneously ignite without any external spark or flame.

Topic: Industrial Ventilation

Q2. An exhaust hood must maintain a capture velocity of 100 feet per minute (fpm) at a distance of 1 foot from a centerline slot hood. If the slot length is 4 feet, which of the following is closest to the required volumetric flow rate (Q) using the standard slot hood equation $Q = 3.7LV$?

A. 400 cfm

B. 1,480 cfm

C. 2,960 cfm

D. 3,700 cfm

Correct Answer: B (1,480 cfm)

💡 Calculation Step-by-Step:
1. Identify the given variables:
    • Slot Length ($L$) = 4 feet
    • Distance ($X$) = 1 foot (Note: The standard slot hood equation $Q = 3.7LV$ is valid for distances up to $X \le 4L$)
    • Capture Velocity ($V$) = 100 fpm
2. Apply the formula: $Q = 3.7 \times L \times V$
3. Calculate: $Q = 3.7 \times 4 \times 100 = 1,480 \text{ cfm}$ (cubic feet per minute).