CIH Engineering Controls and Ventilation 3

Question 1

According to the Fan Laws, if fan speed is doubled while density and size remain constant, fan airflow will:

Accepted Answer

Double

Answer

The First Fan Law states that airflow (CFM) varies directly with fan speed (RPM), so doubling RPM doubles airflow.

Question 2

What is the purpose of an 'air-cleaning device' positioned upstream of a ventilation fan rather than downstream?

Accepted Answer

To protect the fan from abrasive or corrosive particulates in the exhaust stream

Answer

Placing collection devices upstream of the fan protects fan blades from abrasive or corrosive contaminants, extending equipment life.

Question 3

Which type of industrial filter is best suited for capturing sub-micron particles from high-temperature exhaust streams?

Accepted Answer

High-temperature ceramic filter

Answer

Ceramic filters withstand high temperatures where fabric bags would be damaged, and they efficiently capture sub-micron particles that cyclones cannot.

Question 4

In dilution ventilation calculations, 'K factor' (mixing factor) is used to account for:

Accepted Answer

Non-ideal mixing of supply air with room air

Answer

The K factor (typically 3–10) adjusts the theoretical ventilation rate upward to compensate for incomplete mixing of supply air with contaminated room air.

Question 5

The 'suction boundary' for a flanged circular hood compared to an unflanged hood at the same face velocity:

Accepted Answer

Extends farther from the hood face

Answer

Flanging eliminates the reverse airflow behind the hood, directing more suction forward and extending the effective capture distance from the hood face.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Engineering Controls and Ventilation 3