CIH Engineering Controls and Ventilation 4

Question 1

A wet scrubber used in an LEV system primarily controls contaminants by:

Accepted Answer

Physically impacting or absorbing particles and gases into water droplets

Answer

Wet scrubbers use water droplets to capture contaminants through impaction, diffusion, and absorption, making them effective for both particulates and soluble gases.

Question 2

Which parameter is most critical when sizing ductwork to prevent particulate settling in horizontal runs?

Accepted Answer

Minimum transport velocity

Answer

Minimum transport velocity must be maintained in all duct segments to keep particles airborne and prevent settling, plugging, and fire hazards.

Question 3

In the context of industrial hygiene engineering controls, 'process substitution' is classified as which tier in the hierarchy of controls?

Accepted Answer

Engineering control — elimination/substitution

Answer

Substitution (replacing a hazardous process or material) is a type of elimination/substitution engineering control and sits near the top of the hierarchy.

Question 4

The 'capture velocity' needed for a welding fume hood should typically be in which range?

Accepted Answer

100–200 fpm

Answer

Welding fumes are light with some thermal lift, requiring capture velocities of approximately 100–200 fpm at the point of generation.

Question 5

When a ventilation system is tested and actual airflow is 15% below design, the FIRST corrective step should be:

Accepted Answer

Diagnose the cause by measuring static pressures throughout the system

Answer

Systematic static pressure measurements identify whether the deficiency is due to obstructions, leakage, damper settings, or an undersized fan before any corrective action is taken.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Engineering Controls and Ventilation 4