CIH Engineering Controls and Ventilation 2

Question 1

What is the primary purpose of a push-pull ventilation system in an industrial setting?

Accepted Answer

Improve contaminant capture at open-surface tanks

Answer

Push-pull systems use an air supply (push) and exhaust (pull) to control contaminants at open-surface tanks, such as plating baths, by creating a horizontal airflow across the tank surface.

Question 2

When calculating the hood entry loss coefficient (F_h), which formula is correct for a plain duct opening (no flange)?

Accepted Answer

F_h = 0.49

Answer

A plain duct opening (unflanged) has a hood entry loss coefficient of approximately 0.49 velocity pressure units.

Question 3

In local exhaust ventilation, the 'centerline velocity' concept is used to describe:

Accepted Answer

The velocity along the axis of suction in front of a hood face

Answer

Centerline velocity refers to the air velocity along the axis of a hood's suction field, used to determine the capture zone in front of the hood.

Question 4

Which of the following best describes a 'canopy hood' limitation in industrial hygiene?

Accepted Answer

Thermal plumes can carry contaminants past the worker before capture

Answer

Canopy hoods placed above hot processes risk drawing the thermal plume through the worker's breathing zone before the contaminants reach the hood.

Question 5

The ACGIH Industrial Ventilation Manual recommends a minimum duct transport velocity for dry grinding dust of approximately:

Accepted Answer

4,500 fpm

Answer

Dry grinding operations generate heavy, abrasive particles requiring transport velocities of approximately 4,000–4,500 fpm to prevent settling in ducts.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Engineering Controls and Ventilation 2