CIH Engineering Controls and Ventilation 5

Question 1

What effect does increasing duct length have on a ventilation system's total system resistance?

Accepted Answer

Increases resistance proportionally

Answer

Friction losses accumulate along duct length, so total system resistance increases proportionally with duct length, reducing airflow if the fan curve remains constant.

Question 2

When evaluating makeup air requirements for a local exhaust ventilation system, the primary concern is:

Accepted Answer

Ensuring sufficient replacement air to prevent excessive negative pressure that reduces LEV performance

Answer

Insufficient makeup air creates excessive negative pressure (building depressurization), which can reduce exhaust hood airflow below design levels and draw contaminants back into the space.

Question 3

The collection efficiency of a cyclone separator is primarily determined by:

Accepted Answer

Particle size, gas velocity, and cyclone diameter

Answer

Cyclone efficiency depends on centrifugal forces, which are governed by particle mass (size/density), tangential gas velocity, and the radius of the cyclone body.

Question 4

In industrial hygiene, 'engineering controls' are preferred over administrative controls and PPE primarily because:

Accepted Answer

They reduce or eliminate the hazard without relying on worker behavior or compliance

Answer

Engineering controls modify the work environment or process to reduce exposure at the source, eliminating reliance on human behavior that can fail or be inconsistent.

Question 5

A Pitot tube traverse is performed in an industrial duct to determine:

Accepted Answer

The average air velocity and volumetric flow rate in the duct

Answer

A Pitot tube traverse measures velocity pressures at multiple points across the duct cross-section, which are used to calculate average velocity and total airflow (CFM).

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Engineering Controls and Ventilation 5