ACGIH Industrial Ventilation Manual of Recommended Practice for DESIGN: 31st Edition

The Global Reference Standard for LEV Design

The ACGIH Industrial Ventilation Manual is widely regarded as the most influential and comprehensive technical reference available for the design of industrial ventilation and Local Exhaust Ventilation (LEV) systems.

Published by the American Conference of Governmental Industrial Hygienists (ACGIH), the manual has shaped ventilation design practices throughout the world for decades and is often referred to within the industry as:

“The LEV Bible”

The 31st Edition provides detailed technical guidance on the design, selection and application of ventilation systems used to control airborne contaminants in workplaces.

The manual includes:

Fundamental ventilation principles
Hood design and selection
Capture velocities
Duct design
Airflow calculations
Fan selection
Air cleaning devices
System balancing
Energy considerations
Design examples
Industrial process applications

The publication contains hundreds of hood designs, engineering illustrations and design recommendations covering a vast range of industrial processes.

This resource is relevant to:

LEV Designers/Commissioners/Testers/Consultants
Occupational Hygienists
Process Engineers
Health & Safety Professionals
Facilities Engineers
Duty Holders

Source Document

Buy the ACGIH Manual here:

Buy ACGIH LEV Manual

Source: ACGIH
Document Type: Technical Design Manual (31st Ed)
Status: Current Industry Reference
Last reviewed by LEVCentral: June 2026

LEVCentral Expert Commentary

Few publications have had a greater influence on the development of industrial ventilation and LEV engineering than the ACGIH Industrial Ventilation Manual.

For many ventilation engineers, occupational hygienists and LEV specialists, this manual represents the definitive technical reference for designing systems intended to control airborne contaminants at source.

Although HSG258 remains the primary UK guidance document for LEV systems, many of the design principles applied by UK practitioners originate directly from ACGIH methodologies. It is not unusual to find UK LEV designers consulting both publications simultaneously when developing complex ventilation solutions.

One reason for the manual’s enduring reputation is its practical engineering focus.

Rather than concentrating solely on legislation or compliance, the publication explains:

Why contaminants behave as they do
How airflow influences contaminant movement
How hood design affects capture efficiency
Why duct sizing matters
How system losses influence performance
How to achieve effective contaminant control

The manual contains an extensive collection of recommended hood designs that have been developed, tested and refined over many decades. These designs remain the starting point for countless ventilation systems installed around the world.

For LEV professionals, one of the most valuable lessons within the manual is that successful ventilation design is rarely achieved through airflow calculations alone.

The effectiveness of a system depends upon understanding:

Contaminant generation mechanisms
Worker interaction with the process
Airflow behaviour
Process dynamics
Capture requirements
System maintenance considerations

The manual repeatedly reinforces a principle that remains central to modern occupational hygiene:

Effective exposure control begins with understanding the contaminant and the process before selecting the ventilation solution.

Whilst the manual is highly technical, its influence extends far beyond design engineers. Occupational hygienists, exposure monitoring specialists and P601 engineers frequently use its guidance when evaluating existing systems, investigating performance problems and developing exposure-control strategies.

From a LEVCentral perspective, the ACGIH Manual remains essential reading for anyone serious about understanding LEV design. Many modern systems can trace their design philosophy directly back to concepts contained within its pages.

Key Learning Points

Effective LEV Design Starts With Understanding the Process

Successful ventilation systems are designed around the contaminant source, the work activity and the worker rather than simply selecting a fan and ductwork.

Hood Design Is Critical

The hood is often the most important component of an LEV system. Poor hood design can severely limit capture efficiency regardless of airflow rates.

Airflow Alone Does Not Guarantee Control

System performance depends upon capture efficiency, contaminant behaviour and process interaction rather than airflow measurements alone.

Engineering Principles Remain Universal

Although published in the United States, the design principles within the ACGIH Manual are applied globally and underpin many modern LEV systems.

Further Resources

Recommended Learning

Thought Leadership

LEVCentral Observation

There are many excellent LEV guidance documents available worldwide, but few have influenced the profession as profoundly as the ACGIH Industrial Ventilation Manual.

For generations of ventilation engineers it has served as both a technical handbook and a design philosophy.

While regulations and standards evolve, the core principles of contaminant control, airflow management and source capture described within the manual remain as relevant today as they were when the first editions were published.

For anyone wishing to move beyond basic compliance and truly understand LEV design, this publication remains essential reading.