Airflow & ACPH Testing

Airflow velocity and air changes per hour, measured and calculated together

Vanavil Calibrations measures airflow velocity at the point of delivery and calculates air changes per hour (ACPH) from that data — the two figures auditors and quality teams expect to see together when reviewing a controlled space's air handling performance.

Airflow velocity testing measures how fast air is moving at a specific point — typically at a HEPA filter face, diffuser or grille — at the time of test. ACPH (air changes per hour) testing is a calculated rate, derived from measured airflow volume and the room's volume, that describes how many times the space's total air is theoretically replaced every hour. Vanavil Calibrations provides both airflow velocity testing and ACPH testing on-site, as a single assessment of a controlled space's air handling performance.

What Airflow & ACPH Testing Covers

Two related but distinct measurements, assessed together

Airflow velocity and air changes per hour are often discussed as if they were the same thing, but they answer different questions. Velocity tells you how fast air is moving right now, at one point in the room. ACPH tells you how effectively the room's air handling system is turning over the entire air volume across an hour — a figure that depends on the room's dimensions as much as on the airflow itself.

Because a facility's supply diffusers, return paths and room geometry all influence the relationship between the two, we measure airflow velocity directly and then calculate ACPH from the measured airflow volume and the room's actual volume, rather than treating either figure in isolation.

Technician taking an airflow measurement reading with a calibrated instrument

Why It's Required

Contamination control depends on both figures, not one

Contamination Control

Airflow velocity at the delivery point governs how effectively particles are swept away from critical work zones.

Dilution Over Time

ACPH determines how quickly airborne particles generated in the room get diluted and removed across an hour, not just at one point.

Classification Evidence

Both figures are part of the documented evidence a room needs to demonstrate it performs to its assigned classification.

What We Test

Airflow and ACPH parameters covered

Point airflow velocity measurement
Airflow uniformity and distribution mapping
Calculated air changes per hour (ACPH)
Correlation of results with the room's classification

Typical Applications

Where airflow and ACPH testing gets used

Industries Served

Healthcare

Operation theatres & critical care

Pharmaceutical

Manufacturing & sterile areas

Laboratories

Research & QC environments

Industrial

Precision manufacturing

Our Process

Site Assessment

We review the space, its dimensions and classification to define the test points needed.

Airflow Measurement

Point velocity readings are taken across supply outlets using calibrated instruments.

ACPH Calculation

Measured airflow volume is combined with room volume to calculate air changes per hour.

Documented Report

You receive a report covering both velocity and ACPH results, ready for your quality records.

Why Choose Vanavil

One accredited provider for measurement and calculation

NABL-accredited calibration and validation
ISO/IEC 17025:2017-compliant procedures
On-site and laboratory testing capability
20+ years of experience serving 500+ clients across Tamil Nadu

Talk to Our Team

Technician monitoring airflow and ACPH test readings

Related Services

FAQ

What's the difference between airflow velocity and ACPH?

Airflow velocity is a point-in-time measurement of how fast air is moving at a specific location, typically at a filter face or grille. Air changes per hour (ACPH) is a calculated rate — derived from the measured airflow volume and the room's volume — that describes how many times the total air in the room is theoretically replaced in an hour. Velocity is a direct reading; ACPH is a derived figure.

Why does ACPH matter for a controlled space?

ACPH is a key indicator of how effectively a space dilutes and removes airborne particles and contaminants over time. A room can have air moving at an acceptable velocity at individual points and still fail to achieve adequate air changes if volume, layout or return paths aren't accounted for, which is why both figures are assessed together rather than in isolation.

How does airflow and ACPH testing tie into HVAC validation?

Airflow velocity and ACPH are among the core parameters assessed as part of HVAC validation for controlled environments, alongside filtration, pressure and temperature/humidity control. See our HVAC Validation page for how these results fit into the broader validation programme.

Need airflow velocity or ACPH figures for your space?

Tell us about your room and its classification requirement — we'll scope the measurement and calculation.

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