Differential pressure testing for cleanrooms, OTs and isolation rooms
Air always moves from higher pressure to lower pressure. In a controlled facility that simple fact keeps contamination out of clean areas, or keeps infection inside isolation rooms. We test that your pressure cascade works in the right direction, at the right magnitude.
How pressure protects controlled areas
Most cleanrooms are kept at a slightly higher pressure than surrounding corridors, so that when a door opens, clean air flows out rather than dirty air flowing in. Rooms are often arranged in a cascade, with the cleanest area at the highest pressure and each step down leading towards general areas.
Some rooms work the other way. Negative pressure isolation rooms, containment laboratories and some pharmaceutical areas handling potent materials are kept at lower pressure, so contaminated air stays inside. Getting the direction wrong turns a protective room into a risk.
Testing uses a calibrated differential pressure instrument to measure each room against its neighbours with doors closed. Direction and magnitude are compared with design values, and door behaviour is checked to see how quickly pressure recovers after opening.
Wall-mounted gauges are only useful if they read correctly. We also calibrate room pressure gauges and transmitters through our pressure calibration service, so daily readings can be trusted.
The right direction, every time
Contamination control
Correct cascades stop dirty air entering clean areas when doors open.
Containment
Negative pressure keeps infectious or hazardous air inside isolation and containment rooms.
Audit evidence
Inspectors check pressure records and expect periodic independent verification.
Differential pressure tests
- Pressure difference between each room and its neighbours
- Direction of airflow at doorways
- Pressure cascade across a suite of rooms
- Door-open behaviour and recovery
- Anteroom and airlock performance
- Positive and negative pressure rooms
- Calibration of room pressure gauges
- Documented pressure map
Where we test room pressure
Why a pressure map helps
A pressure map is a simple drawing of the facility showing each room's pressure relative to its neighbours and the direction of airflow at every door. It turns a list of numbers into a picture that operators, engineers and auditors can understand at a glance.
Comparing maps over time shows whether the cascade is stable or slowly changing. A shrinking difference between two rooms is often the first sign of loading filters, failing fans or changes made elsewhere in the building's air system.
Why pressure cascades fail
Common causes include doors that do not close fully, weak door closers, gaps around doors and service penetrations, unbalanced supply and exhaust after maintenance, blocked return grilles and loading filters. Pressure problems also affect particle results, so they are often investigated together with cleanroom classification and airflow visualization.
Most causes are mechanical and quick to fix once identified. Retesting after correction confirms the cascade is restored before the area returns to normal use.
Between independent tests
Record room pressure readings daily, check that doors close fully and never prop doors open. A sudden change in readings should be reported straight away so engineers can investigate before it affects the process.
How the work is carried out
Layout review
We review the room layout and the intended pressure of each space.
Measurement
Each room is measured against its neighbours with calibrated instruments.
Door checks
Airflow direction and recovery after door opening are observed.
Pressure report
You receive a pressure map with results against design values.
One accountable team, documented results
NABL-Accredited
Calibration and testing carried out under NABL accreditation and ISO/IEC 17025:2017-compliant procedures.
On-Site & Laboratory Capability
Work carried out at your facility or in our laboratory, by one accountable team.
Serving Since 2022
Serving hospitals, laboratories, pharmaceutical and industrial clients across Tamil Nadu since 2022.
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Frequently asked questions
Verify your pressure cascade
Share your room layout and design pressures, and we will plan differential pressure testing.