A Ho Chi Minh City pharmaceutical plant has taken delivery of a GMP-compliant air handling unit featuring an H14 HEPA filter and a stainless steel interior for cleanroom air treatment.
Why the Configuration Matters
Pharmaceutical cleanrooms must control particulate and microbial contamination during manufacturing. The supplied AHU conditions and filters the air that sets the room's cleanliness class under standards such as ISO 14644 and the relevant GMP annex, so the unit is a primary control, not just a comfort device.
A GMP-compliant cleanroom is classified by the number and size of airborne particles permitted per cubic metre, and in pharmaceutical filling and weighing areas the expectation is typically an ISO Class 5 workstation fed by ISO Class 7 or 8 background air. The H14 HEPA filter is the final barrier in that chain, rated to capture at least 99.995% of particles at the most penetrating particle size, so the supplied air meets the stringent limits the process demands.
Stainless steel interior surfaces are chosen because they resist cleaning agents, do not shed particles, and hold a smooth finish that is easy to wipe and inspect. In a pharma AHU the casing, drain pans, and filter housings are often specified in grade 304 or 316 stainless so the unit itself does not become a source of contamination or corrosion under frequent wash-down and disinfectant use.
The air handling unit must also hold a positive pressure cascade relative to less-clean adjacent spaces, usually 10-15 Pa per room step, so that any leakage flows from clean to dirty rather than the reverse. This is achieved by balancing supply and extract airflow within a few percent and is verified during commissioning with differential-pressure gauges across each boundary.
Filter loading is tracked by the pressure drop across the H14 stage; as the media loads the resistance rises and the fan must hold the required room airflow, so the final resistance and the alarm setpoint are fixed at design and the supplier documents both the initial and final resistance for the plant's maintenance plan.
In a regulated market the documentation trail matters as much as the hardware. The company's 80,000 m² production site builds AHUs under ISO 9001:2015 quality management with CCC certification, and its in-house performance laboratory can witness airflow, leak, and pressure-drop tests so the plant's qualification team receives test-backed records for audit.
An H14 HEPA filter removes at least 99.995% of particles at the 0.3 µm test size, the usual terminal stage for high-grade cleanrooms. Positioned after the cooling and pre-filter stages, it protects the occupied space rather than the coil and is the last line before the critical environment.
A stainless steel interior resists corrosion from frequent sanitisation and avoids the particle shedding associated with painted or galvanised surfaces. This supports the cleanability and visual inspection demands of a GMP environment, where every surface must be documented as cleanable and verifiably clean.
The unit was built to match the room's required air changes per hour. Typical cleanroom ventilation runs from roughly 20 to 60 air changes per hour depending on grade, which drives both coil capacity and fan static pressure, and sets the recovery time after a contamination disturbance or a door opening event.
Key Technical Parameters
Cleanroom AHUs are selected on airflow, filter grade, and the pressure the fan must hold across the final filter. As the HEPA loads, its resistance rises, so the fan needs spare static pressure to keep airflow stable until the scheduled filter change rather than sagging below the design rate.
Face velocity at the HEPA is kept low, often around 0.45 m/s, to limit pressure drop and particle re-entrainment while still meeting the room's recovery-time requirement after a disturbance. Higher velocity saves filter area but raises both energy use and the risk of shedding.
Cooling and dehumidification coils must hold the room temperature and relative humidity setpoints that the process demands, because humidity control is as important as particle control in many pharmaceutical steps, including powder handling and tablet coating where moisture changes product quality.
The stainless enclosure also simplifies validation: surfaces can be mapped, wiped, and inspected, and the unit can be pressure-tested for leaks before it enters service. That evidence feeds the qualification package needed for regulatory inspection and for ongoing periodic re-qualification of the facility.
| Item | Specification | Note |
|---|---|---|
| Final filter | H14 HEPA | 99.995% at 0.3 µm |
| HEPA face velocity | ~0.45 m/s | Low to limit ΔP |
| Air changes | 20-60 ACH | By cleanroom grade |
| Interior | Stainless steel | GMP cleanability |
| Fan static | spare margin | Holds flow as filter loads |
| Compliance | GMP / ISO 14644 | Cleanroom basis |
Selection Checklist
- Fix the ISO class or GMP grade first; it sets air changes, HEPA grade, and recovery time.
- Size the cooling and reheating coils to the room's latent and sensible loads, not just temperature.
- Allow spare fan static pressure for HEPA loading between scheduled changes.
- Specify stainless or coated interior where sanitising and wash-down are routine.
- Plan filter access and a differential-pressure gauge for change scheduling.
- Request factory leak-test and certification documentation for validation files.
About the Manufacturer
Keruite Air Conditioning Group, headquartered in Dezhou, Shandong, has more than 30 years of HVAC manufacturing experience and operates an 80,000 m² production site with its own performance testing laboratory. Products are built under ISO 9001:2015 quality management and carry CCC certification, and are supplied to customers in over 50 countries.
Our engineers respond to selection enquiries within 24 hours and can provide project-specific sizing, performance curves, and documentation to support specification and procurement.