Air Changes per Hour (ACPH)
The number of times the entire air volume of a cleanroom is replaced with filtered air every hour. It is the core HVAC design figure — higher ISO classes need far more air changes. Estimate it with our ACPH calculator.
Air Handling Unit (AHU)
The central HVAC unit that conditions, filters and moves air to the cleanroom, handling temperature, humidity and pressure. It feeds the supply ductwork and terminal HEPA filters.
Airlock
A small transitional space with interlocked doors between two areas of different cleanliness or pressure. It prevents direct airflow and contamination transfer between zones, such as between a corridor and a cleanroom.
Anteroom / Gowning Room
A controlled room where personnel gown up (suits, gloves, masks) before entering the cleanroom. It acts as a buffer that keeps contaminants carried on people out of the critical area.
As-Built / At-Rest / Operational
The three occupancy states defined by ISO 14644 for classifying a cleanroom: as-built (empty, no equipment), at-rest (equipment installed and running, no staff) and operational (full production with staff). Particle limits are stated for the agreed state.
Bioburden
The number of viable microorganisms on a surface, product or in the air before sterilisation. Controlling bioburden is central to pharmaceutical and medical-device cleanrooms.
Cleanroom
A controlled environment where airborne particle concentration is kept within defined limits using HEPA/ULPA filtration, controlled airflow and pressure. Used in pharma, electronics, medical devices, food and aerospace manufacturing.
Cleanroom Classification
The grading of a cleanroom by maximum allowed airborne particles per cubic metre, under ISO 14644 (Class 1–9) or EU-GMP (Grade A–D). Lower ISO numbers are cleaner.
Cleanroom Cost
The total budget for a cleanroom, driven mainly by ISO class, area, scope and HVAC. Get an indicative figure with our cleanroom cost calculator or read the GCC cost guide.
Colony Forming Unit (CFU)
A unit used in microbial monitoring representing a single viable microorganism that grows into a visible colony. Air and surface CFU limits define the microbiological cleanliness of GMP grades.
Contamination Control
The overall strategy — design, gowning, airflow, cleaning and monitoring — used to keep particulate and microbial contamination below acceptable limits in a controlled environment.
Coving
A curved (radiused) join between wall-floor, wall-wall and wall-ceiling surfaces that removes 90-degree corners where dust collects, making a cleanroom easier to clean. Standard on quality modular cleanroom panels.
Differential Pressure
The pressure difference maintained between adjacent rooms so air always flows from cleaner to less-clean areas. A typical cascade is around 10–15 Pa between grades.
Downflow
Vertical, top-to-bottom airflow that sweeps particles down and out of the work zone. Used in unidirectional (laminar) cleanrooms and biosafety cabinets.
EU-GMP Annex 1
The European Good Manufacturing Practice guideline for sterile medicinal products, defining Grades A–D and contamination-control expectations. See our guide on Annex 1 grades vs ISO 14644.
Face Velocity
The speed of air passing through a filter face or opening (such as a fume-hood sash), usually expressed in m/s. It is a key parameter for containment and unidirectional flow.
Fan Filter Unit (FFU)
A self-contained ceiling module with a fan and a HEPA/ULPA filter that delivers clean, uniform air into the room. The number of FFUs is set by the required air changes and HEPA coverage.
Filter Integrity Test (PAO/DOP)
An in-place test that challenges an installed HEPA filter with an aerosol to confirm it has no leaks and meets its rated efficiency. Part of cleanroom validation.
GMP (Good Manufacturing Practice)
The quality system and regulations ensuring products are consistently produced and controlled to quality standards. Pharmaceutical cleanrooms are designed to suit GMP requirements.
Gowning
The disciplined procedure of donning cleanroom garments (coverall, hood, mask, gloves, overboots) in a set sequence to minimise the particles and microbes people shed into the cleanroom.
HEPA Filter
A High-Efficiency Particulate Air filter that removes at least 99.97% of particles at 0.3 microns. HEPA filtration is the backbone of cleanroom air cleanliness.
Humidity Control
Maintaining relative humidity within a defined band (often 45–60% RH) to protect product, reduce static and control microbial growth — important in hot, humid Gulf climates.
HVAC
Heating, Ventilation and Air Conditioning — the system that controls a cleanroom’s temperature, humidity, airflow, filtration and pressure cascade. It is usually the largest single cost driver.
IQ / OQ / PQ
The three validation stages: Installation Qualification (built and installed correctly), Operational Qualification (performs across its operating range) and Performance Qualification (performs under real production). We support your IQ/OQ/PQ validation.
ISO 14644
The international standard series for cleanrooms and controlled environments, defining airborne-particle classification (ISO Class 1–9) and testing methods. ISO 14644-1 sets the class limits.
Isolator
A sealed enclosure providing a Grade A environment with its own filtered air, allowing aseptic work without exposing product to the surrounding room. Common in sterile pharmaceutical filling.
Laminar / Unidirectional Flow
Air moving in parallel streamlines at uniform velocity (typically around 0.45 m/s) that sweeps particles away in one direction. Required for the most critical (ISO 5 / Grade A) zones.
Modular Cleanroom
A cleanroom built from prefabricated wall and ceiling panels and components that can be assembled, expanded or relocated quickly — the system Pak Gusu manufactures and exports.
Negative Pressure
A room held at lower pressure than its surroundings so air flows inward, containing hazardous or contaminating material (such as potent compounds or pathogens) inside the room.
Non-Viable / Viable Particles
Non-viable particles are inert airborne particles counted for ISO classification; viable particles are living microorganisms counted (as CFU) for GMP microbial limits. Cleanrooms control both.
Particle Count
A measurement of airborne particles per cubic metre at specified sizes, taken with a particle counter to verify the room meets its ISO class.
Pass Box / Pass-Through
A small interlocked chamber set into a wall to transfer materials between rooms without people entering, preserving the pressure cascade. Dynamic versions add HEPA filtration. See our pass-through chambers.
Positive Pressure
A room held at higher pressure than its surroundings so air flows outward, keeping contamination from entering — the norm for most pharmaceutical and product-protection cleanrooms.
Pressure Cascade
A planned sequence of differential pressures across connected rooms so air always moves from the cleanest to the least-clean space, protecting the critical zone.
Recovery Time
The time a cleanroom takes to return to its rated cleanliness after a disturbance such as a contamination event. A key ISO 14644 performance test for non-unidirectional rooms.
Return Air
Air drawn back from the cleanroom (via low-wall or ceiling grilles) to the AHU to be re-filtered and recirculated, reducing energy use versus 100% fresh air.
Sandwich Panel
An insulated cleanroom wall or ceiling panel with two facing skins (such as powder-coated steel) bonded to a core (PU/PIR, rockwool or honeycomb). The building block of a modular cleanroom envelope.
SFDA
The Saudi Food and Drug Authority, the regulator for pharmaceutical and medical products in Saudi Arabia. Our cleanrooms are designed to support SFDA submissions.
Smoke Study (Airflow Visualisation)
A test using visible smoke to confirm airflow direction and that air sweeps cleanly from supply to return with no dead spots — often required for Grade A aseptic areas.
Terminal HEPA
A HEPA filter installed at the point of air entry into the cleanroom (in the ceiling), rather than at the AHU, giving the cleanest possible final filtration.
Turbulent / Non-Unidirectional Flow
Mixed airflow that dilutes and removes contamination through many air changes, used in ISO 6–8 / Grade B–D rooms where full laminar flow is unnecessary.
ULPA Filter
An Ultra-Low Particulate Air filter removing at least 99.999% of particles at 0.12 microns, even finer than HEPA, used in the most demanding ISO 3–5 applications.
Validation
The documented process of proving a cleanroom consistently performs to its requirements, via IQ/OQ/PQ and tests such as particle counts, filter integrity, airflow and recovery. We deliver validation-ready cleanrooms.
VHP (Vapour-Phase Hydrogen Peroxide)
A bio-decontamination method that fills a sealed room or isolator with hydrogen-peroxide vapour to kill microorganisms. Surfaces and gaskets must be VHP-compatible.
Planning a cleanroom in the Gulf?
Get an indicative budget in seconds, or request an exact quote from our engineers.
Open the cost calculator →