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They belong to two different standard systems: "grade c" falls under GMP standards, whereas "iso class 7" falls under iso 14644 standards.The ISO system classifies cleanrooms based on airborne particle counts, whereas GMP standards are more rigorous; in addition to particle count requirements, GMP imposes strict regulations regarding the production process, manufacturing workflows, and the layout of personnel and material flow paths.
More importantly, it is far more than a simple particle concentration rule. It serves as a full-process risk management system covering microbial control, staff operation norms, pressure differential gradients and targeted monitoring plans.On the flip side, ISO 7 follows the iso 14644-1:2015 standard. Frankly, it only focuses on particle-based cleanliness classification with no extra risk control requirements.Their particle indicators do overlap — grade c at rest matches ISO 7 parameters. Even so, the difference between Grade C and iso 7 cleanroom is huge in actual engineering practice.
Most project tenders adopt the wording “Grade C (iso class 7 at rest)”, yet many ignore the real gaps. The core difference between Grade C and iso 7 cleanroom lies in operation status, microbial standards, validation scope and regulatory audit priorities.Drawing on Deiiang™’s practical experience in 18 domestic sterile preparation projects, this article analyzes Grade C and ISO 7 in detail.It sorts out their core differences, parameter gaps, applicable scenarios and feasible implementation solutions for cleanroom construction.
What are Grade C and iso class 7?
Definition and Origin of Grade C
The GMP standards for sterile medicinal products adopted in China are aligned with the EU GMP Annex 1 (2022 version); gmp grade C places greater emphasis on both cleanliness and the control of production process flows, rather than merely requiring the control of airborne particle counts.In pharmaceutical production, Grade C and ISO 7 Cleanroom serve totally different scenarios.
In the pharmaceutical industry, Grade C is typically applied in:
Product formulation, mixing, and non-sterile filtration
Background filling and capping zones for terminally sterilized injectables
Raw Material Weighing and Temporary Storage Area
Aseptic filling and product preparation area
During the on-site inspection for GMP certification, the NMPA examines not only dust particle counts but also parameters such as temperature, humidity, pressure gradients, and airflow patterns; furthermore, it conducts a comprehensive review of personnel, material, and waste flows, as well as microbiological data.
Definition and Origin of ISO 7
ISO 7 is one of nine cleanliness tiers from ISO 14644-1:2015, and this single-particle standard makes up a big part of the difference between Grade C and ISO 7 Cleanroom.
It has hard particle limits for sampling: 352,000 ≥0.5μm particles/m³, plus 2,930 ≥5.0μm particles/m³. Unlike Grade C and ISO 7 pairings only common in pharma, ISO 7 works for many other fields:
Non-implant medical device production
Electronics such as OLED and photovoltaic parts
Biobanks and lab animal housing spaces
Core production areas for food and cosmetics
Unlike pharma-focused Grade C, ISO 7 serves as a cross-industry standard. It’s commonly used for medical device manufacturing, electronics assembly, biobank facilities, plus food and cosmetic production.
Localized Perspective: How Are These Standards Interpreted in China?
It’s very common to see Grade C and ISO 7 listed together in Chinese pharmaceutical design and tender documents. Most local projects adopt the typical description: “Grade C (static compliance with ISO Class 7)”, which easily confuses practitioners about the difference between Grade C and ISO 7 Cleanroom.
They sometimes fail to clearly distinguish between the requirements for static and dynamic Grade C conditions; static Grade C complies with the ISO Class 7 particle standard, whereas dynamic Grade C is equivalent to iso class 8.The difference between Grade C and ISO 7 Cleanroom is extremely practical. ISO 7 only evaluates air cleanliness data. In contrast, Grade C adds strict requirements on microbial testing, stable pressure differentials, air change rates, and standardized personnel and material management. The core difference between Grade C and ISO 7 Cleanroom is straightforward. ISO 7 merely measures air purity, while Grade C enforces strict operational management for pharma use.
Standard Parameter Comparison: Grade C vs ISO 7
Particle Limits (At Rest / In Operation vs ISO)
One major difference between Grade C and ISO 7 Cleanroom lies in particle testing standards.
GMP Grade C sets separate particle standards for at-rest and occupied working modes. ISO 7 under ISO 14644-1 has no such two-group division. Key limit data referencing EU and China GMP is shown in the table below.
| Parameter | Grade C (at rest) | Grade C (in operation) | ISO 7 |
|---|---|---|---|
| ≥0.5 μm (particles/m³) | 352,000 | 3,520,000 | 352,000 |
| ≥5.0 μm (particles/m³) | 2,900 | 29,000 | 2,930 |
Note 1: Figures cited pull from EU GMP Annex 1 (2022) and ISO 14644-1:2015 guides.
Note 2: Numbers shift a little across updated editions, so double-check the newest official docs every time.Air Change Rates / Airflow / Pressure Differential
You won’t find hard-set ACH numbers written into official specs, so site teams rely on real-world field standards for Grade C and ISO 7 Cleanroom — one clear practical difference between Grade C and ISO 7. Data pulled from eighteen Deiiang sterile build projects finished 2023 through 2025:Typical on-site ACH sits 25–35; the full industry acceptable window runs 20–40
Pressure gaps stay 10–15 Pa between corridor and Grade C, same split from Grade C to Grade B
H14 HEPA filters (99.995% capture at 0.3μm) go into more than 90% of their builds
Jason.peng, product designer at Deiiang, shares their go-to trick for Grade C and ISO 7 zone planning. Typically, the air change rate for Grade C areas is set at 30 ACH; however, considering the dust particles generated by equipment, personnel, and production processes under actual operating conditions, it is recommended to increase the rate to 35 ACH.
Microbiological Control & Monitoring Frequency
The core difference between Grade C and ISO 7 Cleanroom comes down to microbial requirements, a key detail separating Grade C and ISO 7.Grade C has specific dynamic microbiological requirements:
Viable air: ≤ 100 CFU/m³
90mm 4-hour settle plates: ≤ 50 CFU
55mm contact plates: ≤ 25 CFU each
Although the ISO 14644-1 standard (ISO Class 7) establishes specific limits for airborne particle counts, GMP, USP <797>, and USP <800> impose additional requirements for controlling bioburden. Therefore, a grade c cleanroom is defined as an ISO Class 7 environment supplemented by requirements for microbiological monitoring and the assessment of personnel, equipment, and production processes.
Application Scenarios: When to Choose Grade C vs. ISO 7 Only?
Pharmaceutical / Sterile Preparation Scenarios
Moderate-risk sterile drug tasks have to run under Grade C rules:
Mixing batches before aseptic filling for items without final sterilization
Filling surroundings for injectables that go through terminal sterilization
Unpacking and prepping sterile auxiliary supplies
Short-term storage of washed equipment that hasn’t been sterilized yet
For areas dedicated to oral tablet blending, powder mixing, or routine buffer storage, compliance with ISO Class 7 cleanliness standards is sufficient; meeting GMP Grade C standards is not required.
Medical Devices / Biobanks / Electronics
Most non-implant medical device packaging and assembly lines use plain ISO 7 standards. Any implantable gear or products touching human blood need Grade C’s microbial control rules, or even stricter Grade B.
Electronics work like OLED screen and semiconductor packaging rarely deals with biological contamination, so teams only build to ISO 7. No mandatory microbe testing or strict gmp gowning cuts the extra costs tied to full Grade C compliance.
Decision Logic Flowchart
Deiiang Actual Project Case Study
Project Background
Project Name (codename): This 2024 upgrade project targeted a biopharma sterile injectable plant in Jiangsu, East China.Location: Jiangsu Province, ChinaScale: Its total cleanroom space hits around 3,500 m², with 1,200 m² dedicated Grade C and ISO 7 Cleanroom zones.Objective: The core goal was fixing the old iso 8 layout to reach Grade C and ISO 7 running-state standards, to satisfy domestic China GMP sterile rules and pass EU GMP site inspection.
Project Challenges
Four tricky hurdles came with building this Grade C and ISO 7 Cleanroom. The original 3.6m low ceiling left barely any room for ducts to hit the target 30 ACH. The client also refused full production shutdowns, so all construction had to roll out in phases. We had to align Grade C GMP rules, ISO 7 particle limits and their extra strict pressure backup system all at once. Hot sterilizers and mixing tanks also messed with steady temperature and humidity regulation.
Deiiang's Solutions
Layout Optimization & Airflow Organization
We tucked heat and particle-heavy machines into separate secondary spaces, simplifying staff and material routes in core production zones. Ceiling air supply paired with wall-mounted return columns saved vertical space, delivering solid air exchange despite tight ceiling limits.HVAC & Filtration Configuration
Modular air handlers serve three to four rooms apiece with a spare 20% capacity buffer. H14 HEPA terminals cover all spaces, and extra ffus sit above high-risk spots to deliver enhanced local cleanliness for Grade C and ISO 7 compliance.Monitoring & Validation
More than 40 sensors tracking pressure, heat and humidity across all Grade C areas feed data straight into the EMS system.2024’s nine-month run data shows room pressure stayed within ±3 Pa of targets 95% of the time, while over 600 yearly particle sampling points saw under 0.5% out-of-spec readings.
Comparison Matrix: ISO 7 Only vs. Grade C Design
✅ Designed to Grade C (GMP) Requirements
Easier to pass GMP, EU GMP, and NMPA audits with clearer compliance boundaries.
Systematic microbial control, personnel behavior, and monitoring reduce product risk.
Allows for future upgrades to higher grades (e.g., local Grade B).
Enhances collaboration with multinational pharma and CMO/CDMO clients, improving "international readability."
❌ Designed Only to ISO 7 Particle Limits
Slightly lower initial investment, but retrofit costs to meet Grade C later are high (often 30–50% more).
Lacks systematic requirements for personnel, process, and microbiology, complicating quality risk assessments.
Creates ambiguous "interpretation gaps" during regulatory audits.
Weakens negotiation power for export-oriented or internationally audited projects.
Practical Recommendations: Meeting Both Grade C and ISO 7 in One Project
Key Decisions in the Design Phase
When writing the User Requirements Specification (URS),Do not simply cite the standard.Instead, the relationship between particle size limits and on-site GMP management requirements should be clearly explained in plain language.This avoids ambiguity or misunderstanding in the future.Example of suggested wording:
Cleanroom rating: gmp class c, which must of course comply with the EU GMP 2022 standard.
Separate clearly: Static acceptance testing adopts ISO 7 standard.Dynamic operations are performed using iso 8 particulate matter and microbial limits.This way, people won't apply the wrong values.
HVAC: The total cooling capacity of the system must be reserved, with 20-30% reserved as a backup.
Pressure gradient: General area → Level D → Level C → Level B, with a pressure difference of approximately 10-15 Pa between each level.
Validation & Routine Monitoring Recommendations
Based on Deiiang™'s practical experience across multiple Grade C / ISO 7 projects, we recommend addressing both standards at the following stages:
FAT/SAT: To ensure baseline cleanliness, an ISO 7 particulate matter test must be performed before and after installation,
IQ/OQ (Installation/Operational Qualification): Verify pressure differentials, temperature/humidity, and ACH against design values, and establish baseline data;
PQ (Performance Qualification): In order to create a "comprehensive environmental performance curve", under dynamic conditions (simulating worst-case production), while recording particulate matter + microorganisms + stress.
Deiiang™'s optimized approach: During PQ, for each Class C room, there are at least 2 particle sampling points and 2 microbial sampling points, monitoring for 3 consecutive batches, or running continuously for 7 days.
The data is used to establish Alert and Action Levels.
Partner with Deiiang to implement your Class C/ISO 7 project.
The concepts of Level C and ISO 7 standards can be difficult for many customers to understand at first glance. Therefore, we'll briefly explain the relationship between them.While Level C and ISO 7 standards originate from different standard frameworks, their robust engineering design and comprehensive validation ensure that they can work seamlessly together in any project.Level C standards cover overall environmental control—from process risk management to production areas.ISO 7, though, only lays out hard numerical particle cleanliness metrics to measure air quality.
A true understanding of the differences between class c cleanrooms and ISO class 7 cleanrooms in terms of compliance is fundamental to the successful completion of cleanroom projects.As your supplier, choosing Deyang™ has led to the successful delivery of over 18 local Class C/ISO 7 cleanroom projects across China. You'll work hand-in-hand with an experienced team. Our projects encompass biopharmaceuticals, sterile pharmaceuticals, medical devices, and health food processing, covering a wide range of cleanroom environments.You don't need to handle everything yourself; as a full-service partner, we will take care of all aspects and coordination with numerous suppliers.
Our one-stop service begins with needs analysis, followed by preliminary conceptual design, on-site construction, and finally, professional validation guidance. This comprehensive service enables our clients to meet multiple regulatory requirements at once, including EU GMP, China GMP, and ISO 14644, only exceeding the project budget.
📞 If you have any technical questions or would like us to arrange an on-site assessment, please feel free to contact Deyang™ product designer Jason Peng.
References
[1] EU GMP Annex 1 (2022) – Manufacture of Sterile Medicinal Products.https://www.gmp-compliance.org/files/guidemgr/2022_ann1_en.pdf
[2] ISO 14644-1:2015 – Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness by particle concentration.https://www.iso.org/standard/53394.html
[3] China GMP (2010 Revision) Appendix 1: Sterile Medicinal Products.https://www.nmpa.gov.cn/xxgk/fgwj/gzwj/gzwjyp/20110301094301743.html
[4] Deiiang™ Project Case: Henan Baihuikang Bio-Tech class 100,000 Clean Production Workshop.https://www.cleanroomequips.com/case/3332.html
[5] ISO 14644-1:2015 Particle Concentration Limits (Particle Measuring Systems).https://www.aimil.com/blog/cleanroom-classification-explained/
