Quick answer: Medical device manufacturing needs low, stable humidity where moisture changes a material or a process: moisture-sensitive polymers before moulding, hydrophilic and other coatings, adhesive bonding and curing, diagnostic strips and reagents, device electronics, and sterile-barrier packaging. Many of these need 10–30 % RH or a dew point below about 0 °C, which a refrigerant dehumidifier cannot reach efficiently, so desiccant systems are used, often supplying a cleanroom through its air handler. Start from the product's failure mechanism and specification, then design, install and validate the system (IQ/OQ/PQ) under your quality system.
Quick answer
- Typical needs: 10–30 % RH for diagnostics and some coatings; low dew points for polymer drying; steady 30–50 % RH for general cleanrooms.
- Desiccant units reach low dew points independent of room temperature.
- Validate: installation, operation and performance qualification, with calibrated monitoring.
Where humidity matters in medical devices
| Process or product | Why moisture matters | Typical control |
|---|---|---|
| Moulding hygroscopic polymers (nylon, PC, PEEK, PET and others) | Absorbed water causes defects during moulding | Resin dryers with very dry air (low dew point) at the machine |
| Hydrophilic and drug coatings | Humidity changes coating thickness, curing and performance | Low, stable RH in coating rooms |
| Adhesive bonding and curing | Many adhesives are humidity-sensitive | Process-specific RH range |
| Diagnostic strips, reagents, test kits | Moisture degrades reagents | Often 10–30 % RH in manufacture and packing |
| Device electronics | Moisture-sensitive components; corrosion | Dry storage per J-STD-033; controlled assembly RH |
| Sterile barrier packaging and sealing | Material moisture affects seal strength | Stable conditions in packing areas |
| Storage of finished devices | Label, adhesive, packaging stability | Per product labelling |
The product specification and risk analysis set the actual limits.
Why desiccant systems
- They reach low dew points (well below 0 °C) without coil icing.
- Performance does not depend on a warm room; cleanrooms are often 18–22 °C.
- They can treat make-up air for a cleanroom air handler, so the whole suite stays dry.
- Reactivation heat can use available steam or hot water.
See how a desiccant dehumidifier works and low dew point selection.
System design for cleanrooms and controlled rooms
| Element | Design point |
|---|---|
| Location | Desiccant unit on the make-up or return air of the air handler, outside the clean area |
| Pre-cooling | Removes most moisture from warm make-up air first |
| Post-cooling | Removes heat added by the desiccant process |
| Filtration | Pre-filters before the rotor; final HEPA filtration in the cleanroom system |
| Pressure | Cleanroom pressure cascade maintained |
| Leakage | Tight construction, air locks; leakage is the largest load at low RH |
| Materials | Cleanable, corrosion-resistant casings and ducts |
| Controls | Dew point or RH control with alarms and data logging |
Validation and records
Medical device manufacturers work under quality systems such as ISO 13485 and, in the US, FDA's quality management system regulation, which require controlled, monitored environments where they affect product quality. For humidity systems this typically means:
- IQ (installation qualification): equipment installed as designed, documentation and calibrations in place;
- OQ (operational qualification): each function and alarm works across the operating range;
- PQ (performance qualification): the room holds its limits under real production, over a defined period;
- ongoing monitoring with calibrated sensors, alarm records and periodic review.
Information to prepare before a quote
- Product and process steps that are humidity-sensitive, with limits
- Room sizes, cleanroom class, temperatures, air change rates and pressure cascade
- Make-up air volume and outdoor design conditions
- Number of people and doors
- Available utilities for reactivation (electric, steam, hot water)
- Validation and documentation requirements
Our desiccant dehumidifiers cover process airflows from 93 to 3,000 m³/h; larger and lower dew-point duties need a project-specific system.
FAQ
Frequently asked questions
What humidity is required in medical device manufacturing?
It depends on the product and process: often 30–50 % RH in general cleanrooms, and 10–30 % RH or lower dew points for diagnostics, coatings and polymer drying.
Why use a desiccant dehumidifier in a cleanroom?
To reach low humidity at normal cleanroom temperatures, which refrigerant units cannot do efficiently.
Does a cleanroom standard set humidity limits?
Cleanroom classification standards focus on particles; humidity limits come from the product, process and quality system.
What validation is needed for a humidity control system?
Typically IQ, OQ and PQ under the manufacturer's quality system, plus calibrated ongoing monitoring.
Sources
- ISO 13485, Medical devices: quality management systems.
- US FDA, Quality Management System Regulation (21 CFR Part 820).
- IPC/JEDEC J-STD-033.
- ASHRAE Handbook—HVAC Systems and Equipment, Desiccant dehumidification.
