Quality Engineered Structures Mechanical Image 1
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Cleanroom Mechanical Systems
Precise Temperature and Relative Humidity Control

Quality Engineered Structures Mechanical Image 2 Cleanroom air handling systems control the air changes, temperature, relative humidity and pressurization of each cleanroom zone. Multi zone cleanrooms may require the use of more than one unit. The core of any cleanroom operating system they require cleanroom specific knowledge to design and engineer. They must work in a coordinated method with the cleanroom filtration system, process exhaust systems, and geographical ambient climate to deliver precise temperature and relative humidity control.

Typically operating 24/7 they must feature robust components, ease of maintenance, and in critical operations should be engineered with 100% redundancy and back up electrical systems.


Cleanroom Air Handling Systems:
  • Direct Expansion air handling systems work by circulating a refrigerant through a expansion coil. Humidity control is typically regulated by a separate system that reheats the air to regulate humidity. The most economical air handling systems available they can also be the most energy intensive due to the reheat requirements.
  • Chilled Water or Glycol generates cold water or glycol, which is then pumped to coils located in the air handling units to cool and dehumidify the air stream. There are small packaged air-cooled chillers in addition to the larger chillers common in central chilled water plants serving large cleanroom processes. Less energy intensive than direct expansion type systems their initial investment can be a hindrance.
  • Desiccant Humidity Control systems consisting of an active desiccant wheel, a reactivation heat source, and supply and reactivation fans may be required when relative humidity requirements drop below 55% depending on geographical location.
  • Commissioning and Validation should be completed on all cleanroom air handling systems to assure compliance with design specifications. Testing and balancing, airflow certification, and particulate counts should meet design specifications but may require adjustment when fully operational due to process fluctuations.


A comprehensive design and energy analysis should be utilized to consider all factors in selecting the correct type of system. Factors affecting the decision to select DX Unitary or Chiller-Based Applied systems include:
  • Installed Cost
  • Energy consumption
  • Space requirements
  • Freeze prevention
  • Precision
  • Building height, size, shape
  • System cooling and heating capacity
  • Centralized maintenance
  • Stability of control
  • Individual tenant billing


Cleanroom mechanical air handling systems are the core of the cleanroom environment. Engineered to condition large quantities of both recirculated and fresh air supplies they must operate 24/7 at peak efficiency while maintaining close tolerance control over particulate, pressurization, temperature, relative humidity and atmospheric variables.

Specific industries, biotechnology, pharmaceutical, medical device, and electronics are all regulated by standards and regulatory agencies requiring specific control over environmental conditions for the performance of their processes. Cleanroom mechanical air handling systems deliver this control. Control of high purity air systems involve distinct tolerances for each industry. Cleanroom mechanical systems can be engineered to provide:

  • Particulate Size and Counts to 0.3 µm
  • Cascading Pressurization, Positive or Negative
  • Unidirectional or Non-Unidirectional Airflow Patterns
  • Precise Temperature Controls Typically ± 5° or Greater
  • Precise Relative Humidity Control Typically ± 5% or Greater
  • Electronically Enhanced Microbial Bioburden Control
  • Ionization for Electrostatic Control

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