Aseptic Cleanroom with
Sanitisation Mode ISO 14644-1

The Customer

Due to an NDA we are unable to disclose details of the customer.

The Brief

To design, supply and install a bespoke aseptic cleanroom to maintain ISO7 in both normal operation and during harsh sanitisation process.


The room has been designed to process pharmaceutical materials, which at regular intervals is cleaned down and sanitised with +80°c water and steam.

The Solution

The room is an extension of an existing cleanroom facility, which operates for 50 weeks of the year 24/7 maintaining tight temperature control of 21°c (+/‐ 2°c), humidity of 50% RH (+/‐ 10%) with a positive pressure of 30pa. The design brief was to extend the facility to incorporate a material mixing and preparation process previously outsourced. This was to meet the classification standards of the existing room but also to meet the demands of the area being sanitised while maintaining validation conditions.


The standard method of sweeping the air in the cleanroom is to introduce the air at high level and drag it across and down to low level achieving an air change rate of the room of approximately 25 air changes per hour.


Consideration had to be made towards both the high level of moisture and physics of the steam rising during sanitisation.


In sanitisation mode, dampers on all of the return air points at low level close down 95% and high level dampers open. This forces the air to drop then sweep upwards with the rising steam in the room.

The low level stays open partially to keep air flow through the lower sections of duct to reduce condensation in these legs.


In sanitation mode the fresh air damper opens to 100% and closes the return air path to the AHU, this forces conditioned and filtered air into the space rejecting the dirty wet air to atmosphere.


A total of 11 motorised dampers are choreographed by a bespoke control system to seamlessly operate under a simple 2 button operator’s panel for just normal and sanitation modes.

In addition to the main system controls, the AHU incorporates an inverter drive linked and controlled by pressure and airflow sensors in the duct to maintain a constant volume and pressure regardless of the filter conditions.


Energy efficiency technology incorporated into this project included:

  • Inverter drives.
  • EC fans.
  • Chilled water cooling from a Daikin chiller.
  • LTHW heating sourced from waste heating on the plant process.
  • Trend interfaced BMS controls offering system characteristics and filter degradation monitoring.

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