Design Principles of Cleanrooms

Table of Contents

Theory
     Air Flow
     Materials
Application
     Clean Cube
     Clean Hood
     Clean Shower
     Clean Tent

Theory

Air Flow

ISO 5 (Class 100) and cleaner facilities are built based on laminar flow principles or, to be more specific; unidirectional filtered airflow in which parallel streams of air moving at a consistent velocity of 0.3 to 0.45 m/second are blown across the room with as little turbulence as possible.

The principle is based on ejecting any dust in the airflow using the shortest route. Generally, the greater the frequency with which the air is renewed, the lower the contamination accumulation in the room and the greater the rate at which the impurities are diluted.

There are two types of laminar flow; horizontal cross-flow or vertical down-flow. In a vertical down-flow cleanroom, air enters the room through filters in the roof and exits via vents in the base or floor of the walls. Air can only dissipate or be re-circulated from the base of the walls back up to the filtering system.

In a horizontal cross-flow cleanroom, filtered air enters the room from one side wall and is exhausted in the opposite sidewall and/or re-circulated via a bank of filters.

In both examples, the air velocity has to be determined at an adequately high level to guarantee that dust particles do not thermally travel from the laminar flow.

Materials

It is vital that the materials used in the construction of cleanrooms can be kept sterile and so they should be smooth in surface finish, have a low out gassing rate, and must not shed particulate.

Moorfield can adapt the materials used to match precise process requirements. Clean Environments also creates environments to meet electro static dispersion (ESD), micro-biological, and other hazardous guidelines.

Application

Clean Cube

Air flow

As with traditional cleanrooms, the Clean Cube can house either horizontal cross airflow or, more usually vertical down flow to match the customer’s process requirements.

Materials

The design of the Clean Cube is based on a modular aluminum frame and non-shedding, low static Perspex walling. The Clean Cube houses all the features found in a traditional cleanroom including; powder coated aluminum T section ceiling grid, sealed prismatic light units, anti-static vinyl flooring, vinyl faced ceiling tiles, PVC faced doors, PVC exhaust vents etc.

Clean Hood

Air flow

The Moorfield laminar flow hood can support horizontal cross airflow or, more usually vertical down flow to match the customer’s process requirements.

Materials

The design of the Clean Hood is based on a modular aluminum frame and non-shedding, low static Perspex sides. The electrics pack is placed at a high level into a white PVC conduit trunking.

Clean Shower

Air flow

The Clean Shower can support either horizontal cross airflow or, more generally vertical down flow to match the customer’s process needs.

Materials

The Clean Shower design is based on a modular aluminum frame with a non-shedding, low static Perspex curtain wall (also referred to as soft wall). The Clean Shower can house a traditional cleanroom ceiling including; vinyl-faced ceiling tiles, a powder coated aluminum T section ceiling grid, and sealed prismatic light units. The Clean Shower can also utilize Clean Environments’ non-shedding, low static Perspex walling.

Clean Tent

Air Flow

The Clean Tent functions on the economic principle of clean conditions at the workstation area (i.e. point-of-use) utilizing horizontal cross air flow, as in a conventional cleanroom but also using the positive pressure produced to maintain tent inflation. Air enters the work cabin via the filter at workstation level and moves in a laminar flow across the workstation envelope.

At the fringes of the envelope, positively pressurized air diverges evenly toward the zipper in the skirt, therefore, preventing back eddies returning contamination to the envelope. At the end of the laminar flow stream, air is passed through to the gowning chamber and exhausted to ambient or gathered via exhaust vents and redirected to be returned under pressure to recharge the HEPA.

Using this technique, high-quality air is transported to the workstation area (i.e. where it is needed) without the necessity for 100% wall/ceiling filtering.

Materials

The Clean Tent utilizes the latest advances in textile technology which have enabled synthetics to supersede solid based composites in both technology and performance resulting in a lightweight, low particulate portable work cabin that can generate a superior quality clean environment for the user at a very reasonable price.

This information has been sourced, reviewed and adapted from materials provided by Clean Environments.

For more information on this source, please visit Clean Environments.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this article?

Leave your feedback
Submit