Standard Group Barrier Isolator selection and why is it important

The Standard Group of Companies are a leading supplier of equipment into the Chemical and Pharmaceutical industries.

A key part of the portfolio includes the supply of Barrier Isolators which are pivotal as these devices provide a physical barrier between an employee, the environment and the process media.

Key considerations need to be discussed and agreed with any Barrier Isolator selection.

One of the first key considerations is the OEL level which is the Occupational Exposure Limit.

An OEL level is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials.

OEL categorisation

• OEL 1 - Harmful and / or low pharmacological activity
• OEL 2 - Harmful and / or moderate pharmacological activity
• OEL 3 - Moderately toxic and / or high pharmacological activity
• OEL 4 - Toxic and / or very high pharmacological activity
• OEL 5 - Extremely toxic and / or extremely high pharmacological activity)

The next key factor is the understanding of ISO14644-1

ISO 14644-1:2015 specifies the classification of air cleanliness in terms of concentration of airborne particles in clean-rooms and clean zones and separative devices as defined in ISO 14644 -7.

The following table is used to adhere too and select the correct concentration level.

The next factors to consider is the combination of the following: -

Design type:-

• Flexible
• Rigid

Pressure type:-

• +VE pressure
• -VE pressure

A Flexible isolator is generally used under -VE pressure, therefore the pressure is less inside the isolator than the outside environment, which will protect the operator as harmful toxins cannot escape the enclosed environment.

The design of a flexible isolator includes: -

• Made of plastic thin films
• Generally made of PVC
• Operator friendly
• Made to any shape and size
• Non compatible with most of the solvents

Flexible isolators can be used in either API /  Bulk drug manufacture or Formulation applications.

Typical applications include: -

• Granulation Isolator
• QC Isolator
• Milling & Blending Isolator
• Pack off Isolator
• Reactor Charging Isolator
• Sieving & Weighing Isolator

Flexible isolators are normally used with an OEL level between 1 and 4

A Rigid Isolator is used with either +VE or -VE pressure.

The general design of a rigid isolator has the following attributes: -

• Rigid and sturdy
• Long life
• Withstand corrosive environment
• Generally made of SS 316L

Typical applications include: -

• Micronizes
• Multi-milling
• Pulverising
• Jet milling, Sieving and Weighing
• Handling Cytotoxic drugs
• Oncology drugs and Pack-off
• Aseptic and Asepsis processes
• Tablet presses and coaters

Rigid isolators are used with OEL levels between 1 and 5

When selecting the Pressure for an isolator the following needs to be considered:-

Positive pressure involves the following; -

• Designed to maintain positive pressure inside
• Used when the product is sterile and maintaining an aseptic process.
• Product protection is more important than environment or employee.
• Controlled atmosphere similar to a sterile environment

Negative pressure involves the following: -

• Designed to maintain negative pressure inside
• Used when the product is toxic
• Operator protection is more important than process media
• To prevent contamination of the external environment

In summary when selecting a barrier isolator, the following items need careful consideration: -

• OEL level
• Understanding of air cleanliness (ISO14644-1)
• Design
  
  • Flexible
  • Rigid
• Pressure
  
  • +VE
  • -VE

The Schematic Division specialise in all barrier isolator manufacture paying special attention to the design (DQ or Design Qualification).