Containment Strategy

The main and crucial reason organisations use containment systems is to make sure that their personnel is protected from the active compound; that they will not be sick or harmed in any way by the potent substance. The person responsible for ensuring that safety has to evaluate handling and producing processes of products such as certain powders, hormones, cyto-toxic or radio-pharmaceuticals.

Containment solutions are also needed because of legal requirements and the obligation to comply with Health and Safety at Work regulations. Organisations such as Medicines and Healthcare products Regulatory Agency (MHRA) or the FDA in US may require such systems depending on the type of products being handled.

The third main reason is control of migration. When weighing and dispensing a powder in one room, the containment solution you employ will help make sure the powder doesn’t travel into another room. Controlling the work environments will enhance the safety and protection of every employee.

There are several ways to achieve a controlled contained environment. The main categories of possible containment strategies include: general ventilation, downflow booths – with or without barriers and Isolators that may – or may not – have transfer ports and valves.

Deciding which system is needed at your facility will require a risk assessment. Assess the type of products, how dusty they are, how long the operators will be exposed to them and the quantities that will be handled. Such evaluation will help determine whether there will be a need for a localised exhaust ventilation, additional barriers or even isolators.

Extract Technology always recommends following the containment pyramid figure developed in the early 1990s. This pyramid is often used industry wide for this exact purpose – to determine the potential containment strategies.

Firstly, one has to incline the exposure potential – what are the quantities an operator would potentially have to handle? Grams are considered to be small quantities, kilograms – medium and large quantities are measured in tons. You will have to determine one key exposure factor.

The dustiness of the material is also crucial here. Sand-like products will have a low dustiness potential whereas products resembling finely granulated powdered sugar could blow around easily, placing them at the high end of dustiness level.

The last factor to consider in the upper section of the contamination pyramid is to measure the risk an operator will face is task duration. Short task durations are around 15 minutes; when people work with a compound for hours at time you’d classify that as long durations.

Determining these factors will allow you to establish the exposure potential as EP 1, 2, 3, or 4 as seen in the pyramid.

After you established that you will have to determine the occupational limit (OEL) for the specific product. The limits are broken into bands corresponding with quantities allowed per cubic meter of space, labelled A-F. Usually the product itself will list its band level.

Now you can find the best and most suitable control strategy. Knowing the exposure potential and band level, you can read horizontally to find the recommended strategy.

Downflow booths continually flow and filter the air inside to protect operators.

Downflow booths are steel enclosures that operators will have to step into to work with products that need containment. Air circulates and protects the operator by pushing any dust clouds downward and away from their breathing zone, into filters. The dust is kept inside, whilst the booth operates at slightly negative pressure, continually cleaning, recirculating and pulling air in from outside the room.

Downflow booths vary in size, ranging from 1.5m to 8m wide and various depths. After the booth is installed in the field, the containment line can be measured, determined and marked. The containment depth between the line and the back wall is where the airflow is most effective at protecting the operator. Areas outside this depth are not considered safe for the personnel working inside – and all operations should be performed as close to the back wall as possible.

Choosing the right size requires determining the types of activities that will take place inside, the types and footprint of the processing equipment located within and number of operators working inside. For example, the size of any bulk containers inside the Booth, how products are weighed, packaged and delivered – all these factors have to be considered within the design process. Method of packaging affects sizing of the booth – eg. there is a big difference in handling containment between a product packaged in bucket size container and a product coming on a pallet. The way that product moves from one piece of equipment to another matters as well – does it go through a small mill during weighing, does it land in other containers? Answering all these questions will influence the final design of the containment solution.

You might also have a requirement for manipulation devices inside a downflow booth, eg. conveyor systems or drum handling equipment. Depending on the arrangement within your facility, filters can be accessed for safe change either from inside or outside. If located in a warehouse environment, your booth will need a positive pressure airlock installed on the front to keep the inside cleaner. As for booth’s own requirements, adequate utilities are necessary – chilled water is recommended for booth cooling and three-phase power is needed for the lights, high-efficiency fan drive motors, gauges, and for power inside the booth.

An isolator is an enclosure that contains a qualified controlled environment, sealed to a high standard of leak tightness. Used when products are so potent that a downflow booth couldn’t provide enough protection, Isolators contain the product inside while the operator works with it by placing their arms through glove ports.

When deciding in favour of an Isolator, a factor to consider is cleaning. The Isolator has to be totally neutralised before it’s opened to maintain equipment kept inside. No powder residue can be left as this could cause cross contamination to the next batch.

Isolators are equipped with safe change HEPA filters and fans operating at slightly negative pressure as well as pressure sensors and gauges that monitor the system. If a glove is breached, the fan speeds up to maintain the desired air flow and negative pressure to protect the operator. Users should perform leak testing on a regular basis, following procedures and protocols. A glove testing device might have to be procured alongside the Isolator to ensure safety.

Space is less of a concern when deciding for Isolator in favour of downflow booth however, adequate ceiling height and space around the Isolator is required for testing and maintenance. Another issue to consider beforehand is the size of doorway, room, and the pathway that would be taken during delivery if the Isolator is going into an existing lab.

Isolators require 3-phase power and 15-25 amps (depending on size), compressed air and cleaning liquid (based on the product – provide water for water-soluble products and solvents for solvent-based products).

As e.g. Extract’s Isolators are fabricated from 316L stainless steel and acrylic (complete with special coating), it proves cost-effective and reasonable to create a wooden mock-up construction to make sure the form and fit actually works, and operators can reach everything and perform all desired activities. Gaskets and glove materials are selected based on the compounds to be used inside the Isolator.

Answering the above five questions and considering all the mentioned factors influencing containment within your facility can help you improve the process of purchasing containment systems thus enhancing operators’ safety and the quality of the final product.