Isolator vs. Downflow Booth: Choosing the Right Containment Solution
When planning a new process or upgrading an existing one, the question is not only how to handle powder safely, but also:
- How to protect operators
- How to protect the product
- How to maintain compliance without unnecessary complexity or cost
For many facilities, this decision centers on a key choice: Is a downflow booth sufficient, or is an isolator required—and in some cases, is a combination of both the best approach?
Shared Purpose: Containment and Protection
Both downflow booths and isolators are designed to:
- Reduce airborne exposure to powders and aerosols
- Help facilities meet Occupational Exposure Limits (OELs) for potent compounds
- Support regulatory expectations in pharmaceutical, biotech, chemical, and related industries
In practical terms, both technologies aim to safeguard people, product, and environment. They simply do so at different levels of containment:
- Downflow booth: An open, controlled workspace
- Isolator: A fully enclosed, sealed workspace
The appropriate choice depends on material potency, how the product is handled, and whether sterility is required.
Downflow Booths
A downflow booth is a walk-in work area in which clean, filtered air is supplied from the ceiling and drawn downward past the operator into low-level extraction grilles. This controlled airflow pattern directs dust and particles away from the operator’s breathing zone and into HEPA filters.
CPS downflow booths are typically:
- Self-contained systems with integrated blowers, HEPA filtration, controls, and lighting
- Designed to provide a safe working environment for bulk powder handling, sampling, weighing, and dispensing
- Used to protect both operators and the surrounding facility from airborne powders during open handling operations
Typical Applications for Downflow Booths
Downflow booths are often selected when open access to the product is necessary and strong containment is still required. Common uses include:
- Weighing and dispensing APIs and excipientsSampling from drums or containers
- Splitting or charging batches into smaller containers
- General open transfers where powder dust may be generated
CPS designs downflow booths to meet targeted OELs for medium- to higher-potency compounds, frequently suitable for OELs down to approximately 50 – 100 µg/m³ (possibly lower) in non-sterile operations, depending on the specific process and controls in place.
When a Downflow Booth Is Appropriate
A downflow booth is often a suitable choice when:
- The product is potent but not ultra-high-potency
- The process is non-sterile and does not require aseptic conditions
- Operators require frequent, direct access to open containers
- An existing room needs to be upgraded without installing a full cleanroom or isolator
- A cost-effective, flexible containment solution is needed to support multiple workflows
Isolators
An isolator is a fully enclosed workspace with rigid, transparent walls, glove ports, and closely controlled airflow and pressure. Operators work through glove ports, without direct physical contact with the product.
CPS aseptic isolators, developed in collaboration with ICS, are designed for low OEL and high-containment applications, particularly where both product sterility and operator protection are critical.
Key characteristics of isolators include:
- A sealed, rigid enclosure equipped with glove ports
- Internal pressure control (negative pressure for potent/toxic materials, positive pressure for aseptic product protection)
- Integrated decontamination systems, including options such as vaporized hydrogen peroxide (VHP)
- Capability to maintain clean air conditions around ISO 5/Class 100 or better, depending on configuration
Typical Applications for Isolators
Isolators are typically selected for the most demanding containment and sterility requirements. Common applications include:
- Final weighing and dispensing of highly potent APIs (HPAPIs)
- Sterile sampling, compounding, or quality control testing
- Cytotoxic or hormonal product handling
- Aseptic fill-finish and sterile material transfer
- Hazardous chemical handling where exposure must be maintained below 1 µg/m³ or at even lower OELs
CPS has also integrated isolators into larger automated systems, such as lifting drums into decontamination and delidding isolators, then discharging material through a screener into a blender vessel. These solutions combine high-level containment with notable gains in efficiency and operator safety.
When an Isolator Is the Preferred Option
An isolator is typically the better choice when:
- The material is ultra-potent, cytotoxic, or highly sensitizing
- Product sterility is as important as operator safety (for example, aseptic manufacturing)
- The target OEL is below 1 µg/m³, or very strict containment performance is required
- Any operator exposure, even brief, is unacceptable
- A fully closed system is required to tightly control air quality, pressure, and decontamination
Comparing Downflow Booths and Isolators
The decision between a downflow booth and an isolator can be approached through a few key questions:
1. Material Potency
- Moderate to high potency, non-sterile operations: Often suitable for a downflow booth.
- Highly potent / HPAPIs / cytotoxic materials: Usually require an isolator.
2. Sterility Requirements
- No sterility requirement; focus is on operator and room protection: A downflow booth or other general containment solution may be appropriate.
- Aseptic or sterile conditions are required: An isolator (and potentially RABS or specialized aseptic systems) is typically the natural choice.
3. Degree of Process Openness
- Frequent manual manipulation and open handling: Downflow booths provide open access and good ergonomics while maintaining strong protection.
- Limited access and tightly controlled, defined steps: Isolators perform well in these environments, especially when integrated with automated transfers or robotics.
4. Facility Context: Retrofit vs. New Build
- Upgrading an existing non-sterile room: A downflow booth can often be installed as a self-contained upgrade with minimal changes to the building structure.
- Designing a new high-containment or aseptic suite: A combination of isolators, downflow booths, and custom transfer systems may be used to achieve a fully integrated solution.
In many cases, the optimal solution is not a single technology, but a carefully designed combination—for example, using an isolator for high-potency weighing that feeds into a downflow booth area where less potent blends are packaged or kitted.
How Custom Powder Systems Supports the Decision
Selecting between a downflow booth and an isolator involves more than comparing specifications. It requires a clear understanding of the entire process, including:
- The materials handled today and those anticipated in the future
- How material moves from receipt to finished product
- Where the greatest exposure risks, bottlenecks, or cleaning challenges occur
CPS specializes in custom powder handling and containment systems, including downflow booths, isolators, IBCs, transfer systems, and fully integrated process lines.
We also work closely with Integrated Containment Systems (ICS), our sister company dedicated to isolators, gloveboxes, and specialty enclosures. Together, we design solutions that balance containment performance, ergonomics, cleanability, and day-to-day workflow.
Next Steps
If your team is evaluating whether an isolator, a downflow booth, or a combination of both is appropriate for your application, CPS can assist by:
- Reviewing your OEL targets and process steps
- Identifying where each containment technology fits most effectively
- Helping determine whether a booth, an isolator, or a hybrid approach offers the safest and most economical path forward
When you are ready, sharing a process sketch, current challenges, and target OELs will allow CPS to help translate your requirements into a practical, right-sized containment strategy.
