Using particle counters to evaluate and keep track of minienvironments is an established practice in the cleanroom manufacturing process. Generally, a particle counter is employed as the principle device to complete the testing, characterization and fine tuning process. This is normally the same particle counter used to monitor the main cleanroom

Increase in Continuous Monitoring

Increasingly, certain risk factors are causing manufacturers to opt for continuous particle counting to monitor their minienvionments. Continuous particle counting methods include dedicated particle counting and sequential sampling system.

Dedicated particle counting typically involves a remote particle counter. Lacking many of the features of a portable device, a remote particle counter has its data recorded and displayed by an external computer or other mechanism. The dedicated particle counter is connected to the minienvironment internally or externally with the sample probe situated at a specific location inside the minienvironment.

A sequential sampling system is often referred to as Manifold Particle Counting System or Multiport Sampling System. As its name indicates, it allows a single particle counter to sample many locations in sequence.

Here’s how it works: The particle counter is positioned in a set location attached to the Multiport Sampling System. Tubes connect to multiple areas in the cleanroom or minienvironments. An external blower draws air from the tubes on a continuous basis.

Ultimately, the particle counter samples from each location one tube at a time. Sampling times typically represent the sampling of one cubic foot of air. Multiport Sampling Systems generally can connect up to 32 sample locations to a particle counter.

MiniManifold Provides a New Solution

There are several disadvantages with dedicated and manifold particle counting that have given rise to a new solution. A single particle counter or particle sampling location can’t adequately monitor the entire minienvironment. Adequately monitoring the full environment requires multiple particle counters—which adds considerable expense.

However, a MiniManifold has been developed to solve this dilemma. Essentially, it allows a single particle counter to monitor up to six locations continuously in a single minienvironment or process tool, while correctly counting particles from each location.

The MiniManifold is made up of a manifold sequencing system with a built-in controller and external blower. The controller communicates with the particle counter and can interface with a computer system or process tool. The blower, which can be remotely installed from the manifold, draws from all six locations at the same time.

The MiniManifold also has a buffer to store data records for each location. This greatly increases the coverage of a single particle counter inside this type of equipment. The enhanced coverage, in turn, increases the chance of detecting a contamination event.

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