ISO-90-Monitoring-Head-Options 2


Different formats allow configuration to be adjusted to meet your requirements for continuous monitoring to suit your application

The ISO-90 monitoring head, which utilises the high efficiency slit-to-agar method, contains all the controls and mechanisms required to rotate the agar plate during the monitoring period.  The internal flow sensors in the head send signals to a separate vacuum source, which allows the air flow to be controlled very accurately. 

The ISO-90 monitoring head is 122mm diameter and 107mm from the clamp flange to the top of the inlet.

Differing requirements within RABs and isolators, and between different users, would usually demand the use of different instrumentation.  However, the ISO-90 head inlet can be configured to optimise the sampling parameters.  The default setting allows for 4 hours monitoring onto a single plate with a flow rate of 15 litres per minute, at a d50 rate of 0.53µ.

The operator can easily start, pause or stop a run by pressing a button located on the head.

A number of deployment formats are available for the head, to suit the application.  The chamber can also be supplied with robot compatible manipulation features, to meet the increasing use of robots within isolators.

ISO-90 Brochure


Let's discuss your requirements


The most effective way to achieve Annex 1 compliance could be to stay with your existing, proven, trusted and validated agar based methods

Very low d50 values

Exceptional biological efficiency

ImpactAir air monitors are based on the slit-to-agar method, which has very low d50 values of around 0.5µ with exceptional biological efficient and the ability to easily count real viable microbial events in CFU while being able to identify to species level.

ImpactAir Technology

Twin impingement probability reduced

Air is drawn at high speed through a narrow inlet. Particles and microbes are impacted on to agar in a rotating Petri dish.  Fresh agar is presented constantly, significantly reducing the chance of multiple microbes appearing as a single colony after incubation.

Time Correlated Results

Continuous monitoring using a 9cm agar plate

The rotating agar plate means results are time correlated. Whilst not timed to the second, localised growth on the plate can be time estimate based on its position on the plate.


A few societies and associations we are members and sponsors of


Browse our products and services catalogue


Asked Questions

How much air should we sample?

Typical requirements suggest 1,000 litres per air sample in high risk areas, such as: grade A filling lines, grade B clean rooms, operating theatres etc. As the criticality of the area reduces, the sample size can be reduced. The aim is to achieve a representative sample; so where higher counts would be expected, a smaller sample produces a more realistic number of cfu to count.

Should I use contact plates or Petri dishes for environmental air monitoring?

SAS samplers were originally designed for Contact plates, however, a Petri dish option has been available for a number of years. It is really a personal choice, although this should be decided at time of purchase, as the sampler will be specifically configured for the plate type chosen. There are advantages for each version and we would be happy to discuss your specific needs.

Can I autoclave my SAS sampler?

No, do not put your SAS sampler in a steam autoclave. The only part that can be autoclaved is the drilled head. The unit can be wiped with alcohol wipes to decontaminate it. The only other exception is the SAS Pinocchio, parts of which can be autoclaved.

How frequently should my SAS air sampler be calibrated?

Cherwell Laboratories recommends every 12 months and we will send a reminder for the month it is due. For some situations local procedures demand more frequent recalibrations so Cherwell is happy to offer tailored recalibration date labelling and reminders on request.

Why might I want gamma irradiated media?

The sterility of the packaged medium is assured and all but the outer layer of packaging is also sterile. Thus the risk to the environment to be sampled is greatly reduced. There is an additional benefit that the additional packaging and process extends the room temperature shelf life. This can be sufficient reason for small or irregular users to prefer irradiated.

What is the maximum exposure time for settle plates?

Settle plates are used to monitor the level of viable particles in the environment through a process of passive air sampling. A viable particle settles on agar plates at a rate dependent on its characteristics and the airflow in the environment.

EU GMP Guide Annex 1 has recommended that 90mm settle plates can be exposed in cleanroom environments for up to 4 hours. However, agar plates may dry out during long exposures where the rate of air exchange is high. So, it might be necessary to use deep filled settle plates, or replace the settle plate after a shorter time to ensure satisfactory growth promotion after exposure.

Is it OK to store prepared media in the fridge?

The storage condition for the majority of our prepared media is Ambient not exceeding 25ºC, the exception being a couple of very specialist products.

We have never specified storage in a fridge for our general media as this causes excessive condensation and can result in a very wet agar surface. This makes the product impossible to use.

What is the difference between general purpose and selective growth media?

General purpose media have nutrients that support the growth of most non fastidious culturable microorganisms. Selective growth media contain components that will inhibit the growth of some types of microorganisms, while supporting the growth of others.

General purpose media, such as Tryptone Soya Agar, are used to produce total counts. While selective media, such as XLD for Salmonella species, are used to test presence/absence of specific types of microorganism.


Supplying products is only the start


The best products prepared for you

Our Redipor® media products are batch tested, QC certified and delivered when you need them


Bespoke accessories and services

We provide additional equipment or services to make your environmental monitoring more effective


Best customer service

We build long-standing client relationships on understanding, commitment and trust



The Pharmaceutical and Cleanroom Industry's Guide to Prepared Culture Media

A guide to understanding the logistics, best practices and breadth of available prepared media options for varying applications.


Download Guide