Cleanroom Decontamination Units: Buyer Beware!

By Sandra Hulme

Are you looking to replace an existing cleanroom decontamination unit? The convenience of the Internet makes finding, buying, and even having your new purchase delivered within 24 hours easily enough. Finding a unit that won’t leave you with buyer’s remorse, however, is not that easy.

In the article, Finding a Fumigant, Microbiology Product Specialist and former cleanroom operator, Andrew Ramage, warns:

“There are plenty of systems available that claim ‘no residue’ and ‘rapid removal’ post-fumigation. Each manufacturer or distributor provides – as part of the product literature – papers written in conjunction with customers claiming to prove the effectiveness of their system. As a customer, I would be a little sceptical; few (if any) manufacturers will publish data that suggest their system is not effective. For me, there are too few independent comparison studies of fumigation systems. So many ‘studies’ seem to come from a distinct angle: extolling the virtues of a favoured system. Which one are you going to believe?”

Things you wish you’d considered before buying your decontamination unit

With this conundrum in mind, what are the steps you should take and the questions you should ask to ensure that your choice of decontamination unit is the best choice for your facility?

In this article, I’ll be outlining the important considerations that the person responsible for purchasing and validating a new decontamination unit should make when searching for a replacement to their existing system or designing a new cleanroom.

1. Decontamination Units: Buy or rent?

A first consideration is whether to purchase a unit or to opt for rental. The ease of paying fumigation suppliers to visit your site, to do the decontamination themselves with a portable unit, and then to draw up the necessary reports might seem alluring. Despite the convenience of outsourcing your decontamination, rental is not the best option for every facility and the following factors must be considered before making up your mind:

  • Total Expense. The cost of outsourcing your decontamination is approximately £2,000 for a 100m3 The total cost will vary greatly, depending on the size of your facility and the number of decontaminations that are required per year. An incubator company, for example, usually has several cleanrooms that must be decontaminated after each rental. In such a scenario, purchasing your own mobile unit is likely to be more cost effective than renting a unit tens of times per year.
  • Staffing. Do you have your own decontamination team on staff? In this case, ask yourself whether it makes sense to pay an external company to perform a service that you already have covered.
  • Emergency and convenience. While your standard decontamination schedule can be easily maintained by booking a rental unit well in advance, emergency spillage scenarios are a beast of a different nature. If you have a decontamination unit on site and ready to use at all times, you can be sure that you’ll never find yourself at the mercy of a supplier’s schedule – or emergency call out fee.

2.  Decontamination Method

Once you’ve settled the question of whether buying or renting is the better option for your scenario, the matter of the decontamination method and choice of fumigant will be determined by your facility’s specific requirements, your team’s capacity, the facility’s layout, and validation.

Operational requirements

Both the type of biocontaminants and titer (concentration) of potential spillage that your facility deals with have to be considered. Does the chemical and distribution method of this unit have the ability to penetrate spills and kill pathogens?

Team capacity

Dry fog or wet fog? Your selection will have a big impact on your team, since wet fog coats surfaces with a residue that they’ll have to wipe down manually before operations can resume.

Facility layout

Is your facility modified for the particular distribution method or will additional installation be required?  For example, decontamination with chlorine dioxide requires significant modification of the laboratory to prevent leaks of this highly toxic gas. The presence of electrical equipment in the cleanroom, is a second example, as a wet fogging unit may be inappropriate in this situation.


While suppliers will be more than happy to advise you on the appropriateness of their products for your facility and operations, validating the unit’s efficacy for your particular facility is ultimately the responsibility of the end user.

3. Usability Particular Decontamination Model

Once the matter of decontamination method has been settled, the next step is to review the usability of different models on offer. The following factors can determine whether your new unit relieves or adds to the pressure of cleanroom decontamination:


A single portable unit could be enough to service multiple rooms in your facility, without risk of leakage or requiring any modifications to the laboratory.


A unit’s size, design and construction material will determine whether the unit can fit into an autoclave. Stainless steel units with detachable parts, for example, are easy to fit into an autoclave. Others could present problems that increase process time.

Decontamination execution time

Depending on the method and model, decontamination can be executed in as little as two or as many as twelve hours. Make sure you’re aware and comfortable with being shut down and non-operational for the required period.

Ease of use

While it’s easy enough to fall in love with equipment based on its sophisticated appearance, efficiency and ease of use should always trump the razzle dazzle. The following usability aspects must be considered:

  • How complex is the unit to set up? Especially in situations of spillage, you’ll be glad if your unit is ready to go.
  • Does the unit allow for remote activation? Cleanroom decontamination inevitably means that evacuation is required. Even a momentary exposure to a decontamination disinfectant can be unpleasant and harmful.
  • By which mechanism is the unit operated? Where an electrical connection is required, the decontamination process will have to be adapted. A unit that operates by release of compressed air might seem technically less sophisticated, yet provides greater flexibility in terms of set up.
  • How complex will it be to learn to operate the unit and train new staff on the process? A decontamination unit should be delivered with clear instructions on the type chemicals to use, the volume of chemicals, how to dilute them, and how to validate efficacy. Because these particulars are determined by facility specific factors (humidity, size of the room, and temperature) look out for a supplier that will provide you with a simple way to calculate these aspects.

Decontamination Units – Usability and Efficacy

Don’t be fooled by fancy, complicated decontamination technology. The factors that will ultimately determine your satisfaction with a new decontamination unit are not aesthetic, but practical: cost, effectiveness, ease of use and ability to deal with the greatest challenge that your facility could possibly deliver.

Download Cherwell's Guide to Cleanroom Decontamination


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