Checklist for Choosing Cleanroom Disinfectants

If you’re creating a disinfectant program for your cleanroom, be sure to check these six points before making a decision.

Disinfectant programs are vital to pharmaceutical and medical device manufacturers. Cleanrooms must not only be cleaned, but also disinfected to remain compliant. A program entails a disinfectant rotation as well as the disinfectants themselves. Here is a checklist to consider when choosing disinfectants.

  1. Know the efficacy level of your options. Whether using a disinfectant or a sporicidal agent, it needs to be effective against the specific microorganisms present in your facility.
  2. Know the contact times required to work. Each product will vary in the length of time it needs to make contact to kill microorganisms. For compliance, contact times less than 5 minutes is ideal. Anything longer than that will likely require re-wetting of the surface, which can increase chemical costs.
  3. Test one-step cleaners and disinfectants. One-step products are preferred because extra steps add chemical and labor costs to the process. The EPA requires that all one-step products be tested for efficacy. Some of these options are only effective on pre-cleaned surfaces, which negate the purpose of a one-step process.
  4. Be certain about material compatibility. In life science cleanrooms, stainless steel is an especially important issue. Most processing equipment is made of stainless steel. When bleach or other corrosive products are used frequently, pitting can result. Pits harbor harmful microorganisms like bacteria, resulting in product contamination.
  5. Know whether residue is left behind. Residues can be left behind when using antimicrobial agents. These can lead to product contamination and stainless steel corrosion.
  6. Decide on a concentrate or ready-to-use formulas. Concentrates can compromise safety and quality control. Handling and pouring highly acidic and caustic solutions is a delicate process. Consider all costs involved when choosing between these two options.

Choosing the right disinfectant the first time will reduce significant costs and headaches, so take the time to do your research. If you have questions about cleanroom validation, certification, or construction, contact Gerbig Engineering Company. We have been in the cleanroom business for 30 years. Call us at 888-628-0056 or email

3 Types of Cleanroom Pass-Through Systems

There are many varieties of pass-through systems for cleanrooms, and each meets different unique needs. Here are 3 common varieties.

Pass-through systems are an important part of many cleanrooms. They are necessary for a variety of parts, materials, documents, critical applications, equipment, and even personnel. The type of system you need depends on what you need to move from one side to the other as well as your cleanroom class. Here are three very different kinds of pass-through systems to consider.

  1. Chamber. These provide transfer for a number of critical applications, including requirements to ISO 4 and bio/pharmaceutical operations requiring frequent cleaning and sterilization. No external fasteners or caulking are needed, as a bracket mounts the chamber against the cleanroom wall. There are no horizontal surfaces to collect dust. The internal surfaces are optimized for easy cleaning and sterilization. There are no cracks, grind marks, burrs, or other imperfections to snag wipers or harbor contaminants.
  2. Swing Doors and Convenience Windows. The doors open from either side, and a reinforced shelf is provided for users to place materials or documents. Doors can be made in clear tempered glass or opaque polypropylene. Transfer windows are ideal for situations where users need a fast and easy way to pass materials from one room to another.
  3. Roll-Up. These dual-side segmented access doors automatically roll up and down at the push of a PLC control pad button. The design eliminates door clearance requirements, and gloved personnel can easily open and close doors while holding parts. Motorized lifters are sealed inside non-contaminating housing; doors slide up and down a track. These systems also utilize pressure-sensitive safety circuits to automatically stop door motion and return it to an open position if an object hits the door’s bottom.

There are many pass-through varieties available for cleanrooms, and these are three of the most common. Be sure to choose what is right for your needs and requirements. If you need assistance with cleanroom validation, certification, or construction, contact the experts at Gerbig Engineering Company. We’ve provided cleanroom services for 30 years. Call 88-960-0056 or email today.

Pros and Cons of Cleanroom Air Sampling Methods


When it comes to air sampling for the cleanroom, there are many options. Consider each before choosing the right one for your class of cleanroom

Proactive companies know the importance of an active air-sampling program in a cleanroom. As with anything, each method has different benefits and problems specific to compliance needs.  When it comes to choosing an air sampling method for your cleanroom, you need to do your homework. Depending on your cleanroom class and other needs, some options will be more suitable than others.

1. Sedimentation

This is one of the oldest methods available today. It entails exposing a petri dish to the atmosphere to collect bacteria-laden particles. This passive, non-volumetric method imprecisely represents larger particles because of their rapid settling rate. Plates have to be left out longer to collect smaller particles because air turbulence can cause it to resist settling. This can cause desiccation. In this case, bacterial growth would be poor, reducing the viable count. As a pre-screening tool, sedimentation is inexpensive and helpful, but it cannot be validated and is not accurate.

Impactors represent the rest of the list. In each, samples are collected by drawing air into the sampler and directing the stream at the collection agar.


2. Slit-to-Agar

A determined volume of air is drawn by vacuum through a slit opening and toward an agar-media petri dish. A turntable rotates the plate, which spatially separates microorganisms, allowing analysis of time. Time analysis is a unique benefit to this method, however, it can still be inefficient. The vacuum and rotation of the plate can dry the media leading to poor bacterial growth. Any particles not collected on the agar are forced back into the airstream and reintroduced into the isolator or cleanroom. Additionally, not all particles impact on the plate, skewing true representation of air quality. The greatest drawback is the method’s inefficiency at collecting small particles. This air sampling method would not be appropriate for cleanrooms requiring ISO Class 1 and ISO Class 6. It is, however, efficient at collecting particles larger than .5 microns.


3. Sieve Samplers

These come in several varieties, allowing up to six stages of perforated plates and agar plates. The multiple-stage capabilities offer benefits over other impactors. A six-stage unit has a 40% higher recovery rate than one and two-stage versions. The holes in the successive plates get smaller, allowing larger particles to impact the first stage, and smaller to impact the last. Therefore, a major benefit to a stacked sieve is that it provides data on particle size.

There are a number of downsides to this method as well, though. The main ones include:

  • • The sampling times need to be short and performed in high relative humidity, or the agar beneath the holes can dry out, compromising microorganism growth.
  • • The agar must be completely level in each dish and filled with precisely the suggested amount of agar.
  • • Plastic dishes can create static electricity, deflecting particles away from the dish.
  • • The air flow rate must be fast enough to impact small particles, but if too high, the shear force of impact can kill smaller microorganisms.


4. Centrifugal Samplers

This method creates centrifugal force through a vortex, causing particles to impact along a strip lining the inner wall of the drum. As with many other methods, this one is efficient in collecting large particles. Anything smaller than 15 microns may not be deposited. Using a strip also affects the efficiency in which colony counters can read data, forcing operators to perform manual counts. Overall, there are other problems that can affect the accuracy of this method.

It should be said that centrifugal samplers used to be advantageous because they’re battery operated and small enough to be hand-held. Now, however, other samplers have comparable portability.


5. Impingement Air Sampling

This method draws air through the curved section of a glass impinger and accelerates it through a jet at the bottom. This bottom is filled with a liquid that is suitable for capturing particles. The amount of collection liquid will vary depending on how concentrated you want your collected microorganisms. After sampling, the liquid is filtered and processed as usual. The larger particles are collected on the curved inlet by pipetting collecting fluid into the impinger inlet.

Impingement method air sampling is a very effective method for collecting various sizes of microorganisms and determining the initial air quality of an area. However, it is not a very convenient sampling method. Preparing the non-disposable glass containers every time is time-consuming. With a low flow rate, it also cannot be reliably validated. Other factors also can create higher counts similar to that of the centrifugal impactor.


6. Gelatin Membrane Filtration

This is the most innovative air sampling technology available. The airflow rate is programmable, and the gelatin filter is 300 microns thick, allowing it to capture the smallest microorganism. It is the only method that has both an absolute retention rate and reliably captures airborne viruses. Additionally, processing the filter is convenient and the units are easily read.


Overall the method you choose will depend on your budget, validation needs, setup, and compliance parameters. If you have questions about cleanroom validation, certification, or construction, contact Gerbig Cleanrooms. Our specialists have helped cleanroom operators for over 30 years. Call 888-628-0056 or email

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