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Frequently Asked Questions

Process and Cycle Questions

Application Questions

Compatibility Questions

Safety Questions

Process and Cylce Answers

How is ClorDiSys' chlorine dioxide better than others?
Our generation process creates pure chlorine dioxide, something that other manufacturers cannot say. Other methods generation of chlorine dioxide create harmful byproducts such as hydrochloric acid, chlorine, and chlorous acid along with the chlorine dioxide, which can affect materials within the space being decontaminated.
Why is humidification necessary?
Humidity is required for all spore log reduction, independent upon the agent used. Whether using EtO, formaldehyde, chlorine dioxide gas or VPHP, humidity is required. Humidity softens up the spore walls and allows the decontaminating agent to penetrate and inactivate the spore easier. VPHP humidifies during its injection as 65% water is vaporized and injected into the room along with the VPHP.
How fast are typical cycle times?
Our chlorine dioxide gas systems offer short cycle times for all applications.
  • Sterilizers - 30 ft3 vacuum chamber in under 2.25 hrs. start to finish (6-log reduction of spores)
  • Isolators - 300 ft3 chamber in under 2.5 hrs. start to finish (6-log reduction of spores)
  • Rooms - 2700 ft3 room in under 3.5 hrs. start to finish (6-log reduction of spores)
What kind of concentration monitoring is available?
Our Clordisys-GMP, Minidox-M, and Steridox-VP all offer integrated, precise, and repeatable chlorine dioxide gas concentration monitoring and control. Our concentration monitor has been validated by the United States Army and greatly simplifies validation efforts.
Why keep CD Gas generators outside the room?
We keep our equipment outside of the room during decontamination for user safety. Other competing technologies require that their equipment must be located inside the room to help it work better. If a failure/issue occurs and the equipment is located inside the room, then the user may have to enter the room that is filled with a dangerous agent, to correct the situation and shut the system down. If an issue occurs and the equipment is located outside the room being decontaminated (like the ClorDiSys process) then the user does not have to enter the area and can shut down the process more easily and safely.

Chlorine Dioxide Answers

What is CD Gas? Where is it used? How does it work?
Please visit our What is CD? page to find out more.
What is CD Gas effective against?
ClorDiSys chlorine dioxide gas is EPA registered as a sterilant. This means that chlorine dioxide gas is effective and can be used to destroy or eliminate all forms of microbial life including fungi, viruses, and all forms of bacteria and their spores. Spores are considered to be the most difficult form of microorganism to destroy. Therefore, EPA considers the term Sporicide to be synonymous with 'Sterilizer.' Reference:
Download our Biological Efficacy Brochure for a sample list of organisms which chlorine dioxide gas has been shown effective against.
Can CD Gas be contained?
Yes. Containing CD Gas to the area you want it to decontaminate is fairly easy but the method to do so is different in various facilities. In most cases, duct tape is the only tool necessary.
Can we use CD Gas without 'gas tight dampers'?
Yes. While gas tight dampers are always the easiest to work with when shutting down the HVAC system to perform a decontamination, they are not necessary.
Can we use CD Gas if we can't shut down our HVAC?
Yes, in fact, it is even possible to perform a chlorine dioxide gas decontamination when the HVAC cannot be shut down, with the help of our Room Bladder System or Room Valve System.
How can CD Gas be removed after a decon?
Chlorine dioxide gas can be vented or scrubbed, depending on customer preference.
What does CD Gas break down into?
Abiotic Degradation:
Chlorine dioxide: It has a short half life, and in the presence of sunlight, whether it is in water or as a gaseous molecule, its breakdown products are: chloride and chlorate ions, between pH 4 and 7. Ultimately, oxygen is formed.
Biotic Degradation:
Chlorate and chlorite ions show a tendency to undergo biodegradation under anaerobic conditions only. There are no reports indicating these ions under go biodegradation under aerobic conditions. Biodegradation for chlorate and chlorite have been observed in anoxic ground water, sediments and some soils. The end products are again the same: chloride and oxygen. Reference: Chlorine Dioxide Environmental Fate and Transport Assessment Case 4023 US EPA
What is the difference between chlorine and chlorine dioxide?
Unlike chlorine, CD is non-mutagenic, non-carcinogenic, and relatively non-irritating. CD does not form hydrochloric acid when exposed to water as does chlorine. It also does not combine with organics to form carcinogenic chlorinated hydrocarbons. One could ask what the difference between carbon and carbon dioxide is. Similarly, chlorine is much different than chlorine dioxide gas.
Is CD Gas unstable?
Chlorine dioxide gas does need to be produced in situ, however the life span of chlorine dioxide gas is in the order of days, so there is no danger of chlorine dioxide gas breaking down during decontamination.
What is 'stabilized' chlorine dioxide?
'Stabilized' chlorine dioxide has only trace amounts of chlorine dioxide. It is really buffered sodium chlorite with some peroxide. It is also a far weaker oxidizing agent. Chlorine dioxide is not a stable molecule and cannot be bottled or packaged. It lasts at most a few days, then breaks down into chlorites and chlorates.

Application Answers

Can CD Gas be used in BSL-3 and BSL-4 facilities?
Yes, click here to find out
Why use CD Gas for room decontamination?
  • Remove the human factor from the decontamination process
  • Reduce human exposure to disinfecting agents
  • Reduce overall decontamination time due to short aeration times
  • Only method that offers complete kill
  • No measurable residuals unlike formaldehyde
  • Non-carcinogenic unlike formaldehyde or VPHP (confirmed animal carcinogen according to the ACGIH)
Please visit our Why Choose CD Page for additional information
Can CD Gas be used in large volume spaces?
Yes, our process is very size scalable. Our Decon Services team has done multiple decontaminations of areas over 1,000,000 ft3 all at once. Being a true gas chlorine dioxide gas naturally and evenly fills the space it is within, no matter how large.

Method Comparison Answers

Why use CD Gas instead of hydrogen peroxide vapor?
click here to find out
What is the difference between a true gas and a vapor?
  • Complete Coverage - With chlorine dioxide gas, there are no issues with tight, hidden or difficult to reach areas. Gasses by nature fill the space they are contained within evenly and completely. The chlorine dioxide molecule is 0.124 nm in size, far smaller than viruses, fungi, bacteria and their spores. This means that chlorine dioxide gas is able to contact organisms wherever they are in a space. Vapors are subject to hydrogen bonding, which clumps their molecules together and limits its movement in air
  • Temperature Gradients - With chlorine dioxide gas, there are no issues with temperature or temperature gradients. As a gas, it does not condense out as VPHP does. With as little as one-degree temperature gradient, VPHP concentration can be affected. With VPHP, this small temperature difference can cause different concentrations throughout the chamber
  • Aeration Time - Since chlorine dioxide gas is a true gas and cannot condense on the chamber surfaces, the aeration is far quicker. There is no need to wait for the condensed sterilant on the chamber surfaces to transform back into the vapor state and then be carried out of the chamber
  • No cycle development necessary for chlorine dioxide gas cycles as the process is forgiving enough to overcome the amount and position of equipment and materials within the space, and the temperature/humidity within the space
  • Easy validation of cycles due to accurate concentration monitoring capabilities and complete/even distribution
Why use CD Gas instead of formaldehyde?
click here to find out
Why use CD Gas instead of ethylene oxide?
Our chlorine dioxide gas systems offer safety, ambient temperatures and rapid aeration times. • Chlorine dioxide gas is not carcinogenic. • Chlorine dioxide gas is non-flammable at use concentrations. • Reduced installation costs - our sterilizers do not require Damage Limiting Construction (DLC). • Sterilization at ambient temperatures (15°C to 40°C). • Chlorine dioxide gas does not require high concentrations to achieve sporicidal effects. • Far quicker aeration due to minimal product penetration.
Why use CD Gas instead of steam?
Our chlorine dioxide gas systems offer the ability to sterilize temperature sensitive products. • Ambient temperature sterilization chlorine dioxide gas is efficacious at ambient temperatures, which reduces the stresses of heating and cooling chambers. • Shorter cycle times no need for cool down time as required with steam. • Reduce chamber costs chlorine dioxide gas does not require a ASME pressure rated chamber. Our systems work under vacuum or ambient pressures. Chlorine dioxide gas is a greener process, offering energy and cost savings due to the lack of water and steam.

Material Compatibility Answers

Is CD Gas corrosive?
Most people who ask this are very familiar with the liquid chlorine dioxide solutions available on the market, which can be highly corrosive. The leading liquid chlorine dioxide solutions are produced through the mixing of an acid and a base. It is this acid which makes the liquid chlorine dioxide solution highly corrosive.
ClorDiSys, however, does not produce chlorine dioxide gas in this same way. In our method of generation, a 2% chlorine, 98% nitrogen gas flows through a matrix of sodium chlorite to produce a very pure chlorine dioxide gas. There are no acids involved in this process, making the gas produced much gentler than these liquid solutions which people are familiar with. .
The chlorine dioxide gas generated through the ClorDiSys process has an oxidation potential that is 1.5 times less that of VPHP, making it technically less corrosive than VPHP. Even sensitive computers have been exposed to CD gas and after 25 exposures they are still running.
For more information, read our White Paper, Chlorine Dioxide and the Myth of Corrosion
Does CD Gas leave a residue?
No, chlorine dioxide gas does not leave a residue after decontamination. One of the first commercial uses for chlorine dioxide gas was to sterilize intraocular lenses (implanted contact lenses). As such, it had to be proven that no residue was left after sterilization.
Doesn't CD Gas form hydrochloric acid in water?
Chlorine dioxide gas does not react with water. It stays as chlorine dioxide in water, allowing it to kill organisms in the water and on the surface beneath. Chlorine dioxide is different than chlorine (which does react to form hydrochloric acid) just like carbon dioxide is different than carbon. Hydrochloric acid cannot be formed when using a pure chlorine dioxide as we do.

Safety Answers

How safe is CD Gas?
The very reason decontaminating agents are used is for the purpose of killing organisms. As such, no agent can truly claim to be safe. However, chlorine dioxide gas is the safest fumigant available, due to its physical attributes and process advantages.
Click here to request more information why chlorine dioxide gas is the safest.
Is chlorine dioxide a carcinogen?
No, there is no data to support that chlorine dioxide gas is a carcinogen. In fact, chlorine dioxide is used for treating drinking water and to disinfect a variety of food products.
Why use CD Gas, it has a low safety limit?
Chlorine dioxide gas does have a 0.1 ppm 8 hour threshold, but chlorine dioxide gas provides a better safety factor due to its low odor threshold, making it possible to detect at low levels without sensing equipment. Chlorine dioxide gas has a much quicker cycle time, shortening the overall time that potentially unsafe conditions exist. VPHP and formaldehyde both have longer cycle times, where the unsafe levels exist for a longer time. Chlorine dioxide gas is also used at much lower concentrations than both formaldehyde and VPHP. Combined with the fact that chlorine dioxide gas has a quicker aeration time, this means that in case of an emergency, chlorine dioxide gas can be aerated to safe levels faster than formaldehyde and VPHP.
For more information, please read our white paper, CD Safety on why it's the safest
Is CD Gas explosive?
Not at use concentrations. Chlorine dioxide gas is potentially explosive at high concentrations in a dry environment with an ignition source. ClorDiSys does not generate chlorine dioxide gas at these high concentrations, so there is no danger of explosion when using our process. The use concentration is 250 times less than the explosive level.
Can you smell CD Gas?
Yes, and the fact that chlorine dioxide gas has an odor is a benefit. The odor threshold is the same as the 8-hour safety threshold, so the user can start to detect chlorine dioxide gas while still at safe levels. As a comparison, VPHP can only be detected when concentrations rise above unsafe levels and choking occurs.
Can you see CD Gas?
Yes, and at every installation and service decontamination that we have done, people are always excited to see the chamber/room filled with the yellow-green chlorine dioxide gas. The visibility confirms for people the fact that chlorine dioxide gas gets great distribution, as they see the gas everywhere in the chamber/room. It also provides a safety factor, as the gas is recognizable inside the chamber/room, so it is visually known to be unsafe to enter the chamber/room.