Sterilization and Infection Control News Update - April 2017

We're happy to present you with this month's collection of top industry related news and articles. Enjoy!

 

Turkey Introduces New Standards for Medical Waste Control

Lexology – 6 February, 2017

The Ministry of Environment and Urbanization of Turkey recently adopted the new regulation on control of medical waste.

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Children’s Hospital Fails Federal Surgical Inspection

The Detroit News – 27 March, 2017

Children’s Hospital of Michigan failed a late January inspection conducted by the federal Centers for Medicare and Medicaid Services as part of a broad investigation into dirty surgical instruments at Detroit Medical Center hospitals.

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Detroit Medical Center Submits Corrective Action Olan on Sterile Surgical Problems

Modern Healthcare – 27 March, 2017

Detroit Medical Center has received federal approval for a corrective action plan in response to a surprise inspection in January in which Medicare hospital quality inspectors found numerous violations of federal infection control and patient safety rules.

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Trouble Keeping Up With the Not-So-Daily Responsibilities in Your Dental Practice?

Dentistry IQ – 3 April, 2017

There's no denying the To Do lists for dental team members can be endless, and the not-so-daily chores can get pushed to the back burner. Here's how to keep that from happening and making sure all items are covered.

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Medford parents Now Have Choice for Wind Instrument Sterilization

Wicked Local – 21 March, 2017

Medical instruments must be sterilized but do wind instruments need to be sterilized in between users? Interesting question.

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Sterilization Issue Put 2016 Windsor Regional Hospital Budget In The Red

BlackburnNews.com – 7 April, 2017

Windsor Regional Hospital is dealing with a $5-million operation deficit.

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CDC Chief Fears a Deadly Superbug’s Spread

STATnes.com – 21 April, 2017

Public health officials have a lot on their plate now: Outbreaks of measles and flu, soaring deaths from opioid overdoses, funding cuts.

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Food Packaging Design: How to Comply with Food Processing Methods?

Packaging Innovation – 10 April, 2017

Food packaging, evidently, needs to be as safe as it is appealing. Food processing methods greatly determine packaging requirements, including sterilization, and, hence, food packaging designs.

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High Pressure: Uses for Pasteurization

Food Safety Magazine – 04 April, 2017

High hydrostatic pressure technologies are used in numerous applications, from preparing ceramic composites for aircraft, industrial diamond production, pharmaceuticals and cosmetics, and, more recently, for pasteurizing food.

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Sterilization Monitoring: The Front Line of Infection Prevention

3M Science – 04 April, 2017

Hospital officials are warning heart surgery patients that they may have been exposed to bacteria due to sterilization problems with medical equipment.

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New Guide Supports Cleaning Protocols for Reusable Medical Devices

OHS Online – 11 April, 2017

In 2013, the Centers for Disease Control and Prevention alerted FDA about a potential association between multi-drug resistant bacteria and duodenoscopes, and FDA's investigation showed that infections were occurring despite confirmation that the users were following proper manufacturer cleaning and disinfection or sterilization instructions.

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Pharmacists should also care about sterilization.

 

 

Pharmacist Convicted of Racketeering, Fraud in Fungal Meningitis Outbreak

CNN – 23 March, 2017

A Pharmacist was acquitted on 25 counts of second-degree murder in connection with a deadly 2012 nationwide fungal meningitis outbreak. Sixty-four patients in nine states died in the 2012 fungal meningitis outbreak.

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Duendoscope ToolNECC Trial Witness: Framingham Pharmacy Failed to Sterilize Equipment

Rare  – 24 January, 2017

A former New England Compounding Center employee testified that a key piece of equipment in the clean rooms, which were supposed to be sterile, were not regularly cleaned even as drug production increased tenfold.

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Disclaimer: The views and opinions expressed in the referenced articles and blog posts are solely those of the original authors and other contributors. These views and opinions do not necessarily represent those of Tuttnauer, the tuttnauer.com staff, and/or any/all contributors to this site.

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Methods of Low-Temperature Sterilization: Ozone

Did you know that ozone can be used to sterilize heat- and moisture-sensitive medical devices? Ozone, also known as trioxygen, is an inorganic molecule with the chemical formula O3. It is a pale blue gas, with an unpleasant, distinctive smell similar to chlorine. In fact its name derives from the Greek word ozein, which is the verb “to smell.”

In the earth’s stratosphere, ozone exists in high concentrations and acts as a shield that absorbs most of the sun’s ultraviolet radiation, hence the term “ozone layer.” But as a sterilizing agent, ozone has a very different role.

View of the inside of a pressure cooker - Tuttnauer - Sterilization BasicsIn the stratosphere, ozone acts as a shield that absorbs most of the sun’s ultraviolet radiation

Long used for the disinfection of drinking water, ozone is now getting more attention for its strong oxidizing properties. Tim Stoddard, CEO of Cylopss and a pioneer in the world of ozone sterilization, explains how ozone works:

“Ozone is a unique antimicrobial agent. In fact, it is the most aggressive oxidating (sic) antimicrobial agent known to man. Ozone is formed by applying electrical energy to the oxygen molecule, which splits some portion of those oxygen molecules in half, into singlets of O. Those single O atoms attach to O2 for a very short time period, becoming O3, which has a half-life in its natural state of about 20 minutes before, on its own, it converts back to oxygen by releasing its singlet of O. During that active phase as ozone, it reacts to any organic compound by oxidizing double carbon bonds. So, unlike a lot of other disinfection sterilization technologies, in the act of literally taking a cell membrane apart, in destroying the cell, it converts itself back to oxygen which is a very benign waste product. If you look at water that has been disinfected with a chlorinated compound versus ozone, you’ll see dead microorganisms in the chlorinated water. If the water has been treated correctly with ozone you should literally see nothing because it should break it down to just its basic elements which are hydrogen and CO2."

How Ozone Sterilization Works

An ozone sterilizer is able to harness the unique powers of ozone by producing it inside the sterilizer from medical grade oxygen, which is commonly available in hospitals (as explained above, by applying electrical energy to combine O2 with O to form O3). This capability is well-suited for sterilizing delicate medical devices, like endoscopes, that cannot withstand the high heat and humidity of standard steam autoclaving. Approved by the FDA in 2003 as a new sterilization process for low-temperature sterilization, its microbial efficacy has been proven with a variety of microorganisms, including the most resistant Geobacillus stearothermophilus, (which is often the bacterium of choice for biological indicators).

Actually, on its own, ozone can be quite dangerous: it is toxic, corrosive and flammable, but since the ozone is produced and broken down within the sterilizer, chances of exposure to it are quite minimal. The waste ozone is destroyed by passing through a simple catalyst, which brings it back to a state of oxygen that can be safely expelled into the air.

Advantages Disadvantages
Needs only medical grade oxygen, which is not a dangerous gas to handle or transport Ozone itself is a toxic and flammable gas
Medical-grade oxygen is readily available in hospitals all over the world, removing the additional overhead of stocking expensive sterilant Cycle time is longer than hydrogen peroxide plasma sterilization
Does not leave toxic fumes or residue that must be aerated; rather converts back to oxygen that can be safely released into the air  
If there were to ever be a leak, even very tiny amounts of ozone could be detected from its pungent smell  
Cycle time is shorter than EtO sterilization  
Cost per cycle is cheaper than EtO since oxygen is cheaper to acquire than EtO  

How Popular Is Ozone Sterilization?

In low-temperature sterilization, as we have posted on our blog, there are several options. The most popular remain Ethylene Oxide (EtO), Formaldehyde, and Hydrogen Peroxide Plasma. Today, however, with the health risks associated with formaldehyde becoming more and more worrisome, many hospitals and sterilization departments are phasing out these options. Hydrogen peroxide plasma remains popular, and we are seeing an increased interest in ozone sterilization as a safe and cost-effective alternative. Another type of low-temperature sterilization method gaining attention is nitrogen dioxide sterilization.

Optimistic about Ozone

Ozone has exciting potential as a sterilizing agent in the world of low-temperature sterilization. After all, it has been used for many years to disinfect drinking water, food, and air. Now that the infection control industry has figured out how to maximize its germicidal properties inside a sterilizer, we expect to see more ozone sterilizers in hospital CSSD/SPD rooms. It’s relatively safe and its cost-effectivity will ultimately prove to be a selling point over the more dangerous alternatives, such as formaldehyde. And in some ozone sterilizers it is already being paired with hydrogen peroxide plasma in order to perform a double-fronted assault on microorganisms. One thing is for sure: we will be hearing more in the coming years about ozone as a viable alternative for low-temperature sterilization.

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BSL Autoclaves for Biosafety Sterilization

Besides the well-known biohazard symbol and full body-suit protective gear, many of us know that dangerous diseases are studied in biosafety laboratories, such as Anthrax, and Ebola, etc. Due to their unique and potentially hazardous work, biosafety labs have special requirements in their construction, daily maintenance, and air pressure control.  In fact, some labs must be kept in completely sterile conditions all the time. There are four BioSafety Levels (BSL): BSL 1 to 4, with 1 having the lowest risk of microbial spread and 4 having the highest risk (see table below).

View of the inside of a pressure cooker - Tuttnauer - Sterilization BasicsA(L) Symbol for Biosafety Level 2 Laboratory; (R) Lab Technician in BSL 4 Laboratory, wearing personal protective equipment (PPE): full-body, air-supplied pressure suit/Credit for both images: CDC

In this blog post we will explore the unique aspects of autoclaving in BSL laboratories. First, we will take a look at some of the major differences between sterilization in hospitals versus in biosafety labs. Second, we will discuss bioshield frames, which surround autoclaves in many BSL 3 and 4 labs. And finally, we will explore the two major methods of disposing of autoclave waste, or effluent as it’s known, which are crucial in high-level labs to maintain safe conditions.

View of the inside of a pressure cooker - Tuttnauer - Sterilization BasicsInformation in table and pyramid concept from CDC; Table credit here

What is the Difference Between Hospital and Laboratory Contamination Concerns?

In a hospital’s Central Service Supply Department (CSSD)/Sterile Processing Department (SPD), the main concern is preventing the spread of infection through the medical devices that are processed. For example, it is the CSSD’s job to ensure complete sterility of surgical tool sets used in the operating room (OR), which means that all surgical tools must be completely cleaned, disinfected, and sterilized (autoclaved) before the next surgery. If not, the hospital runs the risk of exposing patients to harmful microorganisms and therefore, potentially causing a hospital-acquired infection (HAI).

Biosafety labs, by contrast, are afraid that the pathogens being studied will actually infect the outside surroundings through contamination. This is a crucial difference. For BSL labs, extra caution must be taken in order to prevent the spread of contaminants from room to room and to the outside environment. For example, the laboratory room is often kept at a specific set pressure in order to prevent the spread of contamination. And sometimes the room itself must be kept in constant sterile conditions when the risk of contamination is great.

What is a Bioshield Frame?

A bioshield frame is a biological seal that creates a complete hermetic seal around the autoclave, thus locking in all pathogens. In low level BSL labs, such as BSL 1-2, the goal of framing the autoclave is to prevent the passage of organisms like insects, and rodents, and other vermin, etc., whereas in the case of BSL 3 and 4 labs, the goal is to prevent the passage of microorganisms and/or gases. A bioshield system meets the bio-safety requirements for BSL3 and BSL4 labs. Exactly framing the hole in the wall where the autoclave is installed, the bioshield frame is made of a continuous, shock-absorbent neoprene seal and stainless steel plates. In addition, the bioshield includes a jacket frame, which is composed of a fully welded metal flange and threaded studs. Any electrical connections to the autoclave pass through special sealed conduits that are part of the frame, thus maintaining completely sealed conditions.

By making sure that the autoclave is completely hermetically sealed into the wall, the BSL lab maintains full isolation of one side of the wall, where items enter the autoclave, which is totally separate from the other side of the autoclave, where these items emerge sterile. This pass-through autoclave system is absolutely crucial in BSL3 and BSL4 laboratories, which have much stricter sterility requirements due to the dangers of pathogen contamination.

For example, many biosafety labs have a “hot room,” which is the most protected and dangerous room of the lab since that is where scientists are working with the highest-risk microorganisms. This area must be protected and isolated from the rest of the lab by a pass-through autoclave, which is built into the wall and sealed by the bioshield frame. A hot room is up to 1000 times more clean, free of particles, and contamination than the operating room (OR) of the hospital!

HEPA Filter

High-Efficiency Particulate Air filters, known more commonly as HEPA filters, are a class of air filter designed to block 99.97% of particles that have the size of 0.3 µm (micrometers). These filters are used in the medical, scientific, and pharmaceutical industries where powerful filters are required to maintain sterile or near sterile conditions.

In BSL labs, HEPA filters are used to block the passage of microorganisms found in the autoclave effluent. The HEPA filter is the most common method of blocking pathogens inside the autoclave since the use of the HEPA filter can be validated by water intrusion tests and/or integrity tests. These are tests that confirm the proper performance of the filter, and are run periodically.

Essentially the HEPA filter catches microorganisms. The filter is placed inside a special housing, which also functions as a steam sterilizer, and it is here that the trapped microorganisms are destroyed. The destruction of pathogens caught inside the filter not only eliminates them in order to maintain the sterile conditions of the surrounding lab, but it also allows for safe, sterile conditions of the next cycle inside the autoclave. In addition, this sterilization step allows for the safe disposal of the HEPA filter at the end of its life time.

Thermal Biohazard System

Less common than HEPA filters, the thermal biohazard system is another way to eliminate dangerous pathogens in the autoclave effluent. In this method, the effluent is mixed with high pressured steam, which enters via an ejector, and then together, the effluent and steam pass through a heat exchanger, which keeps the mixture at a high temperature for a sufficient time to ensure complete annihilation of all pathogenic matter. We can confirm the temperature of the outlet of this heat exchanger in order to verify that we have indeed sterilized the outlet before the effluent leaves the autoclave.

Other Special Considerations for BSL Labs

Sometimes biosafety labs, especially levels three and four, have special installation requirements. For example, autoclaving in these conditions may require clean piping and specialized components like pressure switches, safety valves, and two HEPA filters -- instead of the standard one filter -- in order to double confirm the successful trapping/sterilization of all microorganisms in the effluent.

In addition, some biosafety labs require the addition of a special tank, which is connected to the drain pipe of the autoclave. Instead of simply releasing all effluent liquid and gas to the general public sewage system, this tank is treated with chemicals that act as a further step along the way to ensure proper sterilization, which is also confirmed by chemical testing, before the effluent is finally released to the city drain.

BSL Take-Away Points

Biosafety labs must stop the spread of potential contamination of pathogens, which can be an immediate danger to people in the lab and the outside environment.

  • The goal of biosafety sterilization is to prevent the spread of microorganisms to the outside environment whereas the goal of hospital (CSSD) sterilization is to prevent the spread of infection through maintaining sterile medical equipment used in surgery and other procedures.
  • The bioshield frame creates a complete hermetic seal around the autoclave to maintain high levels of sterility around the autoclave and between the two differently qualified zones on either side of where the autoclave is mounted in the wall, for example both into and directly outside the “hot room.”
  • All autoclave effluent, which is essentially the contaminated air extracted from the autoclave chamber before sterilization, must be blocked and then sterilized before leaving the autoclave by either the use of a HEPA filter or a thermal biohazard system.
  • The HEPA filter blocks microorganisms in the filter, which are then sterilized inside the housing of the filter.
  • The thermal biohazard system uses high-temperature, high-pressurized steam to sterilize the autoclave effluent.
  • There may be more special considerations for autoclaving in BSL conditions, such as double HEPA filters or the addition of a special tank that uses chemicals as an extra safety measure before releasing the autoclave effluent into the main public sewage system

We hope you have learned from and enjoyed our discussion of the special considerations of autoclaving in biosafety laboratories. Please share your comments or questions below. We love hearing from our readers! 

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Air Filtration in Autoclaves

In the previous post we introduced filtration techniques used in the lab to sterilize heat sensitive liquids that cannot be autoclaved. Filtration is not exactly a sterilization technique; unlike any other sterilization method, such as radiation or steam sterilization, it does not kill the microbes, rather it physically blocks their passage. Air filters are common in germ-susceptible locations such as labs and hospitals and even in industrial buildings and airplanes where all the air gets filtered, keeping the environment safe. Just imagine what can happen if there’s a sick person on a plane and the air is not filtered.

In this article we will discuss how air filtration is used in lab steam sterilization. In this case filtration is used as a way to protect the lab environment and lab staff from contamination. However it is relevant to the discussion of sterilization methods since it is used to reduce the bioburden level. In this post you’ll learn about air filtration and

  • how steam sterilization can affect the laboratory environment,
  • how the environment can potentially affect the sterile load.
  • and how filtration solves these two problems.

HEPA Filter Pore Sizes

HEPA filters are designed to target tiny pollutants and particles as small as viruses that can be 10X smaller than standard bacteria. The particles are trapped through a combination of mechanisms called interception, impaction and diffusion. A detailed discussion of how each mechanism works is beyond the scope of this article. The following table specifies the sizes of the different microorganisms and particles.

HEPA filtration:

Filtration TechniquesParticle sizes and applications

Sterilization Can Affect the Environment

In biosafety laboratories with high risk of pathogen exposure, namely BSL3 and BSL4,  the separation of hazardous materials from public spaces is vital for the protection of the lab environment and this is why the control of airflow in the lab is so important. How is this accomplished? By the use of air filters, which protect the lab environment and control airflow in and out of separate pressure zones. HEPA stands for 'high-efficiency particulate air' filters, and they are probably the most commonly used type of air filters. ow do they  work in BSL labs?

Air flow structure of a BSL4 lab

Air Filtration in Steam Sterilization

Filters have two intended uses in autoclaves:

  • protecting the environment from potentially dangerous gasses released from the autoclave
  • protecting the sterilized load from potential external contamination

Why Filter Air-Outlet When Using an Autoclave?

Air needs to be filtered when sterilizing lab instruments and biohazardous materials at pre-vacuum stage because it may contain infectious substances. For example, the air inside the autoclave chamber may include medical waste, which can be contaminated by viruses or toxins. If biohazard is released, there is a chance it will harm the drainage and ambient air, as well as laboratory staff

The HEPA air filter blocks all microorganisms from exiting the chamber during the air removal phase. The filter is so small that it blocks viruses that are an average 10X smaller than standard bacteria. This blockage, therefore, prevents the contaminated air from escaping into the atmosphere and instead, catches the harmful microorganism inside exhausting germ free air.

How Does it Work?

An autoclave sterilization cycle begins with air removal by vacuum. The air removed from the autoclave chamber for optimal steam penetration is released into the lab environment. So, before the chamber content is sterilized we already start sucking air out of the chamber by creating this vacuum. But there’s a catch, the air exiting the chamber potentially has a high level of contamination, endangering the environment. The biohazard filter which is located on the biohazard outlet line blocks these dangerous microorganisms from exiting the autoclave chamber together with the air thus keeping the lab safe.

Who Is Afraid of Water?

HEPA filters are hydrophobic. Hydrophobic filters do not pass water, and this is why they are called Hydrophobic: In Greek Hydra is water and Phobic is fear. Hydrophobic filters are designed to filter out gas for venting. A hydrophobic filter must remain dry. If it gets wet it will become blocked, and air will not be able to pass to or from the chamber. On a side note, since the HEPA filter is hydrophobic, the biohazard outlet is located in the upper-middle part of the autoclave chamber. This is to ensure that the outlet will remain condensation free and water will not block the passage of air.

The air outlet is contaminated since sterilization has not taken place yet. Filters guarantee that the air removed from the autoclave is free of harmful microorganisms. The sterilization of air by HEPA filters at pre-vacuum stage is also called green sterilization, as its main purpose is not to sterilize the media but to keep the environment safe, by leaving all bacteria and viruses inside the chamber. Once the sterilization cycle runs in the autoclave those microorganisms will be killed.

Extra Safety Meassures

We’re not done with simply blocking the bacteria with a HEPA filter. After potentially contaminated air has passed through the filter we are left with a contaminated HEPA filter packed with microorganisms. The filter also needs to be sterilized in order to make it free of living microorganisms. Some users sterilize the filter as a part of the biohazard sterilization cycle. In other cases, there is a specific program dedicated to sterilize the filter post sterilization cycle. In some BSL4 labs two filters are placed serially for extra safety: in case one of the filters fails, the second filter is there to prevent any microorganisms from passing.

Filtration TechniquesSpecial measures of protection are required in BSL3 and BSL4 labs

Trojan Horses in the Lab

We all know the story of the Trojan horse the Greeks used to enter the city of Troy and win the war. The Greeks built a huge wooden horse and hid their soldiers in it. The Trojans pulled the horse into their city and the Greek soldiers came out of the horse at night, easily destroying the city of Troy. HEPA filter's purpose is to prevent these Trojan horses from entering the autoclave chamber.

Air filters prevent the viruses and bacteria from entering the autoclave

Filters are used in autoclaves designed for BSL3 and BSL4 labs when air enters the autoclave chamber at post sterilization drying phase. It’s important that only sterile air enters the chamber after the media has already been sterilized.  If we were concerned about the protection of the environment at pre-vacuum stage while sterilizing biohazard, now our main concern is to protect the integrity of the load. At the end of sterilization phase, the load in the chamber is sterile. This is why the air has to be filtered before entering the chamber to avoid the passage of microorganism which the ambient air contains. This time a HEPA filter is used in the air inlet line. At the end of the drying stage vacuum is broken inside the chamber and this is when the inlet air-line comes into action.

An Autoclave Within an Autoclave

The air filter may become contaminated. Therefore the filter  needs to be sterilized to kill the microorganisms that were blocked by the filter. This is why the filter is placed in a special housing. The housing functions just like a miniature autoclave: it is equipped with a temperature sensor, steam trap for housing chamber and jacket and it sterilizes the filter thus leaving it free of living microorganism ready for the next cycle.

Tuttnauer provides an option to test filters by a WIT (Water Intrusion Test) in order to confirm that the filters are not ruptured. In addition, Tuttnauer autoclave HEPA filters use filter housing that are equipped with ports for in situ (onsite) integrity testing.

Conclusion/Summary

To summarize we just explained how air filtration is used when sterilizing biohazard or in BSL3 and BSL4 labs at pre-vacuum stage to protect the environment and at post vacuum stage to protect the integrity of the load. You are invited to share your questions and comments about HEPA filters and air filtration in lab steam sterilization in the comments section below.

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Lab Autoclave Sterilizer Features

Third post in series, “Understanding Laboratory Autoclaves”

Which features does your laboratory autoclave need? In the concise table below is a reference guide designed to help you figure out which features are right for you. Following the table is a point-by-point discussion of each feature in greater depth. 

Feature Description Physical Components/System
Fast Cooling (up to 75%) Water circulation through cooling pipes cools chamber Coiled pipe around the chamber for cooling
Super Fast Cooling (up to 90%) Water circulation through cooling coils and air ventilation with fan rapidly cools chamber Coiled pipe around the chamber for cooling and fan for accelerated cooling
Efficient Air Romoval - Efficient Moisture Removal Efficient air and moisture removal by vacuum pump Vacuum pump
Efficient Heating Efficient heating by steam from steam generator Steam generator
Active Drying of the Load Uses heating plate and vacuum pump to dry the load quickly Heating plate and vacuum pump
Complete Drying of the Load Steam from generator in combination with vacuum for complete drying Vacuum pump and steam generator
Biohazard and Waste System Biohazard filtration of air removed from chamber before sterilization. Also used for waste sterilization Biohazard system

Fast Cooling

Fast Cooling is an important feature for reducing cooling time, up to 75% less time than cooling under ambient conditions. At the completion of the sterilization phase of the cycle, the chamber pressure is increased by pushing compressed air through a microbiological filter into the chamber. By increasing the pressure inside the chamber, we are able to prevent the boil-over effect for liquids, as well as spills and cracks in containers that may occur under low-pressure conditions. At this point, cold water circulates through the chamber pipes, which are coiled around the chamber and function similar to a jacket. Due to the circulation of cold water, as well as the pressurized air, the liquid load is cooled quickly and safely — thus saving you precious time and resources.

Super Fast Cooling

Used in conjunction with Fast Cooling, another way of cooling a liquid load is Super Fast Cooling, which essentially uses a fan to accelerate the cooling process. By circulating the air faster inside the chamber, the fan is able to transfer the heat from the load to the cold chamber walls, thus cooling the load by as much as 90% faster.

Efficient Air Removal & Moisture Removal

The most efficient way to remove air and moisture (for non-liquid loads) is with a vacuum pump. The vacuum pump uses an advanced system of fractionated pre-vacuum air removal pulses in order to remove more than 99% of the air inside the chamber. This process removes air pockets in the load, which is especially important in hard-to-access places like inside the bottom of a very tall beaker.

More than just removing air efficiently, the vacuum pump also contributes significantly to drying the chamber and load quicker than other methods. During the drying phase, the vacuum pump keeps pressure low, and this low pressure state reduces the boiling temperature and forces the hot moisture to evaporate quickly inside the chamber. In other words, the vacuum squeezes out the vapor (moisture) and the chamber is left completely dry.

Filtration TechniquesVacuum pump used for efficient air & moisture removal

Efficient Heating

The steam generator pumps steam into the coiled pipe around the chamber, and this is what causes the autoclave to heat up quickly. This also provides uniform heat throughout the whole chamber and prevents any cold spots. This is a faster and more efficient method than using a regular electric heating plate on the outer chamber wall surface.

Active Drying & Complete Drying of the Load

It used to be that the way to dry the load at the end of a cycle was to open the door and let the load dry slowly under ambient (room-temperature) conditions. Open-Door Drying, thankfully, has been replaced by Active Drying and the more advanced, Complete Drying.

Active Drying uses a heating plate and vacuum pump in order to dry the load much quicker than open-door drying. The heating plate heats up the chamber, thus speeding up drying of the load. And the vacuum pump lowers the pressure, thus reducing the boiling point, and resulting in high-speed evaporation. The combination of heating and vacuum guarantees that even difficult-to-dry loads such as textiles, hollow instruments and porous loads are completely dried. 

The most advanced method available to dry your load quickly and efficiently is Complete Drying. With Complete Drying, the autoclave uses a vacuum pump (as described in the previous paragraph), as well as a steam generator, which heats up the walls of the chamber by sending steam into a coiled pipe around the chamber, thus heating it up rapidly and completely. The combination of lowering the pressure via the vacuum pump and rapid heating of the chamber equals fast and dependable drying of your load.

Filtration TechniquesThe autoclave's chamber is heated by a heating plate for active drying of the load

Biohazard & Waste System

Since many laboratories deal with biohazard media that can be dangerous both to staff handling the media, as well as the lab environment, it is crucial to have an appropriate sterilization solution in dealing with said biohazard media. The Biohazard & Waste System feature allows for just that.

During the air removal (from closed chamber with load inside) and heat-up stage, the chamber air is passed through a microbiological filter and leaves the autoclave as sterile air. In the sterilization stage, there is no exhaust, thus allowing no opportunity for dangerous fumes to escape. The load is sterilized, as is the air filter. And finally, by cycle end, the load, effluent, and air filter are all completely sterile.

Features for Safety and Productivity

In this guide we have presented you with a quick-reference table of our most common laboratory autoclave features, and then explained each one in more detail.

First we explored Fast Cooling and Super Fast Cooling and discussed how water circulation through cooling pipes cools the chamber, and how the optional fan feature rapidly cools down the liquid load.

Next we looked at Efficient Air Removal and Efficient Moisture Removal and understood how the vacuum pump efficiently removes air and moisture inside the chamber.

Then we explored Efficient Heating in which we discussed the advantage of using a steam generator to distribute steam into a coiled pipe surrounding the chamber, thus heating up the autoclave efficiently and quickly.

In Drying, we focused on the differences between Open-Door Drying, Active Drying, and Complete Drying. We mentioned that Complete Drying is the most advanced option and will dry your load the quickest through its combination of rapid chamber heating by steam from the generator and the vacuum pump.

And finally we explored the Biohazard and Waste System feature in which air is safely removed from the chamber before sterilization and  is sterilized when passed through a microbiological filter. At cycle end, the air, effluent, and filter are all sterile, thus maintaining safety conditions for laboratory staff and the environment.

We hope this pragmatic discussion of laboratory autoclave features was helpful and informative for you, and look forward to reading your questions and comments below.

Stay tuned for our next post in this series in which we will explore topics in biosafety.

Filtration TechniquesTuttnauer´s vertical and benchtop lab autoclaves

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