Autoclave Standard Operating Procedures (SOPs): How to Safely Operate an Autoclave (+SOP Template)

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Written by: Scott Mechler

BS Mechanical Engineering, Mechanical Engineer

Autoclaves, also known as steam sterilizers, use pressurized steam to kill any microbial life that may be present on a contaminated item. For this reason, autoclaves are most commonly used in laboratories, hospital operating rooms and food production facilities in order to sterilize goods and instruments.

Autoclaves are extremely powerful and can be a bit intimidating to those who are inexperienced with operating them, which is why we’ve put together this guide to standard autoclave working procedure to help you get started.

The Importance of Autoclave SOPs for University Labs

To ensure that procedures are followed correctly, maintain the safety of laboratory staff, and increase the likelihood that sterilization is achieved with no errors, having a set of autoclave SOPs is crucial. By establishing these types of guidelines, all technicians (or anyone who uses your lab’s sterilization equipment on a regular basis) are able to stay on the same page when it comes to the best practices for autoclave operation.

But what should you include on your lab’s list of SOPs for sterilization? Information regarding safety procedures, how to operate and maintain your autoclaving units, and how to keep proper usage records are what you should cover at minimum. Read through the rest of this post for an in-depth look at these (and other) important autoclave SOPs.

Autoclave Procedure Training

Prior to operating an autoclave, all laboratory personnel must complete training from their supervisor on standard autoclave working procedure. Training materials should cover:

  •  Proper safety protocol
  •  How to prepare items for sterilization
  •  How to safely load and unload materials from an autoclave
  •  How to select the appropriate cycle based on the contents of the load
  •  Standard autoclave operating procedure
  •  How to maintain accurate autoclave usage records
  •  Standard autoclave maintenance
  •  Autoclave contingency plans

Autoclave Safety

When loading, operating, or unloading an autoclave, laboratory personnel must wear the following:

  • Close-toed shoes
  • Safety glasses
  • Heat-resistant gloves that completely cover the hand and forearm
  • Lab coat

This protective gear is designed to protect the wearer from scalds, burns and other injuries caused by residual steam, hot fluids from boiling liquids and spillage. Since laboratory autoclaves use a jacketed construction, laboratory personnel should be aware that metal surfaces are hot even when the autoclave is not actively in use. Finally, always be mindful of your hands and arms when closing the autoclave door to prevent injury.

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Container Selection

It’s important that laboratory personnel never place sealed containers in the autoclave, as the pressure inside the autoclave could cause glassware to crack or explode. Likewise, never place items that contain solvents into an autoclave, as these can emit toxic fumes when heated. Do not autoclave bleach — or any cleaner containing bleach — because chlorides within the bleach will damage the unit.

The Consolidated Sterilizer Systems team recommends that laboratory personnel always check all items prior to sterilization to ensure that they are autoclave-safe and inspect any glassware for cracks prior to autoclaving.

Preparation, Packaging & Loading of Materials

Laboratory personnel should always observe the following autoclave procedures when loading the unit:

  • Loosen the lids on any containers being loaded into the autoclave and ensure that any bags are not tied shut or otherwise sealed. Steam-penetrable bungs may be used.
  • Empty glassware or other containers that do not need to be sealed should be placed on the side or upside-down to prevent air pockets from forming.
  • Place any goods containing liquid in a secondary containment pan made of an autoclave-safe material. The pan should be large enough to contain a total spill of all the liquid contents.
  • Load all goods in such a way that there is as much space between each item as possible. Make sure that nothing is touching the side wall or bottom floor of the autoclave and that the drain at the bottom is free from blockage.
  • Ensure that there is a metal strainer present in the drain of the autoclave, and check to make sure it is free and clear of debris. If the drain is clogged, the strainer should be removed, cleaned, and put back in place before running the autoclave cycle.
  • Do not overload the autoclave; it’s important that there is sufficient room for steam to circulate through the entire chamber during sterilization cycles.
  • Observe protocol for sharp or biohazardous material for your laboratory when loading the autoclave.

It’s also important to note that most autoclaves are equipped with metal wire rack shelves. When loading goods into this type of autoclave, place all items in such a way that they are easily accessible from the autoclave door, without having to lean into the autoclave itself or against any piece of metal on the side.

Time Selection

Sterilization time will vary depending on a number of factors, including the size of the load, the type of load, and the cycle you choose. If you are uncertain how long to run the autoclave, consult your supervisor and the autoclave manual to determine the best cycle type and appropriate runtime.

Cycle Selection

Once the unit is loaded, be sure to observe the following autoclave working procedures:

  • Close the door fully if you are using a hinged-door autoclave, engaging the locking pins and turning the locking mechanism until it stops moving. Be mindful not to use extreme force on the locking mechanism, as this can damage the gasket or internal mechanism of the door lock. Simply tighten the locking mechanism until it cannot be tightened any further.
  • Choose the appropriate cycle for the goods inside the chamber (e.g. Gravity, Liquid, or Vacuum). When choosing a cycle, keep in mind that Gravity and Vacuum cycles can cause liquid goods to boil over inside the chamber. Vacuum cycles may be insufficient at sterilizing porous or bagged goods. Liquid cycles take longer but will not damage goods suited for Gravity cycles, such as glassware or metal instrumentation.
  • Consult the autoclave manual for assistance in choosing the correct cycle parameters. Autoclave manuals should be stored near the autoclave.
  • Do not attempt to open the autoclave door once the cycle has started. As previously mentioned, autoclave doors feature a mechanical locking mechanism that can be damaged by extreme force. This mechanism will not disengage until the pressure within the chamber has dissipated. Even a few pounds per square inch of pressure on the autoclave can present an extreme safety hazard to the user, and, with enough force, the safety lock can be broken.
  • Abort the cycle using the controller or emergency stop button if you suspect any issues with the autoclave. Wait for both the temperature and pressure to return to a safe range before attempting to open the door lock. The emergency stop button is a standard feature in all Consolidated sterilizers.

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NOTE: Larger laboratory autoclaves are equipped with heated jackets. It’s important that the unit be allowed sufficient time to reach temperature before you run a cycle (this could take up to an hour, depending on autoclave size).

Consolidated Sterilizer System’s autoclaves include an automatic on/off timer, called EcoCalendarTM, which enables you to set the unit to turn on or off at specific times of the day — for example, the unit could be set to reach temperature at the same time the first user enters the building for the day.

Safe Removal of Materials

Once the cycle is complete, unload the unit according to the following autoclave procedure:

  • When the cycle is complete and the pressure within the autoclave has dropped to a safe range, ensure that no one is standing near the unit and open the door one inch. This enables the autoclave to vent and goods to cool.
  • If there is a fume hood above the autoclave, make sure it is turned on while the door is open and the steam inside the chamber vents out.
  • Allow steam to vent and goods to cool for approximately 10 minutes.
  • Liquids can become super-heated by autoclave cycles due to high pressure raising the boiling point. To reduce the risk of scalds or burns, do not agitate any liquid containers or remove caps while unloading.
  • Place all goods in an area that clearly designates that the items are hot and allow them to cool to room temperature. Shut the autoclave door and engage the locking pins.
  • Once the autoclave is unloaded, leave the jacket on and engaged in case other laboratory personnel need to use it. If it is the end of the day, shut down the jacket by turning the appropriate switch.

Updating the Log Sheet

According the Centers for Disease Control and Prevention and the Organization for Safety and Asepsis Prevention, all laboratories should keep a detailed autoclave log sheet. Autoclave log sheets enable laboratories to create and maintain a detailed records of autoclave usage, including time and date, contents of the load and cycle type, for monitoring and maintenance purposes.

If your facility maintains an autoclave use log, be sure to update it every time you operate the unit.

>> Download Your Free Autoclave Log Sheet Template Today

Autoclave Maintenance

Routine preventative autoclave maintenance is a key component of autoclave procedure. Particulates in steam and poor water quality can easily damage an autoclave, resulting in system downtime, poor processing performance and expensive repairs. Therefore, laboratories should conduct planned maintenance inspections on a consistent basis, be it monthly, quarterly or annually in order to ensure that equipment remains in proper working order. These inspections should be comprehensive and cover heating coils, contactors, steam traps, safety valves and more.

>> Get Your Free Autoclave Maintenance Checklist & Log Sheet

Contingency Plans

Although it’s important that laboratory personnel take every precaution to eliminate safety risks, incidents can and do occur. To prevent unnecessary damage or injury, follow the safety protocols listed below.

How to Proceed in the Event of an Equipment Malfunction

If the autoclave does not operate as expected, record the issue in the autoclave log book. Do not attempt to diagnose or fix the issue yourself. Instead, notify the laboratory manager and mark the autoclave as out of order with a sign or a sticker.

Remember, goods should only be removed from the autoclave once it has completely cooled, even if the cycle is aborted. Never attempt to force the safety lock mechanism open in order to retrieve goods from an autoclave that has aborted a cycle.

If the autoclave vents steam into the room, liquid pools underneath the autoclave, or the autoclave emits smoke and sets off the fire alarm, use the three-phase power disconnect to turn off power to the generator.

How to Proceed in the Event of a Spill

Spills can occur when the liquid within a container boils over or when a container breaks. Should a spill occur, do not operate the autoclave until it is cleaned up. Instead, wait until the autoclave’s heat jacket has cooled to room temperature before attempting to clean up a spill.

Once the autoclave has cooled, contain the spill using paper towels or your laboratory’s spill kit.

Then, dispose of any waste, including any potentially cracked glassware, according to your laboratory’s protocol for sharp and biohazardous material.

After the spill is contained and cleaned up, document the incident and clean-up procedure in the autoclave log book.

Ensure Proper Sterilization Processes in Your Laboratory

For guidance on autoclave working procedures for your laboratory, download a copy of our Autoclave SOP Template. This free resource will help your team become familiar with the right sterilization procedures, stay safe, and achieve error-free results.

Need additional guidance on autoclave working procedures or steam sterilizer maintenance? Contact the professionals at Consolidated Sterilizer Systems today.

Free Guide to Laboratory Safety & Standard Autoclave Procedure

Are you staying safe and following procedure when operating an autoclave? Download our free guide to laboratory safety & standard autoclave procedure to help mitigate potential risk.

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Free Guide to Laboratory Safety & Standard Autoclave Procedure