Autoclaves

What is a Laboratory Autoclave?

An autoclave is a machine that provides a physical method of sterilization by killing bacteria, viruses, and even spores by using steam under pressure. Autoclave sterilizes the materials by heating them up to a particular temperature for a specific period of time.

Applications

  • They are used to decontaminate specific biological waste and sterilize media, instruments, and labware.
  • Regulated medical waste that might contain bacteria, viruses, and other biological materials are recommended to be inactivated by autoclaving before disposal.
  • In medical labs, autoclaves are used to sterilize medical equipment, glassware, surgical equipment, and medical wastes.
  • Autoclaves are used for the sterilization of culture media, autoclavable containers, plastic tubes, and pipette tips.
  • Vulcanization of rubber

Other Names

Steam sterilizer

Working Principle

  • The autoclave works on the principle of moist heat sterilization where steam under pressure is used to sterilize the material present inside the chamber.
  • The high pressure increases the boiling point of water and thus helps achieve a higher temperature for sterilization.
  • Water usually boils at 100°C under normal atmospheric pressure (760 mm of Hg); however, the boiling point of water increases if the pressure is to be increased.
  • Similarly, the high pressure also facilitates the rapid penetration of heat into deeper parts of the material, and moisture present in the steam causes the coagulation of proteins causing an irreversible loss of function and activity of microbes.
  • This principle is employed in an autoclave where the water boils at 121°C at the pressure of 15 psi or 775 mm of Hg.
  • When this steam comes in contact on the surface, it kills the microbes by giving off latent heat.
  • The condensed liquid ensures the moist killing of the microbes.
  • Once the sterilization phase is completed (which depends on the level of contamination of material inside), the pressure is released from the inside of the chamber through the whistle.
  • The pressure inside the chamber is then restored back to the ambient pressure while the components inside remain hot for some time.

Different Types of Autoclaves

  • Gravity displacement type autoclave: It is the most common type used in laboratories and is available in various sizes and dimensions.
    – Vertical type (small volume capacity)
    – Horizontal autoclave (small to large volume capacity)
  • Positive pressure displacement type autoclave
  • Negative pressure (vacuum) displacement type.

Basic Layout

1 – Control Panel

2 – Hand Wheel

3 – Door (Safety Door Cover)

4 – Pressure Gauge

5 – Manual Exhaust Valve

6 – Exhaust Tank and Tube

7 – Drain Tube and Tank

8 – Chamber

9 – Heater Cover

10 – Basket

11 – Circuit Breaker

12 – Safety Relief Valve

13 – Power Plug

14 – Lockable Caster

Operating Procedure

  1. Make sure exhaust tank and drain is connected
  2. Fill water in chamber to appropriate level. Use deionized water
  3. Place objects inside. Use baskets if necessary
  4. Close and seal the door and manual exhaust valves
  5. Set the program on the controller and begin sterilization
  6. When cycle is complete check pressure gauge to confirm that ambient pressure is reached inside the autoclave
  7. Open Door and use gloves to remove objects
  8. Empty drain and exhaust bottle if needed (Caution water in exhaust and drain may be hot)

Accessories / Consumables  

  • Exhaust Tank
  • Drain Bucket
  • Baskets
  • Indicators
  • Autoclave deodorant
  • Deionized Water
  • Printer
  • Stool
  • Pressure sensor

Applicable Standards

SANS 347 – is a national standard which is mandated in the PER and is used to ensure technical compliance to regulatory requirements which include hazard categorisation and conformity assessment requirements.

PER – The legal requirements for the importing of pressure equipment are contained in the Pressure Equipment Regulations (PER) of the Occupational Health and Safety Act (OHSA)

Below is an excerpt from the PER regarding SANS 347:

  • Importers and suppliers shall ensure that pressure equipment sold complies with the requirements of this Regulation.
  • The importer shall assume the liability of the manufacturer in terms of this Regulation.
  • Any pressure equipment that requires a permit to be issued by an organization approved by the chief inspector shall ensure that such approval is obtained by the importer or manufacturer before the pressure equipment is placed in the market: Provided that such equipment shall comply with the relevant health and safety standard incorporated in to these Regulation under section 44 of the Act.

Who can we sell to?

Biotechnology, biochemistry, microbiology, virology laboratories.

Information required to to quote on an Autoclave

  1. What do you intend to Autoclave?
  2. Do you require a Horizontal or Vertical autoclave?
  3. What size chamber do you require?
  4. Do you require vacuum?

Further Reading / Videos

https://www.firstsourcels.com/blog/learn-how-to-select-the-best-autoclave/

https://www.rapidmicrobiology.com/test-method/choosing-a-microbiology-laboratory-autoclavesterilizer

https://www.steris.com/healthcare/knowledge-center/sterile-processing/guide-to-steam-sterilization-cycles-steam-flush-pressure-pulse

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