autoclaves

Industrial and domestic Autoclaves

Weigao Biotech AutoclavesAutoclaves are a device to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C or more, typically for 15 to 20 minutes depending on the size of the load and the contents.

Autoclaves are widely used in microbiology, medicine, tattooing, body piercing, veterinary science, mycology, dentistry, chiropody and prosthetic fabrication.

Autoclaves are found in many medical settings and other places that need to ensure sterility of an object. Many procedures today use single-use items rather than sterilized, reusable items.

This first happened with hypodermic needles, but today many surgical instruments (such as forceps, needle holders, and scalpel handles) are commonly single-use items rather than reusable.

Air removal in Autoclaves

It is very important to ensure that all of the trapped air is removed, as hot air is very poor at achieving sterility. Steam at 134 °C can achieve in 3 minutes the same sterility that hot air at 160 °C takes two hours to achieve.[6] Methods of achieving air removal include:

Downward displacement (or gravity type) – As steam enters the chamber, it fills the upper areas as it is less dense than air. This compresses the air to the bottom, forcing it out through a drain. Often a temperature sensing device is placed in the drain. Only when air evacuation is complete should the discharge stop. Flow is usually controlled through the use of a steam trap or a solenoid valve, but bleed holes are sometimes used, often in conjunction with a solenoid valve. As the steam and air mix it is also possible to force out the mixture from locations in the chamber other than the bottom.

Steam pulsing – Air dilution by using a series of steam pulses, in which the autoclaves chamber is alternately pressurized and then depressurized to near atmospheric pressure.

Vacuum pumps – Vacuum pumps to suck air or air/steam mixtures from the chamber.

Superatmospheric – This type of cycle uses a vacuum pump. It starts with a vacuum followed by a steam pulse and then a vacuum followed by a steam pulse. The number of pulses depends on the particular autoclave and cycle chosen.

Subatmospheric – Similar to superatmospheric cycles, but chamber pressure never exceeds atmospheric until they pressurize up to the sterilizing temperature.

Because autoclaves uses saturated steam under high pressure to achieve sterilizing temperatures, proper use is important to ensure operator safety.

Prevent injuries when using the autoclaves by observing the following rules:

  • Wear heat resistant gloves, eye protection, closed toed shoes and a lab coat, especially when unloading the autoclave.
     
  • Prevent steam burns and shattered glassware by making sure that the pressure in the autoclave chamber is near zero before opening the door at the end of a cycle. Slowly crack open the autoclave door and allow the steam to escape gradually.
     
  • Allow items to cool for 10 minutes before removing them from the autoclave.
     
  • Never put sealed containers in an autoclave. They can explode. Large bottles with narrow necks may also explode if filled too full of liquid.
     
  • Never put solvents, volatile or corrosive chemicals (such as phenol, chloroform, bleach, etc.), or radioactive materials in an autoclave.

Inspect your autoclave components regularly. If you find a problem, notify your area mechanic. Do not operate an autoclave until it has been properly repaired.

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