What is The Ideal Sterilizer Steam?


Steam sterilization has four parameters: steam, pressure, temperature and time. The ideal sterilization steam is dry saturated steam and entrained water (drying rate ≥97%).

sterilizer steam, saturated steam, sterilization process

Why does the sterilizer need to be pressurized?


Pressure is a means of getting the high temperatures needed to quickly kill microbes. A specific temperature must be obtained to ensure bactericidal activity. Steam is needed to heat the sterilizer and its contents to between 134°C and 137°C. Since the steam temperature at sea level atmospheric pressure (1.013 bars) is 100°C, it needs to be pressurized to reach the desired higher temperature.


What kind of sterilizer steam is best?


Saturated Steam


1. It must be clean so that it will not leave a bad residue on the processed product when set.

2. It should be “saturated” with steam, but it cannot carry additional water droplets, which can lead to a wet load and then need to reprocess the load.




The dryness value of steam (often referred to as the dryness fraction) is measured on a scale of 0 to 1.

Dryness =0 Only liquid water exists

Dryness =1 Only steam is present


Although dry saturated steam should ideally be used, modern sterilization processes can still tolerate small amounts of water.

With a drying fraction limit of “0.9” for porous loads, the typical steam temperature must be maintained between 134°C and 137°C for at least three minutes to achieve sterilization.

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