Standard methods of the Division of Laboratories and Research of the New York State Department of Health : General laboratory procedures and methods used ... / Augustus B. Wadsworth, director.

  • New York (State). Department of Health. Division of Laboratories and Research.
Date:
1927
Catalogue details

Licence: Public Domain Mark

Credit: Standard methods of the Division of Laboratories and Research of the New York State Department of Health : General laboratory procedures and methods used ... / Augustus B. Wadsworth, director. Source: Wellcome Collection.

    82/754 (page 54)
    An hour is usually required to reach the maximum pressure (125 pounds) after the door is closed. An initial pressure of 110 pounds is necessary to bring the temperature of the chamber to 150°C., at which point the sterilization period is started. A pressure of from 110 to 125 pounds of steam is sufficient to maintain a temperature of from 150 to 162°C. The sterilization period is one hour at this temperature. 4. At the end of the sterilization period, shut off the steam supply and open the door slightly. Allow the material to cool somewhat before opening the door wide. A slip of paper on which the word “‘sterile’’ is written with cobalt-chloride solution is placed in each basket, pipette container, and can, whichis sterilized by dry heat. Theinvisible writing darkens between 140 and 150°C., above which the color becomes deeper. STERILIZATION BY STEAM UNDER PRESSURE Sterilization by means of steam under pressure is usually accom- plished in the autoclaves. In some instances the ‘‘American”’ sterilizer is used. In operation it is necessary to check carefully the thermometer readings and the recorded steam pressures. Autoclaves Procedure.—1. Load the autoclave. 2. Close both pressure and vacuum doors and all valves. 3. Admit steam to the jacket and the chamber until 15- or 16-pounds pressure is registered on the two gauges. Open slightly the exhaust valves of the jacket and the chamber, and leave them open during the period of sterilization. When the temperature reaches 121°C., start to time the sterilization period. Keep the temperature and pressure constant by adjusting the exhaust valve of the jacket. 4, When the sterilization period is ended, close the chamber-exhaust and the steam-inlet valves and open the jacket-exhaust valve. 5. When condensation is not objectionable, reduce the temperature quickly by replacing the steam with air, maintaining the pressure. 6. Do not open the inner door until the temperature has fallen to 98°C. or below, if the load includes media. “‘American”’ Sterilizer Procedure.—1. Heat the jacket slowly. 2. Load the car, run it into the chamber, and close the door. 3. After the sterilizer is warm, allow the steam to enter the jacket until a pressure of approximately 18 pounds is recorded on the jacket gauge. 4, Admit steam to the chamber until a pressure of from 15 to 18 pounds is reached, giving a temperature of 121°C. as indicated on the