BS En 285:2006+a2:2009 Description: Sterilization.

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1 BS En 285:2006+a2:2009 Description: Sterilization. Steam sterilizers. Large sterilizers Steam sterilizers, Sterilizers, Large, Sterilization (hygiene), Medical equipment, Equipment safety, Safety measures, Design, Marking, Dimensional tolerances, Signal devices, Control systems, Temperature-measuring instruments, Pressure gauges, Recording instruments (measurement), Performance, Safety devices, Type testing, Performance testing, Leak tests, Air, Microbiological analysis, Contaminants, Air permeability, Noise (environmental), Steam, Quality, Pressure testing, Instructions for use,

3 Sterilization Autoclaving is the most effective and most efficient means of sterilization. All autoclaves must go through the GMP (good manufacturing practice) process of autoclave validation / Qualification during which, the various programs are verified as conforming to the requirements detailed in the User Requirement Specification (URS). They operate on a time/temperature relationship. These two variables are extremely important. Higher temperatures ensure more rapid killing. Some standard temperature/pressures employed are 115ºC/10 psi, 121ºC/15 psi. and 132ºC/27 psi. Longer times are needed for larger loads, large volumes of liquid, and more dense materials. Autoclaving is ideal for sterilizing bio hazardous waste, surgical dressings, glassware, many types of microbiologic media, liquids, and many other things. When proper conditions and time are employed, no living organisms will survive a trip through an autoclave.

4 Non-condensable gas test The Non Condensable Gas Test demonstrates that the attainment of sterilisation conditions in all parts of a steriliser load (particularly for porous load items) is not impaired by the presence of non condensable gases. The measurement of non condensable gases is made by cooling a steam sample with an efficient condenser, using water siphoned from a tank at 200ml per minute. Minimum requirements are: one metre head and water temperature below 28 degrees centigrade. Pressurised water is not required. When the sampled steam is condensed any noncondensable gases present are released and separated from the cooled condensate into sight glass columns.

5 Presence of air in steam In a mixture of air and steam, the presence of air will cause the temperature to be lower than expected. The total pressure of a mixture of gases is made up of the sum of the partial pressures of the components in the mixture. This is known as Dalton's Law of Partial Pressures. The partial pressure is the pressure exerted by each component if it occupied the same volume as the mixture. Example Consider a steam/air mixture made up of ¾ steam and ¼ air by volume. The total pressure is 4 bar. Therefore the steam only has an effective pressure of 3 bar as opposed to its apparent pressure of 4 bar. The mixture would only have a temperature of 134 C rather than the expected saturation temperature of 144 C. This could render autoclaving ineffective where a minimum temperature is essential in order to kill bacteria. It is therefore of paramount importance during the autoclave validation / Qualification task to validate that all air has been removed from the chamber

6 Non condensable gas test Manual method 1. Steam is sampling out of the steam elbow 2. Steam comes into the condenser coil 3. Since cold water coming at the outside of the condenser coil, the steam will be condensed and become condensate 4. Condensate is going into a container that is full with cold water 5. Since condensate keeps coming into the container, the overflow water is collected in a measuring glass 6. Inside the measuring glass there is a measuring burette that is HALF FULL with water, we have to mark the water level position at the beginning of the test 7. When the overflow water comes into the measuring glass, air or other non condensable gas will goes & move upward into the burette 8. The water level inside the burette will drop 9. At the end of the test, we measure the water inside the measuring glass and the air volume inside the burette 10. Then we will find out the % of non condensable gas inside the steam

7 Dryness test value To ensure and to test that an acceptable amount of moisture is present in the steam supply. For little amount of moisture there is a chance of superheating may occur. Even too little moisture may prevent sterilizing conditions in the chamber. Steam with a dryness fraction of 0.99 consists of 99% steam and 1% water. Similarly, steam with a dryness fraction of 0.95 consists of 95% steam and 5% water. The dryness value of the steam should be equal to or greater than 0.9 for porous loads or 0.95 where metal loads are processed.

DRYNESS Manual method 1. Prepare a thermos flask, check the empty weight of the thermos flask 2. Fill the thermos flask with +/ 650 ml of water & weight thermos flask 3.

8 DRYNESS Manual method 1. Prepare a thermos flask, check the empty weight of the thermos flask 2. Fill the thermos flask with +/ 650 ml of water & weight thermos flask 3. Check the initial water temperature inside the thermos flask with the first temperature sensor 4. Check the temperature of the steam inside the steam test elbow with the other temperature sensor 5. Insert a pitot tube at one of the port of the steam test elbow 6. Connect a rubber hose from the pitot tube to the thermos flask cover & open the steam isolating valve 7. Steam will be coming into the thermos flask 8. Stop the test & close the steam isolating valve when the water temperature inside the thermos flask is about 80 C Shake the thermos flask well 9. Check the new weight of the water inside the thermos flask

9 Superheat steam test There are quite a few reasons why superheated steam is not as suitable for use in steam autoclaves. In heat transfer applications, steam with a large degree of superheat is of little use because it: a) Gives up little heat until it has cooled to saturation temperature. b) Creates temperature gradients over the heat transfer surface as it cools to saturation temperature. c) Provides lower rates of heat transfer whilst the steam is superheated. d) Requires larger heat transfer areas.

10 Superheat test Manual method 1. Insert a pitot tube (orifice) into one of the steam test elbow port 2. Cover the pitot tube with a special cover, so we can insert a temperature sensor in it 3. Insert another temperature sensor at the other port of the steam test elbow 4. Open the steam isolating valve 5. Check the reading of the steam temperature coming out from the pitot tube to atmosphere 6. Check the reading of the actual steam temperature inside the steam test elbow 7. The superheat steam temperature = The steam temperature at the pitot tube The boiling water temperature

12 INTRODUCING: Armstrong QM-3 steam quality testing equipment

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Steam Quality Test Kits. Product Code: SQTK A to L. Description: Datasheet : 040

Steam Quality Test Kits. Product Code: SQTK A to L. Description: Datasheet : 040 Page 1 Steam Quality Test Kits SQTK A to L The range of Steam Quality Test Kits from Thermal Detection consists of seven kits which cover all of the measurement and reporting requirements in accordance