Some guidelines from

Getinge AB

© Getinge AB 1997

STERILIZATION WITH STEAM

Version 9709

CONTENTSPreface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

INTRODUCTIONPopular introduction to steam . . . . . . . . . . . . . . . . . . . . . . . . .7Steam sterilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9The moisture content of the goods . . . . . . . . . . . . . . . . . . . . . . 11

MEDIA QUALITYSteam . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

PACKING MATERIALWrappings of paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Wrappings of textile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Bags or peelable reels of paper or paper mixes . . . . . . . . . . . . . . . 22Peelable reels of plastic foil . . . . . . . . . . . . . . . . . . . . . . . . . 22Goods carriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

PACKAGINGSingle items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Plastic items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Textiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Instrument set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Containers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Baskets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Fold instruction for wrappings . . . . . . . . . . . . . . . . . . . . . . . . 30

PROGRAM MODIFICATIONGeneral advice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Modification procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Post treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Pre treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

THE STERILIZERPre heating the sterilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Doors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41The sterilizer condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42The sterilizer and the steam . . . . . . . . . . . . . . . . . . . . . . . . . 43Replacement of sterile filter . . . . . . . . . . . . . . . . . . . . . . . . . 43Air purging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

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PrefaceA result of a sterilization where steam has been used as the sterilagent, is usually judged from two criteria, the STERILITY and tREMAINING MOISTURE CONTENT of the goods.

The sterility which is dependent on physical, chemical and biologparameters is naturally the most important one. The physical paramcan be verified by means of the sterilizer recording instrument and/ousing chemical indicators. By means of biological indicators packedtogether with the goods, the intended bacterial killing result canproved.

Moisture content is more difficult to judge because the permisslimits are more widely spread and will vary with the great varietyarticles being sterilized.

Both the above criteria are recommendations or demands associn respective countries. These are often issued by the authority ressible for public health and sick care or with organisations associatethese.

The controllable key factorsThe sterilizing result is directly influenced by such key factorsMEDIUM QUALITY, PACKING MATERIAL, PACKING TECH-NIQUE, STERILIZER CONDITION and TYPES OF PROGRAM.

With this reference book GETINGE AB will show the individual usthe possibilities available to influence these factors depending onown conditions, to achieve the best result in each specific case.

To begin with the background is given to the conceptions of sterand moisture content.

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INTRODUCTION

Popular introduction to steamSteam beyond all comparison is the cheapest and most suitable mfor thermal sterilization, because its energy content is very large andemitting, while heating the micro organisms, the moisture necessakill these.

At the appropriate temperature and pressure, all agents can existthree states of aggregation, gaseous, liquid and solid, provided thenot decompose at high temperature. The conversion from one staanother is accompanied by absorbing or emitting heat (and usuallya change of volume). To illustrate this the diagram below shows whappens when heat is added to 1 kg ice at -50oC. The unit for heat is thejoule (J). The most common unit for technical use is the thousand tlarger kilojoule (kJ). An elderly unit was BTU (British Thermal Unit)

At the initial point A, the temperature of the ice is -50oC. Heat which istransferred to the ice increases its temperature. At point B, whentemperature is 0oC the temperature rise suddenly stops in spite of hbeing continuously admitted. This is because all heat is consumemelting the ice. The admitted amount of heat is absorbed in the cosion when the water goes from solid to liquid state and is therecalled the melting (fusion) heat of the ice. As can be seen from the digram the heat amount comes to about 335 kJ.

The water temperature will not increase until all ice is melted, bu100oC (this fictitious laboratory experiment is assumed to take plac

Fig 1.

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atmospheric pressure) the temperature becomes constant aAnother state conversion temperature is attained.

The heat amount which has been admitted to the water of 0oC andcaused its temperature rising from C to D is called sensible heat andcomes to about 420 kJ.

The not occurring temperature rise at point D in spite of heat becontinuously admitted depends on all supplied energy being consuby converting water from liquid state to steam. The energy consuuntil all water has boiled off from D to E in fig. 1 is called latent heatand is at 100oC of the order 2250 kJ. The steam produced from the bing water is called wet steam because minor water particles are caaway by the bubbling water.

At point E where all water is converted into steam, the latter is cadry saturated. Such steam is invisible like atmospheric gases andcharacterized by being free from suspended water drops, but it is nesuperheated, i.e. not heated to a higher temperature than the waterfrom which it was created.

The state dry saturated is an ideal state of steam which is in pradifficult to maintain, but for sterilization purpose the very best.

On continued heat admittance at E when all water is convertedsteam, the steam temperature increases along the line E - F. The is then superheated. At F the heat supply is supposed to be remov

On the diagram the pressure has been assumed to stay consatmospheric pressure why the temperature of the saturated ste100oC. If the heating of the water takes place in a closed vesselsteam pressure and thereby the temperature increases along the lG.

It is also possible to create steam with lower temperature than 10oC,but in that case the steam production has to take place at subatmospressure. The deeper vacuum the lower steam temperature as cseen from fig. 2.

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There exists always a known relationship between temperature anpressure with saturated steam which can be seen on fig. 2.

Steam sterilizationSterilization means total killing of all microorganisms such as sporvirus, bacteria etc. The most difficult killing objects are bacteria in spore state. The sterilization is made cheaper and safer using moheat. The time required depends on the temperature at which the szation process is performed. The killing of spores demand that:

1. The spores must become moistened.

2. The spores must be hot (above 115oC).

The sterilization process consists usually of three main phasesfig. below)

A Pretreatment B Sterilizing C Posttreatment

Fig. 2

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The pretreatmentThe task of the pretreatment is to replace all air with steam in the chber and in the blind space of the packings as well as in cavities andin the goods to be sterilized. If this replacement is not successfspore may be surrounded by air, in which case it may becomeenough but not humidified and therefore survives. In the pretreatmstage therefore a gradual replacement of the air takes place by reedly pumping out the chamber atmosphere, and at each evacureplace it with steam. This first phase also aims at preheating the g

SterilizationDuring the second phase the actual sterilization takes place. The gare heated from room temperature to sterilizing temperature 134oC) by the admitted steam condensating on all surfaces whichcolder than 134oC. When the steam reverts into water all heat onrequired to produce it, is given back and this is why heating with stis outstandingly efficient. It has also the advantage of fulfilling oadditional of the main conditions above, to humidify the spores.

The disadvantage is however that there is much more steam (cosate) required for heating purpose than is needed for humidificaThis is why the goods may become more moisturized than wanted

When the chamber- temperature and pressure has reached the dlevel, usually minimum 121oC respectively 134oC, this is maintainedfor a certain minimum time, the sterilizing time, which is minimum 1respectively 3 minutes. The relationship time - temperature is covein standards.

Post treatmentThe process is finished with a third phase during which the chambersteam is emptied by evacuation to a deep vacuum. This is often cthe drying phase because at this stage, in the best case, all watedensed to steam should boil off in order to enable for the vacuum pto take it away.

This is however not possible if the water has been collected ininstance a wrinkle in a plastic bag, as there is no amount of heat able to evaporate the water. This is sometimes the reason why it becdifficult to reduce the moisture content of the goods.

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The moisture content of the goodsAs said earlier, the heating of the goods is made by steam emittinheat content to the surfaces on which it condenses to water. Thisdensation continues until all all objects have attained the temperatuthe steam itself. Therefore more condensed steam is required the ier an object is.

To increase the temperature to 134oC of a mallet the weight of whichis 0, 5 kg, there will be formed about 10 ml condensate. This watermost probably flow together to drops which are collected somewhethe parcel or the package material.

If the water can later on be removed or not depends on whether icontact with any heated object or not. If the water is collected in a wkle in a plastic bag where it has no contact with an object like instment, bowl or similar the water will hardly be removed by any dryinor post treatment cycle acceptable from the time point of view. Thecontent of the the water itself is sufficient to evaporate only about 1of it.

If on the other hand the condensate is collected where it is in conwith metal surfaces like in the bottom of a bowl or absorbed in a tesurrounding an instrument practically all condensate will evapowith a dry load as result.

A specific problem are articles made of plastic. A comparisbetween two bowls, one made of steel and the other of plastic shownearly the same amount of steam will be required to heat the objecsterilizing temperature. For a common kidney bowl the quantity is amillilitres. The water flows together to a pool on the bottom of the boAfter the drying stage all water has evaporated from the metal bwhile almost all is left in the plastic one. This happens in spite of same amount of heat being accumulated in both objects.

The reason is the good heat conductivity with steel making practicall accumulated energy available in one small spot when evaporathe pool. With the plastic bowl the total amount of heat remains spout and therefore not available where it is needed. There is a differin heat conductivity of about 50100 times, which means that if thereone minute required to evaporate the water in the metal bowl, it wotake about one hour with the plastic one. This illustrates the importof combining goods types and packing material in the right way. Mabout this later.

Does not the sterilizer design and function have any influence onsterilizing result? Yes it has, and in two ways. Technical malfunctresulting in a wet load may occur with the sterilizer itself or with tsteam supplied from a central plant. The sterilizer itself can be cheby means of its own instruments and by weighing the goods beforeafter a sterilization process. The weight should due to moisture shnormally not exceed 1%1 with textiles.

1. Often stipulated in standard

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Another circumstance which has influence on the moisture contethe load is the degree of preheating which takes place during thetreatment stage of the process. This preheating can be made in difways but they all aim at increasing the temperature of the load withmaking use of condensation. In this way the temperature rise, wshall take place later during the sterilizing phase, will be reduced this is also the case with the amount of condensate. In the ideal cassmall amounts of condensate is required that it appears only as dethe goods. This will however be attained only with small instrumen

An additional factor influencing the result is the post treatment phDuring this stage can with a suitable process shaping that part oexcess moisture be evaporated which was necessary to add durinpretreatment stage.

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MEDIA QUALITY

SteamThe result of a sterilization process is greatly influenced by the quaof the sterilization medium which can be either steam from a censteam production plant or steam produced by the sterilizer own elesteam generator. In both cases the feed water quality indirectly inences the quality of the produced steam. Certain demands are theraised on the steam supplying a sterilizer.

The values referred to in this booklet are based upon Getinge's experience and can where appropriate be replaced by values and uring methods given in different standards.

Cleanness

1. Solid particles such as welding pearls, graphite, rust flakes, saetc. must not be present since the steam comes in direct contacthe sterilizing goods.

2. Liquids, except water, must not be found for the same reason above

3. Gases prevent the required close contact between the steam amicroorganisms to be killed and shall be limited as below

· Hydrazine (N2H4) max. 0,01 mg/kg steam

· Ammonia (NH3) max. 5 mg/kg steam

· Air and/or non condensable gases max. 3,5% V/V, formed bygas-air-mixed steam.

4. Chemicals, others than listed below, like residuals from water stening and similar must not occur in sterilization steam.

· Salt content max. 1 mg/kg steam

Analysis of condensateAn analysis of the condensate from the steam gives an idea abocleanness regarding additional agents. These should not, accordin

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the standard EN285, occur in concentrations exceeding the values in mg/kg condensate in the table below.

Pressure

1. Getinge sterilizers should be supplied with steam having a presof 2,5 - 2,7 bar(g), indicated by the sterilizer pressure gauge ”Stsupply”.

2. Permissible pressure variations max. ±0,1 bar.

3. With built in steam generators, the pressure may drop to 2,2 ba

Moisture contentSterilizers should be supplied with dry saturated steam. The physicastate ”dry saturated” is difficult to maintain in a practical applicatioand measurements followed by control of the moisture content iawkward procedure. Practising the advice later given which are bupon practical experience, will generally result in a steam with satistory moisture content. This means that nor will it be superheated, a of the steam which is hazardous in connection with sterilization becit does not contribute with the humidification necessary when destring microorganisms.

The superheating in a sterilizer loaded with one standard textile pmust not exceed 5oC during the first five minutes of the sterilizationperiod.

Evaporation residuals 1,0 from which:

SiO2 0,01

Iron 0,1

Cadmium 0,005

Lead 0,05

Other heavy metals 0,1

Chloride 0,1

Phosphate 0,1

Other desirable properties:

Conductivity < 3µS/cm (at 20 oC)

PH-value 5 - 7

Hardness < 0,1 dH

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Checking-up the piping

A Check that the building steam distribution pipes do not slope upthe flow direction so as to enable for condensate pools to be forand that steam traps, strainers, chokes etc. are in good workingdition. See recommended pipe arrangements under the headlibelow. The main principle in avoiding condensate pools to be formed is to fit the pipe sloping minimum 1:50 in the flow directioarrange with steam traps enabling for the condensate to be discharged and avoid fitting any chokes in horizontal pipes.

B Check the steam traps! A continuously leaking steam trap maycause a too low supply pressure.

C The dewatering devices (see illustration on page 17) should beplaced not further than 1 m away from the sterilizer steam intakthis is not possible for practical reasons, a steam separator canarranged before the sterilizer steam intake. This will remove codensate formed between the system dewatering devices and tsterilizer.

Steam supply via distribution systemDimensioning, dewatering and laying of pipes which are to distribsteam of the high quality required for sterilizing purpose belongs special group of technique. Getinge AB recommends work in this fbeing carried out in accordance with advice given by Spirax-Sarcworld wide well known company with many years experience of stedistribution systems.

An arrangement according to the following description normally sisfies the demand for dewatering, filtration and supervision facilitwhen supplying a sterilizer with steam from a main steam supply li

1. Connect the sterilizer to a live steam line, not to an inadequatedrained or inadequately vented “dead leg”. Long branch connetions to sterilizers should be avoided.

2. Dimension the piping for a steam velocity of 38 m/s at the pres250 kPa. If several sterilizers are connected to the same pipe, clate with a simultaneity factor 0.8.

3. The steam supply pipes should fall minimum 1:50 in the flow dirtion.

4. Introduce reducing valve(s) in the supply line if the pressure ishigher than specified in the installation drawing. The steam presure upstream the reducing valve should not fluctuate more tha10%. Do not reduce the pressure with a factor smaller than 0,5each stage. Use a second reducing valve for greater reduction

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Each reducing valve must be followed by a safety valve.

The safety valve exhaust pipe should have at least the same dsion as the valve exhaust connection and must not contain choor shut off devices. Water pockets formed in the piping, must bdrained.

5. There must be no chokes or restrictions placed in horizontal pi

6. Fit the last reducing valve not more than 6 m pipe length away fthe sterilizer, but not closer than 4 m if maximum reducing ratio(2:1) is utilized.

7. The last dewatering device (see figure below) should not be plafurther than 1 meter away from the sterilizer steam intake.

8. No steam consumers other than sterilizers should be connectedown-streams the last reducing valve.

9. Branch pipes should be connected on top of horizontal main p

10. A connection should be provided between reducing valve and ilizer on the steam supply line to enable sampling steam for quacheck up.

11. Because of its daily use, the shut off valve should be of the easy-to-handle type for instance a remote controlled ball valve.

If the steam in the supply pipe is wet, include dewatering as shown in Figure “A” just before the reducing valve, as shown in the sketches below.

If the reducing valve is positioned much more than six metres from the sterilizer, include dewatering as shown in Figure “A” just before the sterilizer.

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12. Insulate steam pipes up to the sterilizer steam intake

1 High-pressure line 8 Vent

2 Labyrinth diverter / separator 9 Ball valve

3 Shut-off valve 10 Steam trap

4 Filter 11 Remote-controlled valve

5 Reducing valve 12 Non-return valve

6 Safety valve 13 Sterilizer

7 Pressure gauge

Supply line in ceiling

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Steam supply from built in steam generatorThe design pressure for built in steam generators is 3,5 bar(g). Seeon the vessel.

The variation of 10% in opening pressure, shown by all safety valwill not permit the vessel working pressure being almost the same adesign pressure. To make sure the valve does not leak, the workinsure must be kept about 0,3 bar below the design pressure.

The steam generator pressure is controlled in two steps by a preswitch equipped with two contacts.

1. Check all elements for continuous circuit. Use a current clampwhile in use and an ohmmeter when disconnected.

2. Set the pressure switch as described below.

· Set the switch controlling the higher pressure to switch off poat the pressure stated in the electric wiring diagram. The settinto be done at rising pressure.

· Set the other switch to turn on power at the lower pressure gion the electric wiring diagram. This setting should be done atdropping pressure.

Water

Pump service liquidTemperatureMaximum permissible water temperature for maximum pump capaand depth of vacuum is 15oC. Water with higher temperature may bused provided lower pump ratings are accepted.

HardnessIn order to minimize the sterilizer maintenance- and service expethe water hardness should not exceed 4 dH (0,7 mmol/l). The insttion of a water softener is recommended should the water be hard

Water supply common steam generator and sterilizerUsually the steam generator is supplied with water from one comwater source (intake) on the sterilizer, why the values of temperaand hardness will be common for all consuming units of the steriliz

The feed water should be colourless and free from solid particles as rust flakes, graphite etc. The content of other matters may depending on water quality. The content of iron should, however, bmg/l or less to avoid stains on sterilized goods.

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Separate feed water supply for steam generatorIf there is a separate water system supplying the steam generatowater is usually treated through a filter or some other kind of wtreatment device and then connected to a separate tank on the steIn such cases values deviating from the ones given below maaccepted.

Temperature. Separate feed waterIf there is a separate supply and tank for the steam generator feed wthe water temperature should not exceed 60oC.

Deionized waterDeionized water may only be connected if the steam generatodesigned for this.

Should the steam generator be intended for deionized water, theductivity must not be less than 0,5 µS/cm.

Other componentsThe chemical composition of deionized water may vary dependingthe water treatment method used. Sterilizer standard EN285 sguideline values for evaporation deposits in deionized water. Theseues may serve as a guide when assessing water quality, but neenecessarily be complied with for reliable operation.

Guideline values to EN285:

Evaporation deposits 10,0 mg/l, of which:

Silicon in the form of SiO2 1,0 mg/l

Iron 0,2 mg/l

Cadmium 0,005 mg/l

Lead 0,05 mg/l

Other heavy metals 0,1 mg/l

Chlorides 2,0 mg/l

Phosphates 0,5 mg/l

Recommended pH: 5 to 7

Suitable conductivity ≤ 15 µS/cm

Suitable hardness ≤ 0,1 dH

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PACKING MATERIAL

Packing materials and goods carriers are important parts in the sywhich shall lead up to a sterile and dry load. It is not possible to usepiece of paper, cloth or container for packing up the goods to be slized. Certain demands have to be satisfied.

The traditions and standards in different countries often guidesthe choice of and demand for wrapping material and it is thereforedifficult to specify nothing but generally desirable qualities.

For countries associated with EEC or EFTA there is a common stard, which has replace earlier standards in the these countriesdemands presented in several of the following sections are thesharpened for countries associated with EEC or EFTA.

Wrappings of paperPaper used as wrapping material for goods to be sterilized must mcertain requirements. To be suitable for packing purposes shall:

the barrier layer of the paper envelop

• be strong, also when wet.

• allow penetration of air and steam.

• serve as an effective barrier against micro organisms.

• preferably have a colour making it possible to see if it is wet.

• withstand heat to 137oC without becoming brittle.

the water absorbing layer of the paper envelop

• be able to absorb, disperse and keep condensate.

• be able to surround at least bottom and sides of the instrument

The goods should normally be wrapped in several layers of paper wthe inner should have the qualification to absorb and disperse thedensate formed, while the outer should be treated to serve as a bfor microorganisms. Both functions are just as important.

The look and properties of the packing materials available on the ket can vary widely. Following main groups exist:

· Plain paper

· Crepe paper

· Nonwoven

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How these types should be combined in order to obtain the result especified ought to be decided by the paper supplier in consultationthe Sterile Services Manager.

Plastic which is integrated in the fibre structure with some paper ities renders the paper deteriorated penetration and drying abilitiesthis material should be avoided.

Wrappings of textileEnvelops of textile should when coming to use:

• be made of cotton or a mixture of cotton and a synthetic fibre, reant to sterilization without destroying its strength and penetratiofacilities.

• act as an effective stop for micro organisms.

• preferably have a colour indicating if it is wet.

• withstand repeated use without changing its properties.

Bags or peelable reels of paper or paper mixesThe two most common packing types are:

• Bags made entirely of plain paper

• Bags/rolls having a paper backing and front side of clear heat laplastic foil.

The demand raised on paper is valid also for bags and rolled hosepaper mixes when applicable. In addition to this there is a demandsealing the bags or hoses with heat (welding).

The bond between paper / paper or plastic / paper must be senough to resist the sometimes very fast pressure variations occuduring sterilization.

Peelable reels of plastic foilOn markets where plastic foil hoses are still used, it must be obsethat all foil qualities can not be used as packing material. This is becthe porosity in some of these is lost when heated up. A bag of sumaterial can also subtract during the post treatment which causecontent to crush.

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Goods carriers

Baskets

Baskets used as carriers for sterilizing goods should:

• Be made of stainless steel.

• Conform with SPRI-, ISO- or DIN-standard.

Containers

Containers used as goods carriers should:

• Be made according to ISO- or DIN-standard.

• Be vented through filters or sterile filters preferably arranged in tlid. Containers having the ventilation arranged through openingscontrolled by thermal- or pressure difference-based devices shobe avoided because of their worse ventilation abilities

• Preferably be made entirely of an aluminium alloy (also the lid) which will, compared to other materials, show outstanding thermconductivity abilities. See also moisture content on page 14. Staless steel and plastic have opposite abilities and should thereforavoided.

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PACKAGING

The condition in obtaining a sterile and dry load is, as earlier statedthe steam used is of a good quality and that the sterilizer works faulIf this is the case, it is most often possible to achieve a good resuadapting the packaging method to the goods to be sterilized.

Of course the demands and recommendations raised by thehealth- and sick care authorities in different countries must be con-sidered.

Besides these basic conditions, some general recommendationspromote obtaining the best result.

Single itemsSingle items and small sets containing only a few instruments are erably packed in bags. Remember that:

• larger bags than necessary should not be used. Follow instructigiven by the bag manufacturer.

• the bag should not be overloaded with heavy instruments. The bhas limited capability to keep and disperse the condensate. If tolarge condensate quantities are formed, these can not be retainthe instrument but will be collected as drops rolling away from thinstrument. This kind of condensate is difficult to get rid off durinthe post treatment and will consequently remain in the bag.

• the bags should be leaning towards the side of a basket. Place aabsorbing paper at the bottom of the basket. This sucks up the densate formed on the outside of the bag, and stops it from poudown on the basket below.

• bags of paper mixes shall be placed with with the paper side towthe paper side of the next bag, since plastic foils towards paper make the latter as tight as to jeopardize the penetration.

Plastic itemsPlastic items often give rise to wet packings since they do not emit heat content fast enough to make the condensate evaporate durinavailable time.

• Avoid as far as possible the use of reusable items of plastic, or out the instruments on the basis of their material.

25

so here

ucks ses it aper

te if a the

rge the

akeitatesub-roc-pright

t that

ht of

• The result may be improved by arranging the bags in one layer that the condensate as far as possible will remain on the spot wit was created thereby avoiding forming of pools.

• Place a water absorbing paper at the bottom of the basket. This sup the condensate formed on the outside of the bag. In some camay be necessary to wrap the plastic item in a water absorbing pwhich retains the condensate.

• Arrange the bags in the basket in such a way that the condensapossible remains on/close to the instrument. Water collected in wrinkle or a corner will remain when the goods are taken out. If shape of the instrument is such that the condensate can not be retained on or close to the instrument, or if it is that heavy that laquantities of condensate are formed, one should consider usinganother packing method. Place bags containing bowls to make condensate remain in the bowl.

The old rule saying that bowls should be placed in the sterilizer to mall water escape is no longer valid. The aim of this rule was to facilthe air removal at a time when efficient vacuum pumps were rare jects on the market. To day's pumps and the modern sterilizing pesses with several prevacuums can easily remove the air from an ustanding bowl.

• Arrange therefore the bowls leaning backwards to such an extenthe condensate formed remains in the former.

TextilesTo enable adequate air removal and steam penetration, the weigtextile parcels should not exceed 6 kg.

26

be ing he the

y

on-ap-

ol- an ese.

h. ing han .

ing ial -

therep-il in betrays

Instrument setInstrument sets should preferably be packed on instrument trays.

• Select the size of the tray so that the instruments can preferablyplaced in one single layer. If a moisture absorbing- and distributlayer is missing in the outer wrapping, the bottom and sides of ttray should be covered with a water absorbing paper preventingcondensate from flowing out to the outer wrapping.

• Spread the goods evenly by weight over the tray surface therebavoiding condensate flowing together

• Instruments having a flat surface should be laid down on this.

• Place bowls with the opening facing upwards.

• Do not lay cotton or compresses in a bowl since these suck up cdensate which will then not come in contact with hot metal for evoration.

• Distribute plastic items evenly over the tray surface and avoid clecting them in one corner. The result can be improved by layingOP-towel on top of the instruments and in good contact with th

• Divide very heavy sets into two and place them on one tray eacWeights above 6 kg should be avoided if possible. When sterilizheavy goods such as orthopedic instruments, should not more t30% of the total load consist of trays with a weight of up to 10 kg

• Pack preferably the instrument tray in several layers of paper ofwhich the internal should be the moisture absorbing type. Wrappmaterial of textile could also be used. (See also wrapping materpaper textile).

Certain material for orthopedic operations are sold in boxes wheredifferent parts hang on stands. This looks very neat but is directly rehensible from sterilizing point of view. All condensate formed wflow to the bottom of the box where it will be impossible to removespite of the total weight of the items not being larger than it couldexpected to become dry. Sterilize this kind of goods distributed on so that the weight of each tray is kept within given limits.

27

turer

ap-ides or an

, it type.

t be ut also

ated e ing ss

that

ContainersContainers should be packed according to the container manufacrecommendations:

• If the container is equipped with sterile filter and therefore no wrping of the instrument trays are required, the bottom and inner sof the container should be covered with a high absorbing paper OP-towel to disperse the condensate.

• If the instrument tray is to be wrapped in paper instead of textileis important that the paper nearest the tray is of water absorbingSee also packing material.

• Plastic items requiring 121C sterilization temperature should noplaced in containers where the drying will be time-consuming, bshould be packed in bags of paper mixes placed in baskets. Seewrapping methods single items.

• The process time can be shortened if condensate from high situcontainers can be prevented from falling in drops on the lid of thunderlaying ones. This is achieved by placing a moisture absorbpaper under each container, especially when it comes to stainlelids.

• Containers should be loaded on special made Shelf trolleys suchan air space is formed between each container layer

28

loadffec-

ack-

nti-

rs are

n-

e it

BasketsWire baskets intended for sterilizing purposes are the most suitablecarriers since these permit a good steam penetration- and drying etiveness to the same extent for most kind of goods and types of pings.

• Adapt the height of the baskets that there will always be a few cemetre air gap between the goods and the basket above.

LoadingThe dryness of the load depends on the way the baskets/containesituated in the sterilizing chamber.

• Always place heavy goods below the light goods to avoid the codensate wetting the light baskets.

• Never let the goods come in contact with the chamber walls sincwill then become wet.

29

Fold instruction for wrappings

Folding the inner wrapping

1.Put two sheets of wrapping on the table.

Place the instrument tray (parcel) diago-nally on the centre of the wrapper.

2.

Fold your nearest corner of the top wrap-per over the tray.

3.

Fold back the tip of the corner.

4.

Fold the right corner over the parcel and fold back that much of the tip that the par-cel remains covered.

5.

Fold the left corner accordingly.

30

6.

Fold the remaining corner over the parcel.

7.

Turn the parcel half a turn on top of the outer wrapper.

8.

Fold the corner and push it into the wrap-ping close to the parcel. Arrange for the outmost tip to protrude about 5 cm.

Folding the outer wrapping

9.

Place the parcel diagonally on the centre of the wrapper and fold it in the same man-ner as used with the inner wrapping sheet.

10.

Seal the wrapping with two strips of adhe-sive tape without indicator. Attach a 5 cm long indicator tape on top of one of the tapes.

Folding the inner wrapping

31

32

iable

Gly.uld

bili-ord-o bedry

y an-

o-od es.

for ds

con--step more

that e of vali-

PROGRAM MODIFICATION

On delivery, Getinge sterilizers are set and tested to enable a relsterilizing process in the shortest possible time.

As can be seen from the earlier parts MEDIA QUALITY, PACKINMATERIAL and PACKING, the circumstances can vary considerabIt would therefore be impractical to use a single process which woenable sterile and dry load at all events.

Getinge sterilizer control system comprises of a number of possities to make alterations and additions in the sterilizing program accing to certain preformed patterns. This enables for a program tadapted to such groups of products which may be difficult to get after sterilization.

The different types of modifications, which should be made bskilled technician in consultation with with the Sterile Services Maager, are described further in the text.

General advice

• Adapt if possible one program for one type of goods and next prgram for another etc. By doing this the most effective drying methfor each type of goods will result in shortest possible process tim

• If a mixed load is to be sterilized, select a drying method suitableall types of goods and set the time to match the most trying goo(see table for Basic settings).

• Sterilize all temperature stable goods at 134oC since this gives the best result in the shortest time.

• When sterilizing easily damaged goods like certain empty glass tainers which do not resist fast temperature changes, the change3 of the pretreatment can be used separately to make heating upcareful.

• When changes are made to the process, the result of validationshave been done is affected. Always consult the person in charghygiene as to what changes can be made and whether existingdations must be redone.

33

eters theice”about

eat-ene pur-

ingpears

ist by

isteri-

ard- thech

ghtt is the

fer-

-

-

on

foring

Modification procedureAll process alterations are made by changing the program paramfor the appropriate program. How this is made is described underheadline ”Changing parameters with OP2” in chapter ”General advin the service manual. See also menu descriptions in the chapter the control system

It is only with steam sterilization programs that the pre- and post trment can be modified as follows. With formaldehyde and ethyloxide sterilizers these parameters are already occupied for otherposes.All of the Getinge sterilization programs can not be modified accordto this advice. Which are the changeable ones of all parameters apfrom the program phase list and the program combination.

Adjustable parameters are marked on the program combination linforming on the range within the parameter may be set.

Post treatmentThe post treatment is the best part of the process to start with. Thisbecause the process remains in its origin up to and including the slizing cycle and the sterility of the product will therefore not be jeopized. One must remember that goods which are too dry duringsterilizing cycle will not keep the spores sufficiently humidified, whiis a basic condition when sterilizing with steam.

If goods of different material and sets with very much varying weiare to be sterilized in one and the same process, the post treatmenone that should be modified.

• Push program selector button for the program to be changed.

• Follow the advice found in the service manual to program the difent parameters.

• Select DRYING VACUUM when needed by programming ”Postvacuum time”.

• Select DRYING WITH STERILE AIR when needed by programming ”Postpuls. air”.

• Select DRYING WITH STEAM when needed by programming ”Postpuls. steam”.

The different post treatments give varying result, mainly dependingtype of goods, packing material and packing technique.

Prolonging the drying vacuumWhat is called a drying vacuum is the most common drying methodmost types of goods. For textiles is this the most time-saving dry

34

eliv-

ry set-

threer tri-

com- themberentill be

vac-nd 20

method. It is also this drying method which is preprogrammed on dery from the factory.

• Select DRYING VACUUM when needed by programming the desired duration in hours, minutes and seconds in ”Postvacuumtime”.

Always start by prolonging the drying vacuum by 5 - 10 minutes. Twith 15 or 20 minutes should this not be sufficient (see table ”Basictings for drying processes” on page 37)

Drying with sterile airThis alternative is particularly efficient on ordinary goods packed inbaskets where the moisture is evenly dispersed. Always program aminutes long drying vacuum before the air pulses. Suitable steps foals are 11, 15 and 20 minutes.

Note!If this post treatment method is to be used to a large extent, it is remended that the sterile filter is replaced with an absolute filter withcasing made of polypropylene with thread-attachment (article nu470 22 45-01). If the origin filter is used, its condition and attachmshould be checked weekly. Recommended replacement interval wfound under the headline THE STERILIZER.

Drying with steamIf the previous methods should prove insufficient, drying with steacan be programmed. Always program a three minutes long drying uum before the steam pulses. Recommended steps are 11, 15 a

+

35

y be

ureuume the

ri-

minutes. In very difficult cases 24 minutes of steam pulses marequired (see the basic settings table on page 37).

Note!With sterilizers where the process is controlled by common pressswitches, the pressure switch controlling the depth of the pre vacshould be set to close at -0,85 bar(g). Wrong setting can jeopardizdrying and also rehumidify the goods.

Drying with steam is particularly efficient on instrument trays stelized in containers at 135oC.

36

m-am

The table values refer to a fully loaded GETINGE sterilizer with chaber dimensions 660 X 660 x 1250 mm, equipped with a built in ste

Basic settings for drying processesSymbols for suitability: Very good = -#Good = .#Unsuitable = /

No

Ste

riliz

ing

tem

pera

ture

o C

Type of load

Shortest recommended time*1 in min-utes using

*1. Select the time for the most time requiring gods when sterilizing mixed loads.

Tot

al p

roce

ss ti

me*2

in m

inu

tes

ap

pro

x.

*2. The process time is based on the shortest of the setting times in the row.

drying vacuum

3 min. drying vacuum+drying with air pulses

3 min. drying vacuum+drying with steam pulses

1 121

134

Textiles -

-

5

5

.

.

5

5

/

/

43

32

2 121

134

Instruments in paper mixes bags ≤ 1 kg .

.

20

20

-

-

13

15

.

.

18

20

54

45

3 121

134

Instrument trays ≤ 3 kg in paper wrapping .

.

20

20

-

-

11

13

.

.

15

15

52

43

4 121

134

Instrument trays ≤ 6 kg in paper wrapping .

.

20

20

-

-

11

13

.

.

15

20

52

43

5 121

134

Instrument ≤ 10 kg in paper wrapping .

.

25

30

-

-

20

20

.

.

22

22

61

50

6 121 Plastic items in paper mixes bags . 30 - 22 - 20 60

7 121 Plastic and metal items in paper mixes bags. 22 - 18 . 25 58

8 121

134

Instrument tray in aluminium container ≤ 6 kg

-

.

20

25

/

/

/

- 14 42

9 121

134

Instrument tray in aluminium container ≤ 10 kg

-

.

27

30

/

/

/

- 20 48

10 121

134

Instrument tray in stainless steel container ≤ 6 kg

.

.

27

30

/

/

/

- 30 58

11 121

134

Instrument tray in stainless steel container ≤ 10 kg

.

.

35

35

/

/

/

- 35 63

Programming the parameterÆÆÆÆÆxx = No. of minutes as stated above

00: xx: 00 00: xx: 00 00: xx: 00

37

mberimes.

t. A preounergy

heate its

e sep-ied

eacht as

tic-

er-

ing

ent.

influ-

generator. Steam supplied from a central steam plant, other chavolumes and smaller loads may give somewhat deviating process t

Pre treatmentIn some cases modifying the post treatment method is not sufficienpossibility is then to heat the goods more sufficiently by altering thetreatment. All such pre heating which is meant to take place withcondensation taking place is based on the use of the super heat ein steam of a higher temperature.

Be observant on the fact that too intense warming up with super energy can lead to a dehydration of the goods which will jeopardizsterility.

Select therefore one or two programs where such goods should barately sterilized which can not be satisfactorily dry with a modifpost treatment.

It is important that the size and composition of the load is equal atsterilisation. A much diminished load cannot absorb the super heathe load will not be humidified enough to ensure sterility.

Summing-u

• Select one or two programs for treatment of difficult loads in parular.

• Combine one or more type-loads for this (these) program(s).

• Do not make more program modifications than necessary.

• Do not change the composition or size of the type-loads while pforming the test runs.

• Incomplete pre-pulses may indicate too powerful overheating.

• Change the modified program curves in the sterilizer manual usthe curves found at the end of this booklet.

• Always re-validate the sterilizer after a change in the pre-treatm

The programming password is needed in order to alter parametersencing the pre treatment.

A program, the pre treatment of which has been altered, must be validated once more by sterilizing biological indi-cators packed with the actual goods.

38

an

n ing

ds

low.tes.

PRE-

ute

Aced

sag-e by

rssure

A suitable tool for programming the control system is an OPC orOPH.

Modification step 1

A Reprogram the parameter HIGH PULS AP4/1 from 1 to 2 bar osterilizers equipped with an analog pressure transducer (showpressures on the display).Reprogram the parameter HIGH PULS AP4/1 from 0 to 120 oC on all other sterilizers.

B Change the parameter STEAM PULS AP4/2 from 5 to 2 seconand the parameter VAC + STEAM AP4/3 from 30 seconds to 2minutes.

The pre pulses will now appear in a pressure diagram as shown beThe changes has prolonged the total process time by about 8 minu

Modification step 2Retain modifications made in step one and change the parameter VACUUM AP2 from 3 to 4.

By doing this one pulse is added to the pre treatment.This alteration prolongs the process time by about another 5 minand makes the pressure diagram look as shown below.

Modification step 3Keep the changes in step one and two while the parameter STERAMP AP5 is changed from 5 to 2. The modification leads to a reduflow-speed with the steam and consequently a reduced risk for aging steam supply pressure. This alteration prolongs the process timabout another 12 minutes.

STEAM RAMP AP5 can be programmed from 5 to 2 on sterilizewithout analog pressure indication. On sterilizers with analog pres

39

er

of the

indication, AP5 changes from 2.5 bar/min. till 0.3 bar/min. The lowvalue, the lower steam speed.

Combining the changesThe described program modifications can be set together that any pre treatments can be combined with any desired post treatment.

40

e tottonmed

to

byr.

load-.

se

THE STERILIZER

Pre heating the sterilizerAfter the sterilizer has been started it should be given plenty of timheat up with closed door. When the light in the control panel start builluminates, the temperature in the jacket has attained the programvalue.

Allow if possible the sterilizer to heat up for another 20 minutesenable for the entire metal mass to get warm straight through.

An alternative, and a most efficient way is to ensure pre heatingperforming a complete sterilization process with an empty chambe

DoorsTHE STERILIZER DOORS SHOULD BE KEPT CLOSED whenthe sterilizer is not in use. The doors should be opened only when ing and unloading whereupon these should be closed immediately

An open door will quickly be cooled down and may therefore caunot desired condensation during the subsequent process.

41

gtheing

ander

esmaylled.er-

r each

of ra-

a t pro-ent rd-

ityained

meon. whichn and

The sterilizer conditionThe sterilizer working condition is a primary factor for the sterilizinresult, both with regard to the sterility and moisture content of goods. If problems suddenly arise with an earlier correct functionsterilizer, the fault is usually to find with the supply mediums oroccurring sterilizer malfunction. Regarding medium faults, see unthe headline MEDIA QUALITY.

Any kind of fault in the sterilizer or the supplied steam which makit possible for air or other gases to be collected in the goods pack lead to the two conditions heat and moisture not being safely fulfiThe sterilizer function must therefore be checked with following intvals if otherwise is not stated:

• The chamber- pressure and temperature should be checked afteprocess using the recording instrument.

• The efficiency of the humidification should be checked by meansstandardized chemical indicators able to react upon time, tempeture and humidity, for instance sterility integrators.

• The tightness of the sterilizer chamber should be checked onceweek. The easiest way to do this is starting the sterilizer leak tesgram. The test will fail if air is let into the chamber to such an extthat temperature homogeneity and/or steam penetration is jeopaized.

• The condition and rigid attachment of the sterile filter should be checked weekly.

A further indication of the sterilizer condition with regard to is abilto remove and make the steam penetrate porous loads is obtthrough a so-called Bowie-Dick test.

The pattern of the Bowie-Dick indicator paper has to show the sasaturation with colour all over its surface after completed sterilizatiPale parties indicate the presence of air or non condensable gaseshave stopped the steam penetration and jeopardized humidificatioattaining of the correct temperature.

42

ked

rcels areesnual

eam e the ted

- hor-

2,2 seal am

aus-

ans

hend of

ard

An indicator paper for an ordinary Bowie / Dick test should be pacin a porous parcel of a standardized composition.

There are on the market also several types of ready made test paof Bowie/Dick test type having somewhat varying qualities. Theseintended for sterilization without any further wrapping which savtime. Use a make type-approved by Getinge. See the sterilizer maor contact Getinge AB.

The sterilizer and the steam

• Check that the sterilizer is horizontal in all directions.

• Check that the sterilizer steam distribution pipes are not slantingbackwards to prevent for condensate to be collected and that sttraps, strainers, chokes etc. are faultless. The main principle foravoiding condensate collecting pockets to be formed is to arrangpipes sloping in the flow direction. Further that strainers are mounwith the screen pointing upwards to avoid condensate being collected in the strainer housing and that no chokes are mounted inizontal pipes.

• During peak consumption the steam pressure must fall not belowbar(g). Check the function of the steam traps on jacket and doorgroove. A continuously leaking steam trap may cause too low stesupply pressure.

• Check that the jacket drain pipe filters are not clogged thereby cing ineffective heating of the jacket.

• The quality of external water and steam supply should be checked monthly. The sterilizer function should simultaneously be checked by meof biological indicators.

Replacement of sterile filterThe condition of the sterile filter can be deciding for the sterility of tgoods since a defect filter may cause renewed contamination on ethe process.

It is therefore important to:

• check the condition of the sterile filter and its attachment with regto tightness.

• replace the filter at recommended intervals.

The sterile filter life time is influenced by:

43

ber,art-

r but

sureon-

e of the

ay

id-surege in

ion

lues

alled beld be

n the

ient

The cleanness of the air passing through the filterWith increased number of particles in the air admitted to the chamwhich is usually taken from the sterilizer surrounding service compment, the filter will stop up quicker.

This is shown as an increased pressure difference across the filtebecomes most obvious by the prolonged airing times. This does nodeteriorate the filter ability to separate particles but to large a presfall may cause the filter burst and give free access for all kind of ctaminants.

The humidity of the air passing through the filter The air in the service compartment usually holds a higher degrehumidity than the surrounding atmosphere. How much depends onventilation of the compartment. In tropical climate one must alwcount with a high degree of humidity in the air.

A fault with the sterilizer can also expose the filter for extreme humity in the state of steam from the chamber. With a wet filter the presdifference across the filter rises tremendously, and besides breakathe filter material it can be destroyed by bacteria growing through.

The sterile filter should be replaced after the number of sterilizatcycles shown by the table below.

When the air is heavily mixed with particles or is very damp, the vaabove should be reduced.

Air purgingWhere sterilizers without analog pressure measurement are inst

at high altitudes, the lower reversal point of the pre-pulses canadjusted to -0.75 to -0.8 bar. Simultaneously the pre treatment shouset for 4 pre-pulses using PREVACUUM AP2 change the settings icontrol system to ”tropic”.

On certain models with analog pressure measurement it is sufficto set the control system to “tropical”.

NOTE: These changes require the sterilizer to be revalidated.

GE 2044 600

GE 2606 300

GE 2609 275

GE 2612 250

GE 2617 200

GE 6912 200

44

test,te is

e on tha com-vable

doore ster-

res- of aulde is

Leakage

ChamberOn sterilizers having a special program for this, perform a leak rateaccording to instructions in the USER-manual. Permissible leak ra13 bar/ 10 minutes.

If a pressure gauge is available with better resolution than the onthe sterilizer, the accuracy of the reading can be improved. Notethere is no demand for the pressure gauge being of the barometricpensated type but this can be a help in determining deepest achievacuum.

Some places which can be suspected for leakage are:

· Tape sealed threads

· The door seal

· The gland seal of the recorder sensor

· Drain non return valves

· Plug seals on strainers

Note that steam leaking into the chamber from a valve or from the seal is registered as a leak, in spite of not being a catastrophe for thilizing process.

Evacuation systemCheck the vacuumpump ability to create a deep subatmospheric psure by closing the hose for the pump anti-cavitation air at the enddrying vacuum cycle. Provided the chamber is tight, the pump shostart cavitating with accompanying characteristic noise. If not, thera leak between the chamber drain valve and the pump.

Some places which can be suspected for leakage are:

· Tape sealed threads

· Hose claps

· Plug seals on strainers

· Condensor drain valve

45

46