Why To Autoclave Liquids With a Load Probe Written by: Amit Gupta MS Mechanical Engineering, Vice President of Engineering In our previous Sterilization Cycles post on the F0 Cycle, we briefly reviewed the process for autoclaving liquids with a load probe. This post further discusses the benefits of using a load probe for sterilization validation. A load probe is a temperature sensing probe located inside the laboratory’s autoclave chamber. It is configured such that the user can place the tip of the probe within the load being sterilized. Typically, it is placed in the coldest or most difficult to sterilize location. The coldest point in a liquids load is the center of the largest volume (i.e. in the center of a 2L flask). Similarly, the coldest point in a solid load is at the center of the densest bag or pack. Laboratory autoclaves without a load probe measure temperature at the chamber drain (the coldest point in a chamber) and account for sterilization time when the chamber reaches 250°F. The ambient chamber temperature, however, can often be higher than the temperature at the center of the load—a phenomenon referred to as “load lag”¹. This occurs because as steam condenses on a load, the heat must be conducted from the surface to the center of the load. While this is occurring, the load temperature “lags” behind the chamber temperature. If unaccounted for, a discrepancy between the chamber temperature and internal load temperature heightens the risk of non-sterilization. When running a sterilization cycle with a load probe, the autoclave uses the load probe temperature reading as the primary control for the cycle. Therefore, if the cycle parameters are set for 30 minutes at 250°F, the sterilizer doesn’t start the 30 minute timer until the load probe senses a temperature of 250°F. The reason behind delaying the timer is a phenomenon referred to as load lag. In order to guarantee sterilization is achieved, the load must reach at least 250°F (121°C) for a specified amount of time. For example, most LB broth must be sterilized for 15 minutes at 250°F. For loads that exhibit a large load lag (i.e., dense, solid loads or containers with greater than 500 ml of liquid), a load probe should be used to measure the temperature within the load itself. Using a load probe ensures the load has been subjected to a temperature adequate for sterilization for the required amount of time. [1] The size of any given load has a considerable impact on the amount of load lag. For example, a 500ml flask with 300ml of liquid will have a lower lag (i.e., the load will match the chamber temperature quicker) than a 1,000ml flask with 600ml of liquid. 17 Questions to Ask Before Buying Your Next Autoclave With so many models, sizes, options and components to choose from, how can you ever really know exactly what you need to make the most out of your investment? These questions will help you to make informed decisions by outlining what is most important to consider and know about owning an autoclave. 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Phone (Optional)This field is for validation purposes and should be left unchanged. Δ Tweet Like Share
Why To Autoclave Liquids With a Load Probe Written by: Amit Gupta MS Mechanical Engineering, Vice President of Engineering In our previous Sterilization Cycles post on the F0 Cycle, we briefly reviewed the process for autoclaving liquids with a load probe. This post further discusses the benefits of using a load probe for sterilization validation. A load probe is a temperature sensing probe located inside the laboratory’s autoclave chamber. It is configured such that the user can place the tip of the probe within the load being sterilized. Typically, it is placed in the coldest or most difficult to sterilize location. The coldest point in a liquids load is the center of the largest volume (i.e. in the center of a 2L flask). Similarly, the coldest point in a solid load is at the center of the densest bag or pack. Laboratory autoclaves without a load probe measure temperature at the chamber drain (the coldest point in a chamber) and account for sterilization time when the chamber reaches 250°F. The ambient chamber temperature, however, can often be higher than the temperature at the center of the load—a phenomenon referred to as “load lag”¹. This occurs because as steam condenses on a load, the heat must be conducted from the surface to the center of the load. While this is occurring, the load temperature “lags” behind the chamber temperature. If unaccounted for, a discrepancy between the chamber temperature and internal load temperature heightens the risk of non-sterilization. When running a sterilization cycle with a load probe, the autoclave uses the load probe temperature reading as the primary control for the cycle. Therefore, if the cycle parameters are set for 30 minutes at 250°F, the sterilizer doesn’t start the 30 minute timer until the load probe senses a temperature of 250°F. The reason behind delaying the timer is a phenomenon referred to as load lag. In order to guarantee sterilization is achieved, the load must reach at least 250°F (121°C) for a specified amount of time. For example, most LB broth must be sterilized for 15 minutes at 250°F. For loads that exhibit a large load lag (i.e., dense, solid loads or containers with greater than 500 ml of liquid), a load probe should be used to measure the temperature within the load itself. Using a load probe ensures the load has been subjected to a temperature adequate for sterilization for the required amount of time. [1] The size of any given load has a considerable impact on the amount of load lag. For example, a 500ml flask with 300ml of liquid will have a lower lag (i.e., the load will match the chamber temperature quicker) than a 1,000ml flask with 600ml of liquid. 17 Questions to Ask Before Buying Your Next Autoclave With so many models, sizes, options and components to choose from, how can you ever really know exactly what you need to make the most out of your investment? These questions will help you to make informed decisions by outlining what is most important to consider and know about owning an autoclave. First Name* Last Name* Company/Organization* Email* Job Title*Select OneArchitectGeneral ContractorLab ManagerFacilities ManagerService TechnicianScientistSterile Processing TechnicianDistributorOtherDescribe "Other"* Country*AfghanistanAlbaniaAlgeriaAmerican SamoaAndorraAngolaAntigua and BarbudaArgentinaArmeniaAustraliaAustriaAzerbaijanBahamasBahrainBangladeshBarbadosBelarusBelgiumBelizeBeninBermudaBhutanBoliviaBosnia and HerzegovinaBotswanaBrazilBruneiBulgariaBurkina FasoBurundiCambodiaCameroonCanadaCape VerdeCayman IslandsCentral African RepublicChadChileChinaColombiaComorosCongo, Democratic Republic of theCongo, Republic of theCosta RicaCôte d'IvoireCroatiaCubaCuraçaoCyprusCzech RepublicDenmarkDjiboutiDominicaDominican RepublicEast TimorEcuadorEgyptEl SalvadorEquatorial GuineaEritreaEstoniaEthiopiaFaroe IslandsFijiFinlandFranceFrench PolynesiaGabonGambiaGeorgiaGermanyGhanaGreeceGreenlandGrenadaGuamGuatemalaGuineaGuinea-BissauGuyanaHaitiHondurasHong KongHungaryIcelandIndiaIndonesiaIranIraqIrelandIsraelItalyJamaicaJapanJordanKazakhstanKenyaKiribatiNorth KoreaSouth KoreaKosovoKuwaitKyrgyzstanLaosLatviaLebanonLesothoLiberiaLibyaLiechtensteinLithuaniaLuxembourgMacedoniaMadagascarMalawiMalaysiaMaldivesMaliMaltaMarshall IslandsMauritaniaMauritiusMexicoMicronesiaMoldovaMonacoMongoliaMontenegroMoroccoMozambiqueMyanmarNamibiaNauruNepalNetherlandsNew ZealandNicaraguaNigerNigeriaNorthern Mariana IslandsNorwayOmanPakistanPalauPalestine, State ofPanamaPapua New GuineaParaguayPeruPhilippinesPolandPortugalPuerto RicoQatarRomaniaRussiaRwandaSaint Kitts and NevisSaint LuciaSaint Vincent and the GrenadinesSamoaSan MarinoSao Tome and PrincipeSaudi ArabiaSenegalSerbiaSeychellesSierra LeoneSingaporeSint MaartenSlovakiaSloveniaSolomon IslandsSomaliaSouth AfricaSpainSri LankaSudanSudan, SouthSurinameSwazilandSwedenSwitzerlandSyriaTaiwanTajikistanTanzaniaThailandTogoTongaTrinidad and TobagoTunisiaTurkeyTurkmenistanTuvaluUgandaUkraineUnited Arab EmiratesUnited KingdomUnited StatesUruguayUzbekistanVanuatuVatican CityVenezuelaVietnamVirgin Islands, BritishVirgin Islands, U.S.YemenZambiaZimbabweState*Select OneAlabamaAlaskaArizonaArkansasCaliforniaColoradoConnecticutDelawareFloridaGeorgiaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyomingAre You Looking to Purchase an Autoclave?*Select OneYes, ImmediatelyYes, within 6 monthsYes, later than 6 monthsNo, just researchingAre you in a medical/healthcare (patient use) or life science (laboratory) setting?*Select OneMedical/HealthcareLife Science Yes, I'd like to receive occasional tips on sterilization best practices. Phone (Optional)This field is for validation purposes and should be left unchanged. Δ Tweet Like Share
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