Understanding Critical MeasurementParameters in Vaporized Hydrogen Peroxide Bio-decontamination
理解汽化過氧化氫（VHP）消毒的關鍵參數
The Relationships betweenTemperature, Relative Humidity and Relative Saturation
溫度、相對濕度和相對飽和度的關系
Because vaporized hydrogenperoxide leaves no residue and is efficient for bio-decontamination in roomtemperature, it is used widely in applications such as isolators, transferhatches and in different facilities that require reliable decontamination.
由于汽化過氧化氫不會留下殘留物，并且在室溫消毒非常有效，因此廣泛用于隔離器、傳遞倉和不同設施的消毒。
Effective killing ofmicroorganisms can be achieved with different humidity and H2O2 ppm levels. Some manufacturers ofbio-decontamination chambers or isolators prefer subvisiblecondensation, whereas others prefer dry bio-decontamination processes wherehumidity is maintained far from condensation. However, dripping condensationshould be avoided due to potentially negative effects on aeration time,materials and uniform decontamination efficiency. Therefore, it’s crucial tomeasure humidity during vaporized hydrogen peroxide bio-decontamination cycles.However, water (H2O) and hydrogen peroxide (H2O2) have a very similar molecularstructure. Therefore they both affect the humidity of the air.
微生物可以在不同的濕度和 H2O2 ppm 水平下有效殺滅。一些生物凈化艙或隔離器的制造商喜歡微冷凝技術；而另一些制造商則喜歡干霧技術，濕度保持遠遠低于凝露水平。但是，應避免使用噴霧冷凝，因對排氣時間、材料和消毒效果均勻性可能造成負面影響。因此，在汽化過氧化氫（VHP）消毒過程中測量濕度至關重要。然而,水(H2O)和過氧化氫(H2O2)的分子結構非常相似。因此，它們都會影響空氣的濕度。
Relative humidity by itsdefinition indicates the humidity of the air caused only by water vapor.
相對濕度由其定義表示空氣的濕度僅由水蒸氣引起。
Therefore, humidity sensors used in vaporized hydrogenperoxide applications typically use a catalytic layer over a normal humiditysensor. The catalytic layer catalyzes the hydrogen peroxide so that thehumidity sensor measures only water vapor. The measured relative humidityindicates the humidity of the air caused only by water vapor. When measuring H2O2 in a vapor state, relativesaturation is the parameter that indicates the amount of humidity in the aircaused by both hydrogen peroxide and water vapor. The air mixture startsto condense when the relative saturation reaches100 %RS. Relative saturation isthe only parameter that indicates when the air mixture with the water vapor andhydrogen peroxide vapor starts to condense. Therefore, it is essential tofollow the relative saturation value during the bio-decontamination process.
因此，用于汽化過氧化氫（VHP）的濕度傳感器通常在正常濕度傳感器上使用催化層。催化層催化過氧化氫，使濕度傳感器只測量水蒸氣。測得的相對濕度表示空氣的濕度僅由水蒸氣引起。測量蒸汽狀態下H2O2 時，相對飽和度是指示過氧化氫和水蒸氣共同組成的空氣中的濕度參數。當相對飽和度達到 100 % RS 時，空氣混合物開始冷凝。相對飽和度是指示空氣與水蒸氣和汽化過氧化氫的混合物何時開始冷凝的唯一參數。因此，在消毒過程中，必須測量相對飽和值。
Figure 1. Space 1 without H2O2 vapor and space 2 with H2O2 Vapor.
圖 1.空間 1 不含 H2O2蒸汽，空間 2 包含 H2O2 蒸汽。
Figure 1 above shows you twodifferent spaces: Space 1 withoutH2O2 vapor and space 2 with H2O2 vapor. When H2O2 vapor is not present, relativesaturation equals relative humidity. This can be seen in space 1. Within space2, we have the same volume of air with H2O2 vapor introduced. Now, relativesaturation is higher than relative humidity.
圖1顯示了兩個不同的空間：空間1沒有H2O2蒸汽，空間2有H2O2蒸汽。當不存在 H2O2 蒸汽時，相對飽和度等于相對濕度。這在空間1中可以看到。在空間2中，我們在相同體積的空氣中注入了H2O2蒸汽。現在,相對飽和度高于相對濕度
Figure 2. H2O2 ppm as a function of RS/RH at T = 25 °C
25℃下H2O2 ppm濃度與相對飽和度/相對濕度的關系
Figure 2 shows you H2O2ppm asa function of relative saturationand relative humidity at 25 °C. Relative saturation is on the x axis andrelative humidity is on the y axis. Darker shading shows higher ppm of H2O2. As you can see, the morehydrogen peroxide in the air mixture, the greater the difference betweenrelative saturation and relative humidity values. For example, at 25 °C and1000 ppm hydrogen peroxide, the humidity level 25%RH is equivalent to 70%RS.When this gas mixture with 1000 ppm hydrogen peroxide starts to condense(relativesaturation being 100%), relativehumidityis 35%.
圖 2 顯示了不同濃度H2O2ppm 在 25℃下相對飽和度和相對濕度的函數。相對飽和度位于 x 軸上，相對濕度位于 y 軸上。較暗的陰影表示 H2O2 的 ppm 更高。正如你所看到的，空氣混合物中的過氧化氫越多，相對飽和度和相對濕度值之間的差異就越大。例如，在 25℃下， 1000 ppm 過氧化氫，相對濕度 25%RH 與相對飽和度70%RS。當相對濕度為35%時，這種1000ppm氣體混合物即開始冷凝。
Temperature affects how muchhydrogen peroxide can be in the air before condensation (relative saturationequals 100 %RS). Thus, the graph on Figure 2 changes when temperature changes.
溫度影響冷凝前過氧化氫在空氣中的含量(相對飽和度等于 100 %RS)。因此，當溫度變化時，圖也發生變化。
Figure 3. H2O2 ppm as a function of RS/RH at T = 5 °C
圖3 5℃下H2O2濃度與相對飽和度/相對濕度的關系
Figure 3 showssame graph at5 °C. The maximum H2O2ppm level at 5 °C is slightly above 500 ppm. As an example, at 5 °C,500ppm hydrogen peroxide and Relative Saturation 100 %RS, the relative humidity isapproximately 2 %RH. As the relative saturation is 100 %RS, the air mixturewill condense. The difference between %RS and %RH at this temperature isenormous: 100 %RS vs. 2 %RH. Measuring %RH in this particular case is of noreal value.
圖 3 顯示了 5℃下的關系。5℃時的最大 H2O2 ppm 水平略高于 500 ppm。例如，在 5℃、500 ppm 過氧化氫和 100 %RS相對飽和度（微冷凝）條件下，相對濕度約為 2 %RH。由于相對飽和度為 100 %RS，空氣混合物將冷凝。相對飽和度%RS 和相對濕度 %RH 在此溫度下的差值十分明顯：100 %RS vs. 2 %RH。在此情況下測量 %RH沒有實際價值。
The higher the temperature, themore H2O2 ppm can be added to the airmixture before condensation, as seen in Figures 4 and 5. In Figure4, at a temperature of 50 degreesCelsius, an H2O2 concentration of >12000 ppmcan be achieved.
溫度越高，冷凝前可注入到空氣中 H2O2 ppm 越多；如圖 4 和圖 5 所示。在圖 4 中，在 50℃條件下，H2O2濃度可以達到＞12000 ppm。
Figure 4. H2O2 ppm as a function of RS/RH at T = 50 °C
圖4 50℃下H2O2濃度與相對飽和度/相對濕度的關系
Each point in Figure 5 represents a condensation point,I.E. relative saturation is 100 %RS. Temperature is on the x axis and H2O2 ppm is on the y axis. The curvesshow the maximum relative humidity. As an example, at 20 °C and 300 ppmhydrogen peroxide, 60%RH is equivalent to 100%RS. If we increase airtemperature to40°C with an H2O2 concentration at 300 ppm, relative humidity will be 87% andrelative saturation will be 100%. Condensation occurs at a relative humidity of<100% because of the relationship between air temperature and H2O2 concentration. Therefore thehigher the temperature, the higher the maximum RH%. If we increase the hydrogenperoxide level from300ppm to 900 ppm at 40 °C, then themaximum achievable relative humidity decreases from87%RHto 70 %RH. The higher the ppm concentration, the lower the maximum %RH.
圖 5 表示不同相對濕度RH條件下，達到微冷凝（即相對飽和度=100%RS）所需的溫度和H2O2濃度ppm關系。X軸為溫度，y軸為H2O2 ppm 。曲線中的數值表示相對濕度。例如，在 20℃和 300 ppm 過氧化氫條件下，60%RH 相當于 100%RS（達到微冷凝）。如果將空氣溫度提高到 40℃，H2O2 濃度為 300 ppm，則相對濕度需要達到 87%RH，相對飽和度才為 100%RS。由于空氣溫度和H2O2濃度的關系，冷凝發生在＜100%的相對濕度下。因此，溫度越高，達到飽和的最大 RH%越高。如果我們在40℃時將過氧化氫水平從300ppm提高到900ppm，那么可達到的最大相對濕度將從87%RH降至70%RH。因此，ppm 濃度越高，最大 %RH 越低。
Figure 5. The x axis = temperature, y axis = ppmconcentration.
Maximum achievable Relative Humidity (RS = 100 %RS)
不同相對濕度RH條件下，達到微冷凝（即相對飽和度=100%RS）所需的溫度和H2O2濃度ppm關系
These figures illustrate why it isinsufficient to look only at relative humidity in bio-decontamination processesthat use vaporized hydrogen peroxide. Air that is infused with H2O2 will condense at <100%relative humidity, depending on the temperature of the air and theconcentration of hydrogen peroxide. When the air mixture contains vaporized H2O2, relative humidity can neverreach 100% making it nearly impossible to accurately estimate when condensationwill occur. The greater the temperature, the greater the allowable relativehumidity. On the other hand, the higher the H2O2 concentration, the lower ismaximum achievable RH.
這些數字說明了為什么在汽化過氧化氫（VHP）消毒過程中，僅僅關注相對濕度是不夠的。注入 H2O2 的空氣在±100% 的相對濕度下會冷凝,具體取決于空氣的溫度和過氧化氫的濃度。當空氣混合物含有汽化H2O2時，相對濕度永遠無法達到100%，因此幾乎不可能準確估計冷凝何時發生。溫度越高，需要達到的相對濕度越大。另一方面，H2O2濃度越高，可達到的最大相對濕度 RH 越低。
When performing bio-decontamination with vaporized hydrogenperoxide, relative saturation is the only parameter that accurately representsthe true saturation level; that is, the point at which you can expectcondensation to occur.
當用汽化過氧化氫（VHP）進行消毒時，相對飽和度是唯一能準確表示真實飽和度的參數，即，可以預期微冷凝的參數。
