Sterilization of medical equipment is one of the most important medical process, can kill all living microorganisms on medical and dental equipment, including bacteria, spores, viruses and fungi, so as to ensure that these devices are safe and used repeatedly. Although there are many sterilization methods, one of the most widely used methods in medical service centers, hospitals, and dental clinics is hydrogen peroxide because it is effective, safe, and inexpensive. Below you will learn about two sterilization techniques using hydrogen peroxide and how to choose the right pressure sensor for your sterilization equipment based on the sensor's technical parameters and operating characteristics.

main content

one. Hydrogen peroxide sterilization process: process pressure (vacuum pressure gauge), tank liquid level pressure (gauge pressure sensor);

two. Choose the right pressure sensor: pressure range, accuracy, long-term stability, pressure connections, electrical output, media compatibility, overpressure, mounting orientation, and institutional certification.

Hydrogen peroxide sterilization process

1. Vacuum gauge for measuring process pressure in a sterilizer

There are two different sterilization processes for sterilizing with hydrogen peroxide. Each requires a different measuring device to ensure proper operation. The first sterilization process is plasma sterilization using a capacitive vacuum gauge to measure the process pressure in the sterilization cycle. Insert the medical device into the sterilizer compartment. Medical equipment includes scalpels and cardiac catheters, dental equipment (such as periodontal cleaners and extraction forceps), and other devices with grooves and grooves in which microorganisms can grow. The chamber is then sealed and evacuated to create a vacuum. The hydrogen peroxide sterilant in the pre-package is injected into the chamber, and the sterilant vaporizes to interact with the surface of the medical/dental device, which causes an increase in pressure; then the pressure drops again and a plasma is generated. Free radicals of hydrogen peroxide interact with microorganisms and kill them. Hydrogen peroxide then decomposes, leaving only water vapor and oxygen. Medical equipment can be used or stored immediately after sterilization.

To ensure efficient sterilization, a specific base pressure is required in the sterilizer compartment when the plasma is energized. To this end, a capacitive vacuum gauge is installed on the sterilizer to monitor and/or control the chamber pressure and to ensure proper pressure is maintained at various stages of the sterilization process. When choosing the vacuum pressure timer for your application, please work with a supplier that offers a range of these products: with a full-scale pressure range from 10 to 1000 Torr, with a reading accuracy of +/- 0.5% (if possible, Then select +/-0.25% of the reading accuracy option), and the temperature coefficient is negligible within the temperature compensation range of 0 °C to 50 °C.

2. Gauge pressure sensor for measuring liquid level in tank

The second sterilization process uses vaporized hydrogen peroxide, which is stored in a storage tank in a liquid state before being converted to steam in a sterilization chamber. In use, the liquid sterilant in the tank is sprayed into the system to kill microorganisms on the equipment. This application uses a gauge pressure sensor to measure the pressure applied by the liquid in the sterilant tank to the gauge pressure sensor itself to indicate the level of hydrogen peroxide.

The sterilization process works: the pressure sensor is mounted on the bottom of the sterilant tank. The weight of the sterilant can cause pressure on the sensor. The cable on the back of the sensor contains a venting tube that allows the sensor to measure pressure values ​​relative to the local atmospheric pressure (gauge pressure measurement). As the sterilant is consumed, the weight (pressure) is reduced and the output signal sent by the sensor to the redundant monitoring system is correspondingly reduced. The sensor can then issue a warning to the sterilization technician that the tank level is too low. When the sensor register value is 0PSIG, it indicates that the tank has been drained.

Since the gauge pressure sensors are referenced to atmospheric pressure, they "breathe" through the air duct (in some cases the air duct passes through the vents of the cable). To ensure proper operation and to prevent liquid from entering the sensor, the vent tube must be properly connected to a dry location, such as a control cabinet or junction box that is ventilated with the atmosphere. Additional protection can be achieved by installing a desiccant cartridge on the connector surface of the ventilation cable.

Choose the right pressure sensor

1. Pressure range

Specific technical parameters and operating characteristics must be considered before selecting a sensor, one of which is the pressure range. For example, if your application requires 10 Torr, a 20 Torr sensor will achieve the best accuracy. Conversely, buying a 1000 Torr sensor wastes most of the measurement range. Do not specify an excessive sensor operating range "for safety only". The manufacturer gives the sensor safety overload limit and this information should be sufficient. If you specify an excessively high sensor range, the sensor's signal amplitude is reduced and the zero point error increases in percentage with the measurement range.

The available standard range for vacuum gauges is 10, 20, 100, 200 and 1000 Torr. Some medical applications occasionally have unique non-standard pressure range requirements, such as 147 Torr. In this case, the designer should contact the application engineering technician of the sensor supplier. Suppliers may be able to offer customized products to meet the required pressure range with greater precision. The same applies to system engineers and sterilization technicians who design new equipment. Suppliers' engineers and technicians can work together on upcoming projects, provide telephone support, answer questions, and be able to recommend the best sensor for the application, saving significant time and cost.

2. Precision

Accuracy is of course one of the most important considerations when choosing a vacuum gauge or gauge pressure sensor. In both cases, the higher the accuracy, the better the process control. This is especially important during the hydrogen peroxide plasma sterilization process, where the pressure at each stage of the sterilization process must be precisely controlled to work effectively. Confirming the accuracy of a vacuum gauge or gauge pressure sensor is actually measuring their error. Even more complicated is the way each instrument calculates accuracy.

Take the gauge pressure sensor as an example. They usually use the full scale percentage error to indicate the deviation from the expected output value. for example. The full-scale output of a sensor is 10 volts. The sensor's output range is 0 to 10 volts DC (VDC). The exact reading of the 10% output should be 1 volt, but due to the error, the sensor deviation is assumed to be 1 millivolt. If the accuracy is calculated as a percentage of full scale (as the name suggests), divide the 1 millivolt error by the full-scale output and multiply by 100, resulting in a full-scale error of +/- 0.01%.

Vacuum gauges, on the other hand, typically use a percentage reading error. In the same case as the above example, the 1 millivolt error is divided by 1 volt (this is the reading at that point) and multiplied by 100, resulting in a reading error of +/- 0.1%. The same 1 mv is expressed using different error calculation methods, and the percentage error of the reading error is 10 times the full-scale error!

For vacuum manometers, seek a nominal accuracy of +/- 0.5% reading. For gauge pressure sensors, seek +/-0.20% full scale rated accuracy. Please keep in mind that these accuracies are specified accuracy at room temperature. Therefore, if the sensor is installed in an environment that exceeds the typical room temperature range, changes in ambient temperature can cause changes in the sensor's output. The temperature error published by the sensor manufacturer is a function of temperature, so the sterilizer technician can calculate the error and determine the true accuracy of the pressure reading.

3. Long-term stability

Long-term stability is another very important consideration. Long-term stability is a measure of how much the output signal drifts over time under stable operating conditions. Drift is caused by pressure cycling, extreme temperatures, environmental changes, vibration, shock, and aging. Long-term stability is usually expressed as a percentage of full scale within 12 months. For capacitive vacuum gauges, seek +/-0.5% full scale/year (operating temperature 80 °C, +/-1.0% full scale/year at full scale pressure range less than 100 Torr). For gauge pressure sensors, the expected stability is 0.5% full scale per year. The long-term stability and accuracy of the sealed hygienic gauge pressure sensor is guaranteed because of the use of capacitive sensing elements and signal conditioning IC integrated circuits.

All sensors drift over time, regardless of manufacturing quality. The key question that sterilization technicians need to know is: “How high is the sensor accuracy for my application?” A sterilization technician measuring the tank level in a sterilizer may not be concerned with the small sensor drift over time. Especially when using redundant systems. Therefore, the technician only needs to adjust the sensor every two years instead of adjusting it every year. In contrast, vacuum gauges that control pressure require more frequent corrections. Fortunately, drift can be adjusted in the field by adjusting the zero potentiometer or calibration, depending on the application. For gauge pressure sensors, the load on the diaphragm must first be eliminated. The potentiometer screw on the back of the sensor can be rotated to restore the set value at 0 PSI to 0 volts. To set the measurement range based on full scale, it is recommended to return the sensor to the factory or to a certified calibration facility. Retesting depends on the severity of the situation.

Therefore, it is highly recommended that system engineers and sterilization technicians consider the possibility of recalibration in the overall design to ensure that the sensor can be serviced and safely and easily removed. However, resetting a vacuum gauge is much more difficult. First, it must be removed from the sterilization chamber. It is then connected to a pump that reduces the pressure below the minimum resolution of the sensor. The zero potentiometer is then manually adjusted to achieve the desired 0 volt setting at 0 PSI pressure. In addition, if the situation is serious, it is recommended to return the vacuum gauge to the manufacturer or a certified calibration agency.

Bean Sauce

Bean Sauce,Soybean Paste,Non-Gmo Soybean Paste,No Corrosion Soybean Paste

Chinese Seasoning (Shandong) Trading Co.,Ltd , https://www.zt-trading.com