Objective: To explore and study the compressed air quality control standards in line with the actual situation of domestic hospitals. Methods: According to the current status of medical compressed air system construction, the compression control detector was used to detect the quality of compressed air, and the purity indexes such as pipeline pressure, CO2, CO, moisture and oil content were studied to analyze the impact on medical equipment and patients. . Results: Based on the analysis of foreign standards and actual conditions, the quality control standards in line with the actual situation of our hospital were formulated to fill the gap in the quality management of medical compressed air in our hospital. Conclusion: The development of compressed air quality control standards can save hospitals money while ensuring the quality of medical compressed air.
Medical compressed air; quality control; medical compressed air in standard hospitals is mainly to provide positive pressure air supply for medical equipment such as ventilators and anesthesia machines. As the most risky medical equipment, ventilators and anesthesia machines must use pure compressed air, otherwise it will affect the normal use of the equipment and threaten the safety of patients. Therefore, it is especially important to control the quality of medical compressed air.
1 International compressed air quality standards In Western developed countries, medical compressed air is managed as a special drug, and must be strictly in accordance with US and European Pharmacopoeia requirements (see Table 1). Most hospitals in China only manufacture medical compressed air according to the design specifications of compressed air stations and the technical specifications of hospital clean surgical departments. There is no clear standard. This paper studies the compressed air quality according to the specific conditions of domestic hospitals, and develops a set suitable for domestic use. Hospital quality control standards for compressed air.
2 The impact of medical compressed air on equipment The impact of medical compressed air on equipment is mainly reflected in the output pressure. The Medical Engineering Support Management Center of the 302th Hospital of the People's Liberation Army Beijing 100039 Table 1 International compressed air quality standard control index American standard cga American standard nfpa condensed oil and The odour of the particulate matter has no obvious high or low olfactory smell and impure output gas.
2.1 The output pressure is too high or too low. The electronically controlled ventilator consists of the gas path part and the control part. This type of ventilator needs externally supplied compressed air and 2 gas sources. When the ventilator is working, the pressure of the gas source is required to be 0.3~0.67MPa ( 3~6.7bar).
If the output pressure is too high or too low, it will affect the concentration of the mixed output gas (the concentration of oxygen output by the ventilator), and the weight will directly affect the working pressure, causing the ventilator to malfunction.
2.2 Output gas Impure and pure compressed air is a necessary condition to ensure the normal operation of the ventilator. The compressed air output may contain liquid water, oil or impurities due to various reasons. When the impure compressed air enters the inside of the ventilator, it must first pass the air oxygen mixer or the compressed air module. The water will damage these precision instruments. The light will cause the ventilator working pressure to be unstable, and the oxygen concentration deviation of the mixer output. In severe cases, mechanical or electronic components may be damaged, causing the ventilator to malfunction. The presence of oil can jeopardize the health of the patient and the safe operation of the device. Patients such as prolonged inhalation of oily air are prone to pneumonia. Oil can also block ventilators or anesthesia machines, increasing the frequency of failures, resulting in expensive repair costs.
3 Quality control of medical compressed air system According to the influence of compressed air on the equipment, the quality control of medical compressed air system can be carried out from two aspects, one is pressure; the purity of compressed air.
3.1 Pressure quality control standard The pressure of the central compressed air system must be kept relatively constant. When the pipeline pressure is <0.4MPa, the air compressor automatically starts to pressurize the pipeline; when the pipeline pressure is >0.6MPa, the air compressor automatically Stop working and ensure that the pressure in the pipeline is stable between 0.4 and 0.6 MPa. The central compressed air system must also be equipped with a pressure alarm that provides sound and visual cues when the pressure is too high or too low.
After 6 tests of compressed air pressure, they are all within the normal range, and it is confirmed that no patient needs to use compressed air to turn off the compressor for low-pressure alarm test, and the alarm is normal.
3.2 Purity of Purity The quality control standard uses the Aerotest medical gas detector (as shown) produced by Dryer to make 4 gas source quality tests. The detector has 4 detection indicators: H20, O, C2. And C0. In 4 tests, 3 times for the compressed air system, 1 time to detect the output gas of the ventilator's own compressor (see Table 2). After testing, it was found that through standard maintenance, the substances such as oil, C2 and (1) did not exceed the standard conditions in Table 1. According to this, we used several types of impurity standards in Table 1 as the standard for hospital compressed air quality control. However, the water content exceeds the standard. It is estimated that the dryer is not working properly. The compressor has the largest water content, indicating that there is no drying device for the compressor.
Table 2 Compressed air purity 4 times test results Test items Central compressed air room temperature 26C humidity 46% central compressed air room temperature 25C humidity 45% central compressed air room temperature 26C humidity 47% comes with compressor room temperature 20C humidity 45% from the detection of Table 2 The results can be seen in comparison with Table 1. All the indicators except the H2O and C2 contents are in compliance with the standard, and C2 has reached the standard after increasing the ventilation in the room. The standard of EN12021 is established by the standards of CO, C2 and Oil. , respectively: <15ppm, <500ppm and <0.5mg/m3. The water content in compressed air can be expressed by “pressure dew pointâ€. After the humid air is compressed, the water vapor density increases and the relative humidity increases. When the temperature drops to relative When the humidity reaches 1°%, water droplets are deposited from the compressed air. The humidity at this time is the “pressure dew point†of the compressed air. The correspondence between the "pressure dew point" and the atmospheric dew point and the lower the dew point. Our hospital is located in Beijing area, the annual minimum temperature is about -20 C, the pressure in compressed air is 0.7MPa, the corresponding atmospheric dew point is -43T, and according to the relationship between atmospheric dew point and moisture content, we can get 0.7MPa in Beijing area. The moisture content in compressed air must be <0.13g/m3, ie 130ppm. For the sake of conservatism, the standard can be set to <100ppm. Table 3 Our hospital medical compressed air quality standard inspection pressure purity test item storage tank pressure terminal pressure pressure alarm condensation Oil and particulate matter (mg/m) water odor standard has no obvious smell 4 Results and discussion Under the existing conditions, with reference to international relevant standards, the compressed air quality control standards have been studied, mainly including compressed air outlets. Pressure and purity testing. Formulate the operation and maintenance and management regulations in accordance with our hospital's compressed air quality control standards (see Table 3) and equipment. The items to be inspected and recorded weekly are: compressor and equipment control panel, confirm that there is no alarm status; check each pump Check the safety of the compressor and whether there is oil leakage; check the oil of the compressor, if the oil is not enough or there is oil, notify the authorized person (referring to the person with maintenance qualification) to handle; manually open the exhaust valve, Until the airflow sufficiently clears the drain, if there is >0.5L of liquid discharge, notify the authorized person to handle; operate the compressor work selection switch to ensure its correct operation; record the working current of the compressor; record the pressure level of the compressor input and output Ensure that the compressor is in automatic mode; check the status of the dry control panel to ensure there are no alarms.
5 Conclusion Compressing the moisture in the air is a problem faced by many medical compressed air systems in China. The presence of liquid water can cause oxidation of the pipeline and damage the application equipment. It is recommended to replace the existing cold dryer with a medical dryer with a higher quality and low pressure dew point on the basis of the original equipment on the premise of saving money.
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