GMP clean workshop grade ABCD standard
Since March 1, 2011, in accordance with the provisions of something called GMP, the clean workshop has been officially divided into four levels: ABCD. However, there are a large number of companies that are doing things like precision machining, but when it comes time for acceptance, they suddenly find that they have no clear understanding of what the standards at all levels are.
Once the temperature, wind speed, or pressure difference is wrong, the entire production line may need to be reworked. And such losses can easily reach hundreds of thousands.
Rigid indicators for Class A clean areas
This setting of Level A is the top level of the protection level. The air temperature value will be fixed within the range of 20 degrees Celsius to 24 degrees Celsius. At the same time, the humidity control is also restricted to the relative humidity range of 45% to 60%.
The speed requirements for airflow are also very clear. The horizontal wind speed cannot be lower than 0.54 m/s, while the lower limit of the vertical wind speed is 0.36 m/s. In addition, the light intensity index falls between 300lx and 600lx, and there are restrictions on sound decibels. The maximum noise in a dynamic environment cannot exceed 75 decibels.
The core logic is that unidirectional laminar airflow will take away particulate matter directly, so its wind speed requirements are much higher than other levels. In the field of precision machining, key workstations involving exposed surfaces, such as precision grinding and polishing, basically have to be designed according to Class A standards.
Ventilation pressure difference requirements for Class B and Class C
The ventilation frequency of Class B, as well as Class C, cannot be less than 25 times per hour, and the pressure difference relative to the outdoor environment cannot be less than 10 Pa. Between different areas in the same level, a gradient pressure difference must be maintained according to the direction of the air flow. As for the temperature, it should be maintained within the range of 20 to 24 degrees Celsius, and the humidity should be between 45% and 60%.
Level B is usually regarded as the buffer tank of Level A, while Level C is the place responsible for covering weighing, preparation and such routine operations. In terms of illumination and noise indicators, it is consistent with Class A. However, for wind speed, there is no very strict hard threshold requirement like Class A. At this point, the cleanliness standards for precision machining workshops and their design pressure standards are much smaller than Class A.
Why is the D-level temperature relaxed to 18 to 26 degrees?
The temperature range of Class D is directly adjusted to the range of 18 to 26 degrees Celsius, and the frequency of ventilation is reduced to no less than fifteen times per hour. The pressure difference is still required to be higher than ten pascals relative to the outdoor space. The indicators of humidity, illumination and noise are consistent with the three-level standards mentioned above.
This means that Class D is mostly used in non-sterile links such as outer packaging and logistics channels, and the energy consumption of the air conditioning system is much lower than Class ABC. When laying out the precision machining workshop, place non-critical processes in D-level GMP clean workshop grade ABCD standards, which can save tens of thousands in air-conditioning electricity bills a year.
High-efficiency filter leak detection rate unified card 99.97%
The leak detection rates of the four levels of HEPA are all required to be greater than 99.97%. Correspondingly, it is the interception efficiency for 0.3 micron particles. As for this data, it is an internationally recognized dividing line for high-efficiency filtration. At this level, there is no so-called high or low distinction between the four levels of ABCD.
In the actual inspection work, we need to use the fog method of two substances, DOP or PAO, to scan each device. If it is found that the leakage in even one place exceeds the specified standard, the sealing part must be redone, or the filter element must be simply replaced.
The final inspection report issued needs to be saved, and the storage time cannot be less than two years, because when the audit comes, these reports may be retrieved at any time for review.
The easiest pitfalls for companies to step into when launching their business
The first situation is that the frequency of Class B ventilation and the frequency of Class C ventilation are confused. The number written on the construction drawings is 15 times an hour, but the audit unit's requirement is 25 times an hour. Therefore, the air duct needs to be modified and fans added. The cost of rework is at least tens of thousands of yuan.
The second is that the value of the pressure gradient is not gradually reduced according to the flow direction of the air flow. This behavior directly leads to the consequences of cross-contamination.
Third, the illumination measurement value is lower than the standard line of 300lx, which causes the reading error to significantly expand due to factors such as visual judgment when workers perform long-term operations. This ultimately causes the size of precision machining to exceed the allowable range, resulting in a batch of parts being judged as scrap and scrapped.
Which standard level is your factory's precision machining workshop currently operating at? Does the measured data of pressure difference and wind speed meet the specified requirements? Please share and discuss in the comment area. If you find this information useful, please like it and forward the content to your peers for reference.
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