Daily operation of a negative pressure weighing chamber?

The negative pressure weighing chamber is a special clean equipment used in the pharmaceutical, chemical, and other industries. Maintaining an internal negative pressure environment, prevents the spread of dust, ensuring operational safety and environmental cleanliness. The following are the detailed procedures and precautions for its daily operation:
I. Preparations before operation
1. Environmental and equipment inspection
Cleanliness status: Confirm that there is no debris or dust inside the weighing chamber and that the countertop and floor have been cleaned and disinfected (can be wiped with 75% ethanol or a special disinfectant).
Equipment appearance: Check whether the components such as the fan, differential pressure gauge, lighting, and filters (primary, medium, and high-efficiency) are in good condition, without any looseness or damage.
Differential pressure confirmation: Before starting up, observe the reading of the differential pressure gauge to ensure that the negative pressure value meets the design requirements (usually -5Pa to -10Pa, with specific details subject to the equipment manual). If the pressure difference is normal, it is necessary to check whether the filter is clogged or poorly sealed.
2. Preparation of materials and tools
Material verification: Confirm the name, specification, batch number, and other information of the materials to be weighed to ensure consistency with the production instructions.
Tool preparation: Prepare calibrated weighing instruments (such as electronic balances), weighing paper, medicine spoons, containers, etc., and ensure they are clean and in normal condition.
Personal protection: Operators should wear work clothes, masks, and gloves that meet the requirements of the clean area. If necessary, they should wear goggles to avoid contaminating materials.
Ii. Startup and Operation
1. Start the equipment
Start the fan: According to the equipment operation procedures, start the supply fan and exhaust fan to ensure the correct airflow direction (usually supply air from the top high-efficiency filter and exhaust air from the bottom or side).
Preheating during operation: After the equipment is started, it is recommended to idle for 5 to 10 minutes to stabilize the airflow and achieve the specified negative pressure value and cleanliness (such as ISO grade 8 or higher).
2. Weighing operation
Place materials: Move the materials and tools into the weighing chamber through the transfer window or buffer room to avoid negative pressure fluctuations caused by the door being open for too long.
Balance calibration: Before use, calibrate the electronic balance (zero point calibration or weight calibration) to ensure weighing accuracy.
Weighing steps:
Please turn on the lighting in the weighing room and adjust it to an appropriate brightness.
Place the weighing container on the balance, zero it, and peel it.
Take the material slowly with a medicine spoon and pour it into the container. When approaching the target weight, gently tap the medicine spoon to allow the material to be added slowly until the specified weight is reached.
Record the weighing data (including material name, weight, time, operator, etc.).
Dust control: During the weighing process, handle with care to avoid violent shaking that may generate dust. If it spills accidentally, it should be cleaned up immediately with special tools (such as a vacuum cleaner or anti-static cloth). It is strictly forbidden to wipe it directly with your hands.
Iii. Precautions during Operation
Negative pressure monitoring
Keep an eye on the differential pressure gauge at all times. If the negative pressure value deviates from the set range (such as an absolute value less than -5 Pa), stop the operation immediately. Check whether the filter is clogged or the sealing condition of the doors and Windows, and notify maintenance personnel if necessary.
It is prohibited to open multiple entrances and exits (such as the front door and the back door) simultaneously to avoid airflow short circuits causing negative pressure failure.
2. Cleanliness maintenance
During operation, avoid cross-contamination. Different materials should be weighed in separate areas. Tools should be cleaned promptly after use.
Non-essential actions (such as walking or talking with your back to the weighing platform) are prohibited in the weighing room to reduce dust generated by personnel movement.
3. Exception handling
If abnormal sounds, odors, or fan malfunctions occur during the operation of the equipment, the machine should be stopped immediately, the power supply cut off and the equipment management department reported.
In case of a power outage, the equipment switch should be turned off. After the power is restored, clean, start up, and preheat the equipment again.
Iv. Operation Completion and Cleaning
1. Finish the operation
Material handling: The weighed materials should be promptly sealed, labeled (indicating name, weight, batch number, etc.), and sent out of the weighing room through the transfer window.
Waste disposal: Discarded weighing paper, medicine spoons, and other tools should be placed in dedicated waste containers and disposed of by regulations (such as centralized destruction or disinfection).
2. Cleaning and disinfection
Countertop and equipment: Use a clean cloth dipped in disinfectant to wipe the surface of the weighing table, balance, and the outer surface of the equipment to ensure there is no dust residue.
Floor cleaning: Use a vacuum cleaner or a wet mop to clean the floor to avoid water accumulation.
Ultraviolet disinfection (if any): After turning off the fan, turn on the ultraviolet lamp to irradiate for more than 30 minutes to disinfect the space (note that personnel must leave the site to avoid ultraviolet burns).
3. Shutdown records
Turn off the power supply of the fan and lighting, and fill in the "Negative Pressure Weighing Room Usage Record", which should include: usage time, material name, operator, equipment operation status, cleaning and disinfection situation, etc.
V. Daily Maintenance and Care
Filter replacement:
Primary filter: Generally, it should be cleaned or replaced every 1-2 weeks (depending on the frequency of use and the amount of dust).
Medium-efficiency filter: Replace it every 3 to 6 months. The specific replacement should be based on the indication of the differential pressure gauge or the test results.
High-efficiency filters: Their service life is usually 2 to 3 years. Regular detection of filtration efficiency is required. If the pressure difference increases significantly or the cleanliness does not meet the standard, they should be replaced promptly.
Equipment lubrication: Regularly add lubricating oil to the moving parts such as the fan bearings as required by the manual to ensure smooth operation.
Performance verification: At least one test should be conducted annually for indicators such as air velocity, pressure difference, and cleanliness to ensure that the equipment complies with relevant standards such as GMP.
Vi. Safety Warnings
High-risk operations (such as weighing highly toxic or highly active materials) are prohibited in the negative pressure weighing room unless the equipment is equipped with additional protective measures (such as biosafety cabinet functions).
Operators must be trained and qualified before taking up their posts, strictly abide by the operating procedures, and avoid dust leakage or equipment damage caused by misoperation.
Through standardized daily operation and maintenance, the negative pressure weighing chamber can effectively control dust pollution, ensuring production safety and product quality. If there are differences in special materials or equipment models, the operation process needs to be adjusted in accordance with the specific circumstances.