Internal thread diaphragm valves are mainly used in industries such as food machinery, pharmaceutical machinery, dairy products, brewing and beverage, and fine chemicals.
Precautions for using internal thread diaphragm valve:
1、 Precautions during installation phase
1. Specification for threaded connections
Sealing treatment: The internal thread connection should be wrapped with PTFE tape or coated with special thread sealant to ensure sealing.
• Alignment requirement: During installation, it is necessary to ensure that the pipeline flange is coaxial with the valve thread axis to prevent stress concentration caused by deviation.
2. Cleaning and pre-treatment
Pipeline flushing: Before installation, the pipeline should be thoroughly flushed to prevent foreign objects such as welding slag and iron filings from entering the valve chamber and damaging the diaphragm.
Internal inspection of valve: Confirm that there are no residual sand particles or impurities inside the valve body (especially for new valves that may have residual casting sand after leaving the factory).
2、 Operation and usage standards
1. Media adaptability control
Applicable medium: limited to general corrosive liquids (such as weak acid and weak alkali solutions), strictly prohibited for use in strong oxidizing media.
• Temperature limit: Choose the operating temperature based on the diaphragm material.
2. Operation intensity and method
Manual operation taboos: Do not use levers or other tools to forcefully open or close to avoid valve stem deformation or diaphragm tearing.
• Opening control: The opening height should not exceed 90% of the fully open position of the valve to prevent excessive stretching and diaphragm detachment.
3、 Operation and maintenance requirements
1. Regular inspection items
• Diaphragm status: Check the rubber/fluoroplastic diaphragm monthly for aging, cracking, and perforation, and replace it in a timely manner (it is recommended to stock spare diaphragms).
• Thread sealing: Check for leakage at the threaded connection every quarter and reseal if necessary.
2. Cleaning and lubrication
Valve chamber cleaning: When shutting down, rinse the valve chamber with clean water or neutral cleaning agent to prevent medium crystallization or sediment blockage.
Lubrication of moving parts: Apply food grade silicone grease (suitable for the food industry) or molybdenum disulfide dry powder to the threaded part of the valve stem every six months.
4、 Selection and Storage Suggestions
1. Material selection
• Corrosive media: CF8M (316 stainless steel) or fluorine lined valves are preferred for valve body materials.
Food/pharmaceutical industry: Choose EPDM diaphragms and stainless steel valve bodies that meet FDA standards.
2. Long term disuse maintenance
• Drain the medium: Thoroughly drain the liquid inside the valve before stopping to prevent residual medium from corroding.
• Protective treatment: Apply anti rust grease to the threaded area and inject lightweight lubricating oil into the valve chamber to prevent moisture.
In short, internal thread diaphragm valves need to focus on installation sealing, medium compatibility, and diaphragm life management. By standardizing operations, regular maintenance, and timely replacement of vulnerable parts (diaphragms, seals), the service life of valves can be effectively extended and system safety can be ensured.