In polyurethane spraying operation, the stable operation of the feed pump directly affects the feeding efficiency and foaming quality of the whole equipment. Once the feed pump fails to work, the spraying will be interrupted at best, and the whole barrel of raw materials will be scrapped at worst.
Below we summarize several common reasons and suggestions for why the feed pump cannot start or works abnormally , to help you quickly troubleshoot and resume production.
Common causes and solutions
1. The feed pump shaft is stuck due to crystallization.
Phenomenon : If the pump is not cleaned for a long time, the black material or isocyanate component will crystallize when it encounters moisture, causing the pump shaft to get stuck.
Solution :
- Disassemble the pump body and remove the crystallized deposits;
- Use a special cleaning agent (such as acetone) to soak and clean the pump element;
- Strengthen daily maintenance and regularly check the shaft seal area for crystal deposition.
2. The rubber cover of the reversing rubber falls off
Phenomenon : The pneumatic pump reversing system fails, resulting in ineffective reversing or no movement of the pump body.
Solution :
- Open the upper cover of the pump body and check whether the rubber cover is intact;
- If the rubber is found to be falling off, aging or deformed, it must be replaced immediately;
- Check other reversing parts for wear and replace if necessary.
3. The feed pump is inserted into the wrong barrel, causing foaming
Phenomenon : After the A and B materials are inserted into the wrong barrels, a cross-linking reaction occurs inside the pump body, resulting in blockage or foaming and solidification.
Solution :
- After stopping, pull out the pump body immediately and clean it with solvent;
- If the reaction has solidified, the entire feed pump needs to be replaced;
- During operation, it is important to clearly distinguish between black and white material pumps, label them and use fool-proof design.
4. Black material is fixed in the pump
Phenomenon : The black material retained in the pump is caused by poor sealing or failure to clean before shutdown, resulting in internal gelation and solidification.
Solution :
- If it is slightly cured, you can try to use heat + solvent to soften it and then remove it;
- If the whole pump is blocked, it is recommended to replace the pump body directly and check the sealing system;
- It is recommended that the feed pump must be backwashed every time the machine is shut down for more than 1 hour to avoid liquid retention.
Daily maintenance recommendations
- After work each day , clean the feed pump and pipeline with the recommended cleaning agent;
- Use dry compressed air to prevent water vapor from entering the black material system;
- Regularly swap the positions of black and white material pumps and pipelines to check the sealing performance;
- Prepare wearing parts in advance , such as reversing rubber cover, sealing ring, pump core, etc.
Tips
90% of feed pump failures are actually caused by “usage habits” rather than quality problems of the equipment itself. Only reasonable maintenance and standardized operation can truly make the equipment operate efficiently for a long time.
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