In aerosol production, dripping from the filling head is one of the most frequent equipment malfunctions. Dripping refers to the continuous or intermittent dripping of liquid from the filling head after the filling action has stopped. Though seemingly minor, this issue directly affects product quality and production costs – it causes deviations in net content per can, leading to non-conforming products; the leaked material contaminates can bodies, labels, and the production line, increasing cleaning time and costs; and long-term raw material waste represents a significant economic loss – it is estimated that dripping from the filling head can cause material waste rates as high as 8-10%.
Starting from the perspective of frontline operators, this article systematically lists common causes of filling head dripping and provides step by step troubleshooting methods and solutions to help production personnel quickly locate the problem and restore normal equipment operation.
1. Identifying the Dripping Pattern
Before troubleshooting, first accurately identify when the dripping occurs – this helps narrow down the possible causes:
Continuous dripping after filling stops: Liquid drips after the filling head has closed. Usually related to worn seals or a valve that does not close properly.
Dripping during the filling process: Liquid escapes from the gap between the filling head and the can mouth. Often related to alignment accuracy or incorrect filling height settings.
Dripping when the machine is stopped: Material continues to leak after the equipment is shut down. Commonly caused by aged or failed seals.
2. Common Causes of Dripping
The causes of dripping from the aerosol liquid filler’s filling head can be grouped into five main categories:
(1) Aged or worn seals
The O rings, sealing gaskets and other rubber components inside the filling head are consumable parts. Over time and with constant contact with the product, they age, harden or become deformed, resulting in poor sealing and material leakage through the gaps. Moreover, different products have different corrosivity toward seal materials; if the seal material is incompatible with the product, ageing will accelerate.
(2) Blocked or damaged filling nozzle
Residual material or debris on the nozzle tip prevents the filling head from closing properly. A damaged nozzle plug or a worn/deformed nozzle orifice can also cause incomplete sealing after closing, leading to dripping. When the orifice diameter exceeds 7.5 mm, dripping becomes significantly more noticeable.
(3) Faulty ball valve inside the filling head
If the ball valve inside the filling head is damaged or does not seal tightly, the valve cannot close completely and material will continue to flow. Ball valve problems are usually irreparable and require replacement. In addition, corrosion or wear of the O ring inside an angle seat valve is also a common cause of dripping.
(4) Misalignment between filling head and can mouth
If the filling head is not centred over the can mouth, or if the distance between the head and the can is incorrect, material will spill during filling. Too much distance causes splashing and leakage; too little distance may damage the filling head or the can mouth.
(5) Delayed or stuck valve closing
Material residue blocking the valve core, or a weakened return spring, can prevent the valve from cutting off the flow immediately after filling. This type of fault is especially common when filling high viscosity products, as residue tends to stick to the valve core and affect its response.
3. Step by Step Troubleshooting and Solutions
Proceed in the order below, starting from the simplest external checks and moving to internal disassembly:
Step 1 – Inspect and clean the outside of the filling head
Stop the machine and look for obvious product residue or debris on the outside of the filling head. Wipe the head with a dedicated cleaning agent or a compatible solvent, paying special attention to the nozzle tip. Often, dripping is simply caused by dried product blocking the nozzle, and cleaning restores normal operation. Removing the filling head for thorough cleaning at the end of each production day effectively prevents clogging.
Step 2 – Check the filling head seals
If dripping persists after cleaning, check the seals. Remove the filling head and take out the internal O rings or sealing gaskets. Look for cracks, deformation or hardening. If any abnormality is found, replace the seals with identical ones. Before installing new seals, apply a suitable lubricant to the contact surfaces and ensure they fit without gaps to avoid secondary leakage.
For seal replacement intervals, it is recommended to inspect and replace seals every 3 6 months. For heavily used equipment, the interval should be shorter.
Step 3 – Inspect the nozzle orifice and plug
Check whether the nozzle orifice is cracked, deformed or oversized. If it is slightly damaged, remove the nozzle and dress it – after dressing, the orifice diameter should not exceed 7.5 mm, and the orifice face should be gently smoothed on water proof abrasive paper. If the damage is severe, replace the nozzle. Also check whether the nozzle plug is damaged; replace it immediately if necessary.
Step 4 – Check the ball valve inside the filling head
Open the filling head and inspect the internal ball valve. Look for wear or damage on the sealing surfaces of the ball, and check that the spring has sufficient force. If the ball valve is damaged or does not seal properly, it usually cannot be repaired – replace it with a new valve of the same type. After replacement, test that the valve moves smoothly and closes completely.
Step 5 – Verify alignment between filling head and can mouth
Once the mechanical components have been checked, verify the alignment. Using the machine’s touch screen or manual adjustments, set the height and horizontal position of the filling head so that it is exactly centred over the can mouth. The gap between the filling head and the can mouth should generally be 2 5 mm. A larger gap tends to cause splashing; a smaller gap may cause collisions if the can position varies.
Step 6 – Check valve response and valve core condition
If none of the above checks reveal a problem, further examine whether the valve closes in time. Disassemble the valve, flush the valve core with a dedicated cleaning agent to remove any internal residue, and check that the spring is in good condition. If the spring is fatigued, replace the valve core assembly. Calibrate the valve response time through the control system to ensure the valve closes immediately after filling.
Step 7 – Check product parameter compatibility
When the mechanical parts and the valve are both normal but dripping persists, consider whether the product parameters are compatible. High viscosity products that are not heated and kept warm have poor flowability, causing incomplete pressure relief in the line after filling, which leads to dripping. Low viscosity products delivered at too high a pressure can also cause seal failure. Adjust the temperature or delivery pressure according to the product characteristics, and use a filling pump type that matches the product.
4. Preventive Measures and Routine Maintenance Recommendations
Preventing dripping is far more effective than repairing it after it happens. We recommend establishing the following routine maintenance schedule:
Daily checks – Before starting the machine, check the filling head and sealing gaskets for integrity, and confirm there are no air or product leaks. After production, remove the filling head, wash it with a compatible solvent, and blow it dry with compressed air.
Weekly maintenance – Inspect O rings and sealing gaskets for wear; replace immediately if any ageing or deformation is seen. Check filling accuracy using a standard measuring cup to ensure it is within tolerance. Clean the non return valve in the filling head to ensure smooth product flow.
Monthly deep maintenance – Replace all aged seals. Calibrate equipment positioning accuracy and valve response speed. Check the air source triple unit, regularly drain water from the water separator to prevent moisture from entering the air circuit and causing valve core rust and failure.
Seal management – Based on the chemical nature of the product being filled, select seal materials (e.g., Viton, silicone) that are resistant to that product, to avoid rapid ageing due to material incompatibility.
5. Quick Troubleshooting Flowchart
To help frontline operators quickly locate problems, the steps above can be summarised as a flowchart:
① Clean outside of filling head → If solved, done; if not, go to step 2.
② Check seals → If worn, replace; if OK, go to step 3.
③ Check nozzle orifice/plug → If damaged, dress or replace; if OK, go to step 4.
④ Check ball valve → If damaged, replace; if OK, go to step 5.
⑤ Check alignment → If misaligned, adjust; if OK, go to step 6.
⑥ Check valve response & valve core → If sticky, clean/replace; if OK, go to step 7.
⑦ Check product parameter compatibility → Adjust temperature/pressure.
Following this step by step process will resolve most filling head dripping issues within a short time. If the fault recurs frequently or none of the above methods work, contact the equipment manufacturer for in depth repair to eliminate the root cause of the problem.
