How to Circulate White Ink Automatically on a DTF-Converted Epson ET-8550 Using a Pump System

Question:
Is there a way to keep the white ink circulating in a DTF-converted Epson ET-8550 using an external pump, while also allowing the dampers to "tee off" from the same line so the printhead receives ink?

When converting the Epson ET-8550 (or similar EcoTank models) for DTF printing, one of the most common challenges is preventing white ink from settling or separating in the lines. White ink is heavier because it contains titanium dioxide, which tends to sink and cause clogging or uneven prints. That's why circulation systems are often added - they keep the white ink moving and prevent sedimentation.

Here's a detailed breakdown of how to approach white ink circulation with a pump system and a tee-line configuration:

1. Understanding Circulation in DTF Printers

In high-end DTF printers, circulation systems are built to constantly move white ink between the ink tank, lines, and dampers. These typically include:

• A white ink tank with a bottom inlet/outlet

• A small diaphragm or peristaltic pump for continuous low-pressure circulation

• Check valves to prevent reverse flow

• A bypass or tee system so ink can flow both to the dampers and back to the tank

For DIY conversions, this same principle can be applied manually using aftermarket components.

2. How to Set Up a Circulation System for White Ink on the Epson ET-8550

To make the system work while allowing the dampers to receive ink:

1. Install an External Pump
   Use a low-flow peristaltic pump or mini DC diaphragm pump. These are ideal because they maintain steady flow without creating air bubbles. Connect the pump inline between the ink tank and the return line.

2. Use a Tee Connector for Dampers
   From the main supply line (coming from the white ink tank), add a T-junction:

   • One branch goes to the dampers feeding the printhead.

   • The other branch goes to the return line, circulating back to the tank through the pump.

3. Include One-Way Valves
   Install check valves on both sides of the tee line to prevent ink from flowing backward into the dampers when the pump is off. This also ensures stable pressure at the printhead.

4. Control Flow Speed
   Keep the pump flow slow and gentle-you only need enough movement to prevent sedimentation. Too much pressure can flood the dampers or cause leaks inside the printhead assembly.

5. Add a Timer or Manual Switch
   To automate circulation, connect the pump to a digital timer (e.g., circulate for 10-15 minutes every 6-8 hours). Alternatively, use a manual switch so you can circulate ink before printing sessions.

6. Avoid Air Bubbles
   Always prime the lines before activating the pump. Air in the system can cause banding, misfiring, or even nozzle loss.

3. Important Safety & Maintenance Tips

• Never let the pump run dry. Running a pump without ink can damage the pump and introduce air into the system.

• Use white-ink-safe tubing made from PTFE or silicone to prevent pigment adhesion.

• Regularly shake or stir the white ink tank - even with circulation, sediment can collect over time.

• Flush the system every 1-2 weeks if the printer isn't used daily. This prevents thickening of white ink in the tubing.

• Monitor pressure - too much suction or backflow can create printing inconsistencies or ink starvation at the dampers.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems. So, we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We offer an in-person evaluation and repair service via our local diagnostic facility (https://bchtechnologies.com/printer-repair-service). Given the high demand, we operate on a first-come, first-served basis. It may take a few weeks before we can schedule your printer drop-off. Our services cover complete printer repairs or individual part fixes, with clear instructions on how to proceed. However, we understand that our rates aren't always the most economical, so we encourage self-help through resources like our YouTube channel (https://youtube.com/@bchtechnologies). Use the search icon next to "About" on the right-hand side of the channel menu bar to find videos on DTF conversion, pump systems, and white ink circulation.

Thank you again for contacting us and for supporting BCH Technologies. Your engagement helps us improve our community's understanding of printer conversions and maintenance.