What is the maximum viscosity fluid I can apply with a Uni-Roller?

The “maximum viscosity” fluid question is heavily dependent on several variables.

• Dispenser tube hole size - The Uni-Roller^®systems use several different types of dispenser tubes. Our 5-hole standard tubes and 20-hole low volume (LV) tubes are the most common types. 5-hole dispenser tubes have a larger hole size and therefore perform better with thick fluids than 20-hole LV tubes.
• Fluid pressure – More viscous fluids need to be supplied at higher pressures (ex. 70-100 psi ) . With thick fluids there is also more pressure drop along the holes in the dispenser tubes (near push-connect inlet vs. far end). This could result in uneven dispensing along the dispenser tubes if the viscosity is too high or the fluid supply pressure is too low.
• Roller cover type – The higher the viscosity, the longer roller cover saturate times can be. This could have an impact on the fluid priming and rate at which the production line can be run. Generally speaking polyester felt (PF) roller covers are more pourous than polyurethane foam (P) roller covers and can better handle higher viscosity fluids.
• Specific Application - The max viscosity is also highly dependant of the specific customer application. Each application should be analyzed on a case by case basis. Applications where a small amount of a viscous fluid dispensed over a long period may work well for one customer whereas an application requiring a higher volume over a short period may not. Contact Unist for a consultation and recommendation.

Generally speaking, most fluids with a viscosity below 400 cSt will work with 5-hole dispensing tubes and polyester felt roller covers.

Because every fluid has different fluid properties, the best way to know if the fluid is compatible is to test a sample of the fluid. We highly recommend sending a sample of the fluid to our Unist Fluid Testing Lab for evaluation. We maintain a database containing hundreds of different lubricants that have been tested over the years. Contact Unist Sales and Support to get the process started.