M A G U I R E P R O D U C T S , I N C .
10
S e r i e s M P A
PUMP TUBING
The pump tube that is continually compressed by the rotating rollers is the heart of the pump.
Many materials are available for this tube; resiliency and chemical compatibility being the primary
considerations in selection of this material. Virtually all liquid color applications use polyurethane
tubing.
Conditions that affect tube life are resiliency of the tube material selected--urethane being the
best, chemical compatibility, and tubing diameter--smaller diameters having a longer life than
larger diameters.
Three different diameter pump tubes are available for use in the Maguire Six Roller Pump; 1/8",
3/16", and 1/4" I.D. tubes. Theoretical maximum pumping rates of the pump are as follows:
Using 1/8" I.D. pump tube -- 37 CCs/minute @ 56 RPMs.
Using 3/16" I.D. pump tube -- 74 CCs/minute @ 56 RPMs.
Using 1/4" I.D. pump tube -- 123 CCs/minute @ 56 RPMs.
These maximum pumping rates are achievable only for liquids having viscosities similar to, or
lower than, latex paint or easy pouring syrup. Viscosities so high that they do not readily pour can
also be pumped, but at considerably reduced maximum rates.
While the pump is a positive displacement pump and can produce a full vacuum, the liquid flowing
to the pump is pushed only by atmospheric pressure, about 15 PSI. Since high viscosity liquids
flow poorly through small diameter tubes, these two conditions should be observed:
1. Always use as large a diameter supply tube to the inlet side of the pump as is practical and
do not reduce this diameter except upon entering the pump head.
2. Keep the distance to the liquid supply as short as possible.
In selecting tube sizes, keep these factors in mind:
Larger diameter tubes offer higher pumping rates and are generally recommended when coloring
very large parts. They are also better suited for pumping thicker materials.
Smaller diameter tubes always last longer and also pump more accurately for a longer period of
time.
Generally, presses with less than a 500-ton capacity use 1/8" I.D. green tube. Nearly all larger
presses use 3/16" I.D. red tube. Only large extrusion applications use 1/4" I.D. tube.
