Brother MFC4820C Service Manual page 61

[ 4 ] Structure of the needle tubes
The structure of a needle tube is shown below. The innermost layer utilizes FEP tubing, which
provides an excellent and long-term barrier against air getting into the tubes and against ink
evaporation. The outer layer utilizes silicon tubing which features superior flexibility and
durability to the degree necessary to withstand the high-speed movement of the print head unit as
well as long-term constant and extreme bending.
Both types of tubing are adhered with primer to protect against chemical and physical damage and
to ensure that characteristics necessary to these types of tubing are not compromised.
Functional breakdown of
double layered tube
Outer layer:
Superior flexibility
silicon (625 µm)
and durability
Innermost layer:
Provides an excellent
FEP (75 µm)
barrier
4 -2 0
Primer
Ink