SPRING-LOADED VS.
ADJUSTABLE PACKINGS
As packings begin to wear,
paint can start to leak by the packings and out of the top of the fluid section.
This will also result in a loss of pressure and unit performance. There are two
ways to lengthen the life of packings.
Spring
Loaded Packings (Patened
sytem by SprayTech and Wanger)
With this design, the
packings are self-adjusting. As the packings begin to wear, the spring tightens
the tension on the packing and helps to maintain the proper seal.
Adjustable
Packings (Type found in
most Graco units)
With adjustable packings,
the user is required to make periodic adjustments by tightening a packing nut
located at the top of the fluid section. By turning the packing nut, the user is
able to maintain the proper seal.
Spring loaded packings
eliminate the need to continually tighten the packing nut to maintain the proper
seal or load on the packings. Getting too much tension on the packings can
greatly shorten their life (and also the life of the piston rod); too little
tension can result in leakage than can cause early packing and piston wear. The
user should not have to determine how tight the packing nut should be. With
spring loaded packings, the proper tension is engineered into the pump.
FIXED VS. DYNAMIC PACKINGS
All piston pumps have
packings that help prevent the paint from leaking out of the top of the fluid
section and also help direct the paint to the proper fluid outlet. Packings can
be single piece seals or a stack of seals. They are typically made of
polyethylene, Teflon, or leather (often a combination of each).
Fixed Packing Design
In this design, both the
upper packings and the lower packings are stationary. As the piston travels up
and down, it travels through the packings.
Fixed/Dynamic Packing
Design
In this design, the upper
packings are fixed but the lower packing is attached to the piston rod and
travels up and down with the piston. Under these conditions, an additional
internal cylinder sleeve is required to take the wear from the movement of the
lower packing.
A fixed packing system
eliminates one of the most costly wear parts in a paint pump: the cylinder
sleeve. Instead of having both the piston rod and sleeve wear out, a fixed
packing pump has the piston rod wear in two places. The result is lower repair
costs.
