General Guidelines for O-Rings and U-Cup Seals
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General Guidelines for O-Rings and U-Cup Seals
Sizes and materials of construction for o-rings and u-cup seals are selected by Graco based on compatibility with the
chemicals to which they will be exposed. Solvents that may remove residual chemicals often have negative effects
on the mechanical properties of o-rings and seals.
O-Ring Guidelines
•
Always replace o-rings with new o-rings identical in
size, durometer hardness, type and material of con-
struction. Always be alert to the location and size of
each o-ring and be careful not to mix them. Similar
sizes may be used in various locations on the equip-
ment, and if replaced incorrectly, the equipment
may not function properly. See your Machine Oper-
ation and Service Manual for the correct part num-
ber of all o-rings used throughout the equipment.
Replace o-rings with factory approved parts only.
•
Re-use of o-rings is not recommended. Only re-use
o-rings as a last resort. If you must re-use them, be
sure that they are clean, have no cuts or flat spots
and contain NO foreign material. Also, be sure not
to soak them in solvent for extended periods as this
can cause deterioration of the o-ring. Always
replace o-rings that are cut, nicked, or distorted in
shape or cross-section.
•
Always apply a very thin film of Krytox 203GPL
lubricant (84/0200-K3/11) to the entire surface of
the o-ring before installation. Avoid excessive lubri-
cation. If installing o-rings over threads on a shaft or
across sharp edges, roll or push the o-ring carefully
into place, being careful to avoid cutting or nicking it.
•
Avoid stretching the o-ring too much as it may not
return to the proper size.
•
Do not use any sharp tools or objects to install
o-rings.
U-Cup Seal Guidelines
•
Always replace u-cup seals with new u-cup seals
identical in size, durometer hardness, type and
material of construction. Always be alert to the loca-
tion and size of each u-cup seal and be careful not
to mix them. Similar sizes may be used in various
locations on the equipment, and if replaced incor-
rectly, the equipment may not function properly. See
your Machine Operation and Service Manual for the
correct part number of all u-cups used throughout
the equipment. Replace u-cups with factory
approved parts only.
•
Always apply a very thin film of Krytox 203GPL
lubricant (84/0200-K3/11) to the inner and outer lips
of the seal before installation.
•
Re-use of u-cup seals is not recommended. Only
re-use u-cups as a last resort. If you must re-use
them, be sure that they are clean, have no cuts or
flat spots and contain NO foreign material. Also, be
sure not to soak them in solvent for extended peri-
ods as this can cause deterioration of the seal.
Always replace u-cups that are cut, have flat spots,
are distorted in shape or are damaged in any man-
ner.
•
Always be alert to the proper orientation of the seal-
ing lips and re-install them in the same direction as
shown on the specific equipment assembly drawing.
The u-cup seals are intended to seal in only one
direction, and if installed incorrectly, chemical leak-
age through the u-cup can occur.
•
Whenever possible, push the back side of the seal
over the shaft to protect the inner and outer lips. If
this is not possible, carefully tuck the lip in to avoid
rolling it back or cutting it.
•
If installing over sharp edges, slide the seal carefully
into place to avoid cutting it.
•
Do not use any sharp tools or objects to install
u-cups.
