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General Guidelines for O-Rings and U-Cup Seals
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 Inc. based on com-
patibility with the chemicals to which they will be
exposed. Solvents that may remove residual chemicals
often have negative effects on the mechanical proper-
ties of O-rings and seals.
O-Ring Guidelines
•
Always replace an O-ring with the identical one in
size, durometer hardness, type and material of con-
struction. Always be alert to the location and size
of each O-ring as many look alike and be careful not
to mix them. Often similar sizes may be used in var-
ious locations on the equipment and if replaced
incorrectly, the equipment may not function prop-
erly. Refer to the Machine Operation and Service
Manual for the correct part number of all O-rings
used throughout the equipment and replace them
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, item 84/0200-K3/11, to the entire surface
of the o-ring before installation. Avoid excessive
lubrication. 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.
20
U-Cup Seal Guidelines
•
Always replace a U-cup seal with the identical one
in size, durometer hardness, type and material of
construction. Always be alert to the location and
size of each U-cup seal as many look alike and be
careful not to mix them. Often similar sizes may be
used in various locations on the equipment and if
replaced incorrectly, the equipment may not func-
tion properly. Refer to the Machine Operation and
Service Manual for the correct part number of all
U-cups used throughout the equipment and replace
them with factory approved parts only.
•
Always apply a very thin film of Krytox 203GPL
lubricant, item 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.
332094C
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