Loaded Lip Seals are very versatile and can be used as rod seals or piston seals. They are considered to be multi-purpose hydraulic seals and are designed for significantly improved performance. American Seal & Packing Loaded Lip Seals are molded from 92 Durometer Urethane with a 70 Durometer Nitrile energizer. The energizer ensures constant pressure on the sealing lips.
Standard Loaded Lip Seal
The Standard Loaded Lip Seal is the most widely used design of Loaded Lip
Seal. By energizing the sealing lips with an endless O-ring, you are assured
of uniform, positive lip contact and excellent low-pressure sealing. The seal
depth is equal to the radial width, which results in a square design.
Standard Loaded Lip Seals can be widely used to interchange with existing
hydraulic packing and/or O-rings without changing dimensions.
Loaded Lip Seal Type "B"
The Loaded Lip Seal Type "B" features a back-beveled sealing lip. This
provides greater film breaking and increased unit loading at the sealing
surface. The seal depth is generally 1 ½ times the radial width to ensure hydraulic
seal stability in the most rugged applications. It is most commonly used as a
Loaded Lip Seal-Deep Style
The Loaded Lip Seal-Deep Style incorporates the same unique design as the
Sthard Loaded Lip Seal, plus its depth is 1 ½ times greater than the radial
width. This increases seal stability to withstand rugged, high shock,
heavy-duty applications. This seal will replace many kinds of Vee Packing.
When minimum drag is needed, use Standard Loaded Lip Seals or Loaded Lip
U-Cups derive their name from their shape and are self-sealing on both the
inside diameter and outside diameter. They are most often used for sealing
rams or rods and are very popular due to the small gland space required. They
are especially adapted to low speed, low pressure environments for both
pneumatic and hydraulic cylinders. They provide an extremely smooth, steady
movement because of their inherent low friction.
The seal is obtained by means of the flared, flexible lips coming in contact
with the rod or cylinder wall. Clearance is provided at the heel for minimum
friction. Through this design, the packing is preloaded when
installed. Sealing effectiveness is increased by internal pressure of the air
or fluid (hydraulic seal) against the inner surface of the lips. For continued sealing
effectiveness and long seal life, the surface finish of the working surface of
either rods or bores should be a maximum of 16 micro-inches. It is not
recommended that U-cups or any other single lip seal be used in any
application where there is excessive side loading.
8400 Series U-Cups
The 8400 Series U-Cups has a champered lip and is available at American Seal &
Packing in 80 Durometer Nitrile.
6226 Series U-Cups
The 6226 Series U-Cups has a flat sealing lip and is available at American
Seal & Packing in 70 Durometer Nitrile.
U-Cup Installation Data
The lips of the U-Cup should always be toward the pressure force.
The U-Cup is a floating seal which means the height of the U-Cup should be
between .015" to .090" shorter than the depth of the gland. This added gland
space allows the pressure to equalize on both lips, thus keeping the U-Cup
The surface finish for a static seal surface should be 32 RMS maximum. The
dynamic surface should be in the range of 8 to 16 RMS. Finishes rougher than
16 RMS could cause premature lip wear and finishes finer than 8 RMS can result
in failure of the seal due to loss of lubrication.
The main function of the Rod Wiper is to keep the rod and cylinder clean and
free from foreign matter; thus preventing premature failure. The Rod Wiper is
not a pressure sealing element, yet it avoids possible abrasive effects which
may result if contaminates were to reach the sealing and rod bearing elements.
Style WD Rod Wipers
One-piece snap-in type rod wiper scrapers for heavy duty applications. WD
wipers are continuous (not split) and conform with wear and side motion for
effective wiping action over the entire life span of the seal. Part numbers
listed below are molded from 90 durometer urethane for maximum strength and
abrasion resistance. American Seal & Packing also stocks selected sizes in 90
durometer fluoroelastomer. Please inquire.
Style WAN Rod Wipers
Designed for light duty applications where style WD wipers are not required.
Interchangeable with corresponding dash numbers of MS28776 wiper rings.
Consult American Seal & Packing for AN6231 retrofit. Part numbers listed
below are molded from 90 durometer urethane for maximum strength and abrasion
resistance. American Seal & Packing also stocks selected sizes in 90
durometer fluoroelastomer. Please inquire.
Style WH Rod Wipers
Designed for medium duty applications and can provide both wiping and sealing
action in one component in low pressure systems. The external lip scrapes
foreign matter form the rod, and the other lips act as an effective pressure
seal in low pressure applications. This wiper can also be used as a secondary
seal to trap slight leakage from the primary seal. This creates a very dry
rod system. Molded from 90 Durometer Urethane for maximum strength abrasion
Style WK Rod Wipers Double lip design provides the ultimate in wiper action to remove foreign
material from the exposed rod while still maintaining an adequate lubricating
film. It protects both the rod and the primary seal.
Metal Clad Wipers These rod wipers are molded form urethane and encased in a heavy duty metal
case. This gives them exceptional abrasion resistance and outstanding
endurance under difficult operating conditions. Highly effective in removing
dirt and contaminants from the rod. The dimensions for Metal Clad Wipers
stocked by American Seal & Packing are listed below. For availability of
additional sizes not listed, please inquire.
Wear Rings American Seal & Packing Wear Rings are glass filled nylon. The high
compressive strength and load bearing capabilities of this material meet or
exceed that of most metals used for wear rings. The use of these non-metallic
wear rings totally eliminates metal-to-metal contact and the subsequent
galling and scoring of cylinder bores and rods. These wear rings readily
ingest harmful metal flakes, burrs and small chips. They will not generate
contamination as is common with metallic wear rings. They are compatible with
all common hydraulic oils, water emulsions, water glycol, and phosphate ester
fluids. Operation temperature to 350˚F. Butt cut-standard stocking
The T-Seal is compact and provides an excellent option to bulkier types of
seals in a double or single acting application. It requires significantly
less packing space than Vee Packings, V-Cups, or Piston Cups. The result is a
compact, efficient and less costly overall component.
The T-Seal is used in reciprocating hydraulic and pneumatic equipment and in
high-pressure applications. It is an excellent direct replacement for other
packings )such as those in standard grooves). It fits into the same simple
groove as O-rings and eliminates rolling or spiraling, even under long
stroke or dry rod conditions. It does not wedge into clearances or pinch off
under motion or pressure and has good low-pressure sealing capabilities.
Because the T-Seal is supplied with a back-up on both sides of the sealing
area, it functions very well in double acting applications. The back-ups are
split for ease of installation.
Like other similar packings, the T-Seal is compressed to eliminate
low-pressure leakage. However, the back-up rings float between the T-Seal's
flanges and the rod or bore, minimizing friction and wear. When pressure is
applied, a bridge is formed before extrusion can occur.
The T-Seal's back up utilizes hydraulic pressure to keep it in contact with
the rod or cylinder wall. This prevents extrusion from occurring.
The T-Seal resists spiral failure. When piston or rod movement does occur,
even under very low pressures, the design allows the back-up rings to lock the
sealing element in place.
At present, American Seal & Packing stocks 70 Durometer Nitrile T-Seals with
nylon back-ups. Call for availability of other compounds.
American Seal & Packing Vee Packings (or V-Packings) are multiple-lip (chevron) seals
comprised of a group of endless rings and are popular for sealing rods and
pistons. They can be used for low or high pressure applications and with sing
or double acting cylinders.
American Seal & Packing presently stocks Female and Male Adapters (top and
bottom) in fabric reinforced nitrile and V-Rings (center rings) in fabric
reinforced nitrile and in homogeneous 90 Durometer nitrile*. In general,
fabric Vees are for high pressure, and homogeneous Vees are for low pressure.
The selection of fabric or homogeneous compounds should be made on the basis
of operating pressure, temperature, and the type of gaseous or fluid medium
with which the packing must function. (*Call for availability of other
Properly installed Vee Packings will generally outperform other lip-type
seals. They are always installed in sets. Each set contains a number of
V-Rings (based upon the pressure) plus male and female adapters.
The V-Rings in each set are referred to as pressure rings. Refer to the table
below to determine the number of V-Rings per set based on solid rings. This
table applies to the majority of installations. There will be exceptions,
depending upon special operating conditions, where the table guidelines do not
While similar to Vee Packings, the WV style provides sealing properties that
are largely independent of stack packing pressure. The WV is designed so that
it will provide a multiple lip hydraulic seal in a fixed gland depth packing. Because
of the design of the WV packing, te lips of each ring are free to flex when in
a nested stack so each lip automatically reacts to fluid or air pressure,
providing a better seal in a given packing space. There is no compression
adjustment required during the seal life.
Since the WV Packing is a multiple lip hydraulic seal, it is recommended over a single
lip seal for applications where side loading is a factor. The multiple lip
also provides extra stability. If one seal fails, there will be another seal
to serve as back-up.
There is an interference built into both the I.D. lips and the O.D. lips so
that there will be sealing capabilities at low pressure.
American Seal & Packing stocks Center Ring and Flat Back WV packings in
homogenous Buna 90 Durometer and fabric reinforced Buna.
WV Packing Installation Data
Since WV packings are designed to be free floating, it is not recommended that
the rings be installed in a compressed state. Thus should be between .014"
and .060" of area in the gland depth so that the rings are allowed to float.
The amount of this free floating is determined by the ring cross section and
the number of rings being installed. (See chart below).
For designs of medium to high pressure, it is recommended that fabric
reinforced o-rings be utilized. The adjacent table is a guide to pressure
rating of multiple rings. A homogeneous o-ring may be also used for sealing at
low pressure. The homogeneous o-ring should not be included in calculating
Piston Cups are primarily used on piston heads, plungers or rams in hydraulic
or pneumatic service. Its mechanical sealing surface is at its periphery.
Piston Cups are commonly used because of economical cost, excellent service
life, efficient assemble, universal acceptance, and simple accessories.
Homogeneous Piston Cups are recommended to handle low pressures (under 150 psi)
in air, water, hydraulic fluids, and lubricating oils. Homogeneous Piston
Cups stocked by American Seal & Packing are 80 Durometer Nitrile. They are
also available in other homogeneous materials such as EPR, fluorelastomer, and
Fabric reinforced Piston Cups prevent extrusion in medium pressure
installations (up to 1000 psi) or where diametrical clearances are greater.
Piston Cup Installation Data
Figure 1 shows a Piston Cups packing (P) attached directly to a ram ® without
the use of a separate backing plate.
This is a proper method, as long as the rules of good design are observed.
The cylinder should be correctly finished to close tolerances and the ram of a
size and material that can be finished to leave only a minimum working
clearance between it and the cylinder wall. The cylinder and ram must be of
suitable material so that no scoring of the cylinder will take place.
Due to the nature of the work being done by a ram of this type, wear is
inevitable and usually occurs to a great extent on one side. When this wear
has progressed to a certain degree, the Piston Cup packing will not be
To insure lip contact, Piston Cups generally are designed with the heel
.010"-.015" under nominal O.D., and the lip diameter is .020"-.030" over
nominal O.D. This insures heel clearance and full lip contact.
Heel clearance is needed so full pressure is not carried by this narrow area,
or it wears excessively. Clearance between the piston and cylinder wall must
be minimized to prevent extrusion at the cup's heel.
The seal between the bottom of the cup and the piston head is a compression
seal, created by bolting or otherwise fastening the cup between the piston
head (or backing plate) and follower plate. Do not over-tighten the follower
nut especially when using homogenous Piston Cups. Over-tightening will cause
heel to extrude cause premature failure.
Piston Cup packings are installed with the sealing lips toward the pressure
medium, thus the mechanical seals between the piston and the cylinder wall for
which the cup is designed is created by the pressure applied against the cup.
In the dynamic seal area indicated in Figure 2, make sure there is enough
compression, with no gaps, to insure a seal. It is also important to be sure
that the heel of the Piston Cup is thick enough to create compression between
the areas of B and C.
Figure 2 illustrates two Piston Cup packings (A and A) which are installed
back to back against a common backing plate C in a double-acting cylinder. B
serves as the follower plate to compress the static seal. A good solid plate
is provided which is a piston head. Packings should not be installed without
a backing plate between them.