Where is a cup seal used?

Hi-Tech Seals recommends contacting a representative when designing a new application, to ease the selection process. The Seal Application Data Sheet assists with communicating the needs of an application with a Hi-Tech Seals' representative. Eng. | Fr.

U-Cup Selection Criteria Hi-Tech Seals offers an extensive selection of U-cup designs. When selecting the proper U-cup for an application, many design elements and general guidelines must be considered. Using these criteria throughout the selection process will ensure the desired sealing requirements of the application will be met, i.e. resistance to wear and extrusion gap, resistance to high and low temperature, etc. Listed below are general guidelines and design elements to consider during the selection process.

1. Fluid Media - Chemical Compatiblity Look Up
The chemical compatibility guide offers the ability to view over 2000 chemical and their compatibility to a variety of materials.
2. Service Materials
The minimum and maximum service temperature of a seal and fluids will further determine which material and seal type are suitable.
 Material

Temperature

Advantages

 Nitrile

-40°C/-40°F

to

120°C/248°F

 - Exceptional balance of good mechanical, wear resistance,
   and reasonable resilience  Low Temp. Nitrile

-54°C/-65°F

to

116°C/241°F

 - Increased low temperature capabilities  Fluorocarbon

-26°C/-15°F

to

204°C/400°F

 - Resistant to high temperatures
 - Wide range of chemical resistance
 - Very good ozone, weather and aging resistance  Urethane

-54°C/-65OF

to

105°C/221°F

 - High tensile strength, toughness and wear resistance
 - Good combination of hardness and elasticity  Hytrel®

-54°C/-65°F

to

149°C/300°F

 - Excellent strength and toughness properties  Ethylene Propylene

-54°C/-65°F

to

150°C/302°F

 - Excellent resistance to ozone, hot water, steam & aging Hydrogenated Nitrile

-40OC/-40°F

to

160°C/320°F

 - Good extrusion, abrasion and wear resistance
 - Improved chemical resistance  Chloroprene

-40°C/-40°F

to

121°C/250°F

 - Exceptional ozone and weather resistance
 - Mechanical properties retained over a wide temp. range  Virgin PTFE

-268°C/-450°F

to

250°C/482°F

 - Virtually universal chemical resistance  15% Glass filled PTFE

-268°C/-450°F

to

250°C/482°F

 - Increased compression and tensile strength
 - Increased wear resistance
 - Increased cold flow resistance  40% Bronze filled PTFE

-268°C/-450°F

to

250°C/482°F

 - Increased hardness
 - Decreased friction  25% Carbon Graphite Filled PTFE

-268°C/-450°F

to

250°C/482°F

 - Increased hardness
 - Increased wear resistance
 - Decreased friction

*The material information listed above is based on multiple references sources accept by industry. This information is Hi-Tech Seals Inc. accepted standards.

 

3. System Pressure

The ability of a seal material to withstand pressure varies depending on the compound. The figure below displays the maximum operating rating recommended for standard sealing compounds. The maximum pressure, and extrusion gap, will determine the risk of seal extrusion failure in an application.

*A = 70 Durometer Nitrile, Fluorocarbon, Ethylene Propylene
  B = 80 Durometer Nitrile, Fluorocarbon, Ethylene Propylene
  C = 90 Durometer Nitrile, Fluorocarbon, Ethylene Propylene
  D = Virgin PTFE
  E = 15% Glass Filled PTFE
  F = 40% Bronze Filled PTFE
  G = Polyurethane
  H = Hytrel


Note: The pressure ratings are based on a test temperature of 70°C/160°F. Tests were conducted without the use of a back up device and without reduced clearance gaps.

4. General Hardware Design Guidelines

For ease of assembly and to avoid damage to a seal during assembly, Hi-Tech Seals recommends that hardware follow the leading edge chamfers and dimensions guidelines shown below.

Installation Chamfer,
Gland Radius & Taper

Seal
C/S

�A�
Dimension

�R�
Dimension

1/8

0.050

0.015

3/16

0.080

0.015

1/4

0.080

0.015

5/16

0.085

0.015

3/8

0.090

0.015

1/2

0.120

0.030

5/8

0.145

0.040

3/4

0.170

0.040

1

0.225

0.080

5. Leakage & Lip Squeeze




6. Performance Criteria


7. Retrofit and Gland Size

Many U-cup designs are built to fit existing gland designs. Much consideration should be taken to select the U-cup design that will fit the existing gland or the new gland specification.

8. Installation

Some seal types are easily installed, while others are more difficult. Installation methods vary depending on a seal's profile, size, material, and the application where it is being installed. Certain design factors need to be taken into consideration, as to protect the seal during installation. To learn more, contact a Hi-Tech Seals' representative.

9. Seal Life Expectancy

A seal's life expectancy varies depending on seal type and material. Its performance depends on several factors including duty cycle, stroke, speed, pressure, surface finish, and fluid type. Each material is assigned a specific PV (pressure/velocity) values to create a theoretical guideline. In general, products that last longer will have a greater cost.

10. Price and Availability

The ideal U-cup will be a cost-effective solution for the end user.

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