There are several types of hydraulic seals, including:
- Piston seals, Rod seals, Wipers/scrapers, Buffer/backup rings, Rotary seals, Step seals, U-cups, V-rings, O-rings, and Gaskets.
Each type serves a specific function within the hydraulic system and is chosen based on application requirements such as pressure, temperature, speed, and fluid compatibility.
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.
Types Hydraulic Seals 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.
- emperature: -65˚F to +300˚F
- Pressure: 0 to 5000 psi
- Fluids: Petroleum based Hydraulic Fluids
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 Rod Seal.
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 Seals-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 Seals-Deep Style.
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 From Rolling.
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 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 From 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 Resistance.
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 Pressure Rating.
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 Properly Supported. 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.
What is a Hydraulic seal?
A hydraulic seal is a mechanical component that provides a fluid-tight barrier between two moving parts in a hydraulic system. It helps to prevent leakage of fluid, maintain pressure, and prevent contamination of the fluid. The seal type can be any of the above seals, lip seals, o-rings, V-packing or gasket.