Packing Division
Product
Double-Acting Piston Seal Bulletin
OK Profile
No. 5206B1-USA
OK Profile Piston Seal is
for medium to heavy-duty
double-acting hydraulic
piston seal applications
OK Profile Applications
Designed for higher temperatures and pressures, the OK
Packing Division
Piston Seal is recommended for heavy-duty hydraulic
applications. The OK sealing assembly is suitable for
working pressures up to 7250 PSI (500 bar) and
above in some specific situations. The OK Profile is an
effective and less expensive alternative to costly
capped T-Seals and PTFE loaded cap seals. Compound formulated to extend seal life
The cylinder seal ring is produced of W4650, a glass
Advantages reinforced nylon. The tensile strength and flexibility exhib-
• Lower installation costs ited by W4650 provides maximum stretch during installa-
• Extended seal life tion. Other beneficial characteristics of this material include
• High extrusion resistance at high pressures the ability to capture and contain system contaminants
and large gaps due to the special compound such as metal chips, excellent compressive strength and
properties of the cylinder sealing ring the ability to resist extrusion or chipping when passing over
• Resistant to high shock loads cylinder ports. (See W4650 Physical Properties Table)
• Low break-out and running friction even after
lengthy stand-still under high pressures Expander Ring
• High abrasion resistance This is an NBR-based elastomer with 70 shore A
• Premium static and dynamic sealing function hardness. The rubber expander ring provides good
• Small profile compression set resistance which in turn increases
• Suitable housing according to ISO7425 -2 potential seal life.
• Passes over ports without nibbling or
extruding
Contact Parker for More Information
For special requirements (pressure, temperature, speed
Field of application etc.) please contact our technical services personnel ,
Working pressure: 7250 psi (500 bar) so that suitable materials and/or designs can be
Working temperature: -40° F to 250° F recommended.
Surface speed: 3.28 f/s (1 m/s)
Ease of Installation W4650 Physical Properties
This durable two-piece seal is designed to be com-
Physical Property ASTM Test Method Values
pressed in the bore upon installation to minimize
seepage at the gap. The OK piston seal’s split design Tensile Strength D-638 17,000-23,000 PSI
facilitates its installation on solid pistons without the Compressive Strength D-695 21,000-28,000 PSI
necessity of auxiliary tools. The OK Profile can be Flexural Strength D-790 23,000-30,000 PSI
Water Absorption D-570 .50-.70%
snapped into closed-groove spaces. Note: The Elongation D-638 3-10%
installation groove must be carefully deburred and Tensile Modulus D-638 900,000 PSI
cleaned of all foreign material. The cylinder bore must Shear Strength D-732 10,000-12,000 PSI
have a leading edge chamfer. Flexural Modulus D-790 870,000-1,000,000
Hardness, Rockwell D-785 119-121 R 94-96 M
Deformation Under Load D-621 .2-.4%
(2000 PSI @ 122° F)
Copyright © 1998, Parker Hannifin Corporation, Cleveland, OH. All Rights Reserved
Parker Hannifin Corporation
Packing Division
Salt Lake City, UT 84119 Build With The Best!
Phone: 801-972-3000
Fax: 801-972-6663
OK Piston Seal
Available Sizes
A B C D
Part Number Bore Diameter Piston Diameter Groove Diameter Width
OK26902000-282A 2.000/2.005 1.970/1.975 1.457/1.462 0.282/.287
OK26902500-312A 2.500/2.505 2.470/2.475 1.957/1.962 0.312/0.317
OK27903000-312A 3.000/3.005 2.970/2.975 2.437/2.442 0.312/0.317
OK27903250-312A 3.250/3.255 3.220/3.225 2.687/2.692 0.312/0.317
OK27903500-282A 3.500/3.505 3.470/3.475 2.937/2.942 0.282/0.287
OK27903500-312A 3.500/3.505 3.470/3.475 2.937/2.942 0.312/0.317
OK27904000-282A 4.000/4.005 3.970/3.975 3.437/3.442 0.282/0.287
OK27904500-282A 4.500/4.505 4.470/4.475 3.937/3.942 0.282/0.287
OK27905000-282A 5.000/5.005 4.970/4.975 4.437/4.442 0.282/0.287
OK29303543-492A 3.543/3.550 3.510/3.514 2.954/2.958 0.492/0.502
OK29904000-315A 4.000/4.005 3.970/3.975 3.398/3.402 0.315/0.319
OK38005500-377A 5.500/5.505 5.470/5.475 4.735/4.740 0.377/0.382
OK38006000-377A 6.000/6.005 5.970/5.975 5.235/5.240 0.377/0.382
OK38007000-377A 7.000/7.005 6.970/6.975 6.235/6.240 0.377/0.382
OK38008000-377A 8.000/8.005 7.970/7.975 7.235/7.240 0.377/0.382
Warning ! – Failure, improper selection or improper use of the products and/or systems described herein or related items can cause death, personal
injury or property damage. This document and other information from Parker Hannifin Corporation, its subsidiaries and authorized distributors provide
product and/or system options for further investigation by users having technical expertise. It is important that you analyze all aspects of your applica-
tion and review the information concerning the product or system in the current product catalog. Due to the variety of operating conditions and
applications for these products or systems, the user, through his own analysis and testing is solely responsible for making the final selection of the
products and systems and assuring that all performance, safety and warning requirements of the application are met.
Parker Hannifin Corporation
Packing Division
Salt Lake City, UT 84119 Build With The Best!
Phone: 801-972-3000
Fax: 801-972-6663
