28774 Series Split Back-up Ring
The 28774 PTFE back-up rings are proven components used for sealing both low and high pressure systems. Any system pushing the pressure limits on an elastomer seal, 28774 back-up rings are an inexpensive option to increase seal pressure capabilities or increase radial extrusion gaps behind the seal.
The 28774 back-up rings come standard in T-LON® 01 (Virgin PTFE) but can be made from any filled T-LON® PTFE compound or plastic/metal to increase the pressure capabilities.
Consider 28774 back-up rings with elastomer o-rings under the following conditions:
- Pressure above 1000psi (7MPa)
- Radial Extrusion gap >.005″ (.13mm)
- High Reciprocating Stroke Frequency
- High Temperatures
- Medium with Contamination
- Pressure Shock Loads (Fast Pressure Changes)
Advantages:
- Inexpensive option
- Easy to install
- Increase pressure rating of standard o-rings
- Available for cylinders up to 45″ diameter
Applications:
- Mobile Hydraulic Cylinders
- Pneumatic Piston Cylinders
- Agriculture Equipment
- Hydraulic Valves and Pumps
- Filling Machines
- Testing Machinery
- Any sealing application
Technical Data for PTFE compounds:
(1) Temperature Range: -400° to 500°F
(2) T-LON® seal compound determines allowable pressure
- Pressure: Up to 5800 psi (Function of e-gap and T-LON compound)
- Surface Speed: Up to 6 ft/s
Most Common:
Virgin PTFE (“01”)
- Most cost effective
- Most flexible for fitting into tight areas
BRONZE FILLED PTFE (21” OR 22”)
- Higher Extrusion Resistance of PTFE Compounds (Higher bronze content increases extrusion/wear resistance; I.E. larger e-gap allowable)
- Low abrasion characteristics
Also Available for Extreme Pressures of 10,000 psi and above:
PEEK Compounds (“91” or “92”)
Polyamide Compounds (“1N” or “6N”) ACETAL (“1D”)
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