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Hydraulic Wiper Seal Guide: Profiles, Materials, Sizing, and RFQ Data
Quick Answer: A hydraulic wiper seal is mounted in the cylinder head to scrape dirt, dust, moisture and metal particles from the piston rod before the rod seal contacts the rod. CORASEALS supplies hydraulic wiper seals in standard and custom profiles with materials such as polyurethane, NBR, FKM, HNBR and PTFE. Send the rod diameter, bore diameter, groove dimensions, pressure, speed, hydraulic fluid and seal profile for a quotation.
What a Hydraulic Wiper Seal Does
Hydraulic cylinders operate in dirty environments. The piston rod retracts into the cylinder after every stroke. Dirt, sand, ice, dust, water and metal chips stick to the rod surface. The wiper seal scrapes these contaminants off the rod. That scraping action protects the rod seal from scoring. The wiper seal also protects the hydraulic oil from solid contamination. A wiper seal is not a rod seal. A rod seal keeps hydraulic oil inside the cylinder. A wiper seal keeps external material outside.
Common Hydraulic Wiper Seal Profiles
Hydraulic wiper seals are available in several profiles. The profile controls how the seal fits in the cylinder head and how the lip contacts the rod.
- Snap-in wiper seal with an outer retention body for easy groove mounting
- Metal-cased wiper seal for heavy contamination and strong press fit retention
- Double-lip wiper seal with a primary scraping lip and a secondary oil control lip
- Wiper seal with an energizer ring for low temperature or low interference conditions
Catalog codes such as W, AN, WS and similar codes may differ between suppliers. Do not assume full interchangeability from a code alone. Compare the section drawing, rod diameter, bore diameter, width and material before ordering. CORASEALS can review the existing seal drawing or photo.
Material Selection for Hydraulic Wiper Seals
Material selection depends on hydraulic fluid, rod speed, temperature and external contamination. Polyurethane is a common wiper seal material because polyurethane resists abrasion and extrusion. NBR suits many standard mineral oil systems. FKM handles elevated temperatures and aggressive fluids. HNBR offers improved wear and temperature resistance compared with NBR. PTFE based wiper seals work in high sliding speed and low friction applications. Verify the compound with the supplier before changing materials.
| Material | Common Advantage | Main Limitation |
|---|---|---|
| Polyurethane (TPU) | High abrasion resistance, good extrusion resistance | May degrade in hot water or certain esters |
| NBR | Good oil resistance, lower cost | Limited ozone and weather resistance |
| FKM | High temperature and chemical resistance | Not always suitable for low temperature |
| HNBR | Better wear and temperature range than NBR | Higher cost than NBR |
| PTFE | Low friction, broad chemical resistance | Less elastic, may require housing design changes |
Hydraulic Wiper Seal Dimensions and Sizing
To measure a hydraulic wiper seal, record the rod diameter. Measure the bore diameter in the cylinder head where the wiper seal seats. Measure the groove width and groove depth. If the old seal is available, measure the outside diameter and the lip opening. Record the seal profile and installation direction. A drawing or photo helps avoid profile confusion.
Many catalogs describe hydraulic wiper seals by rod diameter × bore diameter × width. Check the catalog drawing because dimension order may change. Groove dimensions are just as important as seal dimensions. A correct seal can fail if the groove is too wide, too narrow or too shallow.