Gasket material

Hypalon (CSM) Gasket Material

CSM (chlorosulfonated polyethylene), long sold by DuPont as Hypalon, is a rubber sheet the Parker® O-Ring Handbook rates excellent in ozone, weather and chemical resistance. We cut it to your drawing on the waterjet.

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Family
Chlorosulfonated polyethylene (CSM)
Designations
CSM (ASTM D1418)
Product
Sheet gaskets waterjet-cut to your drawing in Orange, California

Figures are the cited maker or standards values; the sheet datasheet and your application govern the final choice.

Every common gasket sheet material is quick for us to source, and we cut it to your print on our waterjet. The other sheet materials are on the waterjet-cut gaskets page.

What CSM seals

The Parker O-Ring Handbook's comparison of elastomers rates chlorosulfonated polyethylene excellent in ozone, weather and chemical resistance, good in acid resistance and fair in oil and in water or steam [S2].

For hotter service or fuels, Viton®; for outdoor water service with no oil, EPDM.

The Hypalon name

DuPont sold chlorosulfonated polyethylene under the Hypalon name from 1951 [S3]. Sheet is still ordered by that name, and ASTM D1418 gives the polymer the symbol CSM [S1]. Either name on the drawing gets the same sheet; add the durometer and thickness.

Specifications

Hypalon (CSM) specifications

Values as published by the cited sources; [Sn] refers to the source list below
PropertyValue (in / mm, C / F as stated)Source
CompositionChlorosulfonated polyethylene; ASTM D1418 symbol CSM, in the M class[S2, S3]
Property comparisonExcellent ozone, weather and chemical resistance; good acid resistance; fair oil and water or steam resistance (the handbook's comparison of elastomers)[S2]

How we cut it

Gaskets are waterjet-cut to your drawing in Orange, California. Send a DXF, DWG or PDF with the thickness, the material or the specification callout, and the quantity. There is no die to build, so a single prototype and a repeat run go through the same setup, and a revision needs only a new file. The sheet comes from the sheet makers we buy from, to the callout on your print; the cutting is ours.

Where Hypalon (CSM) is used, and the usual alternatives

The print or the sheet datasheet governs; these are the sheets usually specified instead:

  • Neoprene: when weather resistance is wanted and the chemical exposure is mild.
  • EPDM: when the outdoor service is water or steam with no oil.
  • Viton sheet: when the joint runs hotter or carries fuel or aromatic solvents.
  • Butyl: when gas tightness matters more than chemical resistance.

Related gasket materials: Neoprene Gasket Material, EPDM Gasket Material, Viton (FKM) Gaskets, Butyl Rubber Gasket Material, Red Rubber (SBR) Gasket Material. The full index is on the gaskets hub; send the drawing through request a quote.

Frequently asked

Is Hypalon the same as CSM?

Yes. Hypalon was DuPont's name for chlorosulfonated polyethylene, whose ASTM D1418 symbol is CSM, so sheet ordered by either name is supplied as CSM.

What makes CSM different from neoprene?

The Parker handbook's comparison rates it excellent in ozone and chemical resistance, where it rates neoprene good to excellent in ozone and fair to good in chemicals.

What durometer and thickness should I ask for?

The ones on the drawing. Name them with the callout and the quote names the sheet.

Sources

  1. [S1] ASTM D1418-22, Standard Practice for Rubber and Rubber Latices, Nomenclature, public abstract (CSM in the M class), ASTM International, https://store.astm.org/d1418-22.html, accessed 2026-09-28.
  2. [S2] Parker O-Ring Handbook ORD 5700, Table 2-2, Comparison of Properties of Commonly Used Elastomers, Parker Hannifin, accessed 2026-09-28.
  3. [S3] USPTO trademark status record, HYPALON, Reg. 601793 (registrant E. I. du Pont de Nemours and Company), https://tsdr.uspto.gov/statusview/rn0601793, accessed 2026-09-29.

Viton is a trademark of The Chemours Company; Parker is a trademark of Parker Hannifin. No affiliation or endorsement is implied.

Related guides

O-Ring Chemical Compatibility GuideO-Ring Temperature Ranges by MaterialEPDM vs Fluorocarbon (FKM) O-Rings

Setting Conquest Seal up as a supplier?

Compliance documents for supplier onboardingQuality and certificationsSecond source for O-rings and sealsStocking and vendor-managed inventorySupplier requirementsVendor consolidation for O-rings, seals and gaskets

Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.

Send the Hypalon (CSM) gasket drawing and the quantity

Upload a DXF, DWG or PDF of the gasket with the quote request, or a photo of the part with a ruler if no drawing exists. Add the sheet thickness, the durometer or grade, the quantity and whether adhesive backing is wanted. Gaskets are cut in our own shop in Orange, California; a Conquest representative replies. Quotes answered within one business day. A person answers (714) 632-9830, Pacific business hours.

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