VITON or EPDM? How to pick the seal that survives your chemical
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VITON (FKM) seals resist acids and petroleum solvents. EPDM seals resist bleach, chlorine and caustics. They are close to opposites, and picking the wrong one is the single most common reason a professional sprayer leaks, perishes or fails early. Here is how to get it right the first time.
The rule of thumb
| Seal | Use it for | Keep it away from |
|---|---|---|
| VITON (FKM) | Acids, descalers, petroleum solvents, brake cleaner, concrete sealers | Acetone and other ketones |
| EPDM | Bleach and chlorine, caustics, alkaline degreasers | Acids, petroleum solvents |
| NBR (nitrile) | Water based, non corrosive liquids | Aggressive acids, solvents and bleach |
Why the wrong seal fails
The tank rarely fails. The O-rings and gaskets do. An incompatible chemical makes the seal swell, harden or crack, and then the sprayer loses pressure, drips from the pump, or leaks chemical onto the operator. With aggressive chemicals that can happen in weeks. The seal material is a fraction of the unit's cost, which is why we always start with the chemical, not the sprayer.
The acetone trap
Acetone is a solvent, so most people reach for a solvent-rated VITON unit. That is the classic mistake. Acetone and other ketones such as MEK attack VITON. EPDM handles ketones better in general, but Klager's current resistance list does not recommend any standard sprayer for pure acetone, EPDM included, so for acetone or MEK ask us which model fits your product. For solvent and acetone mixes, ask us about the Klager MASTER SOLVE+, which is built for that job.
What about bleach?
EPDM is the manufacturer's rule for bleach, chlorine and caustics, and our alkaline resistant (EPDM) sprayers are rated up to 12.5% available chlorine. Klager and Gloria also make models rated for bleach, where the whole build is specified for hypochlorite, not just the O ring. The short version: use an EPDM unit or a model rated for bleach, and confirm the concentration against the SDS.
How strong an acid can you spray?
The acid resistant sprayer is rated for hydrochloric and sulphuric acid up to 10 per cent, and for phosphoric and citric acid up to 30 per cent. Sources differ above 10 per cent hydrochloric and sulphuric, and for nitric and acetic acid, so ask us to confirm the model. Hydrofluoric acid is always ask us. If your acid is stronger or hot, talk to us before you buy, and see the full strength limits in the Chemical Compatibility Guide.
Re-seal, do not replace
If your sprayer is already leaking, the fix is usually a genuine seal kit, not a new unit. We stock VITON and EPDM seal kits for Klager, Gloria and the other brands we carry, so the same tank keeps working for years.
Frequently asked questions
Which seal do I need for hydrochloric acid?
VITON. The acid resistant sprayer is rated to 10 per cent hydrochloric acid. From 10 to 25 per cent sources differ, so ask us to confirm the model. Check your concentration on the SDS.
Can one sprayer handle both acids and bleach?
Usually no. Acids want VITON and bleach wants an EPDM or bleach-rated build. Sites that run both usually keep two units, clearly labelled.
What seal does a strong degreaser need?
Most strong degreasers are caustic, so EPDM. Solvent-based degreasers want VITON. The SDS tells you which family you are in.
How do I know which seal my sprayer has?
It is on the datasheet and usually on the label. If you are not sure, send us the model and we will confirm it.
Not sure where your chemical lands? Use the Chemical Compatibility Guide, or request a quote and tell us the chemical. We will match the seal for you.