Rating
| Concentration | 20 °C | 50 °C | Remark |
|---|---|---|---|
| 1-5 % | B | C | |
| 20 % | C | C | |
| 30 % | C | C | |
| 85 % | D | D |
Material comparison at 20 °C
Resistance overview
The resistance of NBR to Phosphoric Acid is concentration-dependent. Across the 4 tested concentrations (1-5 %, 20 %, 30 %, 85 %), the 20 °C rating ranges from B at lower concentrations to D at higher ones. This means engineers must verify which concentration their process actually involves before relying on a single rating. However, at 50 °C the resistance rating drops, indicating that temperature must be factored into the design. For heated applications, additional testing under actual service conditions is strongly recommended.
Application context
Phosphoric Acid is commonly encountered in surface cleaning and metal finishing. NBR (Nitrile butadiene rubber) is an elastomer typically used for seals, O-rings, hoses and flexible connections. Because Phosphoric Acid is classified as corrosive, the choice of containment material is especially critical to prevent leaks, equipment damage, and safety hazards.
Practical recommendation
NBR is not recommended for use with Phosphoric Acid. The D rating indicates that the material will suffer rapid and severe degradation, which may include cracking, dissolution, severe swelling, or complete structural failure. Using this combination risks equipment damage, leaks, and potential safety incidents. Consider using HDPE, LDPE, Polycarbonate instead, which are rated A for this chemical and offer reliable long-term performance.
Did you know?
Temperature is often the deciding factor when selecting materials for Phosphoric Acid: even materials rated A at 20 °C may lose performance at elevated temperatures.
Materials rated A or B at 20 °C
Based on the row for 85 %, 20 °C.
- Thermoplastics
- HDPE A, PP A, PVC Rigid A, LDPE A, Polycarbonate A, PVC Flexible A, Polystyrene A, Polysulfone A, PMP A, SAN A
- Fluoropolymers
- PTFE A, PVDF A, FEP A, ECTFE/ETFE A
- Elastomers
- Viton (FPM) A
- Metals
- SS 316 A, SS 304 B
About NBR
Nitrile rubber resists mineral oils and fuels. Ketones, esters, chlorinated solvents, strong oxidisers and ozone attack it.
Rating scale
- A very good resistance
- B good resistance
- C limited resistance
- D not resistant
- – no data
- K no general statement possible
A rating marked * is an estimate in the source, not a test result. An estimate is given as one value without a temperature.
About this data
The ratings come from the chemical resistance list published by Bürkle GmbH, which compiled them from raw-material manufacturers’ data. They describe laboratory tests on the raw material at 20 °C and 50 °C.
A finished part also sees pressure, mechanical stress, welds and mixtures that a laboratory test does not. Treat the rating as a first filter and test under your own conditions before relying on it.