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Phosphoric Acid Chemical Resistance

Resistance ratings for 24 plastics, elastomers and metals at 20 °C and 50 °C. Listed at 4 concentrations, because the rating depends on it.

At a glance

Based on the row for 85 %, 20 °C.

Rated A, very good resistance
PTFE, HDPE, PP, PVDF, PVC Rigid, Viton (FPM), SS 316, LDPE, FEP, ECTFE/ETFE, Polycarbonate, PVC Flexible, Polystyrene, Polysulfone, PMP, SAN (16)
Rated B, good resistance
SS 304 (1)
Rated C, limited resistance
EPDM (1)
Rated D, not resistant
NBR, Aluminium, Nylon (PA), Acetal (POM) (4)
No data in the source
Silicone, PETG
Rated lower at 50 °C than at 20 °C
PP (A → B), PVC Rigid (A → B), SS 316 (A → C), SS 304 (B → D), Polycarbonate (A → B), Polystyrene (A → B), PMP (A → B), SAN (A → B)
Rating changes with concentration (20 °C)
EPDM: A (1-5 %), C (85 %); NBR: B (1-5 %), D (85 %); SS 304: A (1-5 %), B (85 %); Nylon (PA): C (1-5 %), D (20 %); Acetal (POM): C (1-5 %), D (20 %); Polycarbonate: A (1-5 %), B (20 %); Polystyrene: A (30 %), B (1-5 %)

Based on the row for 85 %, 20 °C.

Rating profile by material family

Phosphoric Acid: Rating profile by material familyThermoplastics: 10 A, 2 D, 1 no data. Fluoropolymers: 4 A. Elastomers: 1 A, 1 C, 1 D, 1 no data. Metals: 1 A, 1 B, 1 D.Thermoplastics (13)Thermoplastics: 10 × A, very good resistance (HDPE, LDPE, PP, PVC Rigid, PVC Flexible, PMP, Polystyrene, SAN, Polycarbonate, Polysulfone)A 10Thermoplastics: 2 × D, not resistant (Acetal (POM), Nylon (PA))D 2Thermoplastics: 1 × no data (PETG)Fluoropolymers (4)Fluoropolymers: 4 × A, very good resistance (PTFE, FEP, PVDF, ECTFE/ETFE)A 4Elastomers (4)Elastomers: 1 × A, very good resistance (Viton (FPM))A 1Elastomers: 1 × C, limited resistance (EPDM)C 1Elastomers: 1 × D, not resistant (NBR)D 1Elastomers: 1 × no data (Silicone)– 1Metals (3)Metals: 1 × A, very good resistance (SS 316)A 1Metals: 1 × B, good resistance (SS 304)B 1Metals: 1 × D, not resistant (Aluminium)D 1
A very good resistanceB good resistanceC limited resistanceD not resistantno data
Number of materials in each family with each rating at 20 °C.

Effect of temperature, 20 °C to 50 °C

Phosphoric Acid: Effect of temperature, 20 °C to 50 °CPP A → B; PVC Rigid A → B; PMP A → B; Polystyrene A → B; SAN A → B; Polycarbonate A → B; SS 316 A → C; SS 304 B → D.ABCDPP: A at 20 °C, B at 50 °CPPPVC Rigid: A at 20 °C, B at 50 °CPVC RigidPMP: A at 20 °C, B at 50 °CPMPPolystyrene: A at 20 °C, B at 50 °CPolystyreneSAN: A at 20 °C, B at 50 °CSANPolycarbonate: A at 20 °C, B at 50 °CPolycarbonateSS 316: A at 20 °C, C at 50 °CSS 316SS 304: B at 20 °C, D at 50 °CSS 304
20 °C50 °C
Materials whose rating differs between 20 °C and 50 °C. Materials not shown keep their rating or have no 50 °C value.

Substance

CAS number
7664-38-2
Formula
H3PO4
Hazard symbols in the source
C (corrosive) (pre-GHS European symbols; check the current safety data sheet)
Concentrations listed
1-5 %; 20 %; 30 %; 85 %
Also listed as
Orthophosphoric acid
Name in the source (German)
Phosphorsäure

Rating by concentration

Phosphoric Acid: Rating by concentrationHDPE: 1-5 % A, 20 % A, 30 % A, 85 % A. LDPE: 1-5 % A, 20 % A, 30 % A, 85 % A. PP: 1-5 % A, 20 % A, 30 % A, 85 % A→B. PVC Rigid: 1-5 % A, 20 % –, 30 % –, 85 % A→B. PVC Flexible: 1-5 % –, 20 % –, 30 % –, 85 % A. PMP: 1-5 % A, 20 % –, 30 % –, 85 % A→B. Polystyrene: 1-5 % B, 20 % –, 30 % A, 85 % A→B. SAN: 1-5 % A, 20 % –, 30 % A, 85 % A→B. Polycarbonate: 1-5 % A, 20 % B*, 30 % A, 85 % A→B. PETG: 1-5 % A, 20 % –, 30 % –, 85 % –. Acetal (POM): 1-5 % C→D, 20 % D, 30 % D, 85 % D. Nylon (PA): 1-5 % C*, 20 % D, 30 % D, 85 % D. Polysulfone: 1-5 % A, 20 % –, 30 % –, 85 % A. PTFE: 1-5 % A, 20 % A, 30 % A, 85 % A. FEP: 1-5 % A, 20 % A, 30 % A, 85 % A. PVDF: 1-5 % A, 20 % A, 30 % A, 85 % A. ECTFE/ETFE: 1-5 % A, 20 % –, 30 % –, 85 % A. EPDM: 1-5 % A, 20 % A, 30 % A, 85 % C. Viton (FPM): 1-5 % A, 20 % A, 30 % A, 85 % A. NBR: 1-5 % B→C, 20 % C, 30 % C, 85 % D. SS 316: 1-5 % A, 20 % A→B, 30 % A→B, 85 % A→C. SS 304: 1-5 % A, 20 % A→C, 30 % A→C, 85 % B→D. Aluminium: 1-5 % D*, 20 % D, 30 % D, 85 % D.1-5 %20 %30 %85 %THERMOPLASTICSHDPEHDPE, 1-5 %: A at 20 °C, A at 50 °CAHDPE, 20 %: A at 20 °C, A at 50 °CAHDPE, 30 %: A at 20 °C, A at 50 °CAHDPE, 85 %: A at 20 °C, A at 50 °CALDPELDPE, 1-5 %: A at 20 °C, A at 50 °CALDPE, 20 %: A at 20 °C, A at 50 °CALDPE, 30 %: A at 20 °C, A at 50 °CALDPE, 85 %: A at 20 °C, A at 50 °CAPPPP, 1-5 %: A at 20 °C, A at 50 °CAPP, 20 %: A at 20 °C, A at 50 °CAPP, 30 %: A at 20 °C, A at 50 °CAPP, 85 %: A at 20 °C, B at 50 °CA→BPVC RigidPVC Rigid, 1-5 %: A at 20 °C, A at 50 °CAPVC Rigid, 20 %: no data–PVC Rigid, 30 %: no data–PVC Rigid, 85 %: A at 20 °C, B at 50 °CA→BPVC FlexiblePVC Flexible, 1-5 %: no data–PVC Flexible, 20 %: no data–PVC Flexible, 30 %: no data–PVC Flexible, 85 %: A at 20 °C, A at 50 °CAPMPPMP, 1-5 %: A at 20 °C, A at 50 °CAPMP, 20 %: no data–PMP, 30 %: no data–PMP, 85 %: A at 20 °C, B at 50 °CA→BPolystyrenePolystyrene, 1-5 %: B at 20 °C, B at 50 °CBPolystyrene, 20 %: no data–Polystyrene, 30 %: A at 20 °C, A at 50 °CAPolystyrene, 85 %: A at 20 °C, B at 50 °CA→BSANSAN, 1-5 %: A at 20 °C, A at 50 °CASAN, 20 %: no data–SAN, 30 %: A at 20 °C, A at 50 °CASAN, 85 %: A at 20 °C, B at 50 °CA→BPolycarbonatePolycarbonate, 1-5 %: A at 20 °C, A at 50 °CAPolycarbonate, 20 %: B at 20 °C (estimate)B*Polycarbonate, 30 %: A at 20 °CAPolycarbonate, 85 %: A at 20 °C, B at 50 °CA→BPETGPETG, 1-5 %: A at 20 °CAPETG, 20 %: no data–PETG, 30 %: no data–PETG, 85 %: no data–Acetal (POM)Acetal (POM), 1-5 %: C at 20 °C, D at 50 °CC→DAcetal (POM), 20 %: D at 20 °C, D at 50 °CDAcetal (POM), 30 %: D at 20 °C, D at 50 °CDAcetal (POM), 85 %: D at 20 °C, D at 50 °CDNylon (PA)Nylon (PA), 1-5 %: C at 20 °C (estimate)C*Nylon (PA), 20 %: D at 20 °C, D at 50 °CDNylon (PA), 30 %: D at 20 °C, D at 50 °CDNylon (PA), 85 %: D at 20 °C, D at 50 °CDPolysulfonePolysulfone, 1-5 %: A at 20 °C, A at 50 °CAPolysulfone, 20 %: no data–Polysulfone, 30 %: no data–Polysulfone, 85 %: A at 20 °C, A at 50 °CAFLUOROPOLYMERSPTFEPTFE, 1-5 %: A at 20 °C, A at 50 °CAPTFE, 20 %: A at 20 °C, A at 50 °CAPTFE, 30 %: A at 20 °C, A at 50 °CAPTFE, 85 %: A at 20 °C, A at 50 °CAFEPFEP, 1-5 %: A at 20 °C, A at 50 °CAFEP, 20 %: A at 20 °C, A at 50 °CAFEP, 30 %: A at 20 °C, A at 50 °CAFEP, 85 %: A at 20 °C, A at 50 °CAPVDFPVDF, 1-5 %: A at 20 °C, A at 50 °CAPVDF, 20 %: A at 20 °C, A at 50 °CAPVDF, 30 %: A at 20 °C, A at 50 °CAPVDF, 85 %: A at 20 °C, A at 50 °CAECTFE/ETFEECTFE/ETFE, 1-5 %: A at 20 °C, A at 50 °CAECTFE/ETFE, 20 %: no data–ECTFE/ETFE, 30 %: no data–ECTFE/ETFE, 85 %: A at 20 °C, A at 50 °CAELASTOMERSEPDMEPDM, 1-5 %: A at 20 °CAEPDM, 20 %: A at 20 °CAEPDM, 30 %: A at 20 °CAEPDM, 85 %: C at 20 °CCViton (FPM)Viton (FPM), 1-5 %: A at 20 °C, A at 50 °CAViton (FPM), 20 %: A at 20 °C, A at 50 °CAViton (FPM), 30 %: A at 20 °C, A at 50 °CAViton (FPM), 85 %: A at 20 °C, A at 50 °CANBRNBR, 1-5 %: B at 20 °C, C at 50 °CB→CNBR, 20 %: C at 20 °C, C at 50 °CCNBR, 30 %: C at 20 °C, C at 50 °CCNBR, 85 %: D at 20 °C, D at 50 °CDMETALSSS 316SS 316, 1-5 %: A at 20 °C, A at 50 °CASS 316, 20 %: A at 20 °C, B at 50 °CA→BSS 316, 30 %: A at 20 °C, B at 50 °CA→BSS 316, 85 %: A at 20 °C, C at 50 °CA→CSS 304SS 304, 1-5 %: A at 20 °C, A at 50 °CASS 304, 20 %: A at 20 °C, C at 50 °CA→CSS 304, 30 %: A at 20 °C, C at 50 °CA→CSS 304, 85 %: B at 20 °C, D at 50 °CB→DAluminiumAluminium, 1-5 %: D at 20 °C (estimate)D*Aluminium, 20 %: D at 20 °C, D at 50 °CDAluminium, 30 %: D at 20 °C, D at 50 °CDAluminium, 85 %: D at 20 °C, D at 50 °CD
A very good resistanceB good resistanceC limited resistanceD not resistantno data
Each cell shows the rating at 20 °C. Where the rating at 50 °C differs, it follows the arrow. * marks an estimate in the source.
Show as a table
Material1-5 %20 %30 %85 %
Thermoplastics
HDPEAAAA
LDPEAAAA
PPAAAA
PVC RigidA––A
PVC Flexible–––A
PMPA––A
PolystyreneB–AA
SANA–AA
PolycarbonateAB*AA
PETGA–––
Acetal (POM)CDDD
Nylon (PA)C*DDD
PolysulfoneA––A
Fluoropolymers
PTFEAAAA
FEPAAAA
PVDFAAAA
ECTFE/ETFEA––A
Elastomers
EPDMAAAC
Viton (FPM)AAAA
NBRBCCD
Silicone––––
Metals
SS 316AAAA
SS 304AAAB
AluminiumD*DDD

* estimated rating, given in the source without a temperature

Resistance table: Phosphoric Acid, 1-5 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PVC RigidAA
PMPAA
PolystyreneBB
SANAA
PolycarbonateAA
PETGA–
Acetal (POM)CD
Nylon (PA)C*–
PolysulfoneAA
Fluoropolymers
PTFEAA
FEPAA
PVDFAA
ECTFE/ETFEAA
Elastomers
EPDMA–
Viton (FPM)AA
NBRBC
Metals
SS 316AA
SS 304AA
AluminiumD*–

* estimated rating, given in the source without a temperature

Not rated in the source, so not in the table: PVC Flexible, Silicone

Resistance table: Phosphoric Acid, 20 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PolycarbonateB*–
Acetal (POM)DD
Nylon (PA)DD
Fluoropolymers
PTFEAA
FEPAA
PVDFAA
Elastomers
EPDMA–
Viton (FPM)AA
NBRCC
Metals
SS 316AB
SS 304AC
AluminiumDD

* estimated rating, given in the source without a temperature

Not rated in the source, so not in the table: PVC Rigid, PVC Flexible, PMP, Polystyrene, SAN, PETG, Polysulfone, ECTFE/ETFE, Silicone

Resistance table: Phosphoric Acid, 30 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PolystyreneAA
SANAA
PolycarbonateA–
Acetal (POM)DD
Nylon (PA)DD
Fluoropolymers
PTFEAA
FEPAA
PVDFAA
Elastomers
EPDMA–
Viton (FPM)AA
NBRCC
Metals
SS 316AB
SS 304AC
AluminiumDD

Not rated in the source, so not in the table: PVC Rigid, PVC Flexible, PMP, PETG, Polysulfone, ECTFE/ETFE, Silicone

Resistance table: Phosphoric Acid, 85 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAB
PVC RigidAB
PVC FlexibleAA
PMPAB
PolystyreneAB
SANAB
PolycarbonateAB
Acetal (POM)DD
Nylon (PA)DD
PolysulfoneAA
Fluoropolymers
PTFEAA
FEPAA
PVDFAA
ECTFE/ETFEAA
Elastomers
EPDMC–
Viton (FPM)AA
NBRDD
Metals
SS 316AC
SS 304BD
AluminiumDD

Not rated in the source, so not in the table: PETG, Silicone

Rating scale

A rating marked * is an estimate in the source, not a test result. An estimate is given as one value without a temperature.

Frequently Asked Questions

Which materials resist Phosphoric Acid at high concentrations?

The materials with an A rating (resistant) for Phosphoric Acid at 20 °C are: PTFE, HDPE, PP, PVDF, PVC Rigid, Viton (FPM), SS 316, LDPE. These can generally be used in direct contact.

Which materials should be avoided with Phosphoric Acid?

Materials rated D (not resistant) for Phosphoric Acid are: NBR, Aluminium, Nylon (PA), Acetal (POM). These should not be used in contact with Phosphoric Acid.

Does temperature affect chemical resistance to Phosphoric Acid?

Yes. 8 of 21 tested materials show a worse rating at 50 °C than at 20 °C for Phosphoric Acid. Materials affected include: PP, PVC Rigid, SS 316, SS 304, Polycarbonate, Polystyrene.

Is PTFE safe for Phosphoric Acid?

PTFE is rated A for Phosphoric Acid at 20 °C. A rating of A means resistant, B means limited resistance, C means partly resistant, and D means not resistant.

Does concentration affect chemical resistance to Phosphoric Acid?

Yes. Phosphoric Acid is tested at 4 concentrations (1-5 %, 20 %, 30 %, 85 %). Some materials change their rating depending on the concentration.

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.

Chemicals with a similar resistance profile

Same 20 °C rating on the share of materials shown.

Hydrogen Peroxide 90 %Fluorosilicic Acid 88 %Ferrous Chloride (Iron(II) Chloride) 82 %Oxalic Acid 82 %Tartaric Acid 82 %Battery Acid 81 %