Perfluoroelastomer (FFKM, Kalrez) FFKM
Perfluoroelastomer (FFKM): a perfluorinated elastomer with more fluorine than FKM (Wikipedia). The sources read do not print its monomers or cure system.
Also known as ASTM FFKM, Kalrez® 4079
Kalrez 4079 is a perfluoroelastomer (FFKM) seal material.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Temperature
316 °C
Vacuum
0.44%
Compression set
37% at 204 °C
Strength
16.88 MPa
Recipe, share of the weight
Best for
Seals that must survive temperatures near 316 °C or aggressive chemicals, where swell and extrusion must stay low (per the Qnity datasheet and DuPont guide)
Weakest at
Low-temperature flexibility (lowest service temperature -19 °C) and compression set that rises from 37% at 204 °C to 45% at 300 °C after 70 hours on O-ring specimens
Risk at a glance
- People No data. No hazard data recorded
- If it fails High. Splitting from over-compression
- Corrosion Moderate. Compression set rises from 37% at 204 °C to 45% at 300 °C after 70 hours on O-ring specimens.
Quick facts: FFKM
| Property | Value | Basis |
|---|---|---|
| Tensile strength | 16.9 MPa | 1 sourced value |
| Maximum service temperature | 316 °C | 1 sourced value |
What is the tensile strength of Perfluoroelastomer (FFKM, Kalrez)?
Perfluoroelastomer (FFKM, Kalrez) has a tensile strength of 16.9 MPa. The source and test conditions are listed in the properties table on this page.
What is the maximum service temperature of Perfluoroelastomer (FFKM, Kalrez)?
Perfluoroelastomer (FFKM, Kalrez) has a maximum service temperature of 316 °C. The source and test conditions are listed in the properties table on this page.
What are the other names and codes for Perfluoroelastomer (FFKM, Kalrez)?
Perfluoroelastomer (FFKM, Kalrez) is also written as ASTM FFKM, Kalrez® 4079. Each code is printed in the source listed beside it in the designations table.
What is Perfluoroelastomer (FFKM, Kalrez) used for?
Uses recorded in the sources include O-ring seal in spacecraft hardware (NASA outgassing compilation for spacecraft materials); Seal for aggressive chemicals or high temperature.
Why it exists
Kalrez 4079 is a perfluoroelastomer, abbreviated FFKM, sold as a seal material. Qnity Electronics gives its maximum continuous service temperature as 316 °C. DuPont's seal design guide says Kalrez parts are often the elastomer of choice where aggressive chemicals or high temperatures are involved, because they can be the only elastomers stable at those temperatures.
Where it's used
Spacecraft hardware
NASA Reference Publication 1124 lists Kalrez 1050 and Kalrez 3018 O-rings in its table of materials screened for spacecraft use. Both show total mass loss in vacuum of 0.44% and 0.40%, with CVCM of 0.00%.
Aggressive chemicals and high temperature
DuPont says Kalrez perfluoroelastomer parts are often the elastomer of choice when sealing aggressive chemicals or at high temperatures.
Oil and gas exploration and production
Qnity lists exploration and production services as the application for Kalrez 4079 and calls the parts best in class for chemical resistance. This is the only application Qnity names on the page.
Recipe
Perfluoroelastomer (FFKM): a perfluorinated elastomer with more fluorine than FKM (Wikipedia). The sources read do not print its monomers or cure system.
Perfluoroelastomer (FFKM) is a perfluorinated elastomer. The sources read do not print its monomers, cure system or atomic formula, so no composition or atomic share is stated here. Kalrez is the brand name of the grade family, and Kalrez 4079 is the grade on the Qnity datasheet.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|
Weight shares are calculated from standard atomic weights.
What it can do
Temperature
316 °C
measured
Kalrez 4079 is rated for a maximum continuous service temperature of 316 °C. Its lowest service temperature is -19 °C, and Qnity notes that performance varies with seal design and application.
Chemical resistance
DuPont says Kalrez can provide the ultimate in chemical resistance, with minimal swell. It also says exposure testing in the real chemical is often the only reliable way to measure swell.
Vacuum
0.44%
measured
In NASA's vacuum test at 125 °C for 24 hours, Kalrez 1050 lost 0.44% of its mass and Kalrez 3018 lost 0.40%. Both grades show CVCM of 0.00%. These are grade values, not Kalrez 4079 values.
Compression set
37% at 204 °C
measured
After 70 hours at 204 °C, a Kalrez 4079 O-ring had 37% compression set. The value rose to 41% at 250 °C and 45% at 300 °C.
Strength
16.88 MPa
measured
Tensile strength at break is 16.88 MPa (2450 psi), with elongation at break of 150%, both by ASTM D412 on dumbbell specimens.
How it compares
Kalrez 4079 is a perfluoroelastomer seal material. DuPont says its linear coefficient of thermal expansion can be in the range of 50% greater than a fluoroelastomer of similar hardness, so the gland volume has to be checked when a lower-temperature seal is replaced by Kalrez. The table compares its service temperature limits and the vacuum mass loss measured for the grades in the NASA table.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | FFKM |
|---|---|
| Thermal behavior and safety | |
| Water vapor regained, Kalrez 1050 | 0.08 %16 |
| Water vapor regained, Kalrez 3018 | 0.08 %17 |
| Physical and electrical | |
| Hardness, pellet, Kalrez 4079 | 75 Shore A6 |
| Hardness, O-ring, Kalrez 4079 | 83 Shore M7 |
| Other measurements | |
| Maximum continuous service temperature, Kalrez 4079 | 316 °C1 |
| Lowest service temperature, Kalrez 4079 | -19 °C2 |
| Tensile strength at break, Kalrez 4079 | 16.88 MPa3 |
| Elongation at break, Kalrez 4079 | 150 %4 |
| 100% modulus, Kalrez 4079ASTM D412 dumbbell test, as reported by Qnity | 7.24 MPa5 |
| Compression set, pellet, 70 h at 204 °C | 25 %8 |
| Compression set, O-ring, 70 h at 204 °C | 37 %9 |
| Compression set, O-ring, 70 h at 250 °C | 41 %10 |
| Compression set, O-ring, 70 h at 300 °C | 45 %11 |
| Total mass loss in vacuum, Kalrez 1050 O-ring | 0.44 %12 |
| Total mass loss in vacuum, Kalrez 3018 O-ring | 0.4 %13 |
| Collected volatile condensable materials, Kalrez 1050 | 0 %14 |
| Collected volatile condensable materials, Kalrez 3018 | 0 %15 |
Why choose it, and why not
Good for
- High-temperature seals. Qnity gives a maximum continuous service temperature of 316 °C for Kalrez 4079.
- Aggressive chemicals. DuPont calls the chemical resistance the ultimate, with minimal swell.
- Vacuum screening. NASA's table lists two Kalrez O-ring grades with low total mass loss.
Watch out for
- Low-temperature limit. The lowest service temperature is -19 °C, and low-temperature or vacuum sealing may need a special gland design.
- Thermal cycling. A seal can leak after cooling because of compression set. Recover it by reheating before pressure is applied, or replace it.
- Grade values. The NASA outgassing values belong to Kalrez 1050 and 3018, not to Kalrez 4079.
Kalrez 4079 suits seals that must survive heat near 316 °C and aggressive chemicals, within the datasheet and design-guide limits. Its hazards come from DuPont's family safety data sheet and technical sheet, not from a 4079 sheet, and the propellant and semiconductor uses were not verified.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| ASTM | FFKM (class designation for perfluoroelastomers, not a grade) |
| Trade name | Kalrez® 4079 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Maximum continuous service temperature, Kalrez 4079 | Maximum continuous service temperature stated on the Qnity Kalrez 4079 physical properties table | grade Kalrez 4079printed 316 (600) °C (°F)test Qnity proprietary test method | — |
| 2 | Lowest service temperature, Kalrez 4079 | Qnity proprietary method, as stated on the physical properties table | grade Kalrez 4079printed -19 (-2.2) °C (°F)note Qnity says performance will vary with seal design and application specifics | — |
| 3 | Tensile strength at break, Kalrez 4079 | ASTM D412 tensile test on dumbbell specimens, as reported by Qnity | grade Kalrez 4079specimen ASTM D412 dumbbellprinted psi 2450 | — |
| 4 | Elongation at break, Kalrez 4079 | ASTM D412 tensile test on dumbbell specimens, as reported by Qnity | grade Kalrez 4079specimen ASTM D412 dumbbell | — |
| 5 | 100% modulus, Kalrez 4079 | — | grade Kalrez 4079specimen ASTM D412 dumbbellprinted psi 1050 | Custom benchmark name: not in the property canon. |
| 6 | Hardness, pellet, Kalrez 4079 | ASTM D2240 on pellet specimens, as reported by Qnity | grade Kalrez 4079specimen pellet | — |
| 7 | Hardness, O-ring, Kalrez 4079 | ASTM D2240 and ASTM D1414 on O-ring test specimens, as reported by Qnity | grade Kalrez 4079specimen AS568 K214 O-ring | — |
| 8 | Compression set, pellet, 70 h at 204 °C | ASTM D395B on pellet specimens, as reported by Qnity | grade Kalrez 4079time 70 hourstemperature 204 °Cspecimen pellet | Custom benchmark name: not in the property canon. |
| 9 | Compression set, O-ring, 70 h at 204 °C | ASTM D395B and D1414 on O-ring test specimens, as reported by Qnity | grade Kalrez 4079time 70 hourstemperature 204 °Cspecimen AS568 K214 O-ring | Custom benchmark name: not in the property canon. |
| 10 | Compression set, O-ring, 70 h at 250 °C | ASTM D395B and D1414 on O-ring test specimens, as reported by Qnity | grade Kalrez 4079time 70 hourstemperature 250 °Cspecimen AS568 K214 O-ring | Custom benchmark name: not in the property canon. |
| 11 | Compression set, O-ring, 70 h at 300 °C | ASTM D395B and D1414 on O-ring test specimens, as reported by Qnity | grade Kalrez 4079time 70 hourstemperature 300 °Cspecimen AS568 K214 O-ring | Custom benchmark name: not in the property canon. |
| 12 | Total mass loss in vacuum, Kalrez 1050 O-ring | Total mass loss (TML) from the NASA GSFC outgassing table | grade Kalrez 1050test ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuumprinted in table 0 44 (decimal point lost in the text layer) | Custom benchmark name: not in the property canon. Values are read from the OCR text layer of a scanned table. |
| 13 | Total mass loss in vacuum, Kalrez 3018 O-ring | Total mass loss (TML) from the NASA GSFC outgassing table | grade Kalrez 3018test ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuumprinted in table 0.40 (printed as 0 40 in the text layer) | Custom benchmark name: not in the property canon. Values are read from the OCR text layer of a scanned table. |
| 14 | Collected volatile condensable materials, Kalrez 1050 | Collected volatile condensable materials (CVCM) from the NASA GSFC outgassing table | grade Kalrez 1050test ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuumprinted in table 0.00 | Custom benchmark name: not in the property canon. |
| 15 | Collected volatile condensable materials, Kalrez 3018 | Collected volatile condensable materials (CVCM) from the NASA GSFC outgassing table | grade Kalrez 3018test ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuumprinted in table 0.00 | Custom benchmark name: not in the property canon. |
| 16 | Water vapor regained, Kalrez 1050 | Water vapor regained (WVR) from the NASA GSFC outgassing table | grade Kalrez 1050test 24 hours at 25 °C and 50% relative humidity after the vacuum testprinted in table 0.08 | Custom benchmark name: not in the property canon. |
| 17 | Water vapor regained, Kalrez 3018 | Water vapor regained (WVR) from the NASA GSFC outgassing table | grade Kalrez 3018test 24 hours at 25 °C and 50% relative humidity after the vacuum testprinted in table 0.08 | Custom benchmark name: not in the property canon. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at 204 to 300 °C for 70 hours (thermal ageing, measured as compression set) | moderate | Compression set rises from 37% at 204 °C to 45% at 300 °C after 70 hours on O-ring specimens.1 |
| Chemical exposure (general statement, no numeric swell value printed) | low | DuPont describes Kalrez as the ultimate in chemical resistance, with minimal swell.2 |
| Vacuum at 125 °C for 24 hours (NASA outgassing test, ASTM E 595 micro-CVCM method) | low | Kalrez 1050 and 3018 O-rings lost 0.44% and 0.40% of their mass in vacuum, with CVCM of 0.00% for both.3 |
| High-pressure gas, carbon dioxide at 2000 psi (rapid gas decompression) | moderate | Rapid gas decompression can blister or split a Kalrez O-ring; DuPont suggests Kalrez 0090 for this case.4 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at 204 to 300 °C for 70 hours (thermal ageing, measured as compression set) | Qnity's table gives O-ring compression set of 37% at 204 °C, 41% at 250 °C and 45% at 300 °C after 70 hours. DuPont says higher compression set in perfluoroelastomers comes mainly from stress relaxation rather than thermal or chemical degradation, so Kalrez parts stay soft after long exposure at high temperature. | specimen AS568 K214 O-ringtime 70 hourstest ASTM D395B and D1414 |
| 2 | Chemical exposure (general statement, no numeric swell value printed) | DuPont says Kalrez perfluoroelastomer parts 'can provide the ultimate in chemical resistance', which means minimal swell and a lower chance of extrusion. It also says exposure testing in the actual chemical is often the only way to get an accurate swell value, and that immersion in fluorinated oils can cause significant swell. | basis qualitative statement; no swell percentage printed in the sources read |
| 3 | Vacuum at 125 °C for 24 hours (NASA outgassing test, ASTM E 595 micro-CVCM method) | NASA's compilation lists only materials with total mass loss of 1.0% or less and CVCM of 0.10% or less. Both Kalrez O-ring grades in the table fall inside those limits. The table gives no value for Kalrez 4079 itself. | grade Kalrez 1050 and 3018test 125 °C for 24 hours in vacuumlimits for listing TML 1.0% or less and CVCM 0.10% or less |
| 4 | High-pressure gas, carbon dioxide at 2000 psi (rapid gas decompression) | DuPont says gas that has dissolved in the seal can expand when system pressure drops suddenly and can blow the O-ring apart. In less severe cases the O-ring may blister or develop small splits. The application guide can select Kalrez 0090 to reduce this problem. | example fluid carbon dioxide at 2000 psi |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
DuPont's 2004 safety data sheet for all Kalrez perfluoroelastomer compounds and its 2010 technical sheet both warn about fire and heat. No GHS hazard statement is printed for Kalrez 4079 in either.
- Safety data sheet
- The Qnity safety data sheet for Kalrez 4079 opens a sign-in page, so the family sheet from DuPont is the one read. Check the current sheet for the grade you buy before handling.
- Fumes and decomposition
- Above 400 °C Kalrez gives off small amounts of hydrogen fluoride and perfluoroolefins, and fumes from overheating can cause polymer fume fever. Heating above the 316 °C service limit is outside the datasheet and should be avoided.
If a seal fails
These risks come from the DuPont design guide and the NASA test data, not from incident reports.
- Over-stretch on installation
- Stretching an O-ring by more than 50% of its elongation at break can break it. DuPont's example avoids more than 60% stretch for an O-ring with 120% elongation.
- Over-compression
- Relative compression of 30% or more can split or crack a Kalrez O-ring. The guide suggests 14% to 18% compression for static seals.
- High pressure and gas
- At high temperature Kalrez softens and can extrude into the gap under pressure. With carbon dioxide at 2000 psi, a rapid pressure drop can blister or split the O-ring.
Handling
- Lubricant
- Use a light film of lubricant on the O-ring. Fluorinated oil can cause significant swell if the O-ring is immersed in it.
- Surface finish
- Use a gland surface finish of 32 µinch in most cases, and 16 µinch or better for gas or vacuum sealing.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Breakage during installationmoderate severity | Stretching the O-ring by more than 50% of its elongation at break; the guide's example avoids more than 60% stretch for an O-ring with 120% elongationThe O-ring can break. For small O-rings the guide suggests keeping installation stretch under 25% of the elongation at break. |
| Splitting from over-compressionhigh severity | Relative compression of 30% or greater, which can happen when parts heat upParts can split or crack, then fail. The guide suggests 14% to 18% compression for static seals. |
| Premature failure from assembled stretchmoderate severity | Assembled stretch greater than 5% on the inner-diameter sealHigh internal stress and premature failure. The guide suggests 1% to 3% assembled stretch when sealing on the inner diameter. |
| Leak after cooling (compression set)moderate severity | Long continuous use at high temperature followed by coolingThe seal keeps its high-temperature shape and can leak as it contracts. The guide says to let it recover by raising the temperature before applying fluid pressure, or to replace it. |
| Extrusion at high temperature and pressuremoderate severity | High temperature, where Kalrez softens and loses modulus, combined with high pressure and a wide clearance gapThe seal extrudes into the gap and can fail. The guide suggests keeping the clearance gap to 0.002 to 0.005 in (0.051 to 0.127 mm) and using anti-extrusion rings at high pressure. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Seal gland and clearance gap | Kalrez parts soften at high temperature and lose some mechanical properties, which can aggravate extrusion. |
| Gland groove volume | The linear coefficient of thermal expansion for Kalrez parts can be in the range of 50% greater than a fluoroelastomer of similar hardness, so the gland volume must be checked when a lower-temperature seal is replaced. |
| Seal dimensions | Immersing a perfluoroelastomer in fluorinated oil can cause significant swell. A thin film of fluorinated oil applied for installation does not affect performance. |
Handling and storage
- Apply a light lubricant film during installation. The guide names fluorinated oil, powdered graphite or water as examples, and the lubricant must not swell or degrade the O-ring.
- Use a gland sealing surface finish of 32 µinch for most applications, and 16 µinch or better when sealing gases or in vacuum.
- For small O-rings, stretch evenly with a special tool such as a cone device. A high localized elongation can break the O-ring.
Mitigations
- Use anti-extrusion (backup) rings for high-pressure applications and keep the clearance gap at the minimum achievable, typically 0.002 to 0.005 in (0.051 to 0.127 mm).
- Use 0% stretch for an O-ring that seals against a rotating shaft, because stretch causes heat build-up (the Gough-Joule effect).
Supply and geography
How common the raw materials are and where they come from.
Fluorspar (fluorine feedstock)
Not stated for fluorspar in the source read
- Top producers (2025)
- China 60%, Mexico 15%, Mongolia 15%
- Critical mineral lists
- US: listed
- Recycling
- USGS: synthetic fluorspar may be produced from waste neutralization in uranium enrichment, petroleum alkylation and stainless-steel pickling, but undesirable impurities constrain its use.
- Substitutes
- USGS: fluorosilicic acid has been used as an alternative to fluorspar in producing AlF3 and HF.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: ffkm-kalrez
spore_version: 0.2
family: fluoroelastomers
name: Perfluoroelastomer (FFKM, Kalrez)
abbreviation: FFKM
role: Perfluoroelastomer O-ring and seal material for high-temperature and aggressive-chemical service
category: seals-adhesives
type: elastomers-and-o-rings
summary: |
Kalrez 4079 is a perfluoroelastomer (FFKM) seal material. Qnity Electronics gives its maximum continuous service temperature as 316 °C (600 °F) and its lowest service temperature as -19 °C. DuPont's seal design guide says Kalrez parts are often the elastomer of choice when sealing aggressive chemicals or working at high temperatures. NASA's outgassing compilation lists two other Kalrez O-ring grades, 1050 and 3018, with total mass loss of 0.44% and 0.40% in vacuum.
best_for: Seals that must survive temperatures near 316 °C or aggressive chemicals, where swell and extrusion must stay low (per the Qnity datasheet and DuPont guide)
weakest_at: Low-temperature flexibility (lowest service temperature -19 °C) and compression set that rises from 37% at 204 °C to 45% at 300 °C after 70 hours on O-ring specimens
identity:
formula: 'Perfluoroelastomer (FFKM): a perfluorinated elastomer with more fluorine than FKM (Wikipedia). The sources read do not print its monomers or cure system.'
source: dupont-kag-seal-design
where: Introduction ('Kalrez perfluoroelastomer parts'); Temperature and Thermal Expansion section; FKM and FFKM comparison in the same section
designations:
- system: ASTM
code: FFKM
note: class designation for perfluoroelastomers, not a grade
source: dupont-kag-seal-design
where: Temperature and Thermal Expansion section, note under the temperature chart
- system: Trade name
code: Kalrez® 4079
source: qnity-kalrez-4079
where: Product page title and grade name (printed with the registered mark)
tags:
environments: []
stresses:
- extreme-heat
applications:
- mechanisms
properties:
- benchmark: max_service_temp
label: Maximum continuous service temperature, Kalrez 4079
value: 316
unit: °C
scope: material
conditions:
grade: Kalrez 4079
printed: 316 (600) °C (°F)
test: Qnity proprietary test method
method: Maximum continuous service temperature stated on the Qnity Kalrez 4079 physical properties table
status: ground
source: qnity-kalrez-4079
where: Physical Properties table, row 'Maximum continuous service temperature'
- benchmark: min_service_temp
label: Lowest service temperature, Kalrez 4079
value: -19
unit: °C
scope: material
conditions:
grade: Kalrez 4079
printed: '-19 (-2.2) °C (°F)'
note: Qnity says performance will vary with seal design and application specifics
method: Qnity proprietary method, as stated on the physical properties table
status: ground
source: qnity-kalrez-4079
where: Physical Properties table, row 'Lowest Service Temperature'
- benchmark: ultimate_tensile_strength
label: Tensile strength at break, Kalrez 4079
value: 16.88
unit: MPa
scope: material
conditions:
grade: Kalrez 4079
specimen: ASTM D412 dumbbell
printed_psi: '2450'
method: ASTM D412 tensile test on dumbbell specimens, as reported by Qnity
status: ground
source: qnity-kalrez-4079
where: Physical Properties table, row 'Tensile Strength at Break'
- benchmark: elongation
label: Elongation at break, Kalrez 4079
value: 150
unit: '%'
scope: material
conditions:
grade: Kalrez 4079
specimen: ASTM D412 dumbbell
method: ASTM D412 tensile test on dumbbell specimens, as reported by Qnity
status: ground
source: qnity-kalrez-4079
where: Physical Properties table, row 'Elongation at Break'
- benchmark: modulus_100_percent
label: 100% modulus, Kalrez 4079
value: 7.24
unit: MPa
scope: material
conditions:
grade: Kalrez 4079
specimen: ASTM D412 dumbbell
printed_psi: '1050'
method: ASTM D412 dumbbell test, as reported by Qnity
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: qnity-kalrez-4079
where: Physical Properties table, row '100% Modulus'
- benchmark: hardness
label: Hardness, pellet, Kalrez 4079
value: 75
unit: Shore A
scope: material
conditions:
grade: Kalrez 4079
specimen: pellet
method: ASTM D2240 on pellet specimens, as reported by Qnity
status: ground
source: qnity-kalrez-4079
where: Physical Properties table, row 'Hardness' (pellet)
- benchmark: hardness
label: Hardness, O-ring, Kalrez 4079
value: 83
unit: Shore M
scope: material
conditions:
grade: Kalrez 4079
specimen: AS568 K214 O-ring
method: ASTM D2240 and ASTM D1414 on O-ring test specimens, as reported by Qnity
status: ground
source: qnity-kalrez-4079
where: Physical Properties table, row 'Hardness' (O-ring)
- benchmark: compression_set
label: Compression set, pellet, 70 h at 204 °C
value: 25
unit: '%'
scope: material
conditions:
grade: Kalrez 4079
time: 70 hours
temperature: 204 °C
specimen: pellet
method: ASTM D395B on pellet specimens, as reported by Qnity
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: qnity-kalrez-4079
where: Physical Properties table, row 'Compression Set, 70 hr at 204 °C' (pellet)
- benchmark: compression_set
label: Compression set, O-ring, 70 h at 204 °C
value: 37
unit: '%'
scope: material
conditions:
grade: Kalrez 4079
time: 70 hours
temperature: 204 °C
specimen: AS568 K214 O-ring
method: ASTM D395B and D1414 on O-ring test specimens, as reported by Qnity
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: qnity-kalrez-4079
where: Physical Properties table, row 'Compression Set, 70 hr at 204 °C' (O-ring)
- benchmark: compression_set
label: Compression set, O-ring, 70 h at 250 °C
value: 41
unit: '%'
scope: material
conditions:
grade: Kalrez 4079
time: 70 hours
temperature: 250 °C
specimen: AS568 K214 O-ring
method: ASTM D395B and D1414 on O-ring test specimens, as reported by Qnity
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: qnity-kalrez-4079
where: Physical Properties table, row 'Compression Set, 70 hr at 250 °C'
- benchmark: compression_set
label: Compression set, O-ring, 70 h at 300 °C
value: 45
unit: '%'
scope: material
conditions:
grade: Kalrez 4079
time: 70 hours
temperature: 300 °C
specimen: AS568 K214 O-ring
method: ASTM D395B and D1414 on O-ring test specimens, as reported by Qnity
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: qnity-kalrez-4079
where: Physical Properties table, row 'Compression Set, 70 hr at 300 °C'
- benchmark: total_mass_loss
label: Total mass loss in vacuum, Kalrez 1050 O-ring
value: 0.44
unit: '%'
scope: material
conditions:
grade: Kalrez 1050
test: 'ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuum'
printed_in_table: 0 44 (decimal point lost in the text layer)
method: Total mass loss (TML) from the NASA GSFC outgassing table
status: ground
note: 'Custom benchmark name: not in the property canon. Values are read from the OCR text layer of a scanned table.'
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), row 'KALREZ 1050 PERFLUOROELASTOMER', %TML column
- benchmark: total_mass_loss
label: Total mass loss in vacuum, Kalrez 3018 O-ring
value: 0.4
unit: '%'
scope: material
conditions:
grade: Kalrez 3018
test: 'ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuum'
printed_in_table: 0.40 (printed as 0 40 in the text layer)
method: Total mass loss (TML) from the NASA GSFC outgassing table
status: ground
note: 'Custom benchmark name: not in the property canon. Values are read from the OCR text layer of a scanned table.'
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), row 'KALREZ 3018 PERFLUOROELASTOMER', %TML column
- benchmark: cvcm
label: Collected volatile condensable materials, Kalrez 1050
value: 0
unit: '%'
scope: material
conditions:
grade: Kalrez 1050
test: 'ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuum'
printed_in_table: '0.00'
method: Collected volatile condensable materials (CVCM) from the NASA GSFC outgassing table
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), row 'KALREZ 1050 PERFLUOROELASTOMER', %CVCM column
- benchmark: cvcm
label: Collected volatile condensable materials, Kalrez 3018
value: 0
unit: '%'
scope: material
conditions:
grade: Kalrez 3018
test: 'ASTM E 595 micro-CVCM method: 125 °C for 24 hours in vacuum'
printed_in_table: '0.00'
method: Collected volatile condensable materials (CVCM) from the NASA GSFC outgassing table
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), row 'KALREZ 3018 PERFLUOROELASTOMER', %CVCM column
- benchmark: water_vapor_regained
label: Water vapor regained, Kalrez 1050
value: 0.08
unit: '%'
scope: material
conditions:
grade: Kalrez 1050
test: 24 hours at 25 °C and 50% relative humidity after the vacuum test
printed_in_table: '0.08'
method: Water vapor regained (WVR) from the NASA GSFC outgassing table
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), row 'KALREZ 1050 PERFLUOROELASTOMER', %WVR column
- benchmark: water_vapor_regained
label: Water vapor regained, Kalrez 3018
value: 0.08
unit: '%'
scope: material
conditions:
grade: Kalrez 3018
test: 24 hours at 25 °C and 50% relative humidity after the vacuum test
printed_in_table: '0.08'
method: Water vapor regained (WVR) from the NASA GSFC outgassing table
status: ground
note: 'Custom benchmark name: not in the property canon.'
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), row 'KALREZ 3018 PERFLUOROELASTOMER', %WVR column
corrosion:
- environment: Air at 204 to 300 °C for 70 hours (thermal ageing, measured as compression set)
headline: Compression set rises from 37% at 204 °C to 45% at 300 °C after 70 hours on O-ring specimens.
effect: Qnity's table gives O-ring compression set of 37% at 204 °C, 41% at 250 °C and 45% at 300 °C after 70 hours. DuPont says higher compression set in perfluoroelastomers comes mainly from stress relaxation rather than thermal or chemical degradation, so Kalrez parts stay soft after long exposure at high temperature.
rating: moderate
conditions:
specimen: AS568 K214 O-ring
time: 70 hours
test: ASTM D395B and D1414
source: qnity-kalrez-4079
where: Physical Properties table; DuPont guide, O-ring Compression Set section
- environment: Chemical exposure (general statement, no numeric swell value printed)
headline: DuPont describes Kalrez as the ultimate in chemical resistance, with minimal swell.
effect: DuPont says Kalrez perfluoroelastomer parts 'can provide the ultimate in chemical resistance', which means minimal swell and a lower chance of extrusion. It also says exposure testing in the actual chemical is often the only way to get an accurate swell value, and that immersion in fluorinated oils can cause significant swell.
rating: low
conditions:
basis: qualitative statement; no swell percentage printed in the sources read
source: dupont-kag-seal-design
where: Chemical Resistance section; Lubrication section
- environment: Vacuum at 125 °C for 24 hours (NASA outgassing test, ASTM E 595 micro-CVCM method)
headline: Kalrez 1050 and 3018 O-rings lost 0.44% and 0.40% of their mass in vacuum, with CVCM of 0.00% for both.
effect: NASA's compilation lists only materials with total mass loss of 1.0% or less and CVCM of 0.10% or less. Both Kalrez O-ring grades in the table fall inside those limits. The table gives no value for Kalrez 4079 itself.
rating: low
conditions:
grade: Kalrez 1050 and 3018
test: 125 °C for 24 hours in vacuum
limits_for_listing: TML 1.0% or less and CVCM 0.10% or less
source: nasa-rp1124
where: Section C introduction (listing criteria); Section 15 table rows for Kalrez 1050 and 3018
- environment: High-pressure gas, carbon dioxide at 2000 psi (rapid gas decompression)
headline: Rapid gas decompression can blister or split a Kalrez O-ring; DuPont suggests Kalrez 0090 for this case.
effect: DuPont says gas that has dissolved in the seal can expand when system pressure drops suddenly and can blow the O-ring apart. In less severe cases the O-ring may blister or develop small splits. The application guide can select Kalrez 0090 to reduce this problem.
rating: moderate
conditions:
example_fluid: carbon dioxide at 2000 psi
source: dupont-kag-seal-design
where: Pressure and Extrusion section, Rapid Gas Decompression paragraph
risks:
hazards:
- text: DuPont product literature states that highly toxic products can be generated when Kalrez parts are exposed to fire or to temperatures above 400 °C, so respiratory equipment should be used if ventilation is inadequate.
ghs: []
source: dupont-kalrez-tech-2010
where: Product Safety section
- text: The KRZ028 family safety data sheet (DuPont Dow Elastomers, 2004) says that above 204 °C small amounts of carbon monoxide and carbon dioxide are given off, and above 400 °C small amounts of hydrogen fluoride and perfluoroolefins are given off.
ghs: []
source: kalrez-krz028-msds
where: Stability and Reactivity, Decomposition
- text: The KRZ028 family safety data sheet says that inhaling fumes from overheating or burning Kalrez, or from smoking contaminated tobacco, may cause polymer fume fever, a flu-like illness with chills and fever that goes away in 24 to 48 hours.
ghs: []
source: kalrez-krz028-msds
where: Hazards Identification, Inhalation
- text: The KRZ028 family safety data sheet (2004) says Kalrez perfluoroelastomer is incompatible with or can react with molten alkali metals and interhalogen compounds.
ghs: []
source: kalrez-krz028-msds
where: Stability and Reactivity, Incompatibility with Other Materials
failure_risks:
- mode: Breakage during installation
trigger: Stretching the O-ring by more than 50% of its elongation at break; the guide's example avoids more than 60% stretch for an O-ring with 120% elongation
consequence: The O-ring can break. For small O-rings the guide suggests keeping installation stretch under 25% of the elongation at break.
severity: moderate
source: dupont-kag-seal-design
where: Stretch section
- mode: Splitting from over-compression
trigger: Relative compression of 30% or greater, which can happen when parts heat up
consequence: Parts can split or crack, then fail. The guide suggests 14% to 18% compression for static seals.
severity: high
source: dupont-kag-seal-design
where: Compression section
- mode: Premature failure from assembled stretch
trigger: Assembled stretch greater than 5% on the inner-diameter seal
consequence: High internal stress and premature failure. The guide suggests 1% to 3% assembled stretch when sealing on the inner diameter.
severity: moderate
source: dupont-kag-seal-design
where: Stretch section, assembled stretch paragraph
- mode: Leak after cooling (compression set)
trigger: Long continuous use at high temperature followed by cooling
consequence: The seal keeps its high-temperature shape and can leak as it contracts. The guide says to let it recover by raising the temperature before applying fluid pressure, or to replace it.
severity: moderate
source: dupont-kag-seal-design
where: O-ring Compression Set section
- mode: Extrusion at high temperature and pressure
trigger: High temperature, where Kalrez softens and loses modulus, combined with high pressure and a wide clearance gap
consequence: The seal extrudes into the gap and can fail. The guide suggests keeping the clearance gap to 0.002 to 0.005 in (0.051 to 0.127 mm) and using anti-extrusion rings at high pressure.
severity: moderate
source: dupont-kag-seal-design
where: O-ring Extrusion Due to High Pressure section
side_effects:
- text: Kalrez parts soften at high temperature and lose some mechanical properties, which can aggravate extrusion.
affects: Seal gland and clearance gap
source: dupont-kag-seal-design
where: O-ring Extrusion Due to High Pressure section
- text: The linear coefficient of thermal expansion for Kalrez parts can be in the range of 50% greater than a fluoroelastomer of similar hardness, so the gland volume must be checked when a lower-temperature seal is replaced.
affects: Gland groove volume
source: dupont-kag-seal-design
where: Temperature and Thermal Expansion section
- text: Immersing a perfluoroelastomer in fluorinated oil can cause significant swell. A thin film of fluorinated oil applied for installation does not affect performance.
affects: Seal dimensions
source: dupont-kag-seal-design
where: Lubrication section
handling:
- text: Apply a light lubricant film during installation. The guide names fluorinated oil, powdered graphite or water as examples, and the lubricant must not swell or degrade the O-ring.
source: dupont-kag-seal-design
where: Lubrication section
- text: Use a gland sealing surface finish of 32 µinch for most applications, and 16 µinch or better when sealing gases or in vacuum.
source: dupont-kag-seal-design
where: Surface Roughness section
- text: For small O-rings, stretch evenly with a special tool such as a cone device. A high localized elongation can break the O-ring.
source: dupont-kag-seal-design
where: Stretch section
mitigations:
- text: Use anti-extrusion (backup) rings for high-pressure applications and keep the clearance gap at the minimum achievable, typically 0.002 to 0.005 in (0.051 to 0.127 mm).
source: dupont-kag-seal-design
where: Pressure and Extrusion section
- text: Use 0% stretch for an O-ring that seals against a rotating shaft, because stretch causes heat build-up (the Gough-Joule effect).
source: dupont-kag-seal-design
where: Stretch section
uses:
- application: mechanisms
device: O-ring seal in spacecraft hardware (NASA outgassing compilation for spacecraft materials)
example: NASA Reference Publication 1124 lists Kalrez 1050 and Kalrez 3018 as O-rings in its Rubbers and Elastomers section, among materials screened for spacecraft use.
source: nasa-rp1124
where: Section 15 (Rubbers and Elastomers), rows for KALREZ 1050 and KALREZ 3018, application column
- application: mechanisms
device: Seal for aggressive chemicals or high temperature
example: DuPont says that when sealing aggressive chemicals or at high temperatures, Kalrez perfluoroelastomer parts are often the elastomer of choice.
source: dupont-kag-seal-design
where: Introduction section
supply:
- subject: Fluorspar (fluorine feedstock)
abundance: Not stated for fluorspar in the source read
producers:
- country: China
share_percent: 60
year: 2025
- country: Mexico
share_percent: 15
year: 2025
- country: Mongolia
share_percent: 15
year: 2025
critical_lists:
- list: USGS 2025 List of Critical Minerals (fluorspar listed)
listed: true
recycling: 'USGS: synthetic fluorspar may be produced from waste neutralization in uranium enrichment, petroleum alkylation and stainless-steel pickling, but undesirable impurities constrain its use.'
substitutes:
- 'USGS: fluorosilicic acid has been used as an alternative to fluorspar in producing AlF3 and HF.'
source: usgs-mcs2026-fluorspar
where: World Mine Production and Reserves table, 2025 column (world total 10,000 thousand t, rounded; shares calculated by Space Mushroom from China 6,000, Mexico 1,500 and Mongolia 1,500 thousand t); Recycling; Substitutes. The USGS text says aqueous HF is the primary feedstock for fluorine-bearing chemicals, including fluoropolymers.
media: []
documents:
- title: Kalrez 4079 product page, Qnity Electronics (physical properties)
type: datasheet
url: https://www.qnityelectronics.com/products/kalrez-4079.html
year: 2026
- title: Seal Design Considerations for Kalrez and Utilizing the Kalrez Application Guide (DuPont)
type: datasheet
url: https://www.dupont.com/KAG/pdf/SealDesignConsiderationsUsingKalrez.pdf
- title: 'NASA Reference Publication 1124, Rev. 3: Outgassing Data for Selecting Spacecraft Materials'
type: report
url: https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf
year: 1993
- title: Mineral Commodity Summaries 2026, Fluorspar
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
year: 2026
- title: Material Safety Data Sheet KRZ028, Kalrez perfluoroelastomer compounds (DuPont Dow Elastomers, revised 14 May 2004; copy hosted by ERIKS)
type: sds
url: https://o-ring.info/en/datasheets/kalrez/ERIKS%20-%20MSDS%20-%20KRZ028.pdf
year: 2004
- title: Kalrez Spectrum and Kalrez Physical Properties and Product Comparisons, Technical Information Rev. 8 (DuPont Performance Elastomers, January 2010; copy hosted by Jefferson Lab)
type: datasheet
url: https://hallaweb.jlab.org/tech/Detectors/public_html/manuals/data_sheets-manuals/D-F/D/dupont/kalrez.pdf
year: 2010
gaps:
- Propellant, oxidiser and semiconductor-vacuum seal uses were not found in any page fetched in this run (the web search budget ran out), so they are not stated as uses.
- No PubChem GHS record for the perfluoroelastomer class was found in a search. The hazards come from DuPont's 2004 family safety data sheet (KRZ028, covering all Kalrez compounds, not a Kalrez 4079 sheet) and the 2010 DuPont technical sheet. The Qnity safety data sheet for Kalrez 4079 opens a sign-in page and was not read. The family sheet prints no GHS hazard statements.
- 'Composition is not disclosed: the monomers and cure system are not printed in the Qnity or DuPont sources read. Wikipedia gives only a general description (more fluorine than FKM).'
- No density, glass transition, or dynamic temperature range was found as text. The DuPont temperature range chart and thermal expansion charts are images with no printed values.
- Chemical swell and retained-sealing-force numbers (Lucas test) are shown only in graphs with no printed values in the text.
- Wikipedia gives a maximum continuous service temperature of 327 °C for certain FFKM grades. It is not used as a value here because it is not the Kalrez 4079 datasheet value.
- The NASA table values for Kalrez 1050 and 3018 are read from the OCR text layer of a scanned table. Decimal points appear lost in some cells, and the values are not Kalrez 4079 values.
- Hardness, compression set, total mass loss, CVCM, water vapor regained and 100% modulus are custom benchmark names because no canonical name fits.
- Producers of perfluoroelastomer itself and their country shares were not found. The fluorspar shares are a feedstock proxy, not perfluoroelastomer supply.
- EU critical raw materials status for fluorspar was not checked.
- The oil and gas exploration and production use named by Qnity has no matching application slug in the brief, so it is described in the story but not listed under uses.
- No images were fetched with a usable licence, so media is empty.
- The Qnity page was read through a summarising fetch, not a raw copy of the page.
sources:
qnity-kalrez-4079:
title: Kalrez 4079, Qnity Electronics product page (physical properties table)
id: Qnity Electronics, Kalrez 4079
url: https://www.qnityelectronics.com/products/kalrez-4079.html
year: 2026
kind: datasheet
license: supplier web page, linked not reproduced
dupont-kag-seal-design:
title: Seal Design Considerations for Kalrez and Utilizing the Kalrez Application Guide
id: DuPont Kalrez application guide (PDF)
url: https://www.dupont.com/KAG/pdf/SealDesignConsiderationsUsingKalrez.pdf
kind: datasheet
license: supplier document, linked not reproduced
nasa-rp1124:
title: Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3
id: NTRS 19940017416; Campbell and Scialdone, Goddard Space Flight Center, September 1993
url: https://ntrs.nasa.gov/api/citations/19940017416/downloads/19940017416.pdf
year: 1993
kind: report
license: public domain (NASA)
usgs-mcs2026-fluorspar:
title: Mineral Commodity Summaries 2026, Fluorspar
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-crit2025:
title: About the 2025 List of Critical Minerals (USGS)
id: USGS final 2025 List of Critical Minerals
url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
year: 2025
kind: web
license: public domain (USGS)
wikipedia-kalrez:
title: Kalrez, Wikipedia (composition and curing description only)
id: en.wikipedia.org/wiki/Kalrez
url: https://en.wikipedia.org/wiki/Kalrez
kind: web
license: CC BY-SA 4.0 (Wikipedia)
kalrez-krz028-msds:
title: Material Safety Data Sheet KRZ028, Kalrez perfluoroelastomer compounds (all compounds in the synonym list)
id: DuPont Dow Elastomers L. L. C., KRZ028, revised 14-MAY-2004
url: https://o-ring.info/en/datasheets/kalrez/ERIKS%20-%20MSDS%20-%20KRZ028.pdf
year: 2004
kind: datasheet
license: supplier document, linked not reproduced
dupont-kalrez-tech-2010:
title: Kalrez Spectrum and Kalrez Physical Properties and Product Comparisons, Technical Information Rev. 8
id: DuPont Performance Elastomers, Rev. 8, January 2010
url: https://hallaweb.jlab.org/tech/Detectors/public_html/manuals/data_sheets-manuals/D-F/D/dupont/kalrez.pdf
year: 2010
kind: datasheet
license: supplier document, linked not reproduced
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 17
unreachable: 1
caveats: 3
note: 'Written by an AI assistant on 2026-11-01 from the Qnity Kalrez 4079 page, the DuPont Kalrez application guide, NASA RP 1124 Rev. 3 (outgassing table), the USGS fluorspar summary, the USGS 2025 critical minerals list, DuPont''s 2004 Kalrez family safety data sheet (KRZ028) and DuPont''s 2010 Kalrez technical sheet. Not verified: the Kalrez 4079 safety data sheet (sign-in page), the propellant and semiconductor uses, and the OCR-read NASA values.'
story:
recipe:
line: Perfluoroelastomer (FFKM) is a perfluorinated elastomer. The sources read do not print its monomers, cure system or atomic formula, so no composition or atomic share is stated here. Kalrez is the brand name of the grade family, and Kalrez 4079 is the grade on the Qnity datasheet.
parts: []
risk_groups:
- title: For people
lead: DuPont's 2004 safety data sheet for all Kalrez perfluoroelastomer compounds and its 2010 technical sheet both warn about fire and heat. No GHS hazard statement is printed for Kalrez 4079 in either.
points:
- label: Safety data sheet
line: The Qnity safety data sheet for Kalrez 4079 opens a sign-in page, so the family sheet from DuPont is the one read. Check the current sheet for the grade you buy before handling.
- label: Fumes and decomposition
line: Above 400 °C Kalrez gives off small amounts of hydrogen fluoride and perfluoroolefins, and fumes from overheating can cause polymer fume fever. Heating above the 316 °C service limit is outside the datasheet and should be avoided.
- title: If a seal fails
lead: These risks come from the DuPont design guide and the NASA test data, not from incident reports.
points:
- label: Over-stretch on installation
line: Stretching an O-ring by more than 50% of its elongation at break can break it. DuPont's example avoids more than 60% stretch for an O-ring with 120% elongation.
- label: Over-compression
line: Relative compression of 30% or more can split or crack a Kalrez O-ring. The guide suggests 14% to 18% compression for static seals.
- label: High pressure and gas
line: At high temperature Kalrez softens and can extrude into the gap under pressure. With carbon dioxide at 2000 psi, a rapid pressure drop can blister or split the O-ring.
- title: Handling
points:
- label: Lubricant
line: Use a light film of lubricant on the O-ring. Fluorinated oil can cause significant swell if the O-ring is immersed in it.
- label: Surface finish
line: Use a gland surface finish of 32 µinch in most cases, and 16 µinch or better for gas or vacuum sealing.
why: Kalrez 4079 is a perfluoroelastomer, abbreviated FFKM, sold as a seal material. Qnity Electronics gives its maximum continuous service temperature as 316 °C. DuPont's seal design guide says Kalrez parts are often the elastomer of choice where aggressive chemicals or high temperatures are involved, because they can be the only elastomers stable at those temperatures.
uses:
- where: Spacecraft hardware
line: NASA Reference Publication 1124 lists Kalrez 1050 and Kalrez 3018 O-rings in its table of materials screened for spacecraft use. Both show total mass loss in vacuum of 0.44% and 0.40%, with CVCM of 0.00%.
- where: Aggressive chemicals and high temperature
line: DuPont says Kalrez perfluoroelastomer parts are often the elastomer of choice when sealing aggressive chemicals or at high temperatures.
- where: Oil and gas exploration and production
line: Qnity lists exploration and production services as the application for Kalrez 4079 and calls the parts best in class for chemical resistance. This is the only application Qnity names on the page.
can_do:
- label: Temperature
benchmark: max_service_temp
value: 316 °C
line: Kalrez 4079 is rated for a maximum continuous service temperature of 316 °C. Its lowest service temperature is -19 °C, and Qnity notes that performance varies with seal design and application.
- label: Chemical resistance
line: DuPont says Kalrez can provide the ultimate in chemical resistance, with minimal swell. It also says exposure testing in the real chemical is often the only reliable way to measure swell.
- label: Vacuum
benchmark: total_mass_loss
value: 0.44%
line: In NASA's vacuum test at 125 °C for 24 hours, Kalrez 1050 lost 0.44% of its mass and Kalrez 3018 lost 0.40%. Both grades show CVCM of 0.00%. These are grade values, not Kalrez 4079 values.
- label: Compression set
benchmark: compression_set
value: 37% at 204 °C
line: After 70 hours at 204 °C, a Kalrez 4079 O-ring had 37% compression set. The value rose to 41% at 250 °C and 45% at 300 °C.
- label: Strength
benchmark: ultimate_tensile_strength
value: 16.88 MPa
line: Tensile strength at break is 16.88 MPa (2450 psi), with elongation at break of 150%, both by ASTM D412 on dumbbell specimens.
compare: Kalrez 4079 is a perfluoroelastomer seal material. DuPont says its linear coefficient of thermal expansion can be in the range of 50% greater than a fluoroelastomer of similar hardness, so the gland volume has to be checked when a lower-temperature seal is replaced by Kalrez. The table compares its service temperature limits and the vacuum mass loss measured for the grades in the NASA table.
compare_rows:
- label: Maximum continuous service temperature
benchmark: max_service_temp
- label: Lowest service temperature
benchmark: min_service_temp
- label: Total mass loss in vacuum (grade 1050)
benchmark: total_mass_loss
handling:
- Keep installation stretch under 50% of the elongation at break, and under 25% for small O-rings.
- Keep compression between 14% and 18% for static seals. 30% or more can split the part.
- Use a light film of lubricant. Do not immerse the O-ring in fluorinated oil, which can cause significant swell.
- Keep the material away from molten alkali metals and interhalogen compounds, which the 2004 safety data sheet lists as incompatible. Check the current supplier safety data sheet for the grade before handling.
good_for:
- High-temperature seals. Qnity gives a maximum continuous service temperature of 316 °C for Kalrez 4079.
- Aggressive chemicals. DuPont calls the chemical resistance the ultimate, with minimal swell.
- Vacuum screening. NASA's table lists two Kalrez O-ring grades with low total mass loss.
watch_out:
- Low-temperature limit. The lowest service temperature is -19 °C, and low-temperature or vacuum sealing may need a special gland design.
- Thermal cycling. A seal can leak after cooling because of compression set. Recover it by reheating before pressure is applied, or replace it.
- Grade values. The NASA outgassing values belong to Kalrez 1050 and 3018, not to Kalrez 4079.
verdict: Kalrez 4079 suits seals that must survive heat near 316 °C and aggressive chemicals, within the datasheet and design-guide limits. Its hazards come from DuPont's family safety data sheet and technical sheet, not from a 4079 sheet, and the propellant and semiconductor uses were not verified.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Kalrez 4079, Qnity Electronics product page (physical properties table) | datasheet | 2026 | 12 values | |
| Seal Design Considerations for Kalrez and Utilizing the Kalrez Application Guide | datasheet | 17 values | ||
| Outgassing Data for Selecting Spacecraft Materials, NASA Reference Publication 1124, Revision 3 | report | 1993 | 8 values | |
| Mineral Commodity Summaries 2026, Fluorspar | report | 2026 | 1 value | |
| About the 2025 List of Critical Minerals (USGS) | web | 2025 | 0 values | |
| Kalrez, Wikipedia (composition and curing description only) | web | 0 values | ||
| Material Safety Data Sheet KRZ028, Kalrez perfluoroelastomer compounds (all compounds in the synonym list) | datasheet | 2004 | 3 values | |
| Kalrez Spectrum and Kalrez Physical Properties and Product Comparisons, Technical Information Rev. 8 | datasheet | 2010 | 1 value |
Updated