Press systems · Seals and media
Seals and media: which medium with which sealing ring
Whether a press system may carry drinking water, heating water, gas, solar fluid or compressed air is decided less by the pipe than by the small ring in the bead of the connector. Five elastomers share the press world; each has its temperature range, its colour code and its list of permitted and excluded media. This page sets them side by side, explains why the manufacturer's statement applies per medium and not per system, and shows in the media matrix which of the systems we carry may carry which medium.
- EPDM
- standard – drinking water, heating, cooling, oil-free compressed air; not oil, not steam
- HNBR
- gas – natural gas, LPG, hydrogen, heating oil; not drinking water
- FKM
- high temperature – solar, district heating, low-pressure steam, oil
- CIIR
- Geberit standard – drinking water, heating
- Nitrile
- Victaulic grade T – petroleum products, air containing oil
- Rule
- Tmax and Pmax apply per medium, not per system
What the sealing element does – and why it determines the release
The press connector does not seal metal on metal. In the bead sits an elastomer ring that is deformed during pressing and bears against pipe and connector; the metallic deformation secures the joint against pull-out and twisting, the ring holds the medium. That is why the media list of a system is in truth a list of the resistance of its sealing element: to the medium, to the temperature, to additives (antifreeze, inhibitors, oils), to oxygen and ageing. A system with EPDM is at home in drinking water and lost in a heating-oil line; the same system with an HNBR ring becomes a gas system.
The manufacturers therefore state limits per medium – Viega in its media list, Sanha in the catalogue, Geberit in the application overview, Victaulic in the data sheets – and the system values (say “16 bar, 105 °C”) are only the widest frame. Drinking water, for instance, is limited with most systems to 80 °C and 10 bar to DIN 1988-200, even if the sealing element could take more. Our data layer carries both values separately; the system finder calculates with the value per medium.
From our practice (experience value, rule 2 of the practical rules): sealing element before system. First clarify medium, temperature and additives, derive the sealing element from that, and only then the system – not the other way round. Whoever starts with the favourite system and checks the medium afterwards usually finds the limit on site.
The five sealing materials
| Sealing element | Material | Colour code | Temperature | Media | Excluded |
|---|---|---|---|---|---|
| EPDM (ethylene propylene diene rubber) | EPDM | black (Viega, Sanha), green stripe (Victaulic grade E) | -30 – 120 °C | drinking water, heating and cooling water, compressed air (oil-free), technical gases, fire-fighting water | mineral oil, petroleum products, steam |
| HNBR (hydrogenated nitrile rubber) | HNBR | yellow (gas systems) | -20 – 70 °C | natural gas, LPG, hydrogen, technical gases, heating oil and diesel (Viega Sanpress Inox G 15-54, Megapress G) | drinking water |
| FKM (fluoroelastomer) | FKM | matt black (Viega Megapress S), red (Sanha HT), blue/white (Geberit) | -20 – 160 °C | district heating, solar, low-pressure steam, compressed air with oil, heating oil, high temperatures | drinking water (system-dependent), hot water heating above manufacturer limit |
| CIIR (chlorobutyl rubber) | CIIR | black | 0 – 120 °C | drinking water, heating (Geberit Mepla) | gas, high temperature (FKM instead) |
| Nitrile rubber (Victaulic grade T) | NBR | orange stripe | -29 – 82 °C | petroleum products, air with oil vapour, vegetable and mineral oils | hot water above 66 C, hot dry air above 60 C |
EPDM – the standard
Ethylene propylene diene rubber is the sealing element for water in all its forms: drinking water, heating and cooling water, fire-fighting water, plus oil-free compressed air and technical gases. Viega, Sanha and Victaulic (grade E) use it black or with a green stripe. Its limit is oils and hydrocarbons: mineral oil, petroleum products and compressed air containing oil make EPDM swell; steam above the manufacturer's limit destroys it. The widest range runs from -30 to 120 °C (Sanha); Viega states 110 °C for its standard sealing elements, 105 °C for Megapress – and for drinking water 80 °C to DIN 1988-200 apply.
HNBR – for gas
Hydrogenated nitrile rubber, marked yellow, is the sealing material of the gas systems (Viega Profipress G, Sanpress G, Sanpress Inox G, Megapress G; Sanha NiroSan Gas, SANHA-Press Gas, Heavy Steel Press Gas): natural gas, LPG, hydrogen, technical gases, with the steel-pipe systems also heating oil and diesel. The temperature range is narrower, -20 to 70 °C, and drinking water is excluded – the gas systems carry their own DVGW approval.
FKM – for heat and oil
Fluoroelastomer (matt black at Viega, red at Sanha, blue or white at Geberit) carries the high-temperature and oil applications: solar, district heating, low-pressure steam, compressed air with oil, heating oil. Viega Megapress S with FKM is released up to 140 °C and 16 bar, Sanha NiroSan Industry up to 160 °C depending on the medium. Drinking water is permissible with FKM only if the manufacturer releases the system for it.
CIIR and nitrile
Chlorobutyl rubber is the standard ring of Geberit Mepla for drinking water and heating (drinking water 0–70 and heating 0–80 °C); gas and high temperature are handled at Geberit by FKM. Nitrile rubber is grade T of the Victaulic couplings (orange stripe) for petroleum products, air containing oil and oils, -29 to 82 °C, not for hot water above 66 °C.
The media matrix of the systems we carry
The matrix comes from the same data layer as the system finder: for each application and system the suitability according to the manufacturer and the sealing element intended for it. Limits per medium and the manufacturer's notes are shown by the system finder for each hit.
Show full table · more than 10 rows
| Application | Viega Profipress (copper) | Viega Profipress G (gas) | Viega Profipress S (solar, high temperature) | Viega Sanpress (gunmetal, stainless steel pipe) | Viega Sanpress G (gas) | Viega Sanpress Inox (stainless steel complete system) | Viega Sanpress Inox G (gas) | Viega Temponox (stainless steel, heating/cooling) | Viega Raxofix (multilayer composite pipe) | Viega Megapress (thick-walled steel pipe) | Viega Megapress S (FKM, higher temperatures) and S XL | Viega Megapress G (gas) | SANHA NiroSan (stainless steel press system) | SANHA NiroSan Gas | SANHA NiroSan Industry (FKM, high temperature) | SANHA-Press (copper) incl. Gas and Solar | SANHA-Therm (galvanised carbon steel, heating/cooling) | SANHA Heavy Steel Press (thick-walled steel pipe) incl. Gas | Geberit Mepla (multilayer composite pipe) | Geberit FlowFit (multilayer composite pipe, lateral press technology) | GF iFIT (push-fit system, polybutene and multilayer pipe) | Victaulic grooved couplings (Style 77 flexible, Style 75, rigid couplings) | Uponor RS 63-110 (modular press and plug-in system, multilayer composite pipe) | Uponor S-Press PLUS 16-32 and S-Press 14, 40-75 (multilayer composite pipe) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| drinking water | ● EPDM | – | – | ● EPDM | – | ● EPDM | – | – | ● without O-ring | – | – | – | ● EPDM | – | – | ● EPDM | – | – | ● CIIR | ● EPDM | ● O-Ring | ◐ EPDM E | ● O-Ring | ● O-Ring |
| heating water (closed circuit) | ● EPDM | – | ● FKM | ● EPDM | – | ● EPDM | – | ● EPDM | ● without O-ring | ● EPDM | ● FKM | – | ● EPDM | – | – | ● EPDM | ● EPDM | ● EPDM | ● CIIR | ● EPDM | ● O-Ring | ● EPDM E | ● O-Ring | ● O-Ring |
| cooling water | ● EPDM | – | – | ● EPDM | – | ● EPDM | – | ● EPDM | ◐ without O-ring | ● EPDM | – | – | ● EPDM | – | – | ● EPDM | ● EPDM | ● EPDM | ● CIIR | ● EPDM | ? | ● EPDM E | ● O-Ring | ● O-Ring |
| cooling water with antifreeze (glycol) | ◐ EPDM | – | – | – | – | ◐ EPDM | – | ◐ EPDM | – | ◐ EPDM | – | – | – | – | – | – | – | – | ◐ CIIR | – | – | ● EPDM E | ◐ O-Ring | ◐ O-Ring |
| solar circuit | ◐ FKM | – | ● FKM | – | – | ◐ FKM | – | – | – | ◐ FKM | ● FKM | – | – | – | ● FKM | ● FKM | ● FKM | – | – | – | – | – | – | – |
| compressed air, oil-free | ● EPDM | – | – | ● EPDM | – | ● EPDM | – | ● EPDM | – | ● EPDM | ● FKM | – | ● EPDM | – | – | ● EPDM | ● EPDM | ● EPDM | ◐ | ● EPDM | – | ● EPDM E | – | – |
| compressed air with oil | ◐ HNBR/FKM | – | ● FKM | – | – | ◐ HNBR/FKM | – | – | – | ◐ FKM | ● FKM | – | – | – | ● FKM | ● FKM | – | – | – | – | – | ● Nitril T | – | – |
| technical gases (nitrogen, argon, CO2) | ● EPDM | ● HNBR | – | ● EPDM | ● HNBR | ● EPDM | ● HNBR | ● EPDM | – | ● EPDM | ◐ FKM | ● HNBR | ● EPDM | ● HNBR | – | – | – | ● HNBR | ◐ CIIR | – | – | – | – | – |
| natural gas (DVGW G 260) | – | ● HNBR | – | – | ● HNBR | – | ● HNBR | – | – | – | – | ● HNBR | – | ● HNBR | – | ● HNBR | – | ● HNBR | – | – | – | – | – | – |
| liquefied petroleum gas (propane) | – | ● HNBR | – | – | ● HNBR | – | ● HNBR | – | – | – | – | ● HNBR | – | ● HNBR | – | ● HNBR | – | – | – | – | – | – | – | – |
| hydrogen | – | ● HNBR | – | – | – | – | ● HNBR | – | – | – | – | – | – | ● HNBR | – | ● HNBR | – | – | – | – | – | – | – | – |
| heating oil, diesel fuel | – | ◐ HNBR | – | – | – | – | ● HNBR | – | – | – | – | ● HNBR | – | – | ● FKM | – | ● FKM | – | – | – | – | ● Nitril T | – | – |
| low-pressure steam | – | – | ● FKM | – | – | ◐ FKM | – | – | – | – | ◐ FKM | – | – | – | ● FKM | ● FKM | – | – | – | – | – | – | – | – |
| fire-fighting water (wet system) | ● EPDM | – | – | ● EPDM | – | ● EPDM | – | – | – | ● EPDM | – | – | ● EPDM | – | – | – | ● FKM | – | ● CIIR | – | – | ● EPDM E | – | – |
| sprinkler system | ◐ EPDM | – | – | – | – | ◐ EPDM | – | – | – | ● EPDM | – | – | ● EPDM | – | ● FKM | – | ● EPDM | ? | – | – | – | ● EPDM E | – | – |
| rainwater, treated water | ● EPDM | – | – | ● EPDM | – | ● EPDM | – | ● EPDM | – | ● EPDM | – | – | ● EPDM | – | – | – | – | – | – | – | – | – | – | – |
| district heating (sub-station side) | – | – | ● FKM | – | – | ◐ FKM | – | – | – | – | ● FKM | – | – | – | ● FKM | ● FKM | – | – | – | – | – | – | – | – |
| mineral oil | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | – | ● Nitril T | – | – |
● suitable · ◐ with restrictions (manufacturer approval) · – not suitable or not in the manufacturer’s list · ? to be clarified
Where the matrix shows “to be clarified”, no manufacturer statement that we publish is yet available – in these cases we ask the manufacturer for you.
Four rules for handling sealing elements
- Check the colour code. Gas systems are marked yellow, high-temperature variants in colour – a black ring in the gas line is a mistake the leak test does not find.
- Do not replace the sealing element except with the system's own replacement. The manufacturers supply replacement rings for some systems (say FKM for Sanpress Inox); any other ring voids the approval.
- Additives are media. Antifreeze, corrosion inhibitors, cleaning agents and disinfection change the resistance – check concentration and product against the manufacturer's media list; cooling water with glycol has its own rows.
- Storage and ageing. Store connectors dry, dark and away from ozone sources; do not “lubricate” sealing elements with oil (manufacturer statement: only approved lubricants or water), do not install damaged rings.
Further reading
Tools of this section: System finder (which system suits medium, pipe and size) · Joining methods compared · Cost comparison calculator · Press systems overview.
The cross-cutting topics: Mixed installation and corrosion · Press profiles and tools · Leak testing and SC-Contur · Zeta values of press connectors
Frequently asked questions on seals and media
Why may a system with EPDM not carry heating oil?
Because EPDM swells in mineral oils and petroleum products. For heating oil and diesel the manufacturers provide HNBR (gas systems) or FKM.
Does the system value 16 bar / 105 °C also apply to drinking water?
No. With most systems drinking water is limited to 80 °C and 10 bar to DIN 1988-200; the manufacturer's statement applies per medium.
How do I recognise a gas sealing element?
By the yellow colour code (HNBR) and by the marking of the connector. Gas systems carry their own DVGW approval.
Can I swap the sealing element for FKM when it gets hotter?
Only if the manufacturer releases replacement rings for this system (say Sanpress Inox). Otherwise the system with an FKM ring is a different system (Megapress S, NiroSan Industry).
What does “conditionally suitable” mean in the matrix?
The manufacturer releases the medium with a restriction – say only up to a temperature, with certain additives or after consultation. The restriction is shown in the system finder with the hit.
Which sealing element for solar?
FKM: Viega Profipress S, SANHA-Press Solar, NiroSan Industry. EPDM does not tolerate the stagnation temperatures.
Medium not in the matrix?
Tell us medium, concentration, temperature and pressure – we ask the manufacturer about the resistance and name the system with the matching sealing element.
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Sources: Viega media list metallic piping systems 11/2025, Viega planning manual industrial technology 08/2026, Viega press connection systems 09/2024, instructions for use Megapress S XL 07/2026; Sanha product catalogue 2026; Geberit supply systems 07/2025; Victaulic 06.04 (01/2025). DIN 1988-200. Zickwolff experience values (class E) of 2026-09-24.