Solenoid Valve Seal Material

Seal Materials

Solenoid Valve Materials and Chemical Compatibility.

Solenoid valves are used to control a wide range of fluid and gas media. In most instances for general purpose applications such as ambient temperature air, water and atmospheric gases a standard Brass solenoid valves with NBR seals will be suitable.

How ever solenoid valves are manufactured from a range of materials such as Brass, 304 Stainless Steel, 316 Stainless Steel, Cast Steel, Cast Iron, Ductile Iron, Bronze, Aluminium and various Plastics such as Nylon, PVC, PVDF, PP and PTFE with options for various seal materials such as NBR, FKM (Viton®), EPDM and PTFE (Teflon®). These various materials of construction and choice of elastomer sealing are designed to cope with more aggressive and corrosive acid and alkali media.

Solenoid valve users are frequently faced with challenging applications were the media being controlled must be compatible with the materials of construction of the valve.

This user friendly material chemical resistance chart is offered as guidance, we would strongly recommend that ever application is checked with the solenoid valve supplier for application compatibility. In some instances the chemicals being used will be brand names, and in this instance it is best practice to contact the technical team or laboratory of the chemical manufacturers to obtain a list of approved and suitable valve materials

Selecting the correct seal for a solenoid valve requires some understanding of the available seal materials in the market today. With so may options for valve materials of construction we have compiled some basic information to assist in choosing the correct valve seal.

Solenoid Valve O Ring and Elastomer Seal Temperature ranges

These are guide minimum and maximum elastomer seal working temperature parameters, which can be achieved with the best grades of sealing material, lesser grades or cheaper materials will have significantly limited ranges, so please check with your material supplier

EPDM

EPDM Rubber.

The chemical name for this EPDM rubber is Ethylene Propylene Diene Monomer rubber. EPDM seals in solenoid valves are well suited for use with hot water, low pressure steam (130°C Max) due to EPDM excellent resistance to heat and offer excellent weather resistance. The maximum working temperature of EPDM is approximately 120-130 degrees Celsius. EPDM is unsuitable for most oils and fuels.

HNBR (Hydrogenated Nitrile Butadine Rubber).

HNBR or Hydrogenated NBR is also known as HSN Highly Satuarated Nitrile rubber is an Buna Rubber with a high saturation of Butadiene Carbon Polymer giving improved chemical, abrasion resistance and dynamic loading resistance compared to standard NBR. Temperature range +150C Max.

HNBR has good resistance to:

  • Motor oils
  • Sour gas
  • Amine oils
  • Oxidised fuels
  • Lubricating oils
  • Mineral oils
  • Animal and vegetable oils
  • Diesel fuels
  • Ozone
  • Dilute acids and alkali's
  • Bio-fuel oils

HNBR has poor resistance to:

  • Concentrated alkali's
  • Esters
  • Alkyl phosphate
  • Ethers
  • Halogenated
  • Solvents
  • Ketone's
  • Halogenated hydrocarbons
  • Flames.

Hypalon ®

Hypalon is similar to Neoprene but with improved acid resistance. Temperature range -17C to +104C

Hypalon = good resistance to:

  • Oxidisation
  • Ozone
  • Flames
  • Nitric Acid
  • Hydrofluoric acid
  • Sulphuric acid
  • Abrasion resistance

Hypalon = poor resistance to:

  • Concentrated oxidising acids
  • Esters
  • Ketones
  • Chlorinated hydrocarbons
  • Aromatic hydrocarbons
  • Nitro hydrocarbons
  • Steam

NBR

NBR ( Buna -N) Nitrile Buna Rubber.

The chemical name for this rubber is Nitrile Rubber is Butadiene Acrylonitrile, however it is typically known as NBR or Buna-N. NBR is probably the most typically used seal for most valves and is the standard seal used by most valve manufacturers for neutral fluids and gases for general purpose applications. NBR is the standard material used by most O ring seals.

NBR will typically withstand temperatures up to +90°C on a continuous basis and can with stand slightly higher temperatures for a short period of time before hardening.

In additional to being used as a solenoid valve seal, NBR is also found in water pumps, carburettor, transmissions, hydraulic pumps and hydraulic actuator seals.

Neoprene

A low compression flame resistant polymer. Temperature range -29C to +107C

Neoprene = good resistance

  • Animal oil
  • Vegetable oil

Neoprene = poor resistance

  • Oxidizing acids
  • Chlorinated solvents
  • Esters
  • Ketone's
  • Aromatic hydrocarbons
  • Hydraulic fluids

PEEK

PEEK (Polyetheretherketone)

Peek Polyetheretherketone is an organic thermosplastic polymer with strong chemicsl, thermal and mechanical resistance, excellent for medical implants. Temperature range -40C to +340C

PEEK has good resistance to

  • Water
  • Steam
  • Acid
  • Alkali
  • Ultra high vacuum

Peek has poor resistance to

  • Halogens
  • Strong Bronsted Acid
  • Strong Lewis Acid such as Sulphuric Acid H2SO4
  • Halogenated compounds
  • Aromatic hydrocarbons at high temperature

PTFE (Teflon ®)

Teflon is a brand name for PTFE which stands for Polytetrafluoroethylene. PTFE is resistant to most liquids. Not suited to liquid alkali's and Fluorine.PTFE is non elastic (not flexible), so this limits is sealing capabilities for certain applications. PTFE can reach very high temperatures up to +230°C, but gives off poisonous gases above +250°C, and is commonly used for cryogenic applications down beyond -200°C. PTFE is the preferred seal for very high pressure solenoid valves, aggressive and corrosive media and extreme temperature applications such as high pressure steam. Virgin PTFE accepted by FDA for food use.

RTFE 15%

Is a 15% glass reinforced tetrafluoroethylene that adds to the pressure that PTFE can withstand. 15% RTFE is not suitable for due to the reaction with the glass reinforcement. Temperature range -40C to +232C.

Good resistance to

  • Load reformation
  • Wear
  • Abrasion
  • Most chemicals

Poor resistance to

  • Hydrofluoric acids
  • Hot caustic solutions

RTFE 25%

Is a 25% glass reinforced tetrafluoroethylene that adds to the pressure that 15% RTFE can withstand. Temperature range -40C to +232C.

Good resistance to

  • Load reformation
  • Wear

Poor resistance to

  • Hydrofluoric acids
  • Hot caustic solutions

Silicone

Silicone (VQM) elastomer seals offers a wide working temperature range from -54°C through to +232°C, but Silicone is a very soft material and therefore is not very good with higher pressure applications typically above 40 bar (depending on orifice size and design).

Silicone good resistance to:

  • Ozone
  • Weathering
  • Heat and Steam
  • Cold
  • Chemicals
  • Oils
  • Acids
  • Electrical
  • Water

Silicone poor resistance to:

  • Tensile Strength
  • Diesel Fuels

TFM® 1600

TFM is a modified TFE tetrafluoroethylene polymer that the same PTDE chemical and heat resistance but with a denser TF polymer construction offers better stress recovery suited to seat, seal and gaskets for valve applications. WRAS, 3A and FDA approved material. Temperature range -40C to +260C.

TFM with Carbon Graphite filling.

TFM® 1600 filled with Amorphous Glass powder and graphite offering huge reduction in thermal expansion co-efficient (expansion due to heat) making it ideal sealing material for steam and other high temperature valves. Temperature range +40C to +260C, or +320C for liquid media.

UHMWPE (Ultra High Molecular Weight Polyethylene).

Ultra High Molecular Weight Polyethylene (UHMWPE) also referred to as High Modulas Polyethylene (HMPE) or High Performance Polyethylene (HPPE) is a very strong seal material.

Good resistance to:

  • Acids
  • Alaki's
  • Friction
  • Abrasion

Poor resistance to:

  • Oxidising acids
  • Organic solvents

Viton® (FKM) Rubber.

Viton is a brand name for a Fluoroelastomer. FKM is well know for its excellent heat resistance, making service temperatures up to +150°C obtainable.

Zurcon® Z80.

Zurcon Z80 is a brand name for virgin ultra high molecular weight Polyethylene or UHMWPE. Zurcon offers zero water absorption and extreme abrasion resistance that is 500% more abrasion resistant than PTFE and is ideally suited for water, food and pharmaceutical processes. Working temperature ranges -120°C to +93°C, beyond this the wear and abrasion properties reduce, with short static maximums ranges from -200°C to +200°C.

Zurcon Z80 offers a virtually dry friction coefficient that even outperforms most PTFE compound seals offering a self lubricating non stick surface.

Zurcon Z80 has good resistance to

  • Abrasion
  • Water absorption
  • Friction
  • Hydraulic fluids
  • Acids
  • Bases
  • Aggressive Media
  • Radiation up to 100kGy
  • Extrusion

Zurcon Z80 has poor resistance to:

  • Aromatic hydrocarbons
  • Halogenated hydrocarbons

Seals & Chemicals

Chemical Compatibility Charts for Seal Materials.

Please find below a range of solenoid valve seal material and body material liquids, gas chemical compatibility guides offering 302 stainless steel, 304 stainless steel, 316 stainless steel, 440 stainless steel, Aluminium, Titanium,, Hastelloy C, Cast Bronze, Cast Iron, Carbon Steel, PVC, Polyacetal, Nylon, ABS, Polyethelyene, Polypropylene, Rylon, Carbon, Viton (FKM), Buna N (NBR), Silicone, Neoprene, Ethylene Propylene (EPDM), Natural Rubber, and Epoxy chemical resistance guides E excellent - G Good resistance - M moderate resistance and X not recommended for everything from Acetaldehyde through to Zinc Sulphate.