Industrial Check Valves (Non‑Return Valves) for Gas Safety and System Performance

EN ISO 5175‑2 Compliance

WITT check valves comply with EN ISO 5175‑2, the international standard governing gas non-return devices. This standard defines safety requirements, leakage limits, performance criteria, and test procedures for valves used with technical gases. Compliance ensures:

• Safe and reliable prevention of reverse gas flow
• Suitability for industrial fuel gases and oxidants
• Verified leak‑tightness and long‑term performance under defined test conditions

Extremely Low Cracking Pressure and Ultra‑Low Leakage

Thanks to the WITT valve architecture and high‑precision elastomer sealing systems, the valves achieve:

• Cracking pressures as low as approx. 0.058 psi (≈4 mbar)
• Extremely low leakage rates for maximum operational safety
• Stable performance even at very low operating pressures found in thermo‑process and biogas applications

Suitable for a Wide Range of Industrial Gases

WITT check valves are suitable for a broad range of technical and industrial gases, including:

• Carbon dioxide (CO₂) • Argon (Ar) • Helium (He) • Town gas • Ethylene (E)
• Natural gas and LPG • Hydrogen (H₂) • Nitrogen (N₂)
• Carbon monoxide (CO) • Oxygen (O₂) • Compressed air

The high‑quality elastomer sealing system delivers excellent gas tightness, while optional inlet filters protect the valve against particulate contamination.

Clear User Benefits

WITT check valves provide measurable benefits for system builders and operators:

• Compact size and low weight
• High flow capacity with minimal pressure drop
• Quiet operation due to reduced valve flutter
• Smaller pipe diameters can be used, reducing installation costs
• Lower operating costs through reduced compressor duty in low‑pressure systems
• In certain applications, valve performance may eliminate the need for an additional flashback arrestor (application- and model-dependent)

ULTRA Series – High‑Performance for Thermo‑Process and Biogas Applications

The ULTRA series represents WITT’s highest-performing non‑return valves and includes:

• Extremely low cracking pressure (~0.058 psi / 4 mbar)
• Very low pressure drop due to flow‑optimized internal geometry
• Quiet, low‑vibration operation
• Optional built‑in inlet filter for extended service life
• Housing materials: brass, stainless steel, aluminum
• Seal options: FPM, EPDM, FFKM
• G or NPT connections from 1/2'' to 2 1/2'' (type‑dependent)
• 100% performance tested before shipment
• Oxygen‑cleanable versions for O₂ service
• Suitable for EN 746‑2 thermo‑process applications

Modular Configuration Options

WITT check valves offer broad configurability:

• Housing materials (stainless steel, brass, aluminum)
• Elastomer sealing options matched to medium and temperature
• Optional inlet filters
• Wide range of G and NPT thread connections (1/2''–2 1/2'')

All oxygen‑service versions are cleaned according to EIGA guidelines, and elastomers are BAM‑approved for oxygen use.

Orientation‑Independent Installation

WITT check valves can be installed in any orientation (depending on model), simplifying OEM integration and enabling placement in tight or complex system layouts. This design flexibility is particularly beneficial in compact burner systems and biogas skids.

Thermo‑Processing and Burner Applications

Thermal processing installations frequently use multiple gases simultaneously—such as natural gas, hydrogen, nitrogen, or mixed process gases. In these systems, WITT check valves:

• Prevent hazardous gas mixtures inside supply lines
• Protect upstream gas mixing, metering, and control equipment
• Maintain stable flow even at very low operating pressures
• Provide reliable performance in continuous furnaces, roller hearth furnaces, vertical kilns, and other thermo‑process equipment

Biogas Applications

Biogas systems require careful control of methane-rich gas and the air/oxygen supply used for biological desulphurization. WITT stainless steel check valves:

• Allow aeration gases to flow in one direction only
• Prevent dangerous mixtures inside the digester
• Operate with extremely low cracking pressure (~0.058 psi)
• Reduce compressor energy requirements through low pressure drop
• Enable easy retrofitting and orientation‑independent installation

Industry‑Wide Check Valve Types

Standard market categories include:

• Poppet check valves
• Lift check valves
• Inline check valves
• Modular check valve configurations

WITT specializes in high‑performance gas check valves optimized for low‑pressure operation, high flow stability, and maximum leak‑tightness.

OEM Benefits

• Orientation flexibility
• Modular material and seal configurations
• Extremely low pressure drop
• Compact dimensions for space‑constrained layouts
• Long service life
• Manufactured under ISO 9001 quality standards

Safety & Quality Assurance

• Oxygen‑cleaned for O₂ service (EIGA/CGA compliant)
• BAM‑approved elastomers
• Each unit is 100% individually tested

Frequently Asked Questions (FAQ)

Q: What is the cracking pressure?
A: Depending on model, as low as approx. 0.058 psi (4 mbar).

Q: Are the valves suitable for oxygen?
A: Yes, oxygen‑cleaned versions are available.

Q: Can WITT check valves be installed in any orientation?
A: Yes, depending on the model.

Flyer: Non-return valves in thermal processing plantsFlyer: Non-return valves in biogas plants