IMI Norgren S/521 Non-return valve - G1/4
Part Number: S/521
Quick Summary
IMI Norgren S/521 non-return valve provides unidirectional flow control for compressed air systems. On busy shop floors, backflow, leaks, and fluctuating pressure can derail production and inflate maintenance costs. This valve family is designed to meet common industry standards, including CE conformity and IP-rated protection where applicable, with SIL-ready options for safety-critical circuits. Its heavy-duty brass body and nitrile rubber elastomer seals deliver long-term reliability in demanding environments. The compact 19x19x48 mm footprint simplifies panel mounting and minimizes install time, while the G1/4 port size supports broad compatibility with standard pneumatic fittings. By combining durability, predictable performance, and spare-kit availability, it helps reduce downtime and total cost of ownership.
Product Information
Extended Description
S/521 Norgren: Allows free flow in one direction only | Simple reliable design | High operating pressure and temperature | Spares kit available
Medium
Compressed air
Operating Temperature
-20 ... 80 °C, -4 ... 176 °F
Operating Pressure
0.3 ... 16 bar, 4 ... 232 psi
Port Size
G1/4
Materials - Body
Brass
Materials - Elastomers
Nitrile rubber
Dimensions - Height
19 mm
Dimensions - Length
19 mm
Dimensions - Width
48 mm
Weight
0.09 kg
Country of Origin
China
Range
S/520 Series
Series
Martonair
Brand
IMI Norgren
Unidirectional flow control is built into a heavy-duty non-return design, which prevents reverse air flow that can cause actuator stalls and compressor cycling. This protection reduces backpressure on valves and minimizes leakage, delivering more consistent performance across automation circuits such as assembly lines and packaging equipment. The brass body and nitrile elastomer seals deliver robust durability in harsh industrial environments, reducing maintenance frequency and part replacement costs. With a wide operating range of -20 to 80 °C and 0.3 to 16 bar, the S/521 offers installation flexibility across multiple pneumatic layouts without requiring multiple SKUs. Its compact footprint and standard G1/4 connections save space in control panels and simplify retrofits. Spares kits ensure quick service, improving uptime and total cost of ownership. Compatible with the S/520 Series Martonair family, it supports scalable automation architectures and longer service intervals.
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FAQs
Ensure correct orientation and thread sealing with PTFE, use standard G1/4 fittings, and follow torque guidelines to prevent leaks and ensure a stable seal in panel-mounted assemblies.
The valve supports -20 to 80 °C and 0.3 to 16 bar, accommodating typical industrial compressed air systems while using nitrile elastomer seals for chemical compatibility with common lubricants and fluids.
Yes, rated up to 16 bar, making it appropriate for many automation and packaging lines where reliable one-way flow is essential; verify compatibility with your specific medium and fittings.
Regular inspection of seals and port connections, use of the available spares kit for seal replacement, and keeping the valve free from contamination will maintain performance and reduce downtime.
Ideal for pneumatic circuits in automation, manufacturing, and packaging equipment, where unidirectional flow protects downstream components and improves cycle consistency.