Stainless Steel Normally Open Solenoid Valve — SS304, Viton Seal, High Temperature up to 180 °C

Cematic's normally open stainless steel solenoid valve is a direct-acting, high-flow solenoid valve designed for industrial systems operating with fluids at elevated temperatures, aggressive fluids, or in environments where brass does not offer the necessary chemical resistance. Its 304 stainless steel body and Viton seal distinguish it from NA brass solenoids with NBR seals: consequently, it extends the working temperature range up to 180 °C and offers compatibility with fluids that degrade NBR or attack brass.

In addition, its direct-acting design ensures reliable operation with zero differential pressure — unlike pilot-operated solenoids, it opens and closes correctly even without line pressure. Therefore, it is the correct choice in steam systems, hot water, synthetic oils, and high-temperature process fluids where flow is required to continue in the event of an electrical failure (safe state = open).

Operating Principle — Normally Open (NO)

In the de-energized state (coil de-energized): the valve remains open — fluid flows freely. When the coil is energized, the electromagnetic field displaces the plunger, closing the fluid passage. When de-energized, the spring returns the plunger, and the flow automatically resumes.

This configuration is correct when:

• Flow must be maintained in the event of an electrical power failure (safe state = open)
• The valve operates energized most of the time — it closes by signal and opens when de-energized
• Automatic opening is required in refrigeration, cooling, or heating systems during unscheduled outages

If your application requires automatic closure in the event of an electrical failure, the correct option is the normally closed (NC) solenoid valve →

Why SS304 + Viton vs. Brass + NBR?

The choice of body and seal material defines the actual application range of a solenoid valve. Therefore, it is important to understand when this combination is correct:

• Temperature: The NBR seal works up to 80–90 °C. Viton, on the other hand, resists up to 180 °C — which enables this valve for low-pressure steam, hot water, high-temperature oils, and thermal process fluids that would destroy an NBR seal in weeks.
• Chemical resistance: SS304 resists process water, moderate aqueous solutions, and many industrial fluids that degrade zinc-plated brass. Likewise, Viton is compatible with a significantly wider chemical range than NBR, including synthetic oils, fuels, and some solvents.
• Hygiene and cleanliness: Stainless steel does not introduce metal ions into the fluid — unlike brass — making this solenoid suitable for purified water applications, industrial utilities in food processing plants, and processes where metallic contamination is unacceptable.

Construction Materials

• Body: 304 Stainless Steel (SS304) — corrosion resistance for water, steam, aqueous solutions, and industrial process fluids. Higher purity surface than brass for applications with cleanliness requirements.
• Plunger: Stainless steel with optimized mass for direct action and fast response.
• Seat Seal: Viton (FKM) — compatible with temperatures up to 180 °C, synthetic oils, fuels, aggressive process fluids, and most non-halogenated industrial solvents. It is the correct seal when NBR cannot withstand the temperature or the fluid.
• Coil: Encapsulated in resin, IP65 protection — suitable for humid environments, with condensation and industrial dust.
• Connection: Female NPT thread — industrial standard in Mexico, compatible with stainless steel, carbon steel, and copper pipes.

Technical Specifications

Voltage Selection

• 24 VDC: Standard in industrial control cabinets with PLC and DC power supply. Safety voltage, the most common option in new installations and modern automated systems.
• 110 VAC: For installations with 110 V single-phase circuits available in the field — the most widespread voltage in industry in Mexico and the United States.
• 220 VAC: For power panels with bi-phase distribution or installations with European voltage standards.

Fluid Compatibility

• ✅ Low-pressure steam up to 180 °C — enabled by the Viton seal; not compatible with standard NBR seal
• ✅ Hot water up to 180 °C — heating systems, heat exchangers, and thermal processes
• ✅ Process water and purified water — no metallic ion contribution from the SS304 body
• ✅ Compressed air up to 1.0 MPa — high-pressure industrial pneumatic service
• ✅ Hydraulic and synthetic oils — Viton resists a wider range of oils than NBR
• ✅ Fuels and mineral oils — check area classification before installation
• ⚠️ Fluids with suspended solids: install an upstream line filter to protect the seal and orifice
• ❌ Concentrated acids, halogenated solvents, fluids with high chlorides: SS304 may be insufficient — consult Cematic's technical team for the need for SS316

Main Industrial Applications

Steam and High-Temperature Process Fluid Control
This is the differentiating application of this solenoid valve compared to brass NA solenoids with NBR seals. The normally open stainless steel solenoid valve with Viton seal operates reliably in low-pressure steam lines, superheated water, and thermal transfer fluids up to 180 °C. Therefore, it is the standard component in industrial heating systems, sterilization, and CIP/SIP processes where the fluid temperature exceeds 90 °C.

Industrial Refrigeration and HVAC Systems
In refrigeration circuits with Viton-compatible refrigerants, this solenoid maintains open flow during normal operation and cuts it off upon receiving a signal from the controller. In addition, in the event of a power outage, flow is automatically restored — preventing overheating in the protected equipment.

Industrial Processes with Aggressive Fluids
In chemical, petrochemical, and manufacturing plants where the process fluid degrades NBR or brass, the SS304 + Viton combination offers the necessary chemical resistance for continuous operation without premature seal replacement. Likewise, it is the correct option in applications with synthetic oils, fuels, and organic heat transfer fluids.

Purified Water and Utilities in Food and Pharmaceutical Industries
The SS304 body does not contribute copper or zinc ions to the fluid — unlike brass — making this solenoid valve suitable for controlling purified water, water for injection (WFI), and industrial utilities in production areas where metallic contamination must be controlled.

Industrial Washing and CIP Equipment
In clean-in-place (CIP) systems with hot alkaline or acidic solutions, the Viton seal resists chemical degradation that would destroy an NBR seal in a few weeks. Consequently, it reduces maintenance costs and downtime due to seal replacement.

For the complete range of solenoid valves, see solenoid valve collection →

Technical Data Sheet