Normally Open High-Temperature Brass Solenoid Valve — Viton Seal, up to 180 °C, 0 to 1.0 MPa

Cematic's high-temperature brass solenoid valve with normally open (NO) configuration is a direct-acting, high-flow solenoid valve for processes that simultaneously require continuous flow in the event of power failure and thermal resistance above 80 °C. Its Viton (FKM) seal extends the operating temperature range up to 180 °C — making it suitable for low-pressure steam, hot water, and thermal process fluids where a standard NBR seal would degrade in weeks.

Unlike the NO brass solenoid with an NBR seal (up to 80 °C), this product is designed for high-temperature environments where flow must remain open in the event of any power cut — for example, refrigeration, heating, and cooling systems where interrupting fluid flow during a power failure would cause damage to the protected equipment. Additionally, the brass body offers a lower-cost alternative to SS304 when the fluid is compatible with this material.

Operating Principle — Normally Open (NO)

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

This configuration is correct when:

• Flow must continue in the event of a power failure (fail-safe = open)
• Fluid temperature exceeds 80 °C, ruling out the standard NBR seal
• The fluid is compatible with a brass body — hot water, low-pressure steam, high-temperature oils
• High-temperature resistance with a brass body is sought as a lower-cost alternative to SS304

If your application requires automatic closure in the event of power failure at high temperatures with a brass body, the correct option is the high-temperature NC brass solenoid →

Why Viton and not NBR at high temperatures

The seal determines the actual thermal operating range of a solenoid valve. Therefore, choosing the correct elastomer is as important as choosing the body material:

• NBR (Nitrile) — up to 80 °C: Standard seal in general-purpose industrial solenoids. Suitable for ambient temperature water, air, and light hydraulic oils. Above 80–90 °C, NBR loses elasticity, leaks, and deforms permanently — leading to premature failures and high maintenance costs.
• Viton (FKM) — up to 180 °C (this product): Fluorinated elastomer with superior thermal and chemical stability. Maintains its sealing properties up to 180 °C and resists synthetic oils, fuels, and aggressive process fluids that would degrade NBR. Consequently, it is the correct seal for steam, hot water, and industrial thermal processes where NBR is insufficient.

Construction Materials

• Body: High-quality brass — corrosion resistance for water, low-pressure steam, compressed air, and hydraulic oils. Cost-effective alternative to SS304 when the fluid is compatible with brass.
• Plunger: Stainless steel — resistant to fluid corrosion and with optimized mass for reliable spring-driven opening and quick electromagnetic closing.
• Seat Seal: Viton (FKM) — compatible with temperatures up to 180 °C, synthetic oils, and high-temperature process fluids. Key differentiator from the NO brass solenoid with standard NBR.
• Coil: Resin encapsulated, IP65 protection — suitable for humid environments, with condensation and industrial dust.
• Connection: Female NPT thread — industrial standard in Mexico, compatible with steel, copper, and PVC pipes with adapters.

Technical Specifications

Voltage Selection

• 24 VDC: Standard in industrial control cabinets with PLCs and DC power supplies. 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 boards with bi-phase distribution or installations with European voltage standards.

Fluid Compatibility

• ✅ Low-pressure steam up to 180 °C — enabled by the Viton seal; standard NBR cannot withstand this temperature
• ✅ Hot water up to 180 °C — heating, cooling systems, and industrial thermal processes
• ✅ Process water at ambient and elevated temperatures — up to 0.7 MPa
• ✅ Compressed air up to 1.0 MPa — industrial pneumatic service
• ✅ Mineral and synthetic hydraulic oils — Viton compatible with a wider range of oils than NBR
• ⚠️ Seawater or fluids with high chlorides at temperature: brass may be insufficient — consider the SS304 stainless steel NO solenoid →
• ⚠️ Fluids with suspended solids: install an upstream in-line filter to protect the seal and orifice
• ❌ Concentrated acids, chlorinated solvents: use a solenoid with an SS304 or SS316 stainless steel body

How to choose between Cematic's high-temperature NO solenoids

When the application requires NO configuration and high-temperature resistance, Cematic offers two variants depending on the body material:

• NO Brass + Viton up to 180 °C — this product: For hot water, low-pressure steam, and thermal processes where the fluid is compatible with a brass body. The lowest-cost solution for high-temperature with NO configuration.
• NO SS304 + Viton up to 180 °C: For fluids that require a stainless steel body — purified water, aggressive fluids, pharmaceutical or food processes. See NO stainless steel solenoid →

Main Industrial Applications

High-temperature industrial refrigeration and cooling systems
In refrigeration circuits with hot water or high-temperature refrigerants, this high-temperature brass solenoid valve keeps the flow open during normal operation and closes it when receiving a signal from the controller. In the event of a power cut, the flow is automatically restored — protecting the equipment from overheating. Therefore, it is the standard configuration in systems where continuous flow is the safety condition.

Steam and hot water control with fail-safe open
In low-pressure steam heating systems where fluid interruption during a power failure would pose an operational risk — pipe freezing, damage to thermal equipment — this NO solenoid with Viton guarantees continuous flow of steam or hot water up to 180 °C even in the event of an unscheduled power cut. Consequently, it is the correct choice when the safe state of the process is open flow.

HVAC and zoned hot water distribution
In heating installations with hot water distribution, this NO solenoid valve controls the closure of specific zones upon receiving a signal from the controller, while maintaining flow in active zones. Furthermore, in the event of any power failure in the control system, operating zones continue to receive hot water without interruption.

High-temperature processes with synthetic oils
In centralized lubrication systems and heat transfer with high-temperature oils, the Viton seal resists chemical and thermal degradation that would render an NBR seal unusable. Likewise, the NO configuration ensures that oil flow is maintained in the event of any power failure, protecting lubricated equipment from damage due to lack of lubrication.

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

Technical Data Sheet