Normally Closed High-Temperature Brass Solenoid Valve — Viton Seal, up to 180 °C

Cematic's normally closed high-temperature brass solenoid valve is a direct-acting, high-flow solenoid valve designed for processes requiring both automatic shut-off in case of power failure (NC) and thermal resistance above 80 °C. Unlike the NC brass solenoid with a standard NBR seal, this solenoid valve incorporates a Viton (FKM) seal that extends the operating temperature range up to 180 °C — enabling its use in low-pressure steam, hot water, and thermal process fluids where NBR would degrade in weeks.

Therefore, it is the intermediate solution between the NC brass solenoid with NBR (up to 80 °C) and the NC stainless steel solenoid with Viton (up to 180 °C), when the process requires high temperatures but the brass body is compatible with the fluid and budget is a relevant factor.

Operating Principle — Normally Closed (NC)

When de-energized (coil off): the valve remains closed — the internal spring holds the plunger on the seat, blocking fluid flow. When the coil is energized, the electromagnetic field lifts the plunger and opens the flow path. When de-energized, the spring automatically returns the plunger to the closed position.

This configuration is correct when:

• The fluid must be automatically shut off in case of electrical power failure (safe state = closed)
• The fluid temperature exceeds 80 °C, ruling out the standard NBR seal
• The fluid is compatible with a brass body — hot water, low-pressure steam, oils at elevated temperatures
• A combination of high temperature and a brass body is sought as a lower-cost alternative to SS304

Viton Seal vs. NBR — when the difference matters

The seal is the most critical component of a solenoid valve in high-temperature applications. Therefore, the correct choice determines the actual service life of the equipment:

• NBR (Nitrile) — up to 80 °C: Standard seal in most industrial solenoids. Suitable for cold water, process water at room temperature, compressed air, and light hydraulic oils. Above 80–90 °C, NBR loses elasticity and begins to leak and permanently deform.
• 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.

Construction Materials

• Body: High-quality brass — corrosion resistance for water, low-pressure steam, compressed air, and hydraulic oils. A cost-effective solution compared to SS304 when the fluid is compatible with brass.
• Plunger: Stainless steel — corrosion-resistant to fluid and with optimized mass for reliable spring closure and quick electromagnetic opening.
• Seat seal: Viton (FKM) — compatible with temperatures up to 180 °C, synthetic oils, and process fluids at elevated temperatures. This is the key differentiator of this product compared to the NC brass solenoid with standard NBR.
• Coil: Resin encapsulated, IP65 protection — suitable for humid, condensing, and industrial dust environments.
• 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 distribution panels with two-phase distribution or installations with European voltage standards.

Fluid Compatibility

• ✅ Low-pressure steam up to 180 °C — enabled by the Viton seal; standard NBR does not withstand this temperature
• ✅ Hot water up to 180 °C — heating systems, heat exchangers, 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 high temperature: brass may be insufficient — consider the NC stainless steel SS304 solenoid →
• ⚠️ Fluids with suspended solids: install an upstream 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 NC solenoids

Cematic offers three direct-acting, high-flow NC variants to cover different temperature ranges and material requirements:

• NC Brass + NBR (up to 80 °C): For cold water, air, and oils at ambient temperature. The standard, lower-cost option for general applications. See NC brass NBR solenoid →
• NC Brass + Viton (up to 180 °C) — this product: For hot water, low-pressure steam, and thermal processes where the brass body is compatible with the fluid. The intermediate solution between cost and high-temperature performance.
• NC SS304 + Viton (up to 180 °C): For fluids requiring a stainless steel body — purified water, aggressive fluids, pharmaceutical, or food processes. See NC stainless steel solenoid →

Main Industrial Applications

Steam and hot water control with safety shut-off
In industrial heating systems, low-pressure steam generators, and hot water circuits, this normally closed high-temperature solenoid valve combines automatic shut-off in case of power failure with the thermal resistance of the Viton seal up to 180 °C. Therefore, it is the standard control component when the safe state requires fluid cut-off and the process temperature exceeds 80 °C.

CIP processes with hot water
In Clean-in-Place (CIP) systems with hot pressurized water, this NC solenoid valve with Viton resists the cleaning cycle temperatures that would degrade an NBR seal. Additionally, the NC closure ensures that the hot water flow is automatically interrupted at the end of each cycle, without the need for manual intervention.

HVAC and hot water heating systems
In hot water heating installations with zone distribution, this NC solenoid controls the opening and closing of each zone from the central controller. Consequently, it allows for the automation of heat distribution with safety shut-off in case of unplanned power outages.

Control of process oils at elevated temperatures
In centralized lubrication systems with hot oil and thermal transfer circuits with synthetic oils, the Viton seal resists the degradation that would render an NBR seal unusable at elevated temperatures. Likewise, the brass body offers the necessary compatibility with hydraulic and mineral oils at a lower cost than SS304.

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

Datasheet