NAMUR Valves [ROSS 95 & 34 Series] Spool or Ball Poppet Design

Product Overview

The ROSS Controls NAMUR 95 Series and 34 Series are directional control valves designed to mount directly onto pneumatic valve actuators at the NAMUR interface, eliminating external tubing, fittings, and support hardware between the pilot valve and the actuator. Both series comply with the VDI/VDE 3847 NAMUR interface standard, providing dimensional interchangeability with actuators and accessories from any manufacturer following this international specification. The 95 Series uses resilient spool and sleeve construction for high-flow 5/2-way directional control, while the 34 Series uses patented ball-poppet technology for compact 3/2 normally closed service with zero internal leakage.

The NAMUR 95 Series valves are compact in-line ported 5/2-way valves with a fixed 1/4" port size. Available in single solenoid (spring return) and double solenoid (detented) configurations with a choice of 24 VDC or 110/120 VAC solenoid control, the 95 Series provides an average Cv of 1.3. The resilient spool and sleeve construction ensures durability in both lubricated and non-lubricated compressed air service. Manual override capability is standard, and pressure ports are conveniently located within the valve body at the NAMUR interface to eliminate external port connections entirely.

The NAMUR 34 Series valves introduce ROSS's ball-poppet technology at the NAMUR interface. The patented ball-poppet internals eliminate internal leakage by providing positive sealing rather than the close-clearance sliding seal used in spool valves. Duck-bill protected exhaust ports resist contamination ingress from washdown and ambient particulate accumulation, extending service life in harsh environments. The epoxy powder coat finish provides corrosion resistance against chemical exposure. The 34 Series is configured as 3/2 Normally Closed, weighs 0.8 lb (0.3 kg), and draws only 0.7 watts on 24 VDC, making it the low-power, compact option in the NAMUR product line.

Both series mount directly to the actuator NAMUR flange using the standard 5 mm fastener pattern and sealed by O-rings in the standardized grooves. This direct mounting approach reduces the number of potential leak paths in the pneumatic circuit compared to tubed installations, improves mechanical robustness against vibration and thermal cycling, and reduces the installed footprint of automated valve assemblies in process piping. The NAMUR interface design is widely adopted in oil and gas, chemical, water treatment, and power generation process automation.

Key Engineering Features

• VDI/VDE 3847 NAMUR Interface Compliance - Both series conform to the VDI/VDE 3847 NAMUR interface standard for 1/4" porting, ensuring dimensional interchangeability with pneumatic actuators from any compliant manufacturer. The standardized bolt pattern, port locations, and O-ring groove dimensions enable direct mounting without custom adapters or transition plates.
• 95 Series: Resilient Spool and Sleeve Construction - High-flow spool valve design with resilient spool and sleeve materials that provide durability in both lubricated and non-lubricated compressed air service. Average Cv of 1.3 delivers fast actuator response for large rotary and linear pneumatic actuators. 5/2-way configuration provides complete directional control of double-acting actuators.
• 34 Series: Patented Ball-Poppet Internals - Ball-poppet design virtually eliminates internal leakage through positive sealing contact, unlike spool valves that rely on close-clearance fits susceptible to wear-induced bypass leakage. Self-cleaning valve seats maintain sealing integrity throughout the valve's operational life without periodic lapping or adjustment.
• 34 Series: Duck-Bill Protected Exhaust Ports - Patented duck-bill exhaust port design limits the entry of washdown fluids and contamination during cleaning operations and in outdoor environments. This protection is critical in food and beverage, pharmaceutical, and outdoor process installations where periodic high-pressure washdown is routine.
• 34 Series: Epoxy Powder Coat Corrosion Protection - The 34 Series valve body features an epoxy powder coat finish that protects against moisture, chemical splatter, and corrosive atmospheric exposure. This finish extends valve service life in environments where painted or bare aluminum surfaces would corrode during normal operations.
• Fast Response Time with Low Wattage Operation - Solenoid pilot design provides rapid shifting response for precise process valve positioning. The 34 Series draws only 0.7 watts on 24 VDC, enabling integration with low-power distributed I/O systems and reducing heat load in multi-valve installations. The 95 Series operates at 2.5 watts DC for fast response with larger actuators.
• 5/2 Double Solenoid (Detented) Option for 95 Series - Double solenoid detented 95 Series valves maintain their actuated position without continuous electrical power after the shift is complete. This eliminates continuous solenoid energization, reduces heat generation, and provides power-loss position retention for applications where maintaining the last commanded actuator position during a power fault is preferred.
• Push-Button Non-Locking Manual Override Standard - Standard non-locking manual override on all solenoid pilot models allows manual valve actuation during commissioning, system testing, and troubleshooting without requiring electrical power. The non-locking design auto-returns to solenoid control when released, preventing inadvertent valve lockout.
• Internal Pilot Supply with Field-Convertible External Pilot - Both series use internal pilot supply from line pressure as the standard configuration. External pilot supply conversion is available for applications where variable inlet pressure is expected or where separate pilot supply pressure is required. Conversion is field-accomplished without valve replacement.
• Dual Voltage Options for Flexible Control System Integration - Available in 24 VDC for PLC and distributed I/O system integration and 110/120 VAC for direct connection to AC industrial power distribution. The 95 Series single solenoid also offers 110/120 VAC for legacy control panel compatibility.
• EN 175301-803 Industrial Connector for Reliable Electrical Connection - The 95 Series uses EN 175301-803 Industrial Form B connectors, providing a standardized, secure electrical interface compatible with standard industrial solenoid valve connectors throughout the installation. The 34 Series offers both Form A and M12 connector options for flexible wiring system compatibility.

Technical Specifications

General Specifications

Temperature Ratings

The 95 Series and 34 Series have different temperature ranges due to their distinct construction and intended environments. The 34 Series lower minimum temperature (-10 C versus 5 C for the 95 Series) reflects the ball-poppet design's better low-temperature performance relative to spool construction.

Important: For media temperatures below 40 F (4 C), compressed air must be free of water vapor to prevent ice formation inside the valve. Dry the compressed air supply to a dew point below the minimum operating temperature.

Electrical Data (Solenoid Pilot Valves)

The 95 Series and 34 Series have significantly different power consumption due to their distinct solenoid designs. The ultra-low 0.7-watt 34 Series is specifically suited for low-power I/O environments and dense valve array installations where total solenoid heat load is a design constraint.

Electrical Connection Options

Flow Performance Data

Flow performance data for both NAMUR series. The 95 Series Cv of 1.3 covers actuators with piston areas up to approximately 80 square inches at typical stroke speeds. The 34 Series Cv of 0.25 is suited for compact actuators with piston areas under 40 square inches. Both series use 1/4" fixed port size per the NAMUR interface standard.

Certifications & Compliance

Typical Applications & Industries

Process Control and Chemical Manufacturing

• Automated ball valve and butterfly valve actuator pilots in chemical and petrochemical process units. The NAMUR direct-mount interface eliminates tubing connections at each actuator, reducing installation labor and the number of potential leak paths in the pneumatic control circuit.
• Large rotary valve actuator controls for process isolation valves in water treatment, pharmaceutical, and food processing facilities where the 95 Series Cv of 1.3 provides the flow capacity needed for fast, full-stroke actuator cycling.
• Batch process sequencing valves in reactor and mixing vessel automation where the 5/2 double solenoid (detented) 95 Series option provides power-loss position retention for safety-critical process states.
• Column and tower feed and reflux valve automation in distillation processes where rapid actuator response to disturbance upsets requires high-flow NAMUR pilot valves.

Oil and Gas Production and Midstream

• Wellhead and production manifold automated ball valve controls where NAMUR-mounted pilot valves minimize the number of fittings and connections on the valve assembly exposed to hydrocarbon environments.
• Pipeline block valve and check valve actuator pilots at compressor stations and meter runs. The 95 Series double solenoid detented configuration provides defined fail-position behavior for ESD valve applications.
• Subsea umbilical-actuated valve pilots and topside process valve automation on offshore platforms where compact, direct-mount NAMUR valve assemblies reduce weight and footprint compared to separately piped solenoid-and-actuator assemblies.

Water and Wastewater Treatment

• Automated sluice gate, diaphragm valve, and butterfly valve actuator pilots in water treatment facilities where the NAMUR interface simplifies installation on standard actuator flanges and reduces maintenance complexity.
• Digester gas handling system valve controls in wastewater treatment plants where chemical resistance of the ball-poppet design and epoxy finish of the 34 Series provide service life advantages in corrosive atmospheres.
• Pump discharge and suction valve automation in water distribution pumping stations where the compact 95 Series single solenoid provides low-profile direct-mount pilot control.

Packaging and Food and Beverage Processing

• Automated fill valve, diverter valve, and product valve actuator pilots in bottling, canning, and aseptic filling lines where the 34 Series duck-bill exhaust protection and epoxy finish provide resistance to periodic washdown with hot water and caustic cleaning solutions.
• Bag-in-box fill station and bag fill valve controls in food processing facilities where compact NAMUR-mounted 34 Series valves reduce the physical envelope of the valve actuator assembly.
• Brewery and winery automated process valve pilots for fermentation tank, bright tank, and filter valve actuation where both low-power operation and food-grade environment compatibility are requirements.

Power Generation and Utilities

• Boiler feedwater control valve actuator pilots and steam isolation valve controls in power plant utility systems where NAMUR direct-mount reduces the number of impulse line connections and associated maintenance points.
• Cooling water and condenser system valve automation where reliable actuation over millions of cycles and resistance to condensation-laden ambient air are requirements.
• Turbine bypass and extraction valve controls in combined-cycle plants where fast response NAMUR pilot valves support rapid load-following valve actuation sequences.

Manufacturing and General Industrial Automation

• Pneumatic actuator-driven jigs, clamps, and press tooling in automotive and general manufacturing where the VDI/VDE 3847 NAMUR interface allows actuator and valve to be sourced independently and assembled on-site.
• Semiconductor and electronics manufacturing process gas isolation and distribution valves where low-contamination direct-mount valve assemblies minimize dead volume and clean room footprint.
• High-cycle packaging and labeling machine actuators where the 34 Series 0.7-watt DC coil reduces total energy consumption and minimizes heat generation in compact machine enclosures housing multiple solenoid valves.

Ordering and Model Number Configuration

The ROSS 95 Series and 34 Series NAMUR valves use separate model number systems reflecting their different construction and function options. Example model numbers are provided for each series. Contact ROSS Controls or visit rosscontrols.com to configure complete model numbers for your specific function, voltage, and connection requirements.

Voltage codes: W = 24 VDC, Z = 110/120 VAC/50/60 Hz. The 95 Series double solenoid models require two coil voltage designators (one per solenoid) in the model number.

The 95 Series is available in single solenoid (spring return) and double solenoid (detented) configurations. Single solenoid provides spring-return fail-safe positioning. Double solenoid provides power-loss position retention.

The 34 Series is available with EN 175301-803 Form A or M12 connector options. Specify the connector type matching your field wiring system.

Both series use 5 mm fasteners for NAMUR interface mounting. Mounting hardware is included with the valve. Torque per NAMUR interface specification to ensure proper O-ring compression and sealing.

For actuator sizing guidance, select the 95 Series (Cv 1.3) for actuators with piston areas above approximately 80 square inches. Select the 34 Series (Cv 0.25) for compact actuators with piston areas below approximately 40 square inches. Contact ROSS for specific actuator sizing calculations.

Accessories

Exhaust Silencers

Sintered bronze thread-on silencers for noise reduction at valve exhaust ports. Available for 1/4" male NPT thread. Do not restrict exhaust flow below valve exhaust capacity.

Warning: Exhaust silencer Cv must equal or exceed valve exhaust Cv. Contaminated or undersized silencers restrict exhaust flow and create back pressure that reduces valve shifting force and can prevent complete actuation.

Speed Control Module (A7106-554)

The A7106-554 speed control module mounts between the directional control valve and the actuator at the NAMUR pad. Functions as a flow control for both cylinder ports simultaneously. Adjust by turning the needles: clockwise decreases actuator speed, counterclockwise increases speed. Compact module with Keystone and NAMUR mounting, O-ring seals for all air passages.

Quick Exhaust, Check, and Shuttle Valves

MQ2 Series quick exhaust valves mount at the NAMUR interface to accelerate exhaust stroke speed by bypassing the directional control valve exhaust path. Available in 1/4" port size with female inlet/outlet and exhaust. Pressure range 0 to 150 psig. Contact ROSS Controls for model numbers based on required flow Cv.

Related Products & Accessories

• NAMUR D20 Series Valves (Automatic Valve) - Balanced spool NAMUR interface valves from the Automatic Valve D20 Series, available in 3/2, 5/2, and 5/3 functions with explosion-proof, intrinsically safe, and ATEX options for hazardous locations. https://www.rosscontrols.com/en/series/3012-namur-valves-automatic-valve-d20-series
• 21 Series Hazardous Location Valves - ROSS 21 Series explosion-proof and ATEX certified poppet valves for inline installation in classified hazardous areas, 2/2, 3/2, and 4/2 functions. https://www.rosscontrols.com/en/series/2828-hazardous-location-valves-21-series
• 27 Series Hazardous Location Valves - ROSS 27 Series explosion-proof and ATEX certified poppet valves in port sizes up to 2-1/2" for high-flow hazardous location inline applications. https://www.rosscontrols.com/en/series/1309-hazardous-location-valves-27-series
• L-O-X Lockout Valves - Pneumatic energy isolation lockout valves for OSHA lockout/tagout compliance during maintenance on actuated process valves controlled by NAMUR pilots. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series
• Exhaust Silencers - Aluminum and sintered bronze silencers for exhaust noise reduction on ROSS directional control valves. https://www.rosscontrols.com/en/series/90-silencers

Frequently Asked Questions (FAQ)

Q: What is the NAMUR interface and why does it matter for valve selection?

A: NAMUR (Normenarbeitsgemeinschaft fur Mess- und Regeltechnik) is an international user association for automation technology that defined a standard interface for mounting directional control valves directly to pneumatic actuators. The VDI/VDE 3847 standard specifies the bolt pattern, port locations, port sizes, and O-ring groove dimensions for the NAMUR interface. Valves and actuators from different manufacturers that both conform to VDI/VDE 3847 are dimensionally interchangeable at the mount face. This standard allows engineers to select the best available valve and actuator independently rather than being locked into a single vendor's integrated assembly.

Q: What is the difference between the 95 Series and the 34 Series?

A: The 95 Series uses spool and sleeve construction in a 5/2-way configuration with an average Cv of 1.3, making it the high-flow option for larger actuators (piston area above approximately 80 square inches) requiring fast, full-stroke cycling. The 34 Series uses patented ball-poppet technology in a 3/2 normally closed configuration with an average Cv of 0.25, suited for compact actuators (piston area below approximately 40 square inches) in harsh or washdown environments where zero internal leakage and duck-bill exhaust protection are priorities. The 34 Series is significantly more compact (2.18 inches long) and draws only 0.7 watts on 24 VDC versus 2.5 watts for the 95 Series.

Q: What operating pressure range do these NAMUR valves support?

A: The 95 Series operates across 22.5 to 150 psig (1.5 to 10 bar). The 34 Series has a maximum operating pressure of 116 psig (8 bar). Both series use internal pilot supply by default, meaning the pilot draws from the line pressure at port 1. For systems where line pressure is below the minimum, convert to external pilot supply and provide a separate regulated pilot source within the operating range.

Q: Can I use the 95 Series or 34 Series in hazardous locations?

A: The standard 95 Series and 34 Series are general industrial valves without hazardous location coil certifications. For classified hazardous area applications requiring explosion-proof, ATEX, or intrinsically safe construction, specify the ROSS D20 Series NAMUR valves, which are available with these certification options in the same direct-mount NAMUR interface format. The D20 Series covers 3/2 and 5/2 functions in the same 1/4" NAMUR port configuration.

Q: Can I use these valves with non-lubricated compressed air?

A: Yes. Both the 95 Series and 34 Series are rated for non-lubricated compressed air service. The resilient spool and seal materials and ball-poppet design operate reliably on clean, dry, filtered compressed air without requiring air line lubrication. If upstream system components use lubricated air, the valves will continue to operate, but once a lubricated air supply is introduced, the lubrication should not be discontinued as the lubricant film can alter the seal friction and compatibility characteristics.

Q: What filtration level does the compressed air supply require?

A: Both series require filtered compressed air. Install an inline filter-regulator upstream of the valve assembly. A 40-micron filter is the typical recommendation for general service. The 34 Series ball-poppet design provides additional tolerance to minor contamination due to its self-cleaning valve seats, but gross particulate contamination or liquid water ingestion will reduce valve service life in any design.

Q: What is the 5/2 double solenoid detented option, and when should I specify it?

A: The 95 Series double solenoid (detented) version uses two solenoids, one to shift the valve in each direction. Once shifted, the valve latches mechanically in the new position and holds there without continued electrical power. Specify this configuration when (1) the application requires power-loss position retention, meaning the actuated valve must stay in its last commanded position rather than fail to a spring-return default, or (2) energy efficiency in long-dwell-time applications is important because the solenoid does not need to remain energized to hold position.

Q: How do I mount these valves to a pneumatic actuator?

A: Align the valve NAMUR interface face with the actuator NAMUR mounting flange. Insert the valve O-rings into the corresponding grooves on the valve or actuator face, ensuring no O-rings are pinched or displaced during assembly. Insert the 5 mm fasteners through the valve mounting holes and into the actuator threaded holes. Torque fasteners to the specification in the installation instructions to achieve correct O-ring compression. Verify that all four air passages (supply, exhaust, actuator port A, actuator port B for 5/2) are aligned with the corresponding actuator passages before tightening.

Q: Can I convert the internal pilot to external pilot in the field?

A: Yes. The internal-to-external pilot conversion is field-accomplished by plugging the internal pilot passage and routing pilot supply to the external pilot port. No replacement parts or special tools are required beyond an appropriate thread plug. Refer to the installation instructions for the specific conversion procedure and the external pilot port location for your model. External pilot supply must be within the valve operating pressure range at all times.

Q: What connector types are available for the 34 Series?

A: The 34 Series is available with EN 175301-803 Form A (standard) or M12 connector electrical connections. The Form A connector is compatible with the common industrial DIN solenoid valve connector ecosystem. The M12 connector (4-pin, A-coded) is compatible with the M12 field-bus and distributed I/O connector systems widely used in European automation. Specify the connector type that matches your field wiring and connector inventory.

Q: What maintenance is required for the 95 Series and 34 Series?

A: Both series are designed for long-term low-maintenance service. Routine maintenance focuses on air supply quality verification (filter element inspection and replacement), visual examination of the valve body and connector for damage, and confirmation of correct actuator response to solenoid signals. The 34 Series self-cleaning ball-poppet seats do not require periodic lapping or seat dressing. For the 95 Series spool design, periodic inspection for spool wear and seal replacement may be indicated after multi-million cycle service in contaminated air environments. Maintain clean, dry, filtered air supply to maximize service intervals.

Q: Are spare seals and service parts available?

A: Yes. ROSS Controls provides service parts for both series through authorized distributors. Contact ROSS Controls at (800) 438-7677 or through rosscontrols.com to identify the applicable seal kit and service part numbers for your specific model configuration. Having seal kits on-hand at facilities with large NAMUR valve populations reduces maintenance downtime.

Installation & Maintenance Guidelines

• Before mounting, verify that the actuator interface conforms to VDI/VDE 3847 dimensions for 1/4" NAMUR porting. Non-standard actuator faces may require a transition plate or adapter; confirm interface dimensions before ordering.
• Inspect valve interface O-rings before installation. O-rings must be intact and free of cuts, nicks, or deformation. Replace any damaged O-rings before assembly. Use only compatible O-ring lubricant to ease installation without compromising seal material.
• Align all four air passage holes on the valve interface with the corresponding passages on the actuator mounting flange before inserting fasteners. Misalignment by even one passage position will result in incorrect actuator function or no actuation.
• Torque the 5 mm mounting fasteners to the specification in the installation instructions. Undertightening will cause air leakage at the interface O-rings. Overtightening can damage the valve body mounting boss or crush the O-rings beyond their intended compression.
• Supply filtered compressed air to the system. Install a filter-regulator upstream of the NAMUR valve assembly and verify the pressure gauge reads within the operating pressure range for the series before energizing the solenoid.
• Confirm supply voltage matches the solenoid voltage marking before making electrical connections. Applying incorrect voltage to the solenoid coil will cause immediate coil failure. Verify the control panel supply voltage and the voltage code in the valve model number before connecting.
• For EN 175301-803 Form B connectors (95 Series), insert the connector plug until it positively snaps or latches. For M12 connectors (34 Series), tighten the locking ring until the connector is secure and meets the IP rating specification. A loose connector will cause intermittent solenoid operation and may allow moisture ingress.
• Perform a commissioning test by momentarily applying the solenoid signal and observing that the actuator strokes to the commanded position. For double-solenoid detented valves, verify that the actuator responds to both solenoid signals and holds position with the signal removed.
• For the non-locking manual override test: depress the manual override button while observing actuator position. Confirm the actuator moves to the actuated position. Release the button and confirm the actuator returns to the spring-return default position (single solenoid) or holds (double solenoid).
• Do not restrict the valve exhaust port. If a silencer is installed, verify its Cv exceeds the valve exhaust flow capacity. On 5/2 valves, exhaust occurs alternately from ports 3 and 5 depending on valve position; both ports must be verified for adequate exhaust capacity.
• For the 34 Series in washdown environments: verify that the duck-bill exhaust ports are oriented so washdown fluid flows away from the port opening rather than directly into it. The duck-bill protection is most effective when the valve is oriented per the installation instructions.
• Check air supply dryness for installations at or below 40 F (4 C). Install a refrigerated or desiccant dryer upstream and verify system dew point is below the minimum operating temperature. Free water in compressed air at sub-freezing temperatures will freeze inside the valve and cause actuation failure.

Warranty & Global Support

ROSS Controls provides a one-year warranty on all products, covering defects in material and workmanship from the date of purchase.

Global technical support is available through ROSS Controls offices in the USA (headquarters in Ferndale, Michigan), Canada, Brazil, Germany, France, United Kingdom, India, China, and Japan.

Contact ROSS Controls USA at (800) 438-7677 or visit rosscontrols.com for product configuration, actuator sizing assistance, technical support, and distributor locator services.

Download the complete ROSS NAMUR 95 and 34 Series catalog for dimensional drawings, complete model number configurators, flow performance curves, and service part numbers.

Download Catalog: https://www.rosscontrols.com/en/documents/9/namur-interface-valves-95-34-series