M35 Series Double Valve Safety Category 4, PL e, External Monitoring with & without Soft-Start

Product Overview

The ROSS Controls M35 Series is a redundant dual-poppet safe exhaust double valve that achieves Safety Category 4, Performance Level e (PL e) per ISO 13849-1:2015, SIL 3 per IEC 62061, and DGUV functional safety certification, using an external monitoring architecture. Each valve element incorporates an integrated solid-state PNP pressure sensor, and by monitoring both sensors on every actuation and de-actuation cycle, the external safety control system achieves up to 99 percent diagnostic coverage, satisfying Category 4 requirements without internal monitoring circuitry.

The M35 Series is built on ROSS's cross-flow dual-poppet technology, which operates the two valve elements synchronously. Both elements must shift for the valve to transition between supply and exhaust states. Parallel exhaust paths within the M35 design provide industry-leading exhaust flow rates, ensuring rapid depressurization of downstream circuits even during faulted conditions where one element may be stuck open. The poppet design delivers superior dirt tolerance, wear compensation, and service life compared to spool-type valves, and the B10D value of 25,000,000 cycles confirms exceptional reliability for high-duty safety applications.

An optional EEZ-ON soft-start module is available for the M35 Series. On energization, the soft-start restricts initial airflow, allowing outlet pressure to increase gradually until it reaches approximately 50 percent of inlet pressure, at which point the valve transitions to full flow. This prevents sudden pressure surges that cause equipment shock loading, component damage, or unexpected actuator motion during machine restart after an emergency stop or maintenance event.

The M35 Series connects to ROSS MD Series FRL units via modular port connections, enabling complete Air Entry System assemblies integrating lockout, filtration, regulation, and safe exhaust in a single engineered package. Built-in silencer modules or threaded exhaust flanges for remote exhaust are available. LED status indicators provide local visual display of valve state to assist with commissioning and troubleshooting.

Functional safety data for the M35 confirms a PFHD of 7.71 x 10^-9, an MTTFd of 301.9 years (at 662,400 operations), and B10D of 25,000,000 cycles. These values document the M35's suitability for the most demanding continuous-duty safety applications. SISTEMA Library files are available for download.

Key Engineering Features

• Safety Category 4, PL e (ISO 13849-1:2015) via External Monitoring - Achieves Category 4, PL e through external monitoring of two PNP pressure sensors, one per valve element, on every actuation and de-actuation cycle. The external safety PLC or safety relay provides the monitoring function.
• SIL 3 (IEC 62061) and DGUV Certified - Third-party certified SIL 3 and DGUV functionally certified, providing documentation required for European press and forming machine safety compliance.
• 99 Percent Diagnostic Coverage - Monitoring both solid-state PNP pressure sensors on each valve cycle detects fault conditions before they can prevent the safety function from operating, achieving up to 99% DC.
• Redundant Dual-Poppet Cross-Flow Design - Two valve elements operating synchronously via ROSS cross-flow technology. A single element failure cannot prevent the safety exhaust function from executing, satisfying Category 4 redundancy requirements.
• Parallel Exhaust Paths for Rapid Depressurization - Internal parallel exhaust routing provides high exhaust flow capacity, ensuring rapid downstream circuit depressurization even in faulted conditions where one element may be partially open.
• B10D: 25,000,000 Cycles - Exceptional reliability rating documents suitability for high-frequency, continuous-duty safety applications with extended service life between component replacements.
• PFHD: 7.71 x 10^-9 / MTTFd: 301.9 Years - Industry-leading functional safety data confirms the M35 as a high-reliability component for any Category 4, PL e safety function design.
• Optional EEZ-ON Soft-Start Module - Gradual pressurization on energization, ramping outlet pressure to approximately 50% of inlet before full flow, preventing shock loads and unexpected motion during machine restart.
• Modular Port Connection for Air Entry System Integration - Modular port interface for direct connection to ROSS MD Series FRL units, lockout valves, and Air Entry System assemblies without separate pipe fittings.
• LED Status Indicators - Visual LED displays for valve status, providing field-level indication for commissioning, troubleshooting, and routine operational verification.
• 5-Pin M12 Solenoid and Sensor Connectors - Industry-standard M12 connectors for both solenoid actuation and pressure sensor wiring, enabling fast, reliable field connection without special tooling.
• Air Quality Rating ISO 8573-1 Class 7:4:4 - Validated for use with compressed air meeting ISO 8573-1 Class 7:4:4, compatible with standard industrial air supply filtered to 5-micron minimum.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Metal Forming, Stamping, and Press Operations

• Mechanical and hydraulic power presses where Category 4, PL e is required, and the M35's external monitoring architecture integrates directly with the machine's existing safety PLC for 99% DC verification on every press cycle.
• Metal stamping and deep-drawing presses on automotive components where the M35's high B10D (25 million cycles) supports extended maintenance intervals on high-stroke-rate operations.
• Metal blanking and progressive die press lines where the M35 optional soft-start prevents pressure surge-induced die misalignment during machine restart after safety events.

Automotive Assembly

• Body-in-white press and transfer press operations where the M35's IP65 solenoid enclosure and M12 connectors meet automotive plant environmental and connector standards.
• Engine and powertrain assembly press operations requiring Category 4 PL e safe exhaust, where the M35 soft-start option prevents assembly line component shock during coordinated multi-press restart sequences.
• Robotic assembly cells with Category 4 pneumatic energy isolation requirements, where M35 M12 connectors simplify integration into standardized automotive robot safety architectures.

Packaging and Material Handling

• High-speed form-fill-seal and flow-wrap packaging machines where the M35 LED indicators provide machine operators with immediate visual valve status feedback during product changeover and maintenance.
• Palletizing robot pneumatic utility supply isolation where M35 external monitoring integrates with the robot safety PLC for verified Category 4 safe exhaust on safety gate opening.
• Stretch hooding and shrink wrapping systems where the M35 modular port connection simplifies integration into standardized ROSS Air Entry System assemblies across multiple packaging lines.

Food and Beverage Processing

• Filling, capping, and labeling machine pneumatic circuits where the M35's IP65 enclosure, M12 connectors, and 5-micron air filtration compatibility support hygienic machine environments.
• Pasteurization and retort system pneumatic door and clamp circuits requiring Category 4 safe exhaust with external safety PLC monitoring for machine interlocking.
• Bottling line accumulation and transfer conveyors where M35 soft-start prevents product disturbance and line shock on restart after safety stops.

Electronics and Semiconductor

• SMT pick-and-place and chip packaging equipment where the M35's low 2.0-watt solenoid power and compact M12 connectors minimize thermal load and connector space in integrated machine architectures.
• Wafer handling and precision assembly equipment where controlled pressurization via EEZ-ON soft-start prevents pneumatic actuation speed spikes that could damage sensitive components during restart.

General OEM and High-Risk Industrial

• OEM machine designs targeting CE marking with Category 4, PL e safe exhaust, where the M35 DGUV certification and SISTEMA Library simplify the technical file documentation process.
• Applications where monthly proof testing intervals are scheduled into the preventive maintenance program, aligning with the M35 recommended minimum proof test frequency.
• Multi-zone safety systems where individual M35 valves per zone report sensor status to a central safety PLC, enabling zone-selective access without full machine shutdown.

Ordering and Model Number Configuration

The M35 Series model number encodes valve function, port size, actuation, voltage, soft-start option, and exhaust configuration. Contact ROSS Controls for the complete M35 configurator, dimensional drawings, CAD models, and accessory listing. SISTEMA Library files available at rosscontrols.com.

Standard voltage: 24 VDC.

Solenoid connection: 5-pin M12 (solenoid and sensor combined or separate connectors depending on configuration).

Soft-start EEZ-ON module: optional; specify at time of ordering.

Exhaust options: built-in silencer module or threaded exhaust flange for remote exhaust piping.

NPT and G (BSPP) thread options available.

Modular port connection available for ROSS MD Series Air Entry System assemblies.

Minimum proof test frequency: once per month.

DGUV, CE certifications standard. SISTEMA Library downloadable at rosscontrols.com.

Contact ROSS Controls at (800) 438-7677 for full configurator and application engineering support.

Accessories

Optional Soft-Start EEZ-ON Module

Modular soft-start add-on for the M35 that controls pressurization rate on energization. Field-installable on applicable M35 configurations.

Analog Pressure Gauges

Operator-visible downstream pressure gauges for visual state confirmation, supplementing the M12 sensor feedback. 0 to 145 psig (0 to 10 bar) range.

Digital Pressure Transducers

4-20 mA output digital transducers for PLC integration, data logging, and condition monitoring of downstream pressure.

Redundant Pressure Switch Assemblies

Dual pressure switch configurations for applications requiring independent redundant downstream pressure feedback channels.

Prewired M12 Connector Kits

Pre-terminated M12 cable assemblies for solenoid and sensor wiring, reducing installation time and field wiring errors.

ROSS MD Series FRL Units and Lockout L-O-X Valves

Upstream air preparation and manual lockout components for complete Safe Air Entry System assemblies with the M35.

Related Products & Accessories

• DM1 Series C Double Valve (Category 4, PL e, Internal Monitoring, Auto Reset) - Internal monitoring alternative to M35 for applications where no external safety PLC is required for monitoring. https://www.rosscontrols.com/en/series/1294-dm1-series-c-double-valve
• DM2C Series Double Valve (Category 4, PL e, Internal Monitoring, Manual Reset) - Internal monitoring with latching fault memory for applications requiring operator reset acknowledgment. https://www.rosscontrols.com/en/series/1295-dm2c-series-double-valve
• RSe Series Double Valve (Category 4, PL e, External Monitoring) - Spool-type redundant valve with PNP proximity sensors for external monitoring applications. https://www.rosscontrols.com/en/series/1297-rse-series-double-valve
• SV27 Series Single Valve (Category 2, PL c) - Single valve with DPST switch for applications where Category 2 is sufficient. https://www.rosscontrols.com/en/series/1293-sv27-series-single-valve
• Safe Air Entry Assembly with M35 Series - Complete air entry system with Lockout L-O-X, FRL, and M35 safe exhaust valve. https://www.rosscontrols.com/en/series/1288-safe-air-entry-assembly-with-m35-series-double-valve

Frequently Asked Questions (FAQ)

Q: How does the M35 achieve Category 4, PL e through external monitoring?

A: Each of the two M35 valve elements has an integrated solid-state PNP pressure sensor. The external safety control system (safety PLC or safety relay) monitors both sensors on every valve actuation and de-actuation cycle. Correct synchronous behavior of both elements on every cycle confirms the safety function is intact. Any discrepancy, such as one sensor not confirming the expected state, is detected immediately and the controller initiates a safety response. This architecture achieves up to 99 percent diagnostic coverage and satisfies Category 4, PL e requirements.

Q: What is the PFHD and MTTFd of the M35?

A: The M35 Series has a PFHD of 7.71 x 10^-9 per hour and an MTTFd of 301.9 years (based on 662,400 operations). The B10D is 25,000,000 cycles. These values represent industry-leading reliability metrics and confirm the M35's suitability for the highest-category safety functions.

Q: What is the EEZ-ON soft-start and when should it be specified?

A: The optional EEZ-ON soft-start module restricts initial airflow on energization, allowing outlet pressure to increase gradually to approximately 50 percent of inlet before the valve opens fully. Specify soft-start for applications where sudden pressurization on machine restart could cause equipment shock, actuator slam, product disturbance, or quality defects. Examples include conveyor drives, assembly fixtures, and multi-actuator systems that must pressurize in a controlled sequence.

Q: What are the port sizes and flow capacities of the M35?

A: The M35 Series is available in 1/2 inch and 3/4 inch port sizes with NPT or G thread options. Supply flow capacity is 4.1 to 4.3 Cv (4,000 to 4,200 Nl/min). Exhaust flow capacity is 7.6 Cv (7,400 Nl/min). The higher exhaust Cv compared to supply Cv is a deliberate design choice to ensure rapid downstream circuit depressurization.

Q: What electrical connections does the M35 use?

A: The M35 uses two 5-pin M12 connectors for solenoid actuation and pressure sensor wiring. Solenoid power is 2.0 watts per solenoid at 24 VDC continuous duty. The IP65 solenoid enclosure per IEC 60529 provides protection against dust and water jet ingress.

Q: What proof test frequency is required?

A: ROSS recommends a minimum operational proof test frequency of once per month. The actual required frequency depends on the ISO 13849-1 safety function calculation for the specific application's nop and mission time. Higher-cycle applications may allow less frequent proof testing if the SISTEMA calculation confirms the required PL is maintained.

Q: Is the M35 compatible with ROSS Air Entry System assemblies?

A: Yes. The M35 modular port connection option integrates directly with ROSS MD Series FRL units and Lockout L-O-X valves, creating complete Safe Air Entry System assemblies with all components in a single, engineered, documented package.

Q: What are the LED indicators on the M35?

A: Integrated LED indicators provide a local visual display of valve status, confirming solenoid energized/de-energized state and aiding field-level troubleshooting and commissioning verification without requiring a separate diagnostic tool.

Q: What certifications does the M35 carry?

A: DGUV functional safety certification, CE marking, and SIL 3 per IEC 62061. SISTEMA Library files are available at rosscontrols.com for ISO 13849-1 documentation.

Q: Can both solenoids be operated independently?

A: No. For the safety function to operate correctly, both solenoids must be operated simultaneously. Independent operation of a single solenoid while the other remains de-energized represents an abnormal condition that should be detected by the external monitoring system. Normal valve actuation and de-actuation requires simultaneous command to both solenoids.

Q: Is a SISTEMA Library file available?

A: Yes. Downloadable from rosscontrols.com. The file contains B10D, PFHD, MTTFd, DC, Category, and PL data for the M35 in SISTEMA-compatible format for ISO 13849-1 safety function verification.

Q: What is the air quality requirement for the M35?

A: Compressed air meeting ISO 8573-1 Class 7:4:4 with minimum 5-micron particulate filtration upstream of the valve. This is consistent with standard industrial compressed air systems using a point-of-use filter.

Installation & Maintenance Guidelines

• Install the M35 in the pneumatic supply line upstream of the machine zone to be protected, with all protected actuators downstream of the valve exhaust port.
• Connect supply to inlet port. Connect machine circuit to outlet port. Connect silencer or remote exhaust line to exhaust port.
• Wire both 5-pin M12 solenoid connectors to the machine safety controller's solenoid outputs. Both solenoids must be simultaneously energized to supply and simultaneously de-energized to exhaust.
• Wire both M12 pressure sensor connectors to the safety controller's sensor inputs. Configure the controller to monitor both sensor states on every actuation and de-actuation cycle.
• Program the safety controller to initiate a safety stop if either sensor fails to confirm the expected state within the specified response window on any cycle.
• Supply filtered compressed air meeting ISO 8573-1 Class 7:4:4. Use a 5-micron filter upstream. Operating pressure: 30 to 150 psig (2 to 10 bar).
• Verify LED indicators show correct state (energized/de-energized) corresponding to solenoid command signals during commissioning.
• For EEZ-ON soft-start equipped valves, adjust the soft-start needle valve to the required pressurization rate before final commissioning.
• Perform a commissioning proof test: energize, confirm supply to downstream and sensor states; de-energize, confirm exhaust and sensor states; verify controller detects correct transitions.
• Schedule monthly (or more frequent per SISTEMA calculation) proof tests and record results in the machine maintenance log.

Warranty & Global Support

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

Technical support: 1-888-TEK-ROSS (1-888-835-7677). Customer service: 1-800-GET-ROSS (1-800-438-7677).

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

SISTEMA Library files, dimensional drawings, 3D PDF models, CAD files, integration guides, and certifications available at rosscontrols.com.

Download Catalog: https://www.rosscontrols.com/en/documents/367/m35-series-double-valves