MDC2 Series Single Valve Safety Category. 2 PL c, External Monitoring

Product Overview

The ROSS Controls MDC2 Series is a single-valve safe exhaust solution that adds integrated solid-state pressure sensing to the proven MDC platform, enabling Safety Category 2, Performance Level c (PL c) per ISO 13849-1:2015 when monitored by an external safety control system. This makes the MDC2 the diagnostic monitoring upgrade within the ROSS MDC family, delivering 60 to 90 percent diagnostic coverage without requiring the full redundancy of a double-valve architecture.

Like the MDC1, the MDC2 operates on a fail-to-safe principle using a three-position, two-way solenoid-controlled poppet. Upon de-energization, the valve simultaneously closes the supply port and opens the dedicated exhaust port, rapidly removing residual pneumatic pressure from the downstream machine circuit. The integrated solid-state pressure sensor distinguishes the MDC2: this sensor continuously reports downstream pressure state via a PNP output and 4-20 mA analog signal, enabling the external safety control system to verify correct valve behavior on each actuation and de-actuation cycle.

By monitoring the pressure sensor signal on every valve cycle, the safety control system detects faults that would prevent the valve from executing its exhaust function, including poppet sticking open, solenoid failure, or sensor disconnection. This cyclic diagnostic coverage between 60 and 90 percent satisfies the ISO 13849-1 Category 2 diagnostic coverage (DC) requirement, improving the safety function integrity compared to a non-monitored Category 1 design.

The optional EEZ-ON soft-start module provides controlled pressurization on energization, ramping outlet pressure gradually to approximately 50 percent of inlet before transitioning to full flow. This protects equipment from pressure surge damage and prevents unexpected actuator motion during machine restart after a safety stop or lockout event.

MDC2 Series valves are available in 1/2 inch and 1 inch body sizes with flow capacities from 3.1 Cv to 30 Cv. Threaded NPT and G port connections are offered, as are modular port configurations for direct integration into ROSS Air Entry System assemblies. SISTEMA Library files are available for download to support ISO 13849-1 safety function documentation.

Key Engineering Features

• Safety Category 2, PL c (ISO 13849-1:2015) - Achieves Category 2, Performance Level c when the integrated pressure sensor is monitored by an external safety control system on each actuation and de-actuation cycle, providing a higher safety integrity level than the MDC1 without full redundancy.
• Integrated Solid-State Pressure Sensor - Factory-installed pressure sensor provides PNP switching output and 4-20 mA analog signal for seamless integration with PLCs, safety controllers, and Industry 4.0 monitoring systems. Supply voltage 8-30 VDC, current consumption less than 4 mA.
• 60 to 90 Percent Diagnostic Coverage - Monitoring the sensor on each valve cycle detects dangerous failures before they propagate, meeting the ISO 13849-1 Category 2 requirement for medium diagnostic coverage (60% <= DC < 90%).
• Fail-to-Safe Poppet Design - Three-position, two-way poppet valve ensures simultaneous supply shutoff and downstream exhaust on solenoid de-energization, eliminating residual pressure in the protected machine zone.
• Dirt-Tolerant, Wear-Compensating Poppet - Self-compensating face-seal geometry provides inherent dirt tolerance and automatic wear adjustment for sustained quick response and high flow capacity over millions of cycles.
• PTFE Backup Piston Rings - Extends valve endurance and supports reliable operation with or without in-line air lubrication, reducing maintenance demands in industrial environments.
• EEZ-ON Soft-Start (Optional) - Controlled pressurization on energization prevents shock loads and unexpected motion, ramping outlet pressure to approximately 50 percent of inlet before opening to full flow.
• Threaded or Modular Port Connection - NPT or G port threads plus optional modular port for direct connection to ROSS Air Entry System assemblies with Lockout L-O-X valves and MD Series FRL units.
• M12 Sensor Connector - Industry-standard M12 connector for the solid-state pressure sensor facilitates fast, tool-free field wiring and replacement without special connectors or hardwired leads.
• SISTEMA Library Support - Downloadable SISTEMA Library files enable efficient ISO 13849-1 safety function verification and documentation with pre-populated safety parameters.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Metal Forming and Stamping

• Stamping and blanking presses where the Category 2 diagnostic capability of the MDC2 enables the safety controller to verify exhaust function completion before permitting die access, reducing the risk of undetected valve failure.
• Hydraulic-pneumatic press brakes with pneumatic clutch-brake controls requiring monitored safe exhaust to confirm pressure removal before bend zone entry.
• Roll forming and straightening lines where pneumatic guide and feed roll actuators must be verifiably exhausted and the MDC2 sensor provides confirmation to the PLC safety system.

Automotive Assembly

• Robotic welding and material handling cells where the safety PLC monitors the MDC2 pressure sensor to confirm pneumatic energy removal before robot cell door interlocks release for maintenance access.
• Assembly press and staking stations requiring monitored pressure verification to confirm tool retraction before operator part loading and unloading.
• Automated assembly conveyor divert and transfer systems where exhaust confirmation from the MDC2 sensor is integrated into the safety gate release logic.

Packaging and Consumer Goods

• High-speed packaging lines where diagnostic monitoring of safe exhaust confirms actuator de-pressurization before guards are released, satisfying audit requirements for documented safety function performance.
• Thermoforming and blister packaging machines requiring monitored pressure removal from forming platens and trim dies before operator mold access.
• Case sealing and labeling equipment where MDC2 sensor feedback is logged by the machine control system for ISO 13849-1 validation records.

Electronics and Semiconductor Manufacturing

• Precision assembly and bonding equipment where monitored exhaust confirms pneumatic tool retraction before sensitive component placement operations.
• SMT (surface mount technology) pick-and-place machine pneumatic actuators requiring verified pressure removal during nozzle change and maintenance procedures.

Food and Beverage Processing

• Pneumatic filling, capping, and labeling equipment where MDC2 diagnostic monitoring supports documented safety function performance for food safety and regulatory compliance.
• Sanitary processing lines where controlled pressurization via EEZ-ON soft-start prevents product splashing or contamination during line restart after CIP or maintenance.

General Industrial and OEM Machine Builders

• OEM machine designs requiring Category 2 safe exhaust documentation for CE marking and EU Machinery Directive compliance, where the MDC2 provides the necessary sensor output for safety PLC integration.
• Multi-zone pneumatic systems where independent MDC2 valves per zone allow the safety system to confirm zone-by-zone pressure removal before access interlocks release.

Ordering and Model Number Configuration

The MDC2 Series is configured using a structured model number that defines body size, soft-start option, port type, voltage, and electrical connection. The MDC2E13MLXX1NAEXCXA is an example of a modular lockout assembly variant with MD4 FRL. Contact ROSS Controls or your authorized distributor for the complete MDC2 model configurator.

Standard voltage: 24 VDC. The solid-state pressure sensor operates on 8-30 VDC supply voltage.

Solenoid connection: EN 175301-803 Form C standard for the MDC2 Series. Feedback sensor uses M12 connector.

Soft-start EEZ-ON option available; specify at time of ordering.

NPT and G (BSPP) thread options available.

Modular port configuration available for ROSS Air Entry System assemblies.

CE and UKCA certifications available. Specify required certification at time of ordering.

SISTEMA Library files downloadable from rosscontrols.com.

Contact ROSS Controls at (800) 438-7677 for complete variant listing, dimensions, and configurations.

Accessories

Analog Pressure Gauges

Operator-visible pressure gauges for visual downstream pressure verification, supplementing the electronic sensor output for independent confirmation of pressure release. Available in 0 to 145 psig (0 to 10 bar) range.

Digital Pressure Transducers

0 to 145 psig (0 to 10 bar) digital pressure transducers with multiple output options including 4-20 mA and digital display, for data logging, condition monitoring, and predictive maintenance integration.

Canister Exhaust Silencers

Threaded canister-style silencers for the MDC2 exhaust port to reduce pneumatic exhaust noise to permissible levels. Size to match or exceed exhaust port flow capacity.

ROSS MD Series FRL Units

Filter-Regulator-Lubricator units with modular port interfaces for complete Air Entry System assemblies with MDC2 safe exhaust valve, providing filtration, regulation, and lubrication in a compact package.

Lockout L-O-X Valves

Manual lockout valves for upstream energy isolation, enabling full lockout/tagout compliance when used with the MDC2 safe exhaust function.

Related Products & Accessories

• MDC1 Series Single Valve (Category 1, PL c) - MDC1 without integrated sensor for applications where monitoring is not required and Category 1 is sufficient. https://www.rosscontrols.com/en/series/1291-mdc1-series-single-valve
• SV27 Series Single Valve (Category 2, PL c with DPST) - 27 Series-based sensing valve with integrated DPST safety switch for 99% diagnostic coverage in Category 2 to Category 3 capable configurations. https://www.rosscontrols.com/en/series/1293-sv27-series-single-valve
• DM1 Series C Double Valve (Category 4, PL e) - Redundant dual-poppet double valve for Category 4 applications requiring the highest safety integrity. https://www.rosscontrols.com/en/series/1294-dm1-series-c-double-valve
• Safe Air Entry Assembly with MDC Series - Complete air entry system integrating Lockout L-O-X valve, MD Series FRL, and MDC2 safe exhaust valve. https://www.rosscontrols.com/en/series/1285-safe-air-entry-assembly-with-mdc-series-safe-exhaust-valve
• Lockout L-O-X Valves (15 Series) - Manual lockout valves for upstream energy isolation. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series

Frequently Asked Questions (FAQ)

Q: What safety performance does the MDC2 Series achieve?

A: The MDC2 achieves Safety Category 2, Performance Level c (PL c) per ISO 13849-1:2015 when the integrated solid-state pressure sensor is monitored by an external safety control system on each actuation and de-actuation cycle. The diagnostic coverage (DC) achieved is between 60 and 90 percent, satisfying the Category 2 medium DC requirement. The valve also carries SIL 1 certification per IEC 61508:2001.

Q: How does the MDC2 sensor work and what is its output?

A: The integrated solid-state pressure sensor continuously monitors downstream pressure state. It provides a PNP switching output and a 4-20 mA analog output, operating on a supply voltage of 8 to 30 VDC with a current consumption of less than 4 mA. The sensor connects via an M12 industry-standard connector. The safety controller monitors the sensor signal to confirm pressure drop upon de-energization and pressure rise upon energization, detecting faults that would prevent the safety function from executing.

Q: What diagnostic coverage does monitoring the MDC2 sensor provide?

A: Monitoring the solid-state pressure sensor on each actuation and de-actuation cycle provides a diagnostic coverage (DC) between 60 and 90 percent, as required for ISO 13849-1 Category 2. This means the monitoring detects 60 to 90 percent of dangerous failures before they prevent the safety function from operating. The exact DC value for a specific application depends on the monitoring architecture and testing frequency.

Q: How does the MDC2 differ from the MDC1?

A: The MDC2 adds a factory-installed solid-state pressure sensor and M12 connector that the MDC1 does not have. When this sensor is monitored by the safety controller, the MDC2 achieves Category 2, PL c versus the MDC1's Category 1, PL c without monitoring. Both valves share the same poppet design, body sizes, and EEZ-ON soft-start option.

Q: What external safety controller interface is required for Category 2?

A: The MDC2 sensor output must be wired to a safety-rated PLC or safety relay that monitors the signal on every valve actuation and de-actuation cycle. The controller must be programmed to initiate a safety stop or prevent machine restart if the sensor signal indicates a fault condition such as pressure not dropping on de-energization or not rising on energization. The specific monitoring logic depends on the machine's safety function requirements.

Q: What is the EEZ-ON soft-start function?

A: EEZ-ON is an optional module that restricts airflow through an adjustable needle valve during pressurization, allowing outlet pressure to rise gradually to approximately 50 percent of inlet before the valve opens fully. This prevents sudden pressure surges on machine restart that could cause equipment shock loads, actuator slam, or product quality issues.

Q: What are the body and port size options?

A: The MDC2 is available in 1/2 inch and 1 inch body sizes. Flow capacity ranges from 3.1 Cv (3,100 Nl/min) for the 1/2 inch body to 30 Cv (30,000 Nl/min) for the 1 inch body. Contact ROSS Controls for the complete port size matrix within each body size.

Q: What is the operating pressure range?

A: The 1/2 inch body MDC2 operates from 30 to 150 psig (2.0 to 10.3 bar). The 1 inch body operates from 36 to 150 psig (2.5 to 10.3 bar). Both use internal pilot supply.

Q: Are CE and UKCA certifications available?

A: Yes. CE marking is standard. UKCA marking is available for UK market compliance. Specify the required certification when ordering.

Q: What is the B10D value for ISO 13849-1 calculations?

A: The MDC2 has a B10D reliability rating of 5,000,000 cycles, used in MTTFD calculations per ISO 13849-1 Annex C to determine the achievable Performance Level for a given nop (number of operations per year) and mission time.

Q: Can the MDC2 be used in modular Air Entry System assemblies?

A: Yes. The modular port configuration option allows the MDC2 to connect directly to ROSS MD Series FRL units, Lockout L-O-X valves, and other Air Entry System components without intermediate pipe fittings, creating a compact, standardized safety-rated air entry assembly.

Q: Is a SISTEMA Library file available for the MDC2?

A: Yes. A SISTEMA Library file is downloadable from rosscontrols.com, containing the safety parameters (B10D, PFHD, DC, MTTFD) required for ISO 13849-1 performance level verification.

Q: What does the pressure switch feedback rating mean?

A: The MDC2 solid-state pressure sensor operates on a supply voltage of 8 to 30 VDC with a current consumption under 4 mA. These are the electrical load ratings that the safety controller's sensor input must accommodate. The sensor output is PNP switching plus 4-20 mA analog, compatible with standard safety PLC digital and analog input modules.

Installation & Maintenance Guidelines

• Install the MDC2 in the supply line immediately upstream of the protected machine zone, ensuring all pneumatic actuators and devices in the zone are downstream of the valve exhaust port.
• Supply filtered compressed air meeting ISO 8573-1 Class 7:4:4. Use a 5-micron filter upstream to protect poppet seats from particulate contamination.
• Connect the M12 sensor connector to the safety controller's input module. Verify wiring polarity matches the PNP sensor output configuration.
• Program the safety controller to monitor the sensor signal on every valve actuation and de-actuation cycle. Configure fault detection logic for: (a) pressure not dropping within expected time on de-energization; (b) pressure not rising within expected time on energization.
• Verify operating pressure remains within range: 30 to 150 psig (1/2" body) or 36 to 150 psig (1" body). Low pressure reduces exhaust speed and sensor fault detection response.
• Do not restrict the exhaust port. Install a properly sized silencer that matches or exceeds the exhaust port flow capacity.
• Perform a commissioning functional test: energize, verify supply pressure downstream; de-energize, verify pressure drops to zero and sensor confirms release; confirm controller receives correct sensor state transitions.
• For EEZ-ON soft-start versions, adjust needle valve for desired pressurization rate before final commissioning.
• Establish a periodic proof test schedule based on the calculated nop and required Mission Time per ISO 13849-1 to maintain the declared PL c throughout the machine's service life.
• Retain all test records and SISTEMA calculation outputs as part of the machine's technical file required by the EU Machinery Directive.

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 headquarters), Canada, Germany, France, United Kingdom, Brazil, India, China, and Japan.

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

Download Catalog: https://www.rosscontrols.com/en/documents/5549