Safe Air Entry Assembly with MDC Series Safe Exhaust Valve Safety Category 1 & 2, PL c, Externally Monitored

Product Overview

The ROSS Controls is a pre-engineered Safe Air Entry Assembly that supports both the MDC1 Series (Category 1) and MDC2 Series (Category 2) single poppet safe exhaust (dump) valves, enabling the assembly to be specified for Safety Category 1 or up to Category 2, Performance Level c (PL c) applications per ISO 13849-1:2015. Both valve variants are externally monitored, requiring the customer's safety control system to verify valve state.

The MDC1 Series valve uses a 3/2 normally closed single poppet design with no pressure sensor, suitable for Category 1 applications. The MDC2 Series adds a solid state pressure sensor that provides feedback to the external safety controller on each valve actuation and de-actuation, enabling diagnostic coverage between 60% and 90% (DC medium) and qualifying for up to Category 2, PL c when used with a properly configured external safety system.

Both MDC variants include the EEZ-ON Soft-Start function on the 1/2 inch body size, which allows gradual downstream pressure buildup during startup. Assembly components include the Classic or Modular L-O-X Lockout valve (15 Series), MD Series filter/regulator/lubricator with metal bowls, and the MDC valve with integrated silencer. All components are factory assembled, piped, and tested before shipment.

For design engineers and safety professionals selecting pneumatic safety systems for machine guarding, the series provides a scalable solution. Specify the MDC1 when Category 1 is sufficient per the risk assessment, or step up to the MDC2 when the risk assessment requires Category 2 diagnostic coverage to achieve the required PLr. SISTEMA Library data is available for download at rosscontrols.com for both variants.

Key Engineering Features

• MDC1 and MDC2 Valve Options in One Assembly Series - Single assembly series covers Category 1 (MDC1, no pressure sensor) and Category 2 (MDC2, solid state pressure sensor) applications. Select the appropriate valve tier based on the risk assessment PLr requirement without redesigning the assembly.
• MDC2 Solid State Pressure Sensor for Category 2 - The MDC2 variant incorporates a solid state pressure sensor that feeds back valve state to the external safety controller. Monitoring the sensor on each actuation and de-actuation provides diagnostic coverage between 60% and 90% (DC medium), enabling Category 2, PL c achievement.
• EEZ-ON Soft-Start Function (1/2 inch body) - Outlet pressure increases gradually during startup until reaching approximately 50% of inlet pressure, then the valve opens fully. Protects personnel and downstream equipment from sudden pressure surges and shock loading.
• Classic or Modular L-O-X Lockout Valve (15 Series) - OSHA 1910.147 and ANSI/ASSE Z244.1 compliant energy isolation. Large push/pull handle, lockable in OFF position only, full-size exhaust port, integrated sensing port with pop-up indicator, and fluorocarbon slipper seals for reliable shifting after extended idle.
• MD Series Air Preparation with Metal Bowls - Filter, integrated filter/regulator, or filter/regulator/lubricator with metal bowls. 5-micron filter element, automatic filter drain, self-relieving regulator, and analog gauge condition compressed air to the safe exhaust valve.
• Factory Assembled and Tested - Every Series assembly is fully configured, piped, leak tested, and performance verified before shipment, reducing field assembly time and eliminating configuration errors that could compromise safety.
• Single Poppet Design for High Reliability - The MDC Series poppet construction is dirt tolerant, wear compensating, and provides near-zero leakage with high flow capacity relative to body size. PTFE backup piston rings enable operation with or without in-line lubrication.
• Inline/Modular Mounting Flexibility - 1/2 inch body size supports inline or modular connection to MD Series FRL units. 1 inch body size is inline only. Bracket, screw, clamp, and mounting adapter available for modular system integration.
• SISTEMA Library Support for Both Variants - SISTEMA-compatible safety data for MDC1 (Category 1) and MDC2 (Category 2) valves available at rosscontrols.com for direct import into safety calculations per ISO 13849-1.
• Configurable Extra Port Blocks and Accessories - Extra port blocks (1/4, 3/8, or 1/2 inch) upstream, downstream, or both; analog gauge; digital transducer; and lockout hasp available as options to complete the safety system.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Machine Guarding - Category 1 and Category 2 Applications

• Machine tools and machining centers where the risk assessment requires PL c performance. Specify MDC1 for Category 1 when the machine architecture and failure history support it; specify MDC2 when Category 2 DC medium is needed to achieve PL c.
• Robotic work cells and automated assembly stations where the safety PLC monitors the MDC2 pressure sensor signal on every cycle, achieving Category 2 per ISO 13849-1 with the programmable safety controller.
• Packaging machinery (form-fill-seal, case erectors, palletizers) where the risk assessment identifies a Category 2 requirement, and the MDC2 pressure sensor integrates with the machine safety relay or controller.
• Conveyor and material handling systems with frequent access points where Category 2, PL c safe exhaust function is required for access control interlocks.
• Printing and converting equipment where Category 1 may be acceptable based on the machine risk assessment, and the MDC1 simplifies the safety system architecture.
• Agricultural and food processing equipment where the EEZ-ON Soft-Start prevents sudden cylinder actuation during system startup, protecting operators performing manual tasks near the machine.

Pneumatic Control and Air Dump/Release Applications

• Pneumatic clamping and fixturing systems where Category 2 diagnostic coverage is required by the risk assessment, and the MDC2 pressure sensor provides the required feedback loop.
• Blow-off and air knife systems where the MDC2 pressure sensor confirms valve de-energization before operator access is permitted.
• Air-powered transfer presses and forming equipment where safe exhaust must be verified before die entry, and Category 2 PL c is specified by the safety architect.
• Pneumatic test fixtures requiring documented Category 2 safe exhaust verification for product certification or insurance compliance.

Ordering and Model Number Configuration

The Series model number encodes the MDC valve variant (MDC1 or MDC2), body/port size, lockout valve type, FRL configuration, and optional accessories. Select MDC1 for Category 1 or MDC2 for Category 2 based on your risk assessment PLr requirement.

MDC1 Series (no pressure sensor) = Category 1, PL c.

MDC2 Series (solid state pressure sensor) = up to Category 2, PL c, SIL 1.

Body size 1/2 inch: port sizes 3/8 to 3/4 inch; inline/modular mounting; EEZ-ON Soft-Start included.

Body size 1 inch: port sizes 3/4 to 1-1/4 inch; inline mounting only.

Exhaust port size: 1 inch on 1/2 inch body.

Standard voltage: 24 VDC. Other voltages available - consult ROSS.

Electrical connections: DIN EN 175301-803 Form C or M12.

Lockout location configurable before or after FRL.

Extra port blocks available in 1/4, 3/8, or 1/2 inch; upstream, downstream, or both positions.

Analog gauge and digital transducer options available.

Explosion-proof solenoid pilot available - consult ROSS.

SISTEMA Library files for both MDC1 and MDC2 downloadable at rosscontrols.com.

Accessories

Pressure Gauges and Transducers

Exhaust Silencers

External exhaust silencers for remote exhaust routing or additional noise reduction.

Warning: Exhaust silencers must have flow capacities at least as great as the valve exhaust capacities. Contaminated or clogged silencers impair safe exhaust function.

Prewired Electrical Connectors

Lockout and Mounting Accessories

Replacement Filter Elements

Related Products & Accessories

• 1282 Series Safe Air Entry Assembly with MDC1 (Category 1 only) - Safe Air Entry Assembly using only the MDC1 valve for Category 1, PL c applications where Category 2 is not required. https://www.rosscontrols.com/en/series/1282-safe-air-entry-assembly-with-mdc1-series-safe-exhaust-valve
• 1284 Series Safe Air Entry Assembly with SV27 Series - Category 2, PL c assembly with SV27 sensing valve using force-guided DPST switch for valve state feedback. https://www.rosscontrols.com/en/series/1284-safe-air-entry-assembly-with-sv27-series-safe-exhaust-valve
• 1285 Series Safe Air Entry Assembly with M35 Series - Category 4, PL e externally monitored assembly with M35 Series redundant dual poppet double valve. https://www.rosscontrols.com/en/series/1285-safe-air-entry-assembly-with-m35-series-safe-exhaust-valve
• 1286 Series Safe Air Entry Assembly with DMC Series - Category 4, PL e internally monitored assembly with DM1C or DM2C Series double valve. https://www.rosscontrols.com/en/series/1286-safe-air-entry-assembly-with-dmc-series-safe-exhaust-valve
• 15 Series L-O-X Lockout Valves - Classic and Modular L-O-X lockout valves for LOTO-compliant energy isolation. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series

Frequently Asked Questions (FAQ)

Q: When should I specify the MDC1 versus the MDC2 in the series?

A: The choice depends on the risk assessment result and required Performance Level (PLr). If the risk assessment identifies a PLr of PL c and the machine architecture allows Category 1 (no DC requirement), specify MDC1. If the risk assessment requires Category 2 with DC medium (60% to 90%) to achieve PLr = PL c, specify MDC2 with its solid state pressure sensor. The SISTEMA Library files available at rosscontrols.com provide the safety data needed to verify your choice.

Q: How does the MDC2 pressure sensor achieve Category 2?

A: The MDC2 includes a solid state PNP pressure sensor that monitors valve outlet pressure. The external safety controller reads the sensor signal on each energization and de-energization cycle. When monitoring detects a discrepancy (valve fails to exhaust, outlet pressure does not drop on de-energization), the controller halts machine operation. This dynamic monitoring provides diagnostic coverage between 60% and 90% (DC medium), which is the requirement for Category 2 per ISO 13849-1.

Q: What is the SIL rating for the MDC2 variant?

A: The MDC2 variant achieves SIL 1 per IEC 62061 when properly integrated with an external safety controller that monitors the pressure sensor on each cycle.

Q: Does the series assembly perform the monitoring itself?

A: No. Both MDC1 and MDC2 variants are externally monitored. The Series assembly provides the physical safe exhaust function and, in the MDC2 case, the pressure sensor signal. The monitoring logic (verifying the sensor state, detecting faults, halting machine operation) must be implemented in the customer's safety controller.

Q: What is the EEZ-ON Soft-Start function?

A: EEZ-ON is ROSS Controls' Soft-Start function available on the MDC Series 1/2 inch body size. On energization, the valve ramps outlet pressure to approximately 50% of inlet pressure before opening fully. This gradual startup prevents sudden cylinder actuation that could injure operators or damage tooling. It is especially valuable in press, clamp, and actuator applications where unpredictable sudden movements are a hazard.

Q: What body sizes are available?

A: The MDC Series is available in 1/2 inch and 1 inch body sizes. The 1/2 inch body supports port sizes from 3/8 to 3/4 inch with inline or modular mounting and includes EEZ-ON Soft-Start. The 1 inch body supports port sizes from 3/4 to 1-1/4 inch with inline mounting only.

Q: Can I position the lockout valve downstream of the FRL?

A: Yes. The lockout valve position (before or after FRL) is configurable in the model number. Some applications require the lockout to be downstream of the FRL so that the air preparation components remain pressurized while the machine is locked out for maintenance. Consult ROSS Controls for guidance.

Q: What air filtration is required?

A: Both MDC1 and MDC2 valves require filtered compressed air meeting ISO 8573-1 Class 7:4:4 as a minimum. The 5-micron filter in the MD Series FRL provides this filtration. Inspect and replace filter elements regularly per the facility maintenance program.

Q: Are these assemblies suitable for hazardous locations?

A: Explosion-proof solenoid pilot versions are available for hazardous area installations. Consult ROSS Controls for Class I Division 1/2 configurations and applicable certifications.

Q: Can I add additional port connections to the assembly?

A: Yes. Extra port blocks in 1/4, 3/8, or 1/2 inch NPT or G thread can be added upstream, downstream, or both. These provide additional connection points for pressure gauges, transducers, branch circuits, or remote exhaust routing.

Q: What is the minimum operating pressure?

A: Minimum operating pressure is 30 psig (2 bar) for all assembly components. Supply pressure below this threshold may cause incomplete valve shifting and unreliable safe exhaust.

Q: Are the assemblies suitable for controlling power press clutch/brake mechanisms?

A: No. Per ROSS Controls specifications and applicable regulations, these valve assemblies are not designed for controlling clutch/brake mechanisms on mechanical power presses. Contact ROSS for appropriate press control valve products.

Q: What SISTEMA data is available?

A: SISTEMA Library files for both MDC1 and MDC2 variants are downloadable at rosscontrols.com. These files include PFH, MTTFD, B10 values, and DC data for direct import into SISTEMA software, enabling verification of Category 1 or Category 2, PL c achievement in your safety function calculation.

Q: Is 230 VAC available?

A: 230 VAC is not available for assemblies sold in the United States. OSHA regulations limit control voltage to no more than 120 VAC. For international applications requiring 230 VAC, consult ROSS Controls.

Installation & Maintenance Guidelines

• Mount in any orientation. Vertical mounting is preferred for optimal condensate drainage from FRL bowls.
• Supply filtered compressed air meeting ISO 8573-1 Class 7:4:4 minimum to protect valve poppets and seals.
• Do not restrict supply lines or exhaust ports. Back pressure on the exhaust port impairs safe exhaust function.
• Connect MDC1 solenoid to external safety controller. Connect MDC2 solenoid and pressure sensor to external safety controller. Implement monitoring logic per the Integration Guide available from ROSS Controls.
• Verify that the external safety controller reads the MDC2 pressure sensor state on every machine cycle and halts operation on any detected fault.
• Position L-O-X lockout valve before or after FRL per facility LOTO program requirements.
• For modular mounting, use bracket, screw, clamp, and mounting adapter kit (R-A118-105M).
• Verify exhaust silencer flow capacity is at least equal to valve exhaust capacity. Replace clogged silencers immediately.
• The L-O-X lockout valve is an energy isolation device per OSHA 1910.147 and ANSI/ASSE Z244.1 - NOT an emergency stop device.
• After installation, perform full functional test: lockout, FRL settings, valve energization/de-energization, exhaust function, pressure sensor signal, and controller response to simulated fault.
• Establish periodic inspection schedule for filter elements, FRL bowl, valve seals, and electrical connections.

Warranty & Global Support

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

Global technical support available through ROSS offices in USA, Canada, Brazil, Germany, France, UK, India, China, and Japan.

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

For complete technical data, dimensional drawings, SISTEMA Library files, and configurator access, visit rosscontrols.com.

Download Catalog: https://www.rosscontrols.com/en/series/1283-safe-air-entry-assembly-with-mdc-series-safe-exhaust-valve