Safe Air Entry Assembly with SV27 Series Safe Exhaust Valve Safety Category. 2, PL c, Externally Monitored

Product Overview

The ROSS Controls is a pre-engineered Safe Air Entry Assembly built around the SV27 Series Safe Exhaust sensing valve, designed for Safety Category 2, Performance Level c (PL c), SIL 2, externally monitored applications per ISO 13849-1:2015. The SV27 valve differentiates itself from other single-channel safe exhaust valves by incorporating a directly operated, safety-rated, force-guided positive-break DPST (Double-Pole Single-Throw) status switch that provides reliable electrical feedback of the valve's physical state to the external safety control system.

Unlike pressure sensors that infer valve state from downstream pressure, the SV27 DPST switch directly senses the internal position of the valve poppet. This force-guided positive-break design means the switch contacts are physically forced open by the valve mechanism - they cannot remain closed if the poppet has moved to its safe (de-energized) position. This direct mechanical linkage provides a higher confidence level of valve state verification compared to indirect pressure-sensing methods.

Assembly components include the Classic or Modular L-O-X Lockout valve for OSHA- and ANSI-compliant energy isolation, MD Series filter/regulator/lubricator with metal bowls for air quality conditioning, the SV27 valve with integrated silencer, and a mounting plate. All components are factory configured, piped, and tested. Explosion-proof solenoid pilot variants and custom designs are available on request. SISTEMA Library data is available at rosscontrols.com.

For safety engineers, machine builders, and OEM designers specifying Category 2 pneumatic safety systems, the series provides a TUV Rheinland of North America certified path to PL c with the enhanced feedback integrity of a directly operated force-guided DPST switch. Port sizes from 1/2 to 1 inch NPT or G thread are available with Classic or Modular lockout valve configurations.

Key Engineering Features

• SV27 Force-Guided DPST Status Switch - Directly operated safety-rated force-guided positive-break DPST switch physically senses valve internal position and state. Contacts are mechanically forced open by the valve mechanism - they cannot remain closed if the poppet is in the safe de-energized position. Provides higher feedback confidence than pressure-based inference methods.
• Safety Category 2, PL c, SIL 2 - SV27 Series valves are rated for Category 2, PL c, SIL 2 per TUV Rheinland of North America certification when the DPST switch is monitored by an appropriate external safety controller on each machine cycle.
• Poppet Construction for Near-Zero Leakage - SV27 poppet design provides near-zero leakage and superior dirt tolerance compared to spool valves, ensuring consistent safe exhaust function across millions of cycles in industrial environments.
• 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 only, full-size exhaust port, integrated sensing port with pop-up indicator, and fluorocarbon slipper seals for reliable operation after extended idle.
• MD Series Air Preparation with Metal Bowls - MD4 Series filter and regulator with metal bowls (Classic LOX assemblies) or MD3 Series integrated filter/regulator with polycarbonate bowl (Modular LOX assemblies). 5-micron filter element, automatic drain, self-relieving regulator, and analog gauge included.
• Mounting Plate Included - A mounting plate is included with Series assemblies for panel or machine frame mounting, ensuring a consistent and secure installation footprint.
• Factory Assembled and Tested - Complete assembly is configured, piped, leak tested, and function verified at the ROSS factory before shipment, minimizing installation time and eliminating field assembly errors.
• Custom Designs and Explosion-Proof Options - Custom assembly configurations and explosion-proof solenoid pilot variants are available. Consult ROSS Controls for hazardous area applications and non-standard configurations.
• Port Sizes 1/2 to 1 inch - Available in 1/2 and 3/4 inch NPT port sizes with MD4 FRL on Classic LOX, and 1/2 inch NPT with MD3 integrated F/R on Modular LOX, with 1 inch port size on high-capacity configuration with Classic LOX.
• SISTEMA Library Support - SISTEMA-compatible safety data for the SV27 valve is downloadable at rosscontrols.com for direct import into safety function calculations per ISO 13849-1.

Technical Specifications

General Specifications

Flow Performance Data

Certifications & Compliance

Typical Applications & Industries

Machine Guarding - Category 2 Applications with Direct State Feedback

• Press brakes and hydraulic presses with pneumatic clamping systems where Category 2, PL c is required and the safety engineer specifies a force-guided switch rather than a pressure sensor to verify the safe exhaust valve state before die entry is permitted.
• Robotic work cells and collaborative robot installations where the safety PLC monitors the SV27 DPST switch contacts on every cycle, verifying the valve has physically moved to the safe position before enabling access.
• Metal fabrication equipment (punches, shears, bending machines) where direct mechanical confirmation of valve position provides higher confidence than pressure inference, satisfying Category 2 requirements without complex pressure thresholding logic.
• Packaging and converting machinery where the safety relay system monitors the SV27 DPST contacts to gate access control interlocks, achieving Category 2 performance per the risk assessment.
• Automotive assembly tooling including pneumatic nut runners, fixture clamps, and transfer systems requiring Category 2, PL c safe exhaust with documented TUV Rheinland certification for plant safety audits.
• Plastics and rubber processing equipment where the SV27 Category 2, SIL 2 rating satisfies both machine safety and process safety requirements simultaneously.

Pneumatic Control and Air Dump/Release Applications

• Air dump systems for large-volume pneumatic cylinders where the force-guided DPST switch confirms complete poppet travel to the de-energized position before downstream access is permitted.
• Pneumatic fixture and clamping systems in high-volume production where the direct switch feedback enables rapid cycle times - the safety controller does not need to wait for a pressure decay threshold before clearing the zone.
• Blow-off and air knife systems in food and pharmaceutical processing where the SV27 provides Category 2 safe shutoff with direct mechanical position verification independent of downstream pressure conditions.
• Test bench pneumatic circuits where regulatory compliance requires Category 2, SIL 2 certified safe exhaust documentation for product liability purposes.

Ordering and Model Number Configuration

The Series assembly model numbers encode the SV27 valve configuration, lockout valve type, FRL option, port size, and voltage. Standard assemblies include the SV27 valve with DPST switch, L-O-X lockout valve, MD Series FRL, and mounting plate. Silencer is included with all assemblies.

Silencer is included with all standard Series assemblies.

Port size 1/2 inch NPT: flow Cv 1-2 = 6.3, Cv 2-3 = 9.2.

Port size 3/4 inch NPT: flow Cv 1-2 = 7.7, Cv 2-3 = 11.

Port size 1 inch NPT: flow Cv 1-2 = 8.0, Cv 2-3 = 12.

Voltages: 24 VDC (W), 110-120 VAC 50/60 Hz (Z), 230 VAC 50/60 Hz (Y). 230 VAC not available in USA.

For other voltages, consult ROSS Controls.

Explosion-proof solenoid pilot available - consult ROSS.

Custom designs available - consult ROSS.

Mounting plate included. Additional mounting accessories available separately.

SISTEMA Library files downloadable at rosscontrols.com.

Accessories

Energy Release Verification Options

Prewired Electrical Connectors

Solenoid Indicator Light Kits

Exhaust Silencers

External silencers for additional noise reduction or remote exhaust routing.

Warning: Exhaust silencer flow capacity must be at least as great as the valve exhaust capacity. Clogged silencers cause back pressure that degrades safe exhaust performance.

Lockout Device

Replacement Filter Elements

Related Products & Accessories

• 1282 Series Safe Air Entry Assembly with MDC1 (Category 1) - Entry-level safe air entry assembly with MDC1 safe exhaust valve for Category 1, PL c. https://www.rosscontrols.com/en/series/1282-safe-air-entry-assembly-with-mdc1-series-safe-exhaust-valve
• 1283 Series Safe Air Entry Assembly with MDC Series (Cat 1 and 2) - Safe Air Entry Assembly with MDC1 or MDC2 safe exhaust valve for Category 1 or Category 2, PL c. https://www.rosscontrols.com/en/series/1283-safe-air-entry-assembly-with-mdc-series-safe-exhaust-valve
• 1285 Series Safe Air Entry Assembly with M35 Series (Cat 4, PL e) - Higher integrity assembly with M35 redundant dual poppet double valve for Category 4, PL e. 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 (Cat 4, PL e, Internal Monitor) - Highest category assembly with DM1C or DM2C internally monitored 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 energy isolation lockout valves. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series

Frequently Asked Questions (FAQ)

Q: How does the SV27 DPST switch differ from the MDC2 pressure sensor for Category 2 monitoring?

A: The SV27 DPST (Double-Pole Single-Throw) switch is a directly operated, force-guided positive-break mechanical switch that physically detects the internal position of the valve poppet. If the poppet moves, the switch contacts change state - they cannot remain in the wrong position due to the force-guided positive-break design. The MDC2 pressure sensor infers valve state from downstream pressure. The DPST switch provides direct mechanical position verification independent of downstream conditions such as residual pressure from trapped volumes or long exhaust paths.

Q: What does 'force-guided positive-break' mean?

A: Force-guided positive-break means the switch contacts are physically forced open by the valve mechanism - spring or gravity force cannot hold the contacts closed if the actuating element (the valve poppet in this case) has moved. This design prevents the dangerous situation where a failed-closed switch contact makes the safety controller believe the valve is in the safe position when it is not. It is a fundamental requirement for safety-rated position sensors in machine safety applications per IEC 60947-5-1.

Q: What safety category and PL does the series achieve?

A: The Series with SV27 valve achieves Safety Category 2, PL c, SIL 2 per ISO 13849-1:2015, certified by TUV Rheinland of North America, when the DPST switch is monitored by the external safety controller on each machine cycle.

Q: Is monitoring automatic or does it require controller programming?

A: Monitoring is external. The Series assembly provides the DPST switch signal. The external safety controller (safety relay, safety PLC, or safety module) must be programmed to read the DPST contacts on each machine cycle, compare the state to the expected state, and halt machine operation if a discrepancy is detected. ROSS provides an Integration Guide with monitoring recommendations.

Q: What voltages are available?

A: Standard voltages are 24 VDC, 110-120 VAC 50/60 Hz, and 230 VAC 50/60 Hz. Note that 230 VAC is not available for assemblies sold in the United States, where OSHA regulations limit control voltage to no more than 120 VAC. For other voltages, consult ROSS Controls.

Q: Does the assembly include a mounting plate?

A: Yes. A mounting plate is included with all Series assemblies. This provides a consistent mounting footprint for panel or machine frame installation. Modular mounting accessories (bracket, screw, clamp, mounting adapter) are available separately for connection to ROSS MD Series FRL units.

Q: Are explosion-proof versions available?

A: Yes. Explosion-proof solenoid pilot versions of the SV27 valve are available for hazardous area installations. Custom designs are also available. Consult ROSS Controls for these configurations.

Q: What is the SV27 DPST switch contact rating?

A: The DPST switch contacts are rated for 2.5 A at 120 VAC, as indicated by the MINI 3-pin and M12 5-pin connector specifications. Refer to the SV27 connector pinout data for complete contact configuration details.

Q: Can the assembly be used on clutch/brake mechanisms of mechanical power presses?

A: No. These valve assemblies are not designed for controlling clutch/brake mechanisms on mechanical power presses. Contact ROSS Controls for appropriate press control products.

Q: What is the maximum flow capacity?

A: Flow capacity is measured in Cv. At 1/2 inch port size: Cv 6.3 (ports 1-2, supply), Cv 9.2 (ports 2-3, exhaust). At 3/4 inch port size: Cv 7.7 (1-2), Cv 11 (2-3). At 1 inch port size: Cv 8.0 (1-2), Cv 12 (2-3). Exhaust Cv is higher than supply Cv by design, ensuring rapid downstream pressure removal.

Q: What SISTEMA data is provided?

A: SISTEMA Library files for the SV27 valve are downloadable at rosscontrols.com. These provide PFH, MTTFD, B10 values, and DC data for direct import into SISTEMA calculations to verify Category 2, PL c, SIL 2 achievement.

Q: What is the operating pressure range?

A: Operating pressure is 30 to 150 psig (2 to 10 bar). Minimum 30 psig is required for reliable valve shifting. Do not exceed 150 psig on any assembly port.

Q: Why does the series include a mounting plate?

A: The mounting plate provides a rigid, pre-drilled mounting base that simplifies installation on machine frames and control panels, ensures consistent component spacing, and supports the assembly weight without relying on pipe connections for structural support.

Q: How does the SV27 assembly support lockout/tagout compliance?

A: The L-O-X lockout valve in the series assembly is compliant with OSHA 1910.147 and ANSI/ASSE Z244.1 energy isolation requirements. It provides a manually operated, lock-capable energy isolation point with full-size exhaust port for rapid pressure release. Combined with the SV27 safe exhaust valve, the assembly enables both safe exhaust for machine cycle safety and positive energy isolation for maintenance.

Installation & Maintenance Guidelines

• Mount in any orientation; vertical preferred for condensate drainage.
• Supply filtered compressed air meeting ISO 8573-1 Class 7:4:4 minimum. 5-micron FRL filter provides this.
• Do not restrict supply lines or exhaust ports. Back pressure on exhaust impairs safe exhaust performance.
• Connect SV27 solenoid and DPST switch to external safety controller per Integration Guide available from ROSS Controls.
• Program safety controller to monitor DPST contacts on every machine cycle. Detect and respond to switch state discrepancies by halting machine operation.
• Position L-O-X lockout valve per facility LOTO program. Lockout valve is an energy isolation device - NOT an emergency stop.
• Install mounting plate to machine frame or control panel per assembly dimensional drawing.
• For modular mounting of FRL components, use bracket, screw, clamp, and mounting adapter accessories.
• Verify exhaust silencer flow capacity is at least equal to valve exhaust capacity.
• After installation, perform complete functional verification: lockout operation, FRL settings, SV27 energization/de-energization, DPST switch contact continuity, and controller fault response.
• Establish periodic maintenance schedule for filter elements, FRL bowl inspection, valve seals, and electrical connection integrity.

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 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 product configurator, visit rosscontrols.com.

Download Catalog: https://www.rosscontrols.com/en/series/1284-safe-air-entry-assembly-with-sv27-series-safe-exhaust-valve