Directional Control Valve [SV27 Series] Safety Category 2 PL c, 2/2-Way Valve, External Monitoring

Product Overview

The ROSS Controls SV27 Series Directional Control Sensing Valves combine the proven durability of the 27 Series poppet valve platform with integrated safety sensing technology, enabling Safety Category 2, Performance Level c (PL c) operation for pneumatic safety circuits. These valves are purpose-built for industrial applications where verification of valve position and state is required by machinery safety standards including ISO 13849-1 and IEC 62061.

Each SV27 valve incorporates a directly-operated, safety-rated DPST (Double-Pole Single-Throw) force-guided positive-break switch with both normally open (NO) and normally closed (NC) contacts. This switch activates whenever the valve poppet is not in its normal home position, providing real-time feedback to an external safety controller. When integrated with a properly configured monitoring system, the SV27 achieves a diagnostic coverage (DC) of 99%.

Available in 2/2 directional control and 3/2 sensing configurations with solenoid pilot or pressure-controlled actuation, the SV27 Series covers port sizes from 3/4 inch to 2 inch with flow capacities ranging from 8 Cv (7,872 Nl/min) to 71 Cv (69,864 Nl/min). An integrated 1/8 inch NPT pressure verification port on each valve accepts an optional visual pop-up indicator or electrical pressure switch for downstream pressure confirmation.

Select SV27 models include ROSS's patented L-O-X lockout feature, providing OSHA 29 CFR 1910.147 and ANSI Z244.1 compliant energy isolation with a lockout that functions only in the de-energized (safe) position. This prevents accidental energy isolation in the energized state and ensures safe maintenance access.

Key Engineering Features

• Poppet Construction with Near-Zero Leakage - Face-sealing poppet design provides positive shutoff with virtually no air bypass in the sealed state, critical for reliable energy isolation during safety events and emergency stops.
• Dirt Tolerant, Wear-Compensating Poppet Design - Self-cleaning high-velocity airflow across poppet seats removes contamination on each cycle. Wear-compensating seals maintain sealing performance across millions of cycles without manual adjustment.
• Integrated DPST Safety Switch - Directly-operated, force-guided, positive-break Double-Pole Single-Throw switch provides both NO and NC contacts. Activates whenever the valve is not in the normal home position, enabling real-time fault detection.
• 99% Diagnostic Coverage (DC) - When the DPST switch output is monitored on each actuation and de-actuation cycle by an external safety-rated controller, the SV27 achieves a diagnostic coverage of 99%, satisfying the requirements for Safety Category 2.
• Integrated 1/8 inch Pressure Verification Port - Accepts optional visual pop-up pressure indicators or electrical pressure switches to provide direct downstream pressure verification, adding a second safety confirmation channel.
• TUV SIL 2 Certified (SIL 3 Redundant) - Third-party TUV Rheinland certification to IEC 61508 and IEC 61511. Achieves SIL 2 and PL c in singular application; SIL 3 and PL e in redundant (HFT >= 1) configuration.
• L-O-X Lockout Feature (Select Models) - ROSS patented lockout mechanism that operates only in the de-energized (off) position, preventing inadvertent energy isolation in the energized state. Supports OSHA LOTO requirements per 29 CFR 1910.147.
• SISTEMA Library Available - Published safety data package for direct import into SISTEMA (Safety Integrity Software Tool for the Evaluation of Machine Applications) for rapid safety circuit documentation and PL verification.
• High Flow Capacity - Available in body sizes from 3/4 inch to 2 inch, delivering flow coefficients from 8 Cv to 71 Cv to support high-demand pneumatic safety exhaust and cylinder control applications.

Technical Specifications

General Specifications

Electrical Data (Solenoid Pilot Valves)

Solenoid pilot controlled models are rated for continuous duty. LED indicators available for visual solenoid status confirmation.

Electrical Connection Options

Flow Performance Data

Flow capacity data for SV27 Series sensing valves by body size and port configuration.

Certifications & Compliance

Typical Applications & Industries

Mechanical Power Press and Stamping Operations

• Pneumatic safety circuit control for single-stroke clutch/brake systems on mechanical power presses, where the SV27 DPST feedback switch confirms full valve actuation before each stroke cycle.
• Die protection and part ejection air circuits on stamping presses requiring Category 2 monitoring to detect valve failures before they result in unexpected motion.
• Slug and scrap blow-off systems on progressive die lines where safe shut-off must be verified after each machine stop.
• Air counterbalance and die cushion circuits on press lines requiring position feedback to confirm pressure release before die change or maintenance access.

Pneumatic Cylinder-Operated Safety Gates and Guards

• Safety gate locking and unlocking actuators on automated manufacturing cells where valve position feedback confirms full pressure release before personnel entry.
• Pneumatic safety barriers on robot work cells and assembly islands requiring redundant monitoring of valve state during guard open sequences.
• Slide gate actuators on conveyors and material handling systems where Category 2 valve sensing integrates with area scanner and light curtain safety loops.

Safe Energy Isolation and Lockout/Tagout

• SV27 with L-O-X lockout for pneumatic energy isolation points on multi-energy machines per OSHA 29 CFR 1910.147, providing lockable energy isolation that can only be applied in the de-energized state.
• Compressed air isolation at machine service access points on injection molding machines, blow molding lines, and extrusion equipment.
• Group lockout stations integrating SV27 isolation valves with pressure verification indicators to confirm full system de-pressurization before maintenance teams enter restricted areas.

Packaging and Converting Machinery

• Case erecting, carton sealing, and palletizing systems requiring safe exhaust of pneumatic actuators when guards are opened, with DPST feedback confirming dump valve actuation.
• Rotary table and indexing actuators on packaging lines where partial valve failures must be detected before the next machine cycle.
• Vacuum pick-and-place systems on form-fill-seal machines incorporating safe dump valves with position sensing to detect sticking poppets.

Automotive Assembly and Body Fabrication

• Pneumatic clamping and fixture actuators on automotive body welding lines requiring Category 2 safety valve monitoring per ISO 13849-1 to satisfy OSHA and customer safety audit requirements.
• Lift-assist and tilt actuators in ergonomic assist devices on assembly lines where valve position feedback integrates with collaborative robot safety controllers.
• Paint line air control for spray booth actuators and booth pressurization systems requiring safe shut-off verification.

Food, Beverage, and Pharmaceutical Processing

• Pneumatic shut-off valves on filling and dosing machines in food and pharmaceutical facilities where safety circuit documentation and proof test intervals must meet regulatory agency requirements.
• Safe pressure release valves on pressurized vessels and mixing systems requiring DPST feedback confirmation of full pressure venting before opening access hatches.
• Pneumatic actuators on washdown-rated processing equipment requiring reliable valve position feedback in high-humidity environments.

Ordering and Model Number Configuration

SV27 Series valves use a structured model number system. Key configuration choices include body size, valve function, actuation type, solenoid voltage, and optional L-O-X lockout.

Solenoid voltage codes: 1D = 24V DC; AA = 120V AC, 50/60 Hz; 1A = 110V AC, 50 Hz or 120V AC, 50/60 Hz; 2A = 230V AC, 50/60 Hz.

For G (BSPP) threads, add 'D' as a prefix to the model number.

L-O-X lockout option is available on select 3/2 sensing valve models. Specify at time of order.

SISTEMA library data is available for download at rosscontrols.com. Contact ROSS for safety data package documentation.

Accessories

Visual Pop-Up Pressure Indicator

Mechanical visual indicator installs into the 1/8 inch NPT pressure verification port on the SV27 valve body. Provides a visible positive indication of downstream pressure presence or absence. Requires no electrical connection.

Electrical Pressure Switch

Electrical pressure switch installs into the 1/8 inch NPT pressure verification port and provides an electrical signal to the safety controller confirming downstream pressure status. Enables dual-channel monitoring: DPST switch for valve position and pressure switch for downstream pressure verification.

Exhaust Silencers

Threaded aluminum exhaust silencers available for 3/2 SV27 valve exhaust ports to reduce exhaust noise. Silencer flow capacity must equal or exceed the valve exhaust flow capacity to avoid back pressure that could affect valve operation.

Related Products & Accessories

• 27 Series Soft Start EEZ-ON Valve - 27 Series soft start valve for gradual pressure buildup at machine startup. Safety Category 1, PL c. https://www.rosscontrols.com/en/series/1299-27-series-soft-start-eez-on-valve
• RSe Series Double Valve - Redundant spool double valve with external monitoring for Safety Category 4, PL e applications. https://www.rosscontrols.com/en/series/1300-rse-series-double-valve
• 77 Series Double Valve - Internally monitored double valve with automatic reset for Safety Category 4, PL e. https://www.rosscontrols.com/en/series/1301-77-series-double-valve
• CrossMirror CM26 Series Double Valves - Self-monitoring double valve with manual reset for Safety Category 4, PL e applications. https://www.rosscontrols.com/en/series/1302-crossmirror-cm26-series-double-valves
• Lockout Valves (L-O-X, 15 Series) - Dedicated pneumatic lockout valves for OSHA LOTO energy isolation compliance. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series
• Exhaust Silencers - Aluminum silencers for SV27 exhaust ports to reduce noise in safety exhaust applications. https://www.rosscontrols.com/en/series/90-silencers

Frequently Asked Questions (FAQ)

Q: What is the SV27 Series and how does it differ from the standard 27 Series valve?

A: The SV27 Series adds an integrated, safety-rated DPST (Double-Pole Single-Throw) feedback switch and a 1/8 inch NPT pressure verification port to the proven 27 Series poppet valve. The DPST switch provides real-time position feedback to an external safety controller, enabling Safety Category 2 PL c monitoring that the standard 27 Series valve cannot provide.

Q: What does the DPST switch actually detect?

A: The DPST switch activates whenever the valve poppet is not in its normal home position. This means a stuck-open poppet, a poppet that has not fully shifted, or any mechanical failure that prevents the valve from reaching its normal de-energized state will trigger the switch contacts, signaling a fault to the external safety controller.

Q: What diagnostic coverage can be achieved with the SV27 Series?

A: When the DPST switch output is monitored by the external safety controller on every actuation and de-actuation cycle, the SV27 achieves a diagnostic coverage (DC) of 99%. This satisfies the diagnostic requirements for Safety Category 2 under ISO 13849-1 and supports the safety performance level calculations.

Q: What safety ratings does the SV27 Series carry?

A: The SV27 Series is TUV Rheinland certified to IEC 61508 and IEC 61511 for SIL 2 in singular application (HFT = 0) and SIL 3 in redundant application (HFT >= 1). Performance Level ratings per ISO 13849-1 are PL c (singular) and PL e (redundant). B10D value is 20,000,000 cycles.

Q: What is the purpose of the 1/8 inch pressure verification port?

A: The integrated 1/8 inch NPT pressure verification port accepts an optional visual pop-up indicator or electrical pressure switch. This allows direct confirmation that downstream pressure has been released, adding a second independent monitoring channel beyond the DPST valve position switch. Many applications use both the switch feedback and the pressure verification simultaneously for higher safety confidence.

Q: What is the L-O-X lockout feature and which models include it?

A: The L-O-X (Lockout in the Off position only) is a ROSS patented lockout mechanism available on select SV27 3/2 sensing valve models. When locked, the valve is maintained in the de-energized (safe exhaust) position and cannot be inadvertently energized. The lockout cannot be applied in the energized position, eliminating the risk of energy being trapped during maintenance. This supports OSHA 29 CFR 1910.147 and ANSI Z244.1 compliance.

Q: What is the operating pressure range?

A: For 2/2 directional control configurations, the operating pressure range is 40 to 150 psig (2.8 to 10.3 bar). For pilot-operated check valve configurations, the range is 15 to 150 psig (1 to 10 bar). Maximum operating pressure is 150 psig (10.3 bar).

Q: What temperature ratings apply to the SV27 Series?

A: Ambient temperature range is 40 to 120 F (4 to 50 C). Media temperature range is 40 to 175 F (4 to 80 C) for standard Buna-N seal configurations. Select configurations with Fluorocarbon seals extend the media temperature range.

Q: What flow capacities are available?

A: The SV27 Series covers body sizes from 3/4 inch to 2 inch. Flow coefficients range from 6.2 Cv (6,100 Nl/min) for the 3/4 inch body with 1/2 inch ports up to 71 Cv (69,864 Nl/min) for the 2 inch body. The 1-1/4 inch body provides 29 Cv (29,000 Nl/min) with 1-1/2 inch ports.

Q: How is the DPST feedback wired to the safety controller?

A: On solenoid pilot controlled SV27 models, the DPST feedback switch is wired through a 5-pin M12 connector that exits the valve body. The solenoid coil uses a separate 3-pin mini connector. Both channels of the DPST switch (NO and NC contacts) should be wired into the safety controller's dual-channel input for maximum diagnostic value.

Q: Is a SISTEMA library file available for the SV27 Series?

A: Yes. ROSS Controls publishes a SISTEMA library file for the SV27 Series that can be downloaded from rosscontrols.com. The library contains the required safety parameters (B10D, MTTFd, DC) for direct import into SISTEMA to support ISO 13849-1 PL verification and machine safety documentation.

Q: What filtration level is required for the supply air?

A: Filtered compressed air is required. A 5-micron filtration level is recommended to maximize valve life and maintain poppet sealing performance. The poppet design provides inherent dirt tolerance, but consistent filtration minimizes wear and extends service intervals.

Q: Can the SV27 be used without external monitoring?

A: The SV27 valve is mechanically functional without external monitoring, but achieving Safety Category 2 PL c requires that the DPST switch output be actively monitored by a safety-rated controller on each machine cycle. Without active monitoring, the diagnostic benefit of the DPST switch is not realized, and the safety level of the circuit cannot be validated to Category 2.

Installation & Maintenance Guidelines

• Mount the SV27 valve inline in any orientation. Vertical mounting with the solenoid facing upward is preferred for optimal condensate drainage and poppet performance.
• Supply filtered compressed air at 5-micron filtration minimum. Contamination accelerates poppet wear and can cause valve misalignment that triggers false DPST switch signals.
• Connect the 5-pin M12 feedback connector to the external safety controller. Wire both NO and NC contacts of the DPST switch into separate input channels of the safety controller for full diagnostic coverage.
• The DPST switch must be monitored on every actuation and de-actuation cycle. Monitoring only at startup or on demand does not achieve the 99% diagnostic coverage required for Category 2.
• Install the optional pressure verification indicator or pressure switch into the 1/8 inch NPT port for applications requiring downstream pressure confirmation as a second monitoring channel.
• For L-O-X lockout models, confirm that the lockout padlock hasp is accessible and operable before installation. The valve must be fully de-energized and depressurized before lockout is applied.
• Do not restrict supply or exhaust ports. Back pressure at the exhaust port can prevent full valve shifting and cause nuisance DPST switch activations.
• Verify operating pressure is within the specified range (40 to 150 psig for 2/2 models). Pressures below 40 psig may result in incomplete poppet shifting and incorrect DPST switch states.
• After installation, perform a proof test by actuating and de-actuating the valve while verifying DPST switch state changes at the safety controller. Confirm that the switch transitions correspond to the correct valve positions.
• Establish a documented proof test interval consistent with the safety PFD (Probability of Failure on Demand) calculation for the application. Annual proof testing is the recommended starting point.

Warranty & Global Support

ROSS Controls provides a one-year warranty on all SV27 Series products, covering defects in material and workmanship from the date of purchase.

Technical support for safety circuit integration, SISTEMA data, and SV27 installation is available from ROSS Controls USA at +1-248-764-1800 or (800) 438-7677.

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

For complete dimensional drawings, CAD models, SISTEMA library files, and TUV certification documentation, visit the SV27 Series product page at rosscontrols.com.

Download Catalog: https://www.rosscontrols.com/en/documents/2618/sv27-series-sensing-valves