Standard Temperatures [Classic 27 Series] 2/2, 3/2, & 4/2 Functions, 1/4" to 2-1/2" Port Sizes

Product Overview

The ROSS Controls Classic 27 Series is a family of inline poppet directional control valves engineered for standard temperature industrial pneumatic applications. Available in 2/2, 3/2, and 4/2 valve functions with port sizes ranging from 1/4" to 2-1/2" in both NPT and G (BSPP) thread forms, the 27 Series delivers flow capacities up to 82 Cv (81,000 Nl/min), making it one of the highest-flow inline poppet valve families in the ROSS Controls product line. Solenoid pilot controlled and pressure (pneumatic) controlled actuation options are available across all valve functions.

The 27 Series poppet construction is the defining engineering characteristic of this valve family. Unlike spool valves that rely on close-tolerance sliding seals and are susceptible to contamination-induced leakage and wear, the 27 Series uses perpendicular poppet face seals that close against precisely machined seats. This geometry creates a high-velocity airflow across the poppet seat on each cycle, generating a self-cleaning action that maintains sealing integrity in dirty, dusty, and contaminated compressed air systems. The result is a positive sealing, near-zero leakage valve with exceptional dirt tolerance and a long service life.

The differential piston design of the 27 Series actuator provides overwhelming shifting forces relative to the spring return load. This force margin ensures that the valve shifts positively and without hesitation on every cycle, including after extended idle periods in environments where seal stiction could compromise a lesser design. The self-compensating seal geometry automatically adjusts as seals wear over time, maintaining consistent response characteristics over millions of operating cycles.

Nine body sizes cover port configurations from 1/4" through 2-1/2", with the larger 2" and 2-1/2" body sizes extending the flow range far beyond what is available from the companion 21 Series. For applications requiring high-volume air control in stamping presses, large cylinders, blow-off systems, and high-throughput automation, the 27 Series provides the flow capacity in a proven, field-reliable inline poppet package. The 27 Series is TUV Rheinland certified to SIL 2 (IEC 61508/61511) in singular applications and SIL 3 in redundant configurations.

Key Engineering Features

• Perpendicular Poppet Face Seals - Creates high-flow paths with positive shutoff and near-zero leakage, eliminating the bypass losses and wear mechanisms inherent in spool-type valve designs.
• Self-Cleaning Poppet Design - High-velocity airflow across poppet seats on each cycle dislodges contaminants and prevents buildup, delivering strong dirt tolerance in contaminated compressed air environments.
• Differential Piston Actuator - Generates overwhelming shifting forces relative to spring return load, providing no-hesitation actuation even after extended idle periods and in sticky or contaminated conditions.
• Self-Compensating Seals - Superior internal guidance system automatically adjusts seal stroke as seals wear, maintaining consistent performance and extending service life without requiring recalibration or adjustment.
• Consistent Response Time Over Valve Life - Poppet construction eliminates the performance degradation common in spool valves. Response characteristics remain predictable and constant across the entire service life of the valve.
• Port Sizes to 2-1/2" - Nine body sizes accommodate port configurations from 1/4" to 2-1/2", with flow capacities reaching 82 Cv (81,000 Nl/min) for 3/2 configurations and 66 Cv (65,000 Nl/min) for 2/2 configurations.
• Internal or External Pilot Supply - Field-convertible pilot supply configuration. Relocating the pipe plug between the external pilot port (X-1) and internal pilot passage converts the valve without requiring new parts or model number changes.
• Classic 1/2" Conduit Electrical Connection - Solenoid pilot valves use 1/2" electrical conduit with 30" leads, providing a secure, hardwired connection suited for permanent industrial installations and harsh environments.
• Non-Locking Manual Override - Standard on all solenoid pilot controlled models for commissioning, troubleshooting, and system verification without requiring external tools or electrical power.
• TUV SIL 2 Certification - Certified by TUV Rheinland to SIL 2 (IEC 61508/61511) in singular applications and SIL 3 in redundant (1oo2) configurations, enabling integration into safety-rated pneumatic control architectures.
• Special Control Adaptors Available - Pressure Booster, Air Index (impulse detent), Timed Sequence, Timed Sequence Extension, and Timed In/Out Sequence adaptors extend the 27 Series base valve with advanced control functions without requiring separate valve bodies.
• Downloadable CAD Models - Available for all 27 Series variants to streamline machine design integration and reduce engineering lead time.

Technical Specifications

General Specifications

Temperature Ratings

The Classic 27 Series is designed for standard industrial temperature environments. Solenoid pilot valves carry a narrower ambient rating due to solenoid coil thermal limits; pressure controlled variants tolerate the full media temperature range as ambient.

Important: For media temperatures at or near the upper limit of 175 F (80 C), verify that the compressed air supply contains no entrained moisture, which can cause accelerated seal degradation at elevated temperatures.

Electrical Data (Solenoid Pilot Valves)

All solenoid coils are rated for continuous duty. The 27 Series uses classic 1/2" conduit connections with 30" leads. Indicator light kits are available as optional accessories.

Electrical Connection Options

Flow Performance Data

Flow performance data for Solenoid Pilot Controlled and Pressure Controlled valves. 3/2 Cv values shown for 1-2 (supply) and 2-3 (exhaust) directions. 4/2 Cv values shown for 1-2/1-4 and 4-3/2-3 directions. Response time formula: Response Time (msec) = M + (F x V), where V is the downstream volume in cubic inches to fill to 90% of supply pressure or exhaust to 10% of supply pressure.

Response Time Formula: Response Time (ms) = M + (F x V), where M is the minimum response constant (milliseconds), F is the fill or exhaust factor (ms/cubic inch), and V is the downstream volume in cubic inches to be filled to 90% of supply pressure or exhausted to 10% of supply pressure. M and F values for each body size and function are tabulated in the ROSS 27 Series catalog.

Certifications & Compliance

Typical Applications & Industries

Metal Stamping and Press Forming

• Mechanical and hydraulic press clutch-brake controls requiring high Cv flow for rapid cylinder actuation and exhaust. The 2" and 2-1/2" body sizes deliver the volume flow needed to meet press cycle time requirements.
• Blanking, drawing, and progressive die operations where reliable valve shifting over millions of cycles is critical to uptime. The poppet design eliminates spool wear-induced leakage that causes press timing drift.
• Coil feed, transfer, and automation circuits integrated with stamping lines where multiple 27 Series valves provide coordinated directional control.
• SIL 2 certified safety circuits for press guarding systems where TUV-rated valves are required to meet OSHA and ISO 13849 compliance.

Automotive and Assembly Manufacturing

• Body shop welding fixtures, clamp and unclamp circuits, and gate automation where high flow and fast response reduce cycle time. The self-cleaning poppet design tolerates weld spatter and metal dust contamination.
• Paint booth and coating line pneumatic actuators where long, maintenance-free service life reduces production interruptions.
• Assembly line material handling, lift and tilt tables, and actuator circuits requiring the full port size range from 1/4" to 2-1/2" within a single product family.
• Engine and transmission test cell pneumatics where consistent response time over valve life ensures reliable test repeatability across millions of cycles.

Packaging and Material Handling

• Case erecting, carton sealing, palletizing, and stretch wrap systems where high-cycle solenoid valves must operate reliably in dusty, cardboard-fiber environments. The dirt-tolerant poppet construction reduces unplanned maintenance.
• Conveyor diverters, pushers, stoppers, and transfer stations using double-acting cylinders controlled by 4/2 configurations for positive bidirectional position control.
• Vacuum packaging and form-fill-seal lines requiring fast, repeatable airflow control to meet packaging line rates.
• Bag filling and bulk material handling systems using the 2" and 2-1/2" body sizes for high-volume air supply and exhaust.

General Industrial and Process Manufacturing

• Tire molding, rubber curing, and plastics processing pneumatics where the standard temperature range (to 175 F media) covers typical process ambient conditions.
• Woodworking machinery including clamp, feed, and positioning circuits requiring reliable cycling in sawdust-laden environments. The self-cleaning poppet resists contamination better than spool designs.
• Air blow-off systems, part ejection, and cleaning stations using large body sizes for maximum instantaneous flow.
• Printing and converting equipment where consistent valve response maintains register and cut accuracy across long production runs.
• Foundry and casting support equipment, transfer automation, and mold handling circuits where particulate contamination is unavoidable.

Safety and Energy Isolation Systems

• Safety exhaust and dump valve circuits using the TUV SIL 2 certified 27 Series in Category 3 and Category 4 safety architectures for press, robot, and hazardous motion guarding.
• Redundant pneumatic safety circuits (1oo2) using paired 27 Series valves to achieve SIL 3 safety integrity level for the highest-risk applications.
• Energy isolation circuits for machine lockout/tagout procedures where the 27 Series is used as the primary pneumatic isolation element upstream of tool-change or maintenance zones.

Ordering and Model Number Configuration

The ROSS Classic 27 Series uses a structured model number system that encodes valve function, body/port size, actuation type, and voltage. The model number structure is shown below for a solenoid pilot controlled 3/2 normally closed valve.

Voltage codes: W = 24 VDC; Z = 110-120 VAC, 50/60 Hz. For other voltages, contact ROSS Controls.

G (BSPP) thread versions: Prefix the model number with 'D' (e.g., D2773B5001W). Available for all body sizes and functions.

Adaptor suffixes: Pressure Booster Adaptor models append '9' to the size code (e.g., 2773B5009W). Air Index Adaptor appends '8'. Timed Sequence Adaptor appends '4' (timed-in) or '5' (timed-out). Contact ROSS for detailed adaptor model configurator.

Direct Double Solenoid models (3/2 and 4/2 functions, detented) omit the actuation digit from the model number prefix. Consult the ROSS 27 Series catalog for complete Direct Double Solenoid model numbers.

D2 models for 1-1/2" and 2" body sizes are available with oversized port configurations (up to 2-1/2" ports on 1-1/2" body) for maximum flow. These are denoted by the D2 designation in the catalog.

Solenoid Pilot Controlled 2/2 Valve Model Numbers (Selected Sizes)

Solenoid Pilot Controlled 3/2 Valve Model Numbers (Selected Sizes)

Pressure Controlled 3/2 Valve Model Numbers (Selected Sizes)

Accessories

Exhaust Silencers

Aluminum exhaust silencers reduce compressed air exhaust noise at the valve exhaust port. Available for port sizes 1/4" through 2-1/2". Pressure rating 0 to 290 psig (0 to 20 bar).

Warning: Exhaust silencers must have flow capacities at least as great as the exhaust flow capacity of the valve. Undersized or contaminated silencers create back pressure on the exhaust port that reduces differential pressure across the poppet seat and can cause incomplete or erratic valve shifting.

Indicator Light Kits

Optional indicator light kits provide visual solenoid-energized confirmation on solenoid pilot controlled 27 Series valves. Available for 24 VDC, 110-120 VAC, and 220 VAC voltages. Model numbers: 862K87-W (24 VDC), 862K87-Z (110-120 VAC), 862K87-Y (220 VAC).

Pressure Booster Adaptor

Mounts between the solenoid pilot and the valve body to allow operation at pilot pressures as low as 15 psig (1 bar). The Pressure Booster Adaptor converts low-signal pilot pressure into full operating force using supply pressure, enabling the 27 Series to operate in pneumatic circuits with low-pressure pilot signals. Models append '9' to the size code (e.g., 2773B5009W).

Air Index Adaptor

Converts a solenoid pilot controlled 27 Series valve into an impulse-controlled, mechanically detented valve. A momentary electrical signal to the solenoid shifts the valve and holds it in the actuated position without continuous power. A second momentary signal from the same solenoid returns the valve to the deactuated position. Useful for applications requiring power-off position retention.

Timed Sequence Adaptor

Provides continuously adjustable time delay between solenoid energization and valve shifting. For 2/2 valves, adjustable delay is up to 30 seconds. For 3/2 and 4/2 valves, up to 3 seconds. Tapered needle provides smooth, repeatable time adjustment. Timed Sequence Extension Adaptors extend the range up to 60 seconds with snap-action response.

Related Products & Accessories

• 21 Series Standard Temperature Classic Valves - Companion inline poppet valve family for standard temperature applications with port sizes up to 1-1/2". Shares poppet construction and operating principles with the 27 Series; select when 1-1/2" maximum port size is sufficient. https://www.rosscontrols.com/en/series/229-standard-temperatures-classic-21-series
• 27 Series Low/High Temperature Classic Valves - Classic conduit-connection variant of the 27 Series configured for extreme temperature applications with Fluorocarbon or Buna-N seals for operation outside the standard 40-175 F range. https://www.rosscontrols.com/en/series/231-low-high-temperatures-classic-21-series
• 2759 Series Low/High Temperature DIN/M12 Connection 21 Series - 21 Series poppet valves with DIN EN 175301-803 and M12 quick-disconnect connections for extreme temperature environments from -40 F to 300 F. TUV SIL 2 certified. https://www.rosscontrols.com/en/series/2759-lowhigh-temperatures-din-m12-connection-21-series
• SV27 Series Sensing Valves - 27 Series poppet valve bodies with integrated DPST position switch for pneumatic safety circuits. Provides 99% diagnostic coverage and Category 2 / PL c compliance without redundant valve pairs. https://www.rosscontrols.com/en/series/1298-directional-control-valve-sv27-series
• Exhaust Silencers - Aluminum silencers rated to 290 psig for exhaust port sizes 1/4" through 2-1/2" to reduce compressed air exhaust noise from 27 Series valves. https://www.rosscontrols.com/en/series/90-silencers
• L-O-X Lockout Valves - Pneumatic lockout valves for safe energy isolation during maintenance per OSHA lockout/tagout requirements. Compatible with 27 Series pneumatic systems. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series

Frequently Asked Questions (FAQ)

Q: What is the maximum port size available in the Classic 27 Series?

A: The Classic 27 Series is available in port sizes up to 2-1/2" NPT or G (BSPP). The 2" body size accommodates inlet and outlet port sizes up to 2-1/2" in 3/2 configurations. The 2-1/2" body size provides 2-1/2" ports with flow capacities reaching 70 Cv (70,000 Nl/min) in 3/2 NC configuration.

Q: How does the 27 Series differ from the 21 Series?

A: The primary distinction is body size and flow capacity. The 21 Series offers port sizes up to 1-1/2" with maximum flow of approximately Cv 33. The 27 Series extends to 2-1/2" port sizes with maximum flow reaching Cv 82 for 3/2 configurations. Both series share the same poppet construction principles, and the 27 Series uses the same classic 1/2" conduit electrical connections as the 21 Series standard connection models.

Q: What actuation options are available for the 27 Series?

A: Three actuation types are available: (1) Solenoid Pilot Controlled, using an integral solenoid to generate a pilot signal that shifts the poppet; (2) Direct Double Solenoid Controlled, with dual solenoids providing positive detented control in both directions without spring return; and (3) Pressure (Pneumatic) Controlled, using an external pneumatic pilot signal. All three are available across 2/2, 3/2, and 4/2 functions.

Q: What is the operating pressure range for the 27 Series?

A: Body sizes 3/8" through 1-1/2" operate from 15 to 150 psig (1 to 10 bar). The 2" body size requires a minimum of 30 psig (2 bar) and has the same 150 psig (10 bar) maximum. For pressure controlled models, external pilot supply pressure must be equal to or greater than inlet pressure.

Q: Can the pilot supply be changed from internal to external in the field?

A: Yes. The 27 Series is field-convertible between internal and external pilot supply. Removing the existing pipe plug from the external pilot port (X-1) and supplying external pilot pressure to X-1 converts the valve to external pilot operation. Installing a plug in X-1 and using the inlet supply restores internal pilot operation. No new parts are required.

Q: What is the temperature rating for the Classic 27 Series?

A: The standard Buna-N sealed 27 Series is rated for ambient temperatures of 40 to 120 F (4 to 50 C) with solenoid pilot models, and 40 to 175 F (4 to 80 C) for pressure controlled models. Media temperature is 40 to 175 F (4 to 80 C) for all configurations. For operation outside this range, the low/high temperature 27 Series with alternate seal materials is required.

Q: Are G (BSPP) thread versions available?

A: Yes. All 27 Series valve models are available with G (BSPP) threads by prefixing the model number with 'D'. For example, a 2773B5001W (NPT) becomes D2773B5001W (G threads). This applies to all body sizes, functions, and actuation types.

Q: What special control functions are available with adaptors?

A: Four adaptor types extend the base 27 Series valve: (1) Pressure Booster Adaptor for low pilot pressure operation down to 15 psig; (2) Air Index Adaptor for impulse-controlled mechanically detented operation from a single solenoid; (3) Timed Sequence Adaptor for adjustable time delay up to 30 seconds (2/2) or 3 seconds (3/2 and 4/2); (4) Timed Sequence Extension Adaptor for delays up to 60 seconds with snap-action response.

Q: Is the 27 Series safety certified?

A: Yes. The Classic 27 Series is TUV Rheinland certified to SIL 2 (IEC 61508/61511) with HFT = 0 in singular applications and SIL 3 with HFT >= 1 in redundant configurations. Performance Level ratings are PL c (singular with application-specific diagnosis) and PL d (redundant) per EN ISO 13849-1. CE Declaration of Conformity and EAC Declaration are included.

Q: What filtration is required for the 27 Series?

A: Compressed air supply should be filtered to a minimum of 5 microns to maintain optimal valve performance and service life. The poppet design is inherently more tolerant of contamination than spool valves, but coarse particulate contamination above 5 microns can accelerate seat wear over time.

Q: Does the 27 Series require lubrication?

A: The valve does not require lubrication of the compressed air supply. If lubrication is used or present in the system, use only petroleum-based lubricant with an aniline point between 180 F and 220 F, ISO 32 viscosity or lighter, at approximately one drop per minute. Avoid phosphate-ester-type hydraulic fluid additives, which will degrade Buna-N seals.

Q: How do I calculate valve response time?

A: Use the formula: Response Time (ms) = M + (F x V), where M is the minimum response constant in milliseconds, F is the fill or exhaust factor in ms/cubic inch, and V is the downstream volume in cubic inches to fill to 90% of supply pressure or exhaust to 10% of supply pressure. M and F constants for each body size, port configuration, and valve function are tabulated in the ROSS 27 Series catalog.

Q: Are CAD models available for the 27 Series?

A: Yes. Downloadable CAD models are available for all 27 Series configurations through the ROSS Controls website at rosscontrols.com. CAD models support major platform formats to enable direct integration into machine design assemblies.

Installation & Maintenance Guidelines

• Mount inline in any orientation. Vertical mounting with the solenoid upward is preferred for optimal condensate drainage from the valve body.
• Supply filtered compressed air at 5-micron filtration minimum. Coarse particulate contamination accelerates poppet seat wear and can prevent positive sealing.
• Do not restrict supply lines or exhaust ports. Undersized supply plumbing reduces available pressure below the minimum operating threshold and causes erratic valve response.
• For external pilot supply configurations, ensure pilot pressure is equal to or greater than inlet supply pressure at all times during operation. A pilot pressure drop below inlet pressure will prevent the valve from shifting or holding position.
• Minimum operating pressure is 15 psig (1 bar) for body sizes 3/8" through 1-1/2" and 30 psig (2 bar) for the 2" body size. Do not operate below these thresholds.
• Exhaust silencers must have flow capacities at least as great as the exhaust flow capacity of the valve. Install silencers rated for the applicable exhaust port size. Contaminated silencers increase back pressure on the exhaust port and can prevent complete valve shifting.
• When using lubricated compressed air, use only petroleum-based lubricant (ISO 32 viscosity or lighter, aniline point 180 F to 220 F) at approximately one drop per minute. Synthetic and phosphate-ester lubricants will degrade Buna-N seals.
• For solenoid pilot controlled valves, verify that supply voltage and frequency match the solenoid coil rating before energizing. Operating at incorrect voltage or frequency will damage the coil.
• The non-locking manual override on solenoid models is intended for commissioning and maintenance use only. Do not use the manual override as a substitute for electrical control in normal production operation.
• When installing with adaptor options (Pressure Booster, Timed Sequence, Air Index), verify that the adaptor configuration is appropriate for the system operating pressure range. Consult the ROSS 27 Series catalog for adaptor-specific operating parameters.
• Allow adequate clearance above the solenoid assembly for coil removal and manual override access during maintenance. Refer to dimensional drawings in the 27 Series catalog for body-size-specific clearance requirements.
• For D2 model variants (oversized ports on 1-1/2" or 2" body), verify that the connecting plumbing and downstream components are sized to accept the larger port diameter without creating flow restrictions.

Warranty & Global Support

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

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

For product configuration, technical support, dimensional drawings, and distributor locator services, contact ROSS Controls USA at (800) 438-7677 or visit rosscontrols.com.

The ROSS 27 Series catalog provides complete technical data, model number configurator, dimensional drawings for all body sizes, and application guidance. Download directly from rosscontrols.com.

Download Catalog: https://www.rosscontrols.com/en/documents/395/Directional_Control_Valves_Classic_27_Series_ROSS-27-H_EN.pdf