Double Valves with Pneumatic L-G Monitor, Ports 3/8 to 3/4 SERPAR® 35 Series

Product Overview

The ROSS Controls SERPAR 35 Series Double Valves with Pneumatic L-G Monitor for 3/8 to 3/4-inch ports are Basic Size 4 internally monitored double valves designed for press clutch/brake control and Category 3 and 4 safety circuits requiring smaller port sizes. These valves provide a Cv of 3.0 in the in-out direction with exhaust Cv from 6.0 to 9.0 depending on the outlet port size selected, making them suitable for smaller-tonnage presses and auxiliary safety circuits.

The SERPAR 35 Series Basic Size 4 with L-G monitor contains the same internally monitored pneumatic lockout-gate (L-G) monitoring device used in the larger sizes. The built-in monitor verifies synchronous valve element operation on every actuation and deactuation cycle. A valve element fault immediately exhausts pilot air, closes both elements, and mechanically latches the L-G spool with a lockout pin that prevents further operation until a deliberate reset is performed.

A key distinction of the Size 4 configuration is that the inlet port can be located on either the right or left side of the valve body, providing piping flexibility for compact press control enclosures. The valve uses cord-grip solenoid connections (ordered separately) rather than the terminal strip used on Sizes 8, 12, and 30. Reset pressure for remote models requires at least 30 psig; manual reset models use internal valve pressure.

Basic Size 4 valves are inline mounted with piping flanges and include built-in non-clogging silencers. Available with or without manual overrides, and in both right-inlet and left-inlet configurations, these valves cover the 3/8, 1/2, and 3/4-inch port size range required for smaller mechanical presses and secondary press safety circuits.

Key Engineering Features

• Internal Pneumatic L-G Monitoring - No External Hardware - Self-contained pneumatic lockout-gate monitoring detects asynchronous valve element movement on every cycle without requiring external monitoring relays, safety PLCs, or additional monitoring circuitry.
• Automatic Lockout with Mechanical Memory - L-G lockout pin holds the monitoring spool in the locked-out position after fault detection, preventing valve operation regardless of air supply cycling or solenoid state changes until a deliberate reset is performed.
• Right or Left Inlet Port Option - Basic Size 4 is available with the inlet port on either the right or left side of the valve body, providing piping layout flexibility for compact press control enclosures and retrofit applications.
• SERPAR Crossflow Poppet Design - Crossflow passages with dual poppet and spool valve elements produce parallel, balanced flow paths. Outlet pressure is limited to less than 2% of inlet pressure when one element is open and the other is closed.
• Manual and Remote Pneumatic Reset Options - Manual reset uses internal valve pressure via a push-button actuator. Remote reset connects a 3/2 normally closed reset valve to the 1/8-inch reset port and requires at least 30 psig reset pressure.
• PTFE Backup Piston Rings - Enable reliable valve operation with or without in-line air lubrication, reducing FRL maintenance requirements in applications where continuous lubrication is not practical.
• Built-In Non-Clogging Silencer - Integrated high-flow exhaust silencer resists clogging and maintains exhaust Cv, preventing back pressure from extending clutch/brake response times in high-cycle press operations.
• Optional Manual Overrides - Valve elements can be individually overridden for commissioning, troubleshooting, and functional testing without energizing the solenoids, available as an option on Size 4 models.
• Cord-Grip Solenoid Connections - Size 4 uses cord-grip style electrical connections at the solenoids. Connectors must be ordered separately, allowing selection of the appropriate cable length and connection type for the installation.
• Compact Footprint for Small Press Integration - Basic Size 4 dimensions (7.4 x 6.3 x 7.4 inches) with 3/8 to 3/4-inch flanged ports enable installation in press control enclosures where space constraints prohibit larger valve assemblies.

Technical Specifications

General Specifications

Temperature Ratings

Temperature ratings apply to all SERPAR 35 Series Basic Size 4 configurations.

Important: At media temperatures near 40F (4C), compressed air must be free of water vapor to prevent ice formation inside valve passages.

Electrical Data (Solenoid Pilot Valves)

Solenoids are rated for continuous duty. The L-G monitor operates pneumatically with no separate electrical power requirement.

Flow Performance Data

Flow data for SERPAR 35 Series L-G Monitor Basic Size 4. Response time: T(msec) = M + F x V.

Response Time Formula: Valve Response Time (msec) = M + F x V. Consult ROSS response time charts (Bulletin 380 / ROSS catalog) for Size 4 M and F constants.

Certifications & Compliance

Typical Applications & Industries

Small-Tonnage Mechanical Press Clutch/Brake Control

• Small-tonnage stamping presses with compact clutch/brake actuator volumes where 3/8 to 3/4-inch port sizes provide adequate flow at Cv 3.0 for acceptable press clutch engagement and brake exhaust timing.
• Punch press clutch/brake control for sheet metal fabrication shops where compact valve dimensions and right- or left-inlet port options simplify integration into existing press control enclosures.
• Coil-fed progressive die press operations at lower tonnage where the Size 4 SERPAR L-G monitor provides full Category 4, PL e safety compliance without the larger footprint of Size 8 or 12 valves.
• Inclinable open-back press (OBI) clutch/brake control where the self-contained L-G monitor eliminates the need for external monitoring circuits in older press control systems being safety-upgraded.

Press Auxiliary Safety Circuits

• Press counterbalance air circuit isolation where a redundant normally closed double valve with internal monitoring is required to isolate counterbalance cylinders during die change per machine safety specifications.
• Die cushion control safety interlocks where the Size 4 SERPAR L-G valve provides internally monitored control of the die cushion air supply with full Category 4 monitoring in a compact package.
• Press automation safety zones where a 3/4-inch port double valve with internal L-G monitoring controls air supply to part-transfer grippers or other automation devices in a Category 3 or 4 safety architecture.

Category 3 and 4 Safety Circuits - General Industrial

• Alternative lockout systems for energy isolation on smaller air-powered machines where the SERPAR L-G monitor provides internal monitoring without requiring a safety PLC or external monitoring hardware.
• Pneumatic fixture clamp and hold-down systems in welding and assembly automation where a Category 4 double valve with automatic lockout protects operators from inadvertent fixture release during access.
• Air-powered cylinder presses in assembly operations where the OSHA hazardous energy control standard requires a control-reliable valve with internal monitoring on the press cylinder supply circuit.

Retrofit and Upgrade Applications

• Older press control systems being upgraded from legacy single valves or non-monitored double valves to current Category 4, PL e safety standards, where the right- or left-inlet port option enables drop-in replacement without repiping.
• Press safety audits that identify existing double valves lacking dynamic monitoring capability, requiring replacement with SERPAR L-G monitored valves to achieve current OSHA and ISO 13849-1 compliance.
• Export press lines being modified for European CE marking compliance, where Category 4 press control valves with DGUV and CE certification are required for conformity with EU Machinery Directive.

Ordering and Model Number Configuration

SERPAR 35 Series Basic Size 4 with L-G Monitor uses the standard ROSS 35-series model number format. Port size, inlet orientation, reset type, and override options are encoded in the model number.

Size 4 valves are supplied with piping flanges installed. For replacement valve body only (without piping flanges), use model numbers 3573D4241 through 3573D4246 depending on reset type and inlet orientation.

Specify inlet orientation (right or left) when ordering Size 4 valves. Right inlet is the standard configuration; left inlet models use the -5 and -6 suffix instead of -1 and -2 in the port code.

Cord-grip solenoid connectors must be ordered separately for Size 4. Contact ROSS for compatible connector options.

Remote reset models for Size 4 require a reset pressure equal to inlet pressure, minimum 30 psig (2 bar). Manual reset models use internal valve pressure for reset actuation.

All standard voltages are available: 24 VDC, 100-110 VAC 50 Hz, 100-120 VAC 60 Hz, 110 VDC. For non-standard voltages, consult ROSS.

Accessories

Piping Flange Kits for Size 4

Connection piping kits for inline mounting of SERPAR Size 4 double valves. Include all required seals and mounting bolts for two flanged connections.

Reset Valves - Manual Pushbutton (12 Series)

3/2 normally closed manual pushbutton reset valves for remote pneumatic reset of SERPAR Size 4 L-G monitor valves. Minimum reset pressure 30 psig.

Downstream Pressure Monitoring Switches

Factory-preset electrical pressure switches for energy release verification, preset to 5 psi (0.3 bar) falling. Model 586A86 with DIN EN 175301-803 Form A connector, 1/8 NPT thread.

Related Products & Accessories

• SERPAR 35 Series L-G Monitor, 1/2 to 2" (Series 183) - L-G monitored double valves for larger 1/2 to 2-inch port sizes, Basic Sizes 8, 12, and 30. https://www.rosscontrols.com/en/series/183-double-valves-with-pneumatic-l-g-monitor-ports-1-2-to-2
• SERPAR 35 Series E-P Monitor (Series 186) - Electro-pneumatic internally monitored double valves with solenoid reset, Basic Sizes 8, 12, and 30. https://www.rosscontrols.com/en/series/186-double-valves-with-electro-pneumatic-e-p-monitor
• CrossFlow 35 Series, 1/4 to 3/4" (Series 182) - Externally monitored double valves for small port sizes 1/4 to 3/4 inch with or without pressure switches. https://www.rosscontrols.com/en/series/182-double-valves-with-or-w-o-pressure-switches-ports-1-4-to-3-4
• DM2 Series D (Series 52) - Self-monitored double valve with total dynamic monitoring and complete memory for press clutch/brake control. https://www.rosscontrols.com/en/series/52-double-valves-for-clutch-brake-control
• Piping Flange Kits (Series 2839) - Connection piping kits for inline mounting of SERPAR and CrossFlow double valves. https://www.rosscontrols.com/en/series/2839-piping-flange-kits
• L-O-X Lockout Valves - Energy isolation lockout valves for press pneumatic system lockout/tagout per OSHA 1910.147. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series

Frequently Asked Questions (FAQ)

Q: What press tonnage range is appropriate for SERPAR Size 4 with 3/8 to 3/4-inch ports?

A: Size 4 with Cv 3.0 in-out is typically suited to smaller-tonnage presses in the range of 25 to 100 tons where clutch and brake actuator volumes are moderate and the 3/8 to 3/4-inch port flow capacity provides acceptable response times. For larger tonnage presses with higher flow requirements, Size 8, 12, or 30 valves are appropriate.

Q: Why does Size 4 use cord-grip connectors while larger sizes use terminal strips?

A: The Size 4 valve body is more compact and is designed for individual cord-grip solenoid connections. The larger Size 8, 12, and 30 valves include a terminal strip that simplifies multi-solenoid wiring in press control enclosures. For Size 4, connectors appropriate to the installation must be ordered separately and matched to the required cable diameter.

Q: Can I specify the inlet port on either side of the valve?

A: Yes. Basic Size 4 is unique in the SERPAR 35 Series in offering right-inlet and left-inlet port configurations. The appropriate orientation is specified through the port code in the model number. This flexibility allows direct replacement of existing valves with different inlet orientations without repiping.

Q: What is the minimum reset pressure for Size 4 remote reset models?

A: For Size 4 remote reset models, the reset pressure must equal the inlet operating pressure, with a minimum of 30 psig (2 bar). This is lower than the 60 psig minimum required for Sizes 8, 12, and 30. Manual reset models use internal valve pressure and require no separate reset air supply.

Q: How does the Cv 3.0 in-out rating compare to the exhaust Cv for Size 4?

A: For Size 4, the in-out Cv is 3.0 for all port sizes (3/8, 1/2, and 3/4 inch). The exhaust Cv varies with port size: 6.0 for 3/8-inch, 8.0 for 1/2-inch, and 9.0 for 3/4-inch. The higher exhaust Cv is an inherent characteristic of the SERPAR Crossflow design, which provides faster exhaust than inlet flow for rapid brake engagement.

Q: Is the Size 4 valve available with manual overrides?

A: Yes. SERPAR 35 Series Basic Size 4 valves are available with or without manual overrides. Manual overrides allow individual valve elements to be held in the actuated position for commissioning and troubleshooting without energizing the solenoids. Specify with overrides when the commissioning procedure requires individual element testing.

Q: What is the difference between the L-G monitor and the E-P monitor for this size range?

A: The L-G monitor is purely pneumatic and uses a mechanical lockout pin to hold the monitoring spool locked out. Reset is pneumatic (manual or remote air signal). The E-P monitor adds an electrical switch contact that breaks the solenoid circuit, providing both pneumatic isolation and electrical de-energization. The E-P monitor resets via a solenoid reset signal. E-P monitors in this size range are available only in Sizes 8, 12, and 30; Size 4 uses the L-G monitor exclusively.

Q: Can these valves be used for applications other than press clutch/brake control?

A: Yes. SERPAR 35 Series valves are appropriate for any Category 3 or 4 safety circuit requiring an internally monitored double valve. Common alternative applications include alternative pneumatic lockout systems for energy isolation, air cylinder load-holding safety circuits, safety zone entry control, and other critical pneumatic safety functions requiring self-contained monitoring without external monitoring hardware.

Q: What certifications apply to the SERPAR 35 Series Basic Size 4?

A: All SERPAR 35 Series valves including Size 4 are certified to Category 4, PL e per ISO 13849-1 and SIL 3 per IEC 62061. They are DGUV tested, CE marked, and designed to satisfy OSHA 29 CFR 1910.217. B10D = 20,000,000 cycles; PFHD = 7.71x10-9; MTTFD = 301.9 years.

Q: How often must the valve be cycled to maintain proper function?

A: At minimum once per month. This periodic exercise ensures all valve elements, the monitoring spool, and the lockout mechanism are free to operate and that the self-monitoring function is verified on a regular basis.

Q: What happens if only one solenoid is energized?

A: The SERPAR valve design requires simultaneous energization of both solenoids to shift the valve elements. If only one solenoid is energized, the single element that shifts will cause a monitoring pressure imbalance in the L-G spool, triggering lockout. This behavior is intentional and ensures that single-solenoid failures are immediately detected.

Q: Are replacement valve bodies available without piping flanges?

A: Yes. For in-service valve replacement without disturbing the piping, replacement valve bodies without flanges are available. For manual reset models, use 3573D4241 (right inlet) or 3573D4245 (left inlet). For remote reset models, use 3573D4242 (right inlet) or 3573D4246 (left inlet). These replacement valves have equivalent weight of approximately 7.5 lb (3.4 kg).

Installation & Maintenance Guidelines

• Mount the valve vertically with pilot solenoids pointing upward as the preferred orientation. Horizontal mounting with valve on top of the piping flange assembly is acceptable if vertical is impractical.
• Install 5-micron filtration upstream to protect SERPAR poppet seating surfaces from particulate contamination.
• Specify the correct inlet orientation (right or left) for the installation before ordering. Inlet orientation cannot be changed in the field without replacing the valve body.
• For remote reset, connect a 3/2 normally closed reset valve to the 1/8-inch reset port using a 1/8-inch air line. Reset pressure must equal inlet pressure, minimum 30 psig.
• Solenoid connectors for Size 4 must be ordered and installed separately. Ensure connectors are rated for the solenoid voltage and that cord grips are properly tightened to maintain IP65 protection.
• Verify that both solenoids are energized and de-energized simultaneously. Independent solenoid timing that exceeds the monitor spool's tolerance for asynchronous element movement will cause false lockouts.
• After installation, perform at minimum 10 complete actuation cycles to confirm clean valve shifting, absence of false L-G monitor trips, and correct status indication before connecting the press clutch/brake circuit.
• Do not restrict the exhaust port. Silencers or piping connected to the exhaust port must have Cv ratings equal to or greater than the valve's exhaust Cv to prevent back pressure.
• Cycle the valve at minimum once per month during planned press downtime as required for ongoing function verification.
• Before any reset after a lockout event, identify and correct the root cause of the asynchronous valve element operation that triggered the lockout.

Warranty & Global Support

ROSS Controls provides a one-year warranty on all SERPAR 35 Series products, covering defects in material and workmanship from date of purchase. Warranty is void for misuse, misapplication, improper maintenance, modification, or tampering.

Global technical support is available through ROSS offices in the USA, Canada, Brazil, Germany, France, United Kingdom, India, China, and Japan.

Contact ROSS Controls USA at +1-248-764-1800 or Technical Service at 1-888-TEK-ROSS (835-7677), or visit rosscontrols.com.

For dimensional drawings, response time charts, CAD models, and SISTEMA library files, visit the ROSS Controls SERPAR 35 Series product page or contact ROSS Controls at (800) GET-ROSS (438-7677).

Download Catalog: https://www.rosscontrols.com/en/series/184-double-valves-with-pneumatic-l-g-monitor-ports-3-8-to-3-4