35 Series SERPAR® CrossFlow® Double Valves Installation Instructions — Basic Size 1 & 2

Overview

The ROSS Controls 35 Series SERPAR® CrossFlow® Double Valves (Basic Sizes 1 and 2) are inline-mounted pneumatic press safety double valves designed for use with an external monitoring system. The CrossFlow® design routes air through crossflow passages between the two main valve elements, ensuring that both elements must shift together for Port 2 to be pressurized. This inherent redundancy provides reliable protection for press brake, shear, and other hazardous machine applications.

These valves do not include integrated monitors and must be paired with an approved external monitoring system. Some models include pressure switches that sense whether the two valve elements moved synchronously. These switches are indicators only — they do not independently lock out the valve and should not be treated as a substitute for a proper external monitor.

Basic Sizes 1 and 2 use plug-in connectors (EN 175301-803 Form B for Size 1; Form A for Size 2) for clean, secure solenoid connections. ROSS Controls, founded in 1921, has over 100 years of fluid power expertise. For additional technical documentation, visit www.rosscontrols.com or call 1-800-GET-ROSS.

Key Features

CrossFlow® Architecture for Dual-Element Redundancy

The CrossFlow® design means air flows through crossflow passages between the two main valve elements. Both elements must shift fully before Port 2 can be pressurized. This architecture prevents a single-element failure from allowing unintended press stroke actuation, providing a fundamental layer of mechanical safety beyond electrical monitoring.

Compact Inline Mounting for Space-Limited Installations

Basic Sizes 1 and 2 are the smallest configurations in the 35 Series CrossFlow® family. Their inline mounting design is well-suited to compact press control circuits where panel space or plumbing runs are restricted. NPT port connections in 1/4 and 3/8 inch sizes accommodate typical small-press pneumatic plumbing.

Optional Pressure Switches for Discordance Detection

Select models include two pressure switches that detect when the two valve elements did not shift simultaneously. Each switch has four electrical contacts: contacts 1 and 2 are closed when no pressure signal is applied; contacts 1 and 4 close when pressure is applied. Contact 3 is a ground. These outputs can be used by an external monitoring system to detect and respond to valve discordance events.

SERPAR® Double Valve Technology

SERPAR® — ROSS Controls' proprietary double valve technology — combines two independent valve elements in series and parallel to deliver genuine redundancy. If one element fails to operate, the other prevents unintended output pressure. The SERPAR® design is the foundation of the 35 Series product line and has been proven across decades of press safety applications worldwide.

Technical Specifications

The following specifications are drawn directly from the 35 Series SERPAR® CrossFlow® installation instructions (SS146):

Construction: Dual poppet, inline mounting
Pilot Solenoids: Two, rated for continuous duty
Standard Voltages: 24 volts DC; 110–120 volts AC, 50/60 Hz
Power Consumption — Basic Size 1: 12 VA max inrush, 9.8 VA max holding (50/60 Hz); 7.5 watts nominal DC
Power Consumption — Basic Size 2: 8.5 VA max inrush, 8.5 VA max holding (50/60 Hz); 6 watts nominal DC
Electrical Connections: Basic Size 1 — EN 175301-803 Form B (P/N 266K77); Basic Size 2 — Form A (P/N 937K87)
Ambient Temperature: 40° to 120°F (4° to 50°C)
Media Temperature: 40° to 175°F (4° to 80°C)
Flow Media: Filtered compressed air (5-micron filter recommended)
Inlet Pressure: 30 to 125 psig (2 to 8.5 bar)
Port Sizes (Size 1): 1/4 inch NPT inlet/outlet, 3/8 inch exhaust
Port Sizes (Size 2): 3/8 inch NPT inlet/outlet, 1/2 inch exhaust
Monitoring: External monitor required; optional integrated pressure switches available

Applications

Compact Press Brake and Shear Machine Safety Circuits

Basic Size 1 and 2 CrossFlow® valves are designed for press brake, shear, and other light-to-medium tonnage mechanical press applications where a compact inline double valve is needed. When connected to an appropriate external monitor, they help meet OSHA 29 CFR 1910.217 requirements for clutch/brake control double valves on mechanical power presses.

Pneumatic Safety Circuits Requiring External Monitoring

Any pneumatically controlled machine or system that requires an externally monitored, redundant safety shutoff valve can use the 35 Series CrossFlow®. The valve's inline format and small footprint make it especially useful in retrofits, auxiliary safety circuits, and installations where base-mounted double valves cannot be accommodated.

Safety and Compliance Standards

The 35 Series SERPAR® CrossFlow® Double Valves are designed to operate as part of safety circuits conforming to applicable machine safety standards, including OSHA 29 CFR 1910.217 (mechanical power press safety) when used with appropriate external monitors. ROSS Controls recommends consulting applicable national and international standards — including ISO 13849-1 for safety-related control system design — when applying these valves in safety-critical circuits.

OSHA 29 CFR 1910.217 — Mechanical power press safety (with external monitor)
ISO 13849-1:2015 — Safety-related parts of control systems
EN 13736 — Safety of machinery; pneumatic requirements
EN 175301-803 — Electrical connectors for solenoid valves
ROSS recommended: 5-micron-rated inlet air filter

Installation and Setup Guide

Pre-Installation: Air Line Preparation

Before installing the valve in a new or existing system, the air lines must be blown clean of all contaminants. Install a 5-micron-rated air filter in the inlet line close to the valve. Clean air supply is the single most important factor in preventing premature valve failure in press safety applications.

Port Connections

Valve Inlet (Port 1): Ensure the supply line is of adequate size and free of crimps, sharp bends, or clogged filter elements. The air supply must provide sufficient pressure and adequate volume on demand. Valve Outlet (Port 2): Locate the valve as close as possible to the actuated mechanism to minimize pressurizing and exhausting times. Lines must be free of restrictions. Valve Exhaust (Port 3): Do not restrict exhaust flow — restriction adversely affects valve operation. Efficient ROSS silencers can reduce exhaust noise by up to 25 dB with minimal back pressure.

Pipe Thread Installation

To install NPT pipe in valve ports: engage pipe one turn, apply pipe thread sealant (tape not recommended), and tighten. This procedure prevents sealant from contaminating the valve interior. For parallel threads (SAE, ISO 228-G), do not use sealant.

Electrical Connections and Solenoid Supply

Connect pilot solenoid electrical power via the plug-in connectors. Electrical supply must match the solenoid voltage and frequency ratings. If power is supplied by a transformer, it must handle inrush current without significant voltage drop. See valve specifications for inrush current data.

External Monitor Wiring

These valves must be connected to a compatible external monitor. Wire the pressure switch contacts (if equipped) to the monitor per the circuit diagram supplied with the valve. For pressure switch connection guidance, contact ROSS Technical Service at 1-888-TEK-ROSS.

Why Choose ROSS Controls

ROSS Controls was founded in 1921 and has over 100 years of expertise in fluid power engineering and machine safety. The company's SERPAR® double valve technology is a foundational innovation in press safety, providing reliable redundant control for mechanical power presses and other hazardous pneumatic machinery worldwide.

ROSS manufactures double valves across a wide range of sizes, safety categories, and configurations — from basic crossflow designs to fully self-contained monitors and hydraulic safety systems. Every product is built to stringent quality standards and backed by ROSS's global technical support network. Contact ROSS at 1-800-GET-ROSS or visit www.rosscontrols.com.

Download This Document

The official 35 Series SERPAR® CrossFlow® Double Valves Installation Instructions (SS146) are available as a free PDF download from ROSS Controls.

PDF Download URL: https://ross-admin-global-us-east.s3.amazonaws.com/production/uploads/document_language_file/file/47/ROSS_35_Series_SERPAR_Crossflow_Double_Valves_1-2_Installation_Instructions_SS146.pdf

Additional technical documentation, service manuals, and certifications are available at www.rosscontrols.com. For technical support, call 1-800-GET-ROSS.

Frequently Asked Questions

Q: Do the 35 Series CrossFlow® Basic Size 1 and 2 valves include an integrated monitor?

A: No. These valves do not have their own monitors and must be connected to an external monitoring system. The external monitor must inhibit valve operation if a system malfunction occurs. Pressure switches (where equipped) are indicators only and do not substitute for a monitor.

Q: What is the difference between the pressure switch option and a valve monitor?

A: Pressure switches detect that the two valve elements did not shift simultaneously and report this condition to the machine control system. They are sensors only — they do not lock out the valve themselves. A monitor (external or integral) is required to actually inhibit further valve operation upon detecting discordance.

Q: What are the available Basic Sizes for the 35 Series CrossFlow® valves?

A: The installation document SS146 covers Basic Sizes 1 and 2 (compact inline versions). Larger Basic Sizes 4, 8, 12, and 30 are covered in separate 35 Series CrossFlow® documentation.

Q: What inlet pressure range is required?

A: The 35 Series SERPAR® CrossFlow® valves require an inlet pressure of 30 to 125 psig (2 to 8.5 bar).

Q: What standard voltages are supported?

A: Standard voltages are 24 volts DC and 110–120 volts AC at 50/60 Hz. The electrical supply must match the solenoid ratings to prevent early solenoid failure.

Q: Can these valves be used on mechanical power presses?

A: These valves are designed for press safety applications including press brake and shear machine clutch/brake control when connected to a suitable external monitor that complies with OSHA 29 CFR 1910.217 requirements.

Q: What type of air filtration is recommended?

A: ROSS recommends a 5-micron-rated air filter installed close to the valve inlet. The filter bowl should be drained regularly. Automatic drain filters are recommended where manual draining is inconvenient.

Q: How do I obtain service kits for this valve?

A: Service kits for the valve body, gaskets, and seals are available from ROSS Controls and authorized distributors. Contact ROSS at 1-800-GET-ROSS or visit www.rosscontrols.com to locate your nearest ROSS distributor.

Q: What lubricants are compatible with this valve?

A: Although the valve itself does not require lubrication, if used with lubricated air, use petroleum-based oils with oxidation inhibitors, aniline point 180–220°F (82–104°C), ISO 32 or lighter viscosity. Avoid oils with phosphate additives (e.g., zinc dithiophosphate) and diester oils, which can damage valve seals.

Q: How should I clean the valve?

A: Clean with a good commercial solvent. Do not scrape varnished surfaces or use chlorinated solvents or abrasives. Before reassembly, lubricate sliding surfaces with MobilGrease 28 or equivalent. Establish a regular cleaning schedule based on air supply cleanliness.