77 Series CrossMirror® Pressure Controlled Double Valves Installation Instructions

Overview

ROSS Controls, founded in 1921 with over 100 years of leadership in fluid power, offers the 77 Series CrossMirror® Pressure Controlled Double Valves as high-integrity, control-reliable 4-way double valves for machine safety applications requiring pneumatic AND-gate control. Two independent pneumatic pilot signals (S1 and S2) must both be applied within approximately 500 milliseconds of each other to actuate the valve. This two-hand anti-tie-down architecture ensures that the valve only functions when both operator input signals are simultaneous, preventing inadvertent machine actuation.

The 77 Series uses precision stainless steel spools as main valve elements for consistent, reliable actuation performance. The valve achieves Category 4, Performance Level e (ISO 13849-1) and SIL 3 (IEC 62061), with DGUV certification (HSM 02064 and HSM 13022). The valve is base mounted with Port 2 normally open and Port 4 normally closed — Port 4 pressurizes only when both valve elements are actuated within the 500-millisecond discordance window.

IMPORTANT: This valve is not designed for controlling clutch/brake mechanisms on mechanical power presses. For questions, contact ROSS at 1-800-GET-ROSS or www.rosscontrols.com.

Key Features

CrossMirror® Dual Air Pilot AND-Gate Safety Architecture

The CROSSMIRROR® design uses two fully redundant, mirrored valve elements controlled by two independent pneumatic signals. Proper actuation requires both S1 and S2 pneumatic signals within 500 milliseconds of each other. If signals are not provided within this window, or if either valve element fails to operate, the valve defaults to the safe state with full inlet pressure at Port 2 and Port 4 exhausted. This self-monitoring architecture eliminates the need for an external monitoring system in many applications.

Category 4 PL e / SIL 3 Safety Performance

The 77 Series achieves Category 4, Performance Level e per ISO 13849-1:2015 and SIL 3 per IEC 62061:2001, the highest safety performance levels achievable for standard pneumatic double valves. Functional safety data: B10D = 20,000,000; PFHD = 7.71×10⁻⁹; MTTFD = 301.9 (nop: 662,400). DGUV certifications HSM 02064 (Sicherheit geprüft / tested safety) and HSM 13022 confirm independent verification of safety performance.

Optional Pressure Switch Status Indicator

Models with model numbers ending in "1" include a pressure switch status indicator for signaling asynchronous or out-of-step valve element movement to an external monitoring system. The status indicator pressure switch rating is max 4A at 250 V AC; max 50 mA at 24 V DC. When operating normally (ready-to-run), the switch is pressurized; abnormal operation or removed inlet pressure de-pressurizes the switch.

Technical Specifications

Construction: Double spool and sleeve, precision stainless steel spools
Mounting Type: Base mounted
Ambient Temperature: 40° to 120°F (4° to 50°C)
Media Temperature: 40° to 175°F (4° to 80°C)
Flow Media: Filtered air
Inlet Pressure: 40 to 100 psig (2.7 to 7 bar)
Pilot Pressure: Must be equal to or greater than inlet pressure (not to exceed max)
Signal Ports (S1 and S2): Supplied by 3-way NC pilot valves, Cv ≥ 0.3
Signal Port Supply Lines: Equal length, 3/16 inch (5 mm) minimum inside diameter
Discordance Window: ±500 milliseconds
Port 2: Normally open (pressurized when de-actuated or discordant)
Port 4: Normally closed (pressurized only when both elements actuated within 500 ms)
Pressure Switch Rating: Max 4A / 250 V AC; Max 50 mA / 24 V DC
Functional Safety Data: Category 4 PL e; B10D: 20,000,000; PFHD: 7.71×10⁻⁹; MTTFD: 301.9
Certifications: CE Marked, BG, DGUV HSM 02064, DGUV HSM 13022
Vibration/Impact Resistance: Tested to BS EN 60068-2-27
Flow Cv (Basic Size 2): 2.0 (1-2), 1.6 (1-4)
Flow Cv (Basic Size 4): 3.2 (1-2), 3.4 (1-4)

Applications

Two-Hand Anti-Tie-Down Control Stations

The 77 Series pressure-controlled double valve is the core pneumatic component of a two-hand anti-tie-down control station. Two palm buttons, each connected to one pilot port (S1 and S2) of the valve, require the operator to simultaneously activate both buttons within 500 ms to pressurize Port 4 and enable machine operation. Release of either button returns the output to the safe state. This prevents the operator from tying down one button and activating the machine with a single hand in the machine's point of operation.

Pneumatic Safety Control in Machine Guarding

The 77 Series valve integrates into machine guarding systems where two independent pneumatic guard-closed sensors must both confirm machine safety before allowing a hazardous cycle to begin. Used in pneumatic cylinder presses, bending machines, and automated assembly equipment, the valve provides the pneumatic AND-gate function required by machine safety standards without requiring electronic safety relay or safety PLC for the valve monitoring function.

Safety and Compliance Standards

Pneumatic equipment must be installed by trained personnel. Signal port supply valves must be 3-way normally closed, Cv ≥ 0.3. Signal lines must be equal length, minimum 3/16-inch ID. Do not restrict exhaust ports (Ports 3 and 5). Clean valve with a non-chlorinated, residue-free solvent. Avoid oils with anti-wear or phosphate additives. See ROSS CrossMirror® service documentation for complete maintenance procedures.

Installation and Setup Guide

Installation Steps

Step 1: Blow air lines clean. Install 5-micron rated filter on inlet line.
Step 2: Mount valve and base assembly; connect inlet Port 1 with adequate supply line size.
Step 3: Connect Ports 2 and 4 to appropriate machine actuator circuits.
Step 4: Do not restrict Exhaust Ports 3 and 5.
Step 5: Connect signal ports S1 and S2 to 3-way NC pilot valves (Cv ≥ 0.3) with equal-length lines (min 3/16-inch ID).
Step 6: Pressure switch: connect to monitoring circuit if status feedback is required.
Step 7: Pressurize both S1 and S2 simultaneously to test normal actuation.
Step 8: Test discordance protection: pressurize one signal, delay >500 ms, then pressurize the other — valve should not actuate Port 4.
Step 9: Verify status indicator switch responds correctly to normal and faulted conditions.

Why Choose ROSS Controls

ROSS Controls, founded in 1921 with over 100 years of leadership in fluid power, invented CrossMirror® double valve technology and has been the global leader in control-reliable pneumatic safety valves for over 50 years. The 77 Series provides Cat. 4 PL e / SIL 3 performance with DGUV certification. Contact ROSS at 1-800-GET-ROSS or www.rosscontrols.com.

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Frequently Asked Questions

Q: What is the discordance window for the 77 Series air pilot valve?

A: Approximately 500 milliseconds. Both S1 and S2 pilot signals must be applied within 500 ms of each other for Port 4 to pressurize.

Q: What is Port 2 function?

A: Port 2 is the normally open port — pressurized when the valve is de-actuated or when the valve elements are not actuated within 500 ms of each other.

Q: What is Port 4 function?

A: Port 4 is the normally closed port — pressurized only when both main valve elements are simultaneously actuated within the 500 ms window.

Q: What is the safety performance rating?

A: Category 4, Performance Level e (ISO 13849-1:2015) and SIL 3 (IEC 62061:2001). PFHD: 7.71×10⁻⁹.

Q: What Cv rating must the signal port supply valves have?

A: Signal port supply valves must be 3-way normally closed with a Cv rating of not less than 0.3.

Q: What is the inlet pressure range?

A: 40 to 100 psig (2.7 to 7 bar).

Q: Can this valve be used for press clutch/brake control?

A: No. The 77 Series is not designed for controlling clutch/brake mechanisms on mechanical power presses.

Q: What certifications does the 77 Series carry?

A: CE Marked, BG, DGUV HSM 02064 (Sicherheit geprüft), DGUV HSM 13022.