Product Overview

The ROSS 21 Series represents industry-leading inline poppet valve technology specifically designed for vacuum service applications. These valves deliver exceptional performance in lifting, holding, vacuum packaging, material handling, and leak testing operations across manufacturing environments. With port sizes ranging from 1/4" to 2-1/2" and maximum flow capacity up to 71 Cv (70,000 Nl/min), the 21 Series provides versatile solutions for both standard and full vacuum applications.  

Key Features & Benefits

Poppet Construction Excellence
The 21 Series utilizes perpendicular poppet face seals that create superior high-flow characteristics and positive sealing performance. Unlike spool valves, the poppet design eliminates sliding action on seats, requiring no lubrication while delivering near-zero leakage. This closed crossover design ensures the exhaust poppet seals before the inlet opens, preventing intermediate states and providing precise control during switching operations.   

Differential Piston Design
Advanced differential piston technology delivers fast and consistent response times across the valve's operational life. The carefully calculated surface areas of the piston poppet, exhaust poppet, and inlet poppet produce overwhelming shifting forces in each direction, ensuring reliable no-stick operation even after extended periods of inactivity.   

Self-Cleaning & Dirt Tolerance
High-velocity airflow across poppet seats creates a self-cleaning effect that provides exceptional dirt tolerance. The superior internal guidance system combined with self-compensating seals automatically adjusts for wear by changing stroke length, maintaining consistent performance and extending operational life.   

Technical Specifications

Valve Configurations

• 2/2 Valves: Available in normally closed and normally open configurations with solenoid or pressure control actuation
• 3/2 Valves: Versatile three-port design for applications requiring exhaust functionality
• Flow Capacity: 1.6 to 71 Cv (1,600 to 70,000 Nl/min) depending on configuration 
• Port Sizes: 1/4" through 2-1/2" to accommodate diverse system requirements 

Operating Parameters

• Pressure Range: Vacuum to 150 psig (Vacuum to 10 bar) 
• Temperature Ranges: Standard (-17°C to 50°C), High (-17°C to 150°C), and Low (-40°C to 80°C) temperature options 
• Response Time: Rapid actuation with response constants as low as 0.12 to 0.13 milliseconds 
• Flow Media: Vacuum and filtered compressed air 

Safety Certifications

SIL 2 Certified Functional Safety
The 21 Series is certified by TÜV Rheinland to Safety Integrity Level 2 (SIL 2) in accordance with IEC 61508 and IEC 61511 standards, and Performance Level c (PL c) per EN ISO 13849-1. In redundant applications with Hardware Fault Tolerance (HFT≥1), the valves achieve SIL 3 and PL e ratings. This certification ensures reliable performance in safety-critical applications where valve failure could pose risks to personnel or equipment.   

Construction & Materials

Robust Industrial Design

• Valve Body: Cast aluminum construction for durability and corrosion resistance 
• Poppet Components: Aluminum and stainless steel for longevity 
• Seal Options: Fluorocarbon seals for high-temperature applications or Buna-N for standard service 
• Enclosure Rating: IP 65 protection against dust and water ingress 

Electrical Specifications

Solenoid Pilot Control Options

• DC Voltage: 12V (4.5W), 24V (4.8W) 
• AC Voltage: 120V 60Hz (6.5 VA), 240V 60Hz (6.8 VA) 
• Electrical Connections: DIN EN 175301-803 (Form A & B), M12 connector, or 1/2" conduit with leads 
• Duty Cycle: Rated for continuous operation 

Industrial Applications

The 21 Series vacuum valves excel in diverse automation scenarios:  

Material Handling & Clamping
Vacuum pad systems facilitate precise workpiece positioning and secure clamping in automated production lines, reducing handling errors and increasing productivity. The valves' rapid response enables high-speed pick-and-place operations in packaging, assembly, and logistics applications.  

Pneumatic Conveying
Both pressure and vacuum conveying systems benefit from the 21 Series' precise flow control for transporting powders, granules, and bulk materials including flour, sugar, and plastic pellets. 

Leak Testing
The positive sealing characteristics and near-zero internal leakage make these valves ideal for critical leak detection applications in quality control processes.  

Vacuum Packaging
Food processing, pharmaceutical, and consumer goods industries utilize 21 Series valves for consistent vacuum packaging operations requiring reliable atmospheric pressure control. 

Model Configuration Guide

The comprehensive catalog includes detailed model number configurators for both 2/2 and 3/2 valve configurations. Engineers can specify: 

• Port thread types (NPT or G) 
• Body and port sizes 
• Actuation methods (solenoid or pressure controlled) 
• Voltage and current specifications 
• Temperature ranges and seal materials 
• Electrical connection types 

Accessories & Support Components

The catalog details compatible accessories including: 

• Prewired electrical connectors with and without LED indicators
• Cable assemblies in various lengths
• Exhaust silencers for noise reduction (flow capacity up to 39 Cv/38,000 Nl/min) 
• Manual override options for maintenance and troubleshooting 

Installation & Mounting

Flexible Orientation
21 Series valves feature inline threaded port connections and can be mounted in any orientation, with vertical mounting preferred for optimal performance. This flexibility allows installation close to actuators, reducing pipe length and improving cycle times.   

Compliance & Quality

ROSS Controls maintains strict adherence to international standards including:

• ISO quality management systems
• CE Declaration of Conformity 
• Certificate of Compliance documentation 
• OSHA 1910.147 and EN 1037 safety guidelines 

Why Choose ROSS 21 Series?

Since 1921, ROSS Controls has pioneered fluid power safety solutions for critical industrial applications. The 21 Series vacuum valves represent over a century of engineering excellence, combining: 

• Proven Reliability: Engineered for long-life operation in demanding environments  
• Superior Performance: High flow capacity with minimal pressure drop  
• Safety Assurance: SIL 2 certified for functional safety applications  
• Cost-Effective Operation: Low maintenance requirements and extended service life  
• Global Support: Comprehensive technical assistance and replacement parts availability 

Download Your Technical Catalog

Access complete technical specifications, dimensional drawings, performance curves, model selection guides, and installation instructions for the ROSS 21 Series Directional Control Vacuum Valves. This comprehensive resource provides engineers and procurement professionals with all necessary information for system design, valve selection, and integration planning.

The catalog includes:

• Detailed specifications for all valve configurations
• CAD models available for download 
• Performance data and response time calculations 
• Electrical wiring diagrams and pinout specifications 
• Accessory compatibility charts 
• Application examples and best practices 
• Warranty information and support contacts 

For technical assistance or custom solutions, contact ROSS Controls at 1-800-438-7677 or visit www.rosscontrols.com.