21 Series Poppet Valves – High & Low Temperature Installation & Operating Instructions

Overview

The ROSS Controls® 21 Series is a premium-quality poppet valve with metal internals designed for inline mounting, offering exceptional performance across extreme temperature ranges. Manufactured by ROSS Controls, a company with over 100 years of fluid power expertise since its founding in 1921, the 21 Series is available in both high-temperature and low-temperature configurations to serve the full spectrum of industrial temperature environments.

The 21 Series is TÜV Rheinland certified for Safety Integrity Level (SIL) applications. In singular application with HFT = 0, the valve achieves SIL 2 and PL c or PL d (with application-specific diagnosis) per IEC 61508, IEC 61511, and EN ISO 13849-1. In redundant application with HFT ≥ 1, it achieves SIL 3 and PL e – making it suitable for safety-critical machine control and energy isolation circuits.

IMPORTANT NOTE: ROSS 21 Series valves are not designed as control valves for air clutch/brake mechanisms on mechanical power presses and must not be installed for such use. Only double valves conforming to OSHA standards should be used in press clutch/brake applications. Contact ROSS at 1-800-GET-ROSS or visit www.rosscontrols.com for application guidance.

Key Features

TÜV Rheinland SIL 2 and SIL 3 Certified Safety Performance

The 21 Series is certified by TÜV Rheinland in accordance with IEC 61508 and IEC 61511 for SIL 2 (singular application, HFT = 0) and SIL 3 (redundant application, HFT ≥ 1). It also meets EN ISO 13849-1 PL c or PL d in singular and PL e in redundant configurations. This certification makes the 21 Series appropriate for integration into safety-rated pneumatic control systems.

Extended High-Temperature and Low-Temperature Ranges

High-temperature models: Model numbers ending with 001, 011, 051, or 061. Ambient temperature: 0° to 250°F (-17° to 122°C). Media temperature: 0° to 300°F (-17° to 150°C). Low-temperature models: Model numbers ending with 002, 003, 012, 013, 052, 053, 062, or 063. Ambient temperature: -40° to 120°F (-40° to 50°C). Media temperature: -40° to 175°F (-40° to 80°C). For temperatures below 40°F (4°C), air must be free of water vapor to prevent ice formation.

Metal Internals for Inline Mounting

The 21 Series uses a poppet valve with metal internals specifically designed for inline mounting, differentiating it from base-mounted or manifold-mounted designs. The inline mounting simplifies retrofit into existing piping systems. Pressure-controlled, single solenoid, and direct double solenoid pilot-controlled configurations are available.

High- and Low-Pressure / Vacuum Service Kits Available

For special valves with an 8 or 9 as the second digit after the center letter in the model number (e.g., D2173B3952), ROSS Technical Services can provide high-pressure and vacuum service kits. These special features must be verified with ROSS Technical Services before ordering service parts.

Technical Specifications

The following specifications are from the official ROSS Controls 21 Series Poppet Valve High Low Temp Installation Instructions (Doc ID 56, Form SS099):

Construction: Poppet with metal internals
Mounting Type: Inline
Flow Media: Filtered air
Pilot Pressure: Must be equal to or greater than inlet pressure
For vacuum service models requiring external pilot supply: minimum pilot pressure 30 psig (2.1 bar)
Pressure Controlled – High Temp Ambient/Media: 0° to 300°F (-17° to 150°C)
Pressure Controlled – Low Temp Ambient/Media: -40° to 175°F (-40° to 80°C)
Pressure Controlled – Inlet Pressure: 30 to 150 psig (2 to 10 bar)
Solenoid Pilot – Single: 87 VA inrush, 30 VA holding on AC; 14 watts on DC
Solenoid Pilot – Double (each solenoid): 190 VA inrush, 40 VA holding on AC; 20 watts on DC
Solenoid Pilot High Temp – Ambient: 0° to 250°F (-17° to 122°C)
Solenoid Pilot Low Temp – Ambient: -40° to 120°F (-40° to 50°C)
Safety Certification: TÜV Rheinland; SIL 2 (HFT=0) and SIL 3 (HFT≥1); PL c/d and PL e per EN ISO 13849-1

Applications

Safety-Critical Machine Control Circuits

The TÜV Rheinland SIL certification of the 21 Series makes it a strong candidate for integration into safety-rated pneumatic circuits on manufacturing machinery, robotic systems, and process equipment. Its SIL 2 (HFT=0) and SIL 3 (HFT≥1) ratings support a range of safety-integrity requirements without requiring extensive additional safety architecture.

Extreme Temperature Industrial Applications

With high-temperature media ratings to 300°F (150°C) and low-temperature media ratings to -40°F (-40°C), the 21 Series serves environments that fall outside the operating range of standard pneumatic valves. Applications include outdoor equipment in Arctic climates, hot press machinery, foundry automation, cold storage facilities, and cryogenic processing.

Safety and Compliance Standards

The 21 Series is certified by TÜV Rheinland per IEC 61508, IEC 61511, and EN ISO 13849-1 for safety integrity levels SIL 2 and SIL 3 and performance levels PL c, PL d, and PL e. All installation and maintenance must be performed by trained pneumatic personnel. Before service, disconnect electrical supply, shut off air, and exhaust the system.

ROSS 21 Series valves must not be used as control valves for air clutch/brake mechanisms on mechanical power presses. Do not restrict the exhaust port of the valve body or pilot body as this can adversely affect valve operation. Use a 5-micron air filter in the inlet line.

Installation and Setup Guide

Model Identification and Temperature Verification

Before installation, identify whether your valve is high-temperature or low-temperature using the model number suffix as described above. For special model variants (second digit after the center letter is 8 or 9), consult ROSS Technical Services to verify special features before installation.

Pilot Supply Connection

For pressure-controlled models, connect a 1/4-inch control line to the threaded port in the air head at the top of the valve. For solenoid-controlled models with internal pilot supply, no special connection is required. For external pilot supply, connect a 1/8-inch pilot supply line to port X-1 in the pilot housing. Refer to valve specifications for pressure requirements.

Exhaust Port Guidance

Do not restrict air flow from the exhaust port (Port 3) or pilot body as this can adversely affect valve operation. To reduce exhaust noise, an efficient silencer may be used. ROSS silencers reduce impact noise by as much as 25 dB and produce little back pressure.

Why Choose ROSS Controls

ROSS Controls has been engineering fluid power solutions since 1921. The 21 Series exemplifies ROSS's commitment to safety engineering through its TÜV Rheinland certifications, extended temperature capabilities, and comprehensive documentation. ROSS provides complete application support for SIL-certified pneumatic circuit design.

Contact ROSS at 1-800-GET-ROSS or visit www.rosscontrols.com for SIL application support, service kits, and distributor locations.

Download This Document

The official ROSS Controls 21 Series Poppet Valve High Low Temp Installation Instructions (Doc ID 56, SS099) can be downloaded from the ROSS Controls document library.

PDF Download URL: https://ross-admin-global-us-east.s3.amazonaws.com/production/uploads/document_language_file/file/56/ROSS_21_Series_Poppet_Valve_High_Low_Temp_Installation_Instructions_SS099.pdf

Frequently Asked Questions

Q: What is the SIL rating of the 21 Series valve?

A: The 21 Series is TÜV Rheinland certified for SIL 2 and PL c or d (with application-specific diagnosis) in singular application with HFT = 0, and SIL 3 and PL e in redundant application with HFT ≥ 1, per IEC 61508, IEC 61511, and EN ISO 13849-1.

Q: What is the maximum media temperature for high-temperature 21 Series models?

A: High-temperature 21 Series models (model suffix 001, 011, 051, or 061) support media temperatures from 0° to 300°F (-17° to 150°C), and ambient temperatures from 0° to 250°F (-17° to 122°C) for solenoid pilot models.

Q: What is the minimum temperature for low-temperature 21 Series models?

A: Low-temperature models (suffix 002, 003, 012, 013, 052, 053, 062, or 063) support media temperatures from -40° to 175°F (-40° to 80°C). For temperatures below 40°F (4°C), the air supply must be free of water vapor to prevent ice formation in the valve.

Q: Can 21 Series valves be used on mechanical power press clutch/brake applications?

A: No. ROSS 21 Series valves are expressly not designed for air clutch/brake control on mechanical power presses. Only double valves conforming to OSHA standards should be used in such applications.

Q: What is the solenoid power consumption for a double-solenoid 21 Series valve?

A: Each solenoid on a double-solenoid 21 Series valve consumes 190 VA inrush and 40 VA holding on AC, and 20 watts on DC. Single-solenoid models consume 87 VA inrush, 30 VA holding on AC, and 14 watts on DC.

Q: How is the pilot supply connected on pressure-controlled 21 Series valves?

A: Connect a 1/4-inch control line to the threaded port in the air head at the top of the valve. See valve specifications for the required pilot supply pressure, which must be equal to or greater than inlet pressure.

Q: What inlet pressure range do 21 Series pressure-controlled valves support?

A: Pressure-controlled 21 Series valves operate at 30 to 150 psig (2 to 10 bar). For vacuum service models requiring external pilot supply, a minimum pilot pressure of 30 psig (2.1 bar) is required.

Q: Where can I obtain service kits for special 21 Series valve configurations?

A: Standard service kits are available from ROSS and authorized distributors. For special valve configurations (model numbers with 8 or 9 as the second digit after the center letter), contact ROSS Technical Services to verify the valve's special features and obtain the appropriate high-pressure or vacuum service kit.