21 Series Explosion-Proof Poppet Valves Installation & Operating Instructions

Overview

ROSS Controls, founded in 1921 with over 100 years of leadership in fluid power, offers the 21 Series Explosion-Proof Poppet Valves as heavy-duty directional control valves with encapsulated explosion-proof solenoids for use in the most demanding hazardous classified environments. Distinguished from the 27 Series by their metal poppet internals, the 21 Series valves provide enhanced durability and contamination resistance, making them suitable for applications where air quality may be marginal or metal-seated valves are preferred for long-term reliability.

The 21 Series carries the same comprehensive explosion-proof approvals as the 27 Series: Ex m II T4 and Division 1, CSA Class I Division 1 Groups A, B, C, D; Class II Groups E, F, G; Class III; Class I Division 2 Groups A, B, C, D; and FM explosion-proof and nonincendive ratings per applicable standards. This makes the 21 Series suitable for chemical plants, oil and gas facilities, grain elevators, paint booths, and other classified areas requiring NEC-compliant pneumatic control valves.

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

Key Features

Metal Poppet Internals for Enhanced Durability

The 21 Series uses metal poppet internals, providing greater wear resistance and contamination tolerance than valves using polymer poppets. Metal seating maintains consistent sealing performance across a wider range of operating temperatures and after extended service periods. This makes the 21 Series the preferred choice for applications with demanding duty cycles or in environments where air cleanliness cannot be guaranteed.

Full Explosion-Proof Approvals (Ex m II T4)

CSA approval: Class I, Division 1, Groups A, B, C, and D; Class II, Groups E, F, and G; Class III; Class I, Division 2, Groups A, B, C, D. FM approval: Explosion-proof Class I, Division 1, Groups A, B, C, D, T4, Ta=60°C; Encapsulation/explosion-proof Class I, Zone 1, AEx m II T4, Ta=60°C; Dust-ignition-proof Class II/III, Division 1, Groups E, F, G, T4, Ta=60°C; Nonincendive Class I, Division 2, Groups A, B, C, D, T4, Ta=60°C; Suitable for Class II, III, Division 2, Groups E, F, G, T4, Ta=60°C. Standards: CSA CLASS 2258 02; FM CLASS 3600, 3611, 3615, 3810.

Internal Pilot Supply

Pilot pressure is supplied internally for most 21 Series valve configurations, eliminating the need for external pilot supply lines. This simplifies installation in classified areas and reduces the number of potential leak points in the pneumatic circuit. The electrical supply voltage and hertz ratings are labeled on the pilot housing; the power supply must be capable of handling maximum power demands.

Technical Specifications

Construction: Poppet with metal internals
Mounting Type: In-line
Valve Functions: 2/2, 3/2, 4/2-way (NC, NO)
Pilot Supply: Internal (most configurations)
CSA Certificate: Class I Div 1 Groups A, B, C, D; Class II Groups E, F, G; Class III; Class I Div 2 Groups A, B, C, D
FM Certificate: Explosion-proof Class I Div 1 ABCD T4 Ta=60°C; AEx m II T4; Dust-ignition-proof Class II/III Div 1 EFG T4; Nonincendive Class I Div 2 ABCD T4; Suitable Class II/III Div 2 EFG T4
CSA Standard: CLASS 2258 02; FM Standards: CLASS 3600, 3611, 3615, 3810
Hazardous Location: Ex m II T4 and Division 1
Applicable Requirements: C22.2 No. 0-10; CSA C22.2 No. 25-1966; CSA C22.2 No. 142-M1987; C22.2 No. 213-M1987; CAN/CSA E79-0-95; CAN/CSA E79-18-95
Noise Reduction with ROSS Silencer: Up to 25 dB

Applications

Grain Elevators and Agricultural Processing

Grain elevators and agricultural processing facilities operate in Class II hazardous locations due to combustible grain dust. The 21 Series carries dust-ignition-proof approval for Class II Division 1 Groups E, F, and G, making it appropriate for pneumatic conveying systems, gates, dampers, and other pneumatic equipment in these facilities. The metal internals handle the higher contamination levels typical of agricultural environments.

Offshore and Marine Applications

Marine and offshore installations expose pneumatic components to salt spray, corrosive atmospheres, and classified electrical hazard areas. The 21 Series explosion-proof rating and metal internal construction provide the combination of hazardous location approval and durability required for reliable valve operation in these environments over extended service periods without frequent replacement.

Safety and Compliance Standards

Install and service pneumatic equipment only with trained, qualified personnel. Match electrical supply to solenoid voltage and hertz ratings on pilot housing. Do not restrict exhaust or pilot exhaust ports. Before service, shut off electrical power, shut off and exhaust air pressure, and lock out all power sources. Supply 5-micron filtered air. Contact ROSS for detailed service manual and replacement parts information.

Installation and Setup Guide

Installation Steps

Step 1: Blow air lines clean before installing the valve.
Step 2: Install 5-micron rated filter upstream of the valve.
Step 3: Connect Inlet (Port 1), Outlets (Ports 2 and 4), and Exhaust (Port 3).
Step 4: Do not restrict exhaust (Port 3) or pilot exhaust ports.
Step 5: Apply sealant on tapered pipe threads (not tape); engage one turn then tighten.
Step 6: Verify electrical supply matches voltage and hertz rating on pilot housing.
Step 7: Pilot supply is internal — no external pilot line required for standard configurations.
Step 8: Test valve operation before returning to service.

Why Choose ROSS Controls

ROSS Controls, founded in 1921 with over 100 years of leadership in fluid power, provides the complete range of explosion-proof poppet valves needed for pneumatic control in the most demanding hazardous classified environments. The 21 Series metal poppet design delivers extended service life and reliable performance. Contact ROSS at 1-800-GET-ROSS or www.rosscontrols.com.

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Frequently Asked Questions

Q: What distinguishes the 21 Series from the 27 Series?

A: The 21 Series uses metal poppet internals for enhanced wear resistance and contamination tolerance. Both carry the same explosion-proof approval ratings.

Q: Can the 21 Series be used for press clutch/brake applications?

A: No. 21 Series valves must not be used as control valves for press clutch/brake mechanisms. Only OSHA-compliant double valves should be used for those applications.

Q: What hazardous location classifications are covered?

A: Class I Div 1 Groups A, B, C, D; Class II Groups E, F, G; Class III; Class I Div 2 under both CSA and FM certifications.

Q: Is external pilot supply required?

A: No — pilot pressure is supplied internally for most configurations.

Q: What is the Ex designation?

A: Ex m II T4 — encapsulation protection, Group II surface industry gases/dusts, Temperature Class T4.

Q: What filter is recommended?

A: 5-micron rated air filter, installed close to the valve inlet.

Q: What ROSS silencer noise reduction is available?

A: ROSS silencers reduce impact noise by up to 25 dB with minimal back pressure.

Q: How do I access the detailed service manual?

A: A general service manual with detailed information is available from ROSS upon request. Contact ROSS at 1-800-GET-ROSS or visit www.rosscontrols.com.