High-Flow Series Port Sizes 1"; Flow to 450 scfm (12744 l/min)

Product Overview

The ROSS Controls is a high-flow inline pneumatic relief valve providing overpressure protection for large-volume compressed air circuits requiring flow relief capacity up to 450 scfm (12744 l/min) through a 1" port. The Series is designed for applications where the miniature relief capacity of the 127 Series is insufficient for the downstream circuit volume and potential relief event magnitude.

The Series incorporates a 1/4" NPTF pilot port in addition to the standard main body inlet and outlet ports. In many large-volume pneumatic systems, the series is used in combination with a remotely piloted fill regulator: the fill regulator (such as a ROSS 126 Series remote pilot regulator) fills the downstream volume to the commanded pilot pressure, and the series relief valve exhausts air when downstream pressure rises approximately 2 psig (0.1 bar) above the fill regulator's commanded set point. This configuration provides both fill regulation and high-flow relief in single- or multi-actuator large-volume pneumatic circuits.

Using diaphragm construction, the series achieves high sensitivity to excess pressure conditions, opening precisely at the set relief pressure without significant overshoot before high-flow relief commences. The inlet pressure rating of 200 psig (14 bar) covers standard industrial compressed air working pressure ranges, and the adjustable outlet pressure from 0 to 200 psig (0 to 14 bar) encompasses the full range of working pressures in these systems.

The self-relieving design exhausts vented air through the valve body. With flow capacity to 450 scfm (12744 l/min) and a 1/4" NPT pilot port for remote pilot signal input, the series provides both high-flow relief capability and the flexibility for remotely commanded relief pressure set points in sophisticated large-volume pneumatic control systems.

Key Engineering Features

• High-Flow Relief Capacity - Provides relief flow up to 450 scfm (12744 l/min) through a 1" port, addressing large-volume downstream circuits where small relief valves are insufficient to control pressure during rapid overpressure events.
• Remote Pilot Port for Circuit Integration - 1/4" NPTF pilot port allows the series relief set point to be controlled by a remote pilot signal, enabling integration with remotely piloted fill regulator circuits where the fill pressure and relief pressure are linked.
• Diaphragm Construction - Large diaphragm sensing area relative to the valve seat provides precise, repeatable opening at the set relief pressure with minimal overshoot, consistent with other ROSS diaphragm FRL components.
• Self-Relieving Design - Vents excess downstream pressure through the valve body to atmosphere when system pressure exceeds the relief set point, without requiring separate exhaust piping in standard industrial installations.
• Wide Pressure Range - Adjustable from 0 to 200 psig (0 to 14 bar), covering the full range of standard industrial compressed air working pressures from low-pressure instrument air to maximum industrial working pressure.
• Dual Gauge Port Orientation - 1/4" NPT gauge ports front and rear allow outlet pressure monitoring at the main body for commissioning verification and periodic maintenance checks.
• Aluminum Body Construction - Aluminum body with Zinc dome, Brass valve, and Nitrile seals provides corrosion resistance and durability for industrial compressed air service within the rated temperature and pressure ranges.
• Extended Temperature Rating - Rated to 175 F (79 C) ambient and media temperature, consistent with the ROSS high-capacity FRL product family, enabling installation in warm industrial environments near process equipment.
• Inline Installation - Direct inline installation in 1" compressed air piping, compatible with standard NPTF or G (BSPP) threaded connections for integration into existing piping systems.
• Compact for High Flow - Physical dimensions of 4.4" x 4.8" x 2.5" (111 x 122 x 62 mm) at 1.8 lb (0.8 kg) provide a compact footprint relative to the 450 scfm relief flow capacity.

Technical Specifications

General Specifications

Temperature Ratings

The Series is rated to the higher temperature range of the ROSS high-capacity FRL product family, consistent with installation locations near process equipment and in industrial utility areas.

Flow Performance Data

Relief flow data at 1" port. Maximum 450 scfm at full-open relief. Relief flow at various inlet pressures: at 75 psig inlet approximately 350 scfm, at 100 psig inlet approximately 400 scfm, at 140 psig inlet approximately 450 scfm.

Certifications & Compliance

Typical Applications & Industries

Remotely Piloted Fill Regulator Systems

• Large-volume pneumatic actuator circuits where a ROSS 126 Series (or similar) remote pilot fill regulator fills the actuator volume to the commanded pressure, and the series exhausts at approximately 2 psig (0.1 bar) above the fill pressure to prevent overpressure. This fill-regulate-and-hold circuit architecture is fundamental to large pneumatic actuator control in industrial automation.
• Pneumatic accumulator filling systems where a remote pilot regulator controls fill pressure in a large accumulator, and the series provides high-flow relief if accumulator pressure exceeds the set point during fill or due to thermal expansion.
• Large-bore cylinder supply circuits where the series handles relief flow requirements for the combined cylinder and supply line volume during rapid overpressure events, complementing a remote pilot regulator that sets the working pressure.
• Pneumatic press circuits where the series provides rapid venting if press approach pressure exceeds the set limit during a cycle, protecting the press structure and tooling from overload.
• Blow-off and filling station circuits in bottling and container manufacturing, where the series relieves fill pressure in large-volume containers when pressure exceeds the process set point.

Large-Volume Pneumatic Systems

• Central compressed air receiver and accumulator protection where large volumes of stored air must be protected against overpressure from compressor output variations, temperature-driven pressure rise, or control system failures.
• Air bag and cushion inflation systems in manufacturing and testing applications, where high-flow relief capacity prevents overpressure during high-speed fill operations.
• Pneumatic conveying system surge tank pressure relief, where the series provides high-capacity venting when surge tank pressure rises above the working limit during conveying cycles.
• Large pneumatic tire inflation and balancing equipment relief protection, where high-flow relief accommodates the rapid pressure decay required if fill pressure is exceeded.
• Hydraulic intensifier and booster supply pressure protection, where the pneumatic supply side requires high-flow relief capacity to accommodate sudden pressure changes in high-ratio intensifier systems.

Process Industries and Chemical Plants

• Chemical plant instrument air header relief protection for large-diameter headers serving many actuators and instruments, where the series provides header protection against overpressure events caused by compressor station faults.
• Petroleum refinery pneumatic actuated valve supply protection where high-flow relief is required to prevent overpressure damage to large actuated control valve assemblies and associated piping.
• Water treatment and wastewater facility large-bore supply header protection for pneumatic aeration blowers and actuated valve arrays.
• Pharmaceutical manufacturing large-volume pneumatic supply protection for filling, packaging, and sterilization equipment supply headers.
• Automotive paint shop supply header relief for large-volume atomization air systems where supply pressure excursions could damage spray equipment or produce non-conforming coating conditions.

Test and Evaluation Facilities

• Aerospace and defense test chamber pneumatic supply protection where large volumes of compressed air at precisely controlled pressures are used for load application, simulation, and environmental testing. The Series provides the high-flow relief capacity required to rapidly vent chamber pressure if target pressure is exceeded.
• Automotive component test facility supply regulation and relief for pneumatic test rigs evaluating tires, suspension components, and hydraulic systems under controlled air pressure, where overpressure events could damage test specimens or rig structures.
• Industrial valve and actuator test bench supply protection for high-flow bench systems testing large pneumatic actuated valves at full rated pressure and flow, where relief capacity must match test article flow requirements.
• Performance testing of pneumatic components and systems where precisely controlled large-volume air supply requires both accurate fill regulation (via remote pilot) and high-flow relief protection for test article safety.

Ordering and Model Number Configuration

The ROSS is available in a single port size (1") in NPTF and G (BSPP) thread. Outlet pressure is adjustable from 0 to 200 psig. The pilot port (1/4" NPTF) is standard on all units for remote pilot or plugged operation.

The Series is available in one port size (1") with NPTF or G (BSPP) thread. Model 5X00D6012 for NPTF; C5X00D6012 for G thread.

Pilot port (1/4" NPTF) is standard. If remote pilot control is not used, plug the pilot port with a 1/4" NPTF plug.

Outlet pressure is adjustable 0 to 200 psig (0 to 14 bar). Set the relief pressure via the adjusting knob after installation.

Maximum inlet pressure is 200 psig (14 bar). This is lower than many ROSS FRL components; verify supply pressure does not exceed 200 psig at the series inlet.

Contact ROSS Controls for application-specific configurations, including higher inlet pressure requirements or special seal materials.

Standard Model Numbers

Accessories

Pressure Gauges

0 to 200 psig (0 to 14 bar) gauges for the 1/4" NPT front and rear gauge ports. Essential for commissioning verification of the relief set point and periodic maintenance checks of downstream circuit pressure.

Remote Pilot Regulators (for fill regulator circuits)

ROSS 126 Series High-Capacity Remote Pilot Regulators are commonly used as the fill regulator in systems where the series provides downstream relief. The fill regulator commands downstream pressure via a remote pilot, and the series relief valve exhausts at approximately 2 psig above the commanded fill pressure. Contact ROSS Controls for complete circuit design assistance.

Pilot Port Plugs

1/4" NPTF pipe plugs for plugging the pilot port when the series is used as a standalone relief valve without remote pilot control.

Related Products & Accessories

• 127 Series Miniature Relief Valves - Miniature inline relief valves for 1/8" and 1/4" port sizes, flow to 40 scfm, for small-bore overpressure protection. https://www.rosscontrols.com/en/series/127-miniature-series
• 126 Series High-Capacity Remote Pilot Regulator - High-capacity inline remote pilot regulator (flow to 4000 scfm) frequently used as the fill regulator in systems where the series provides relief protection. https://www.rosscontrols.com/en/series/126-high-capacity-series-remote-pilot-reg
• 123 Series High-Capacity Precision Regulator - High-capacity inline precision regulator for circuits requiring precision regulation at large port sizes. https://www.rosscontrols.com/en/series/123-high-capacity-precision-series
• 124 Series Full-Size Remote Pilot Regulator - Full-size modular remote pilot regulator commonly used as fill regulator in smaller-volume circuits with 127 Series relief protection. https://www.rosscontrols.com/en/series/124-full-size-series-remote-pilot-reg
• ROSS High-Capacity Inline Filters - Large-bore inline filters for upstream particulate protection of the series in high-flow applications. https://www.rosscontrols.com/en/categories/filters
• ROSS Pressure Gauges and Transducers - Pressure monitoring instruments for downstream circuit pressure verification in Series relief valve circuits. https://www.rosscontrols.com/en/categories/pressure-gauges

Frequently Asked Questions (FAQ)

Q: What is the maximum flow capacity of the series?

A: The Series provides maximum relief flow of 450 scfm (12744 l/min) through the 1" port. This is more than 10 times the 127 Series miniature relief valve capacity (40 scfm), making the series appropriate for large-volume circuits where rapid overpressure events require high-flow venting capacity.

Q: What is the maximum inlet pressure for the series?

A: The maximum inlet pressure is 200 psig (14 bar). This is lower than many other ROSS FRL components (which typically accept 300 psig). Verify that the supply system pressure does not exceed 200 psig at the series inlet under all operating conditions, including compressor transients.

Q: What is the pilot port used for?

A: The 1/4" NPTF pilot port allows the series relief set point to be commanded by an external pilot signal. In fill regulator circuits, the pilot signal from the fill regulator (e.g., ROSS 126 Series) is also connected to the series pilot port, causing the series to exhaust at approximately 2 psig above the fill regulator's commanded pressure. If the pilot port is not used, it must be plugged with a 1/4" NPTF plug.

Q: How does the series work with a remote pilot fill regulator?

A: In a remotely piloted fill and hold circuit, a fill regulator (such as a 126 Series) fills a downstream volume to the commanded pilot pressure. The Series relief valve is connected to the same downstream circuit with its pilot port connected to the same pilot signal (or offset by 2 psig). When downstream pressure rises approximately 2 psig above the fill set point, the series opens and vents the excess to prevent overpressure. This provides both fill regulation (by the fill regulator) and overpressure relief (by the series) in a single coordinated circuit.

Q: How does the series differ from the 127 Series?

A: The 127 Series is a miniature relief valve for 1/8" and 1/4" port sizes with maximum flow of 40 scfm and pressure ranges from 1 to 140 psig. The Series is a high-flow relief valve for 1" port with maximum flow of 450 scfm and pressure range 0 to 200 psig, and includes a remote pilot port. The Series is approximately 11 times higher flow capacity and is intended for large-volume circuit protection rather than small-bore instrument and tool circuit protection.

Q: What pressure range is adjustable on the series?

A: The Series is adjustable from 0 to 200 psig (0 to 14 bar) via the adjusting knob. Set the relief pressure to approximately 5 to 10 psig above the normal working pressure to prevent nuisance venting during normal operation while still providing overpressure protection during fault conditions.

Q: What construction type does the series use?

A: The Series uses diaphragm construction, consistent with the ROSS FRL product family's approach to high-sensitivity relief and regulation. The large diaphragm sensing area provides precise cracking and reseating at the relief set point.

Q: What is the operating temperature range?

A: The Series with Nitrile seals operates from 40 to 175 F (4 to 79 C) for both ambient and media temperature. This extended rating (vs. 125 F for some other ROSS FRL components) allows installation in warmer industrial utility areas and near process equipment.

Q: Does the series come in port sizes other than 1"?

A: The standard Series catalog configuration is 1" port only (NPTF model 5X00D6012 and G thread model C5X00D6012). For higher flow applications requiring larger port sizes and up to 4000 scfm relief capacity, consult ROSS Controls for extended high-capacity configurations.

Q: What upstream filtration is required?

A: A minimum 5-micron upstream filter is recommended to protect the series valve seat. ROSS Controls high-capacity inline filters matched to 1" port should be used for large-flow installations where particulate entrainment in high-velocity flow could contaminate the valve seat.

Q: Can the series be used without a pilot connection?

A: Yes. The Series can be used as a conventional inline relief valve without a pilot connection. In this configuration, the relief set point is determined entirely by the adjusting knob spring setting. Plug the 1/4" NPTF pilot port with an appropriate pipe plug to seal it when the pilot function is not needed.

Q: What is the application relationship between the 126 Series regulator and the series relief valve?

A: The 126 Series High-Capacity Remote Pilot Regulator and Series High-Flow Relief Valve are complementary components frequently used together in large-volume fill-and-hold pneumatic circuits. The 126 Series fills the downstream volume to the pilot-commanded pressure, and the series provides the high-flow relief protection if that pressure is exceeded by approximately 2 psig. ROSS Controls can provide complete circuit design assistance for these combined applications.

Installation & Maintenance Guidelines

• Install the series inline in the 1" compressed air circuit with the adjusting knob accessible. Support the regulator body independently from piping loads at the 1" connection.
• If using the series with a fill regulator circuit, connect the 1/4" NPTF pilot port to the fill regulator's pilot signal line or to the downstream circuit directly (depending on circuit design). The pilot port pressure sets the relief cracking point.
• If not using the pilot port function, install a 1/4" NPTF pipe plug in the pilot port. An open unplugged pilot port will behave as a 0 psig set point command, causing the relief valve to remain open.
• Ensure inlet supply pressure does not exceed 200 psig (14 bar). The Series has a lower maximum inlet pressure than many other ROSS FRL components. Do not exceed this limit.
• Install a minimum 5-micron upstream filter to protect the valve seat. At 1" port and 450 scfm capacity, particulate in high-velocity flow can damage seating surfaces.
• Set the relief pressure via the adjusting knob. In fill-regulator circuits, set the series relief at approximately 2 psig above the fill regulator's maximum commanded working pressure.
• Verify gauge ports: install 0-200 psig gauges in the front or rear 1/4" NPT gauge ports to monitor downstream pressure. Plug unused gauge ports with 1/4" NPT plugs.
• Ensure the outlet venting location is safe. At 450 scfm, relief air discharge is substantial and must be directed away from personnel, ignition sources, and sensitive equipment.
• Maintain ambient temperature within 40 to 175 F (4 to 79 C). Nitrile seals support the full 175 F range in standard configuration.
• Commission by verifying relief cracking pressure: slowly increase downstream pressure above the set point and confirm the series opens at the expected relief pressure. Document the verified cracking pressure for maintenance records.

Warranty & Global Support

ROSS Controls provides a one-year warranty on all products, covering defects in material and workmanship from the date of purchase.

Technical support for the series and fill regulator circuit design is available through ROSS Controls USA at (800) 438-7677.

Global support through ROSS Controls offices in Canada, Brazil, Germany, France, United Kingdom, India, China, and Japan.

Visit rosscontrols.com for Series technical data, dimensional drawings, fill regulator circuit design application notes, and authorized distributor information.

Download Catalog: https://www.rosscontrols.com/en/documents