MD4 Series Remote Pilot Reg Port Sizes 3/8" to 3/4"; Flow to 190 scfm (5381 l/min)

Product Overview

The ROSS Controls is a family of remote pilot pressure regulators built on the MD4 modular platform, combining the higher flow capacity of the MD4 system with the remote pressure set point capability of pilot-operated regulation. Available in 3/8", 1/2", and 3/4" port sizes, the series delivers flow up to 190 scfm (5381 l/min) with outlet pressure from 0 to 250 psig (0 to 17 bar) commanded by a remotely located pilot regulator connected to the 1/4" NPTF pilot port.

Remote pilot regulators allow main regulator bodies to be installed in physically inaccessible, hazardous, or environmentally hostile locations, while pressure set point adjustments are made from a convenient remote location. The pilot signal line can be routed over substantial distances, giving design engineers wide flexibility in separating the main pressure control point from the operator adjustment interface. The Series extends this capability to the higher-flow MD4 platform, serving applications where the 124 Series full-size flow capacity is insufficient.

The Series is designed for direct integration into ROSS MD4 FRL manifold assemblies, connecting without pipe fittings to upstream MD4 filters and downstream MD4 lubricators. This modular construction creates compact, organized FRL stations with minimum pressure drop and simplified maintenance. Both self-relieving and non-relieving configurations are available, addressing the full range of pneumatic circuit requirements for downstream pressure handling behavior.

With an extended ambient temperature rating of 175 F (79 C) and inlet pressure capability of 300 psig (21 bar), the series can be installed in a broader range of industrial environments than many comparable products, without requiring special seal options or modifications to the standard configuration.

Key Engineering Features

• MD4 Platform Remote Pilot Capability - Combines the compact MD4 modular FRL platform's higher flow capacity with remote pilot pressure control, enabling MD4 manifold assemblies to be installed in inaccessible locations while pressure is adjusted remotely.
• Highest Flow in MD4 Remote Pilot Class - Delivers up to 190 scfm (5381 l/min) at 3/4" port size, exceeding the 124 Series full-size remote pilot regulator (155 scfm) and the 122 Series MD4 precision regulator (170 scfm) in the same general body size category.
• Self-Relieving and Non-Relieving Options - Both self-relieving (downstream pressure vents through body on set point reduction) and non-relieving (downstream pressure maintained when set point rises) configurations are available, addressing both standard and pressure-hold circuit requirements.
• Remote Pilot Port - 1/4" NPTF pilot port accepts output from a remote pilot regulator, allowing operators to control downstream pressure from any convenient location. Pilot line length has minimal effect on regulation accuracy for typical applications.
• Modular MD4 Platform Compatibility - Designed for direct integration into ROSS MD4 FRL manifold assemblies without pipe fittings, enabling compact filter-remote pilot regulator-lubricator combinations on the MD4 manifold platform.
• Wide Outlet Pressure Range - Outlet pressure from 0 to 250 psig (0 to 17 bar) commanded by pilot pressure, providing a broader regulation range than the 124 Series standard (0-200 psig), accommodating high-pressure tool and process requirements.
• Extended Temperature Rating - Rated to 175 F (79 C) ambient and media temperature in standard configuration, allowing installation in warmer industrial locations near ovens, furnaces, or in hot-climate outdoor installations.
• High Inlet Pressure Rating - Accepts inlet supply pressures up to 300 psig (21 bar), accommodating high-pressure compressed air headers while delivering remotely commanded working pressure downstream.
• Dual Gauge Port Orientation - Front and rear 1/4" NPT gauge ports allow pressure gauge installation at the main body to verify that commanded pilot pressure is accurately reproduced at the downstream connection point.
• NPTF and G Thread Options - All port sizes available in both NPTF and G (BSPP) thread standards for compatibility with North American and international pneumatic systems.

Technical Specifications

General Specifications

Temperature Ratings

The Series is rated to a higher maximum temperature than the miniature-series and precision-series units, with standard Nitrile seals supporting 175 F (79 C) operation without modification.

Flow Performance Data

Flow performance measured at 91 psig (6.3 bar) inlet pressure. Maximum 190 scfm at 3/4" port size.

Certifications & Compliance

Typical Applications & Industries

MD4 FRL Remote Pilot Station Installations

• MD4 FRL manifold assemblies installed inside machine cabinets, enclosures, or overhead structures where the manifold is inaccessible during normal operation. The Series remote pilot capability routes the pressure set point to a conveniently accessible remote panel without requiring access to the manifold location.
• Machine tool and machining center MD4 FRL stations mounted inside the machine's coolant enclosure or chip guard, with remote pilot adjustment accessible from the operator panel on the machine exterior.
• Robotic assembly cell FRL stations mounted on the robot arm or base structure, inside guarded cell areas, with pilot adjustment at the cell control pendant outside the guard boundary.
• Automated assembly systems where MD4 FRL manifold groups serve multiple actuators inside the machine frame, with pilot regulators at the HMI panel allowing operator pressure adjustment without machine access.
• Semiconductor and electronics manufacturing clean room FRL stations mounted inside the clean room envelope, with pilot adjustment from outside the clean room to avoid introducing personnel into the controlled environment.

Automotive Manufacturing

• Body shop welding fixtures and clamping actuator supply regulation, where MD4 FRL manifolds inside the welding cell are remotely controlled from the cell panel, eliminating operator entry into the welded zone for pressure adjustments.
• Paint shop conveyor and door-opening mechanism supply regulation with MD4 FRL stations inside the oven or spray zone, remotely adjusted from outside the hazardous environment.
• Engine test cell pneumatic supply regulation where the series main bodies are inside the test cell and pilots are outside the cell at the control station.
• Assembly line fixture clamping supply where different model variants require different clamping pressures; remote pilot control allows recipe-driven pressure changes without stopping the line or accessing the manifold.
• Transmission assembly hydraulic test bench compressed air supply, where test pressure set points change with part type and are controlled from the operator console via pilot regulators.

Process and Chemical Industries

• Chemical plant supply regulation for pneumatic actuated control valves in process areas, with MD4 FRL manifold stations in the process zone and pilot adjustments at the local panel or central control room.
• Oil and gas facility compressed air supply regulation for pneumatic valves and actuators in the process area, with remote set point adjustment from the safe area control room.
• Pharmaceutical manufacturing supply regulation for filling and packaging lines, where MD4 FRL stations inside the process room are remotely adjusted from outside the controlled area.
• Food processing supply regulation for hygiene-sensitive areas where personnel access to the FRL station for adjustment is undesirable, with remote pilot control from outside the process area.
• Water treatment facility aeration and actuator supply regulation with submerged or remote-area FRL stations remotely adjusted from the facility control room.

High-Pressure and High-Flow Applications

• Applications requiring flow capacity above 155 scfm (the 124 Series maximum) but below 740 scfm (the standard 126 Series maximum), where the series 190 scfm capacity fills the gap at 3/8" to 3/4" port sizes.
• High-pressure tool supply requiring remotely commanded outlet pressure up to 250 psig (17 bar), exceeding the 124 Series standard 200 psig maximum.
• MD4 manifold configurations where multiple Series remote pilot units serve different pressure zones in the same manifold assembly, each independently controlled from remote pilot lines.
• Automated test systems where programmatically controlled pilot pressures (via I/P transducers) command different downstream pressures for different test conditions without manual adjustment.

Ordering and Model Number Configuration

The ROSS model number structure specifies relieving option, gauge option, port size, and knob color. The MD4 platform prefix identifies the MD4 manifold compatibility.

Specify relief option at order: 1 = self-relieving (standard), 2 = non-relieving. Non-relieving maintains downstream pressure when set point is raised.

Yellow knob option (code Y) provides visual identification of remote pilot regulator stations in multi-unit MD4 manifold assemblies.

Pilot port is 1/4" NPTF. The pilot supply line connects from the remote pilot regulator output to this port.

G (BSPP) thread port codes are C, D, and E (3/8", 1/2", 3/4"). NPTF port codes are 3, 4, and 5.

A pilot regulator (ROSS 120 Series or equivalent) is required separately. Pilot regulator output must cover the required Series outlet pressure range.

Relief Option Codes

Port Size and Thread Codes

Accessories

Remote Pilot Regulators

Any ROSS Controls standard or precision regulator can serve as the pilot supply for the series. ROSS 120 Series Miniature Precision Regulators are commonly used at remote adjustment panels due to their compact footprint and high set-point accuracy.

Pressure Gauges

0 to 200 psig (0 to 14 bar) gauges for the 1/4" NPT gauge ports at the main body. Used to verify outlet pressure at the main body location during commissioning and periodic maintenance checks.

MD4 FRL Modular Components

ROSS Controls MD4 platform filters, lubricators, and MD4 L-O-X lockout valves integrate directly with the series in modular manifold configurations. Contact ROSS Controls for complete MD4 assembly design assistance.

Related Products & Accessories

• 122 Series MD4 Precision Regulator - MD4 platform precision regulator with direct local set point adjustment, for installations where remote pilot control is not required. https://www.rosscontrols.com/en/series/122-md4-precision-series
• 124 Series Full-Size Remote Pilot Regulator - Full-size modular remote pilot regulator for 1/4" to 3/4" ports, flow to 155 scfm, on the standard full-size FRL platform. https://www.rosscontrols.com/en/series/124-full-size-series-remote-pilot-reg
• 126 Series High-Capacity Remote Pilot Regulator - High-capacity inline remote pilot regulator for 3/4" to 2" ports, flow to 4000 scfm, for large-bore remote pilot applications. https://www.rosscontrols.com/en/series/126-high-capacity-series-remote-pilot-reg
• 120 Series Miniature Precision Regulator - Compact precision regulator commonly used as the pilot supply for Series installations. https://www.rosscontrols.com/en/series/120-miniature-precision-series
• ROSS MD4 FRL Filters - MD4 platform modular filters for upstream particulate removal in Series MD4 assemblies. https://www.rosscontrols.com/en/categories/filters
• ROSS MD4 L-O-X Lockout Valves - MD4 compatible lockout valves for LOTO-compliant energy isolation upstream of Series MD4 assemblies. https://www.rosscontrols.com/en/categories/lockout-valves

Frequently Asked Questions (FAQ)

Q: How does the series differ from the 124 Series?

A: Both are remote pilot regulators using diaphragm construction with remote pilot ports. The Series is built on the MD4 modular platform (vs. the full-size platform of the 124 Series), provides higher maximum flow (190 vs. 155 scfm), offers a higher outlet pressure range (0-250 vs. 0-200 psig standard), includes both self-relieving and non-relieving options, and is rated for 175 F (79 C) vs. the 124 Series standard range. The Series requires MD4 manifold components rather than full-size FRL manifold components.

Q: What is the advantage of the non-relieving option?

A: A non-relieving regulator maintains downstream pressure when the regulator is shut off or when inlet pressure drops temporarily below set point. This is useful in pneumatic circuits where downstream actuators must hold position and not exhaust when supply pressure is temporarily lost. The standard self-relieving option is appropriate for circuits where downstream pressure can vent safely when set point is reduced or inlet pressure drops.

Q: What is the maximum outlet pressure of the series?

A: The Series maximum outlet pressure is 250 psig (17 bar), set by the remote pilot regulator output. This exceeds the 124 Series standard maximum of 200 psig, making the series appropriate for high-pressure tool and process applications requiring remote pilot control.

Q: What is the maximum flow capacity?

A: The Series delivers up to 190 scfm (5381 l/min) at 3/4" port size. This is the highest flow capacity among full-size and MD4 modular remote pilot regulators in the ROSS FRL lineup. For flow exceeding 190 scfm, the 126 Series High-Capacity Remote Pilot Regulator (to 4000 scfm) is required.

Q: Can I use any regulator as the pilot supply?

A: Yes, any regulator providing a clean, filtered pilot signal in the required pressure range can serve as the pilot supply. ROSS Controls 120 Series Miniature Precision Regulators are a common choice. The pilot regulator output pressure range must span the full required Series outlet pressure operating range.

Q: What is the pilot port size and location?

A: The pilot port is 1/4" NPTF, located on the main regulator body. The 1/4" OD pilot signal tubing connects from the remote pilot regulator outlet to this port. The port location allows flexible tubing routing in MD4 manifold assemblies.

Q: Is the series compatible with electro-pneumatic (I/P) transducers as the pilot source?

A: Yes. An I/P (current-to-pressure) transducer can supply the pilot signal, allowing digital or analog control systems to command downstream pressure proportionally. This configuration enables automated, recipe-based pressure control for applications requiring programmatic pressure changes.

Q: What upstream filtration is required?

A: 5-micron minimum filtration for the main supply line. ROSS MD4 filters connect directly to the series in modular manifold assemblies. Also filter the pilot signal supply line with appropriate clean air to prevent pilot valve contamination.

Q: What is the operating temperature range?

A: The Series with standard Nitrile seals operates from 40 to 175 F (4 to 79 C) for both ambient and media temperatures. This extended rating (vs. F for miniature and full-size precision series) allows installation in warmer industrial environments.

Q: Can the series be used as a standalone inline regulator?

A: Yes. Although designed for MD4 modular manifold use, the series can be installed inline using its NPTF or G threaded ports. The remote pilot function remains available regardless of mounting method.

Q: What happens if the pilot signal line is disconnected during operation?

A: If the pilot signal line is disconnected, the pilot port vents to atmosphere, effectively commanding a 0 psig set point. The main body will open fully in a self-relieving configuration, venting downstream pressure. In a non-relieving configuration, the downstream pressure is maintained at the last set point until consumed. Reconnect the pilot line to restore normal regulated operation.

Q: How is the series ordered with the non-relieving option?

A: Specify relief option code 2 (non-relieving) in the model number structure. The model structure is MD4 52K [Relief] [Gauge] [Port] [Color] B. For example, a non-relieving, no-gauge, 3/4" NPTF, black knob unit would be ordered as MD4 52K 2 A 5 2 B. Confirm the non-relieving configuration is appropriate for the specific downstream circuit before ordering.

Installation & Maintenance Guidelines

• Route the 1/4" NPTF pilot signal tubing from the remote pilot regulator outlet to the series pilot port. Use clean, dry 1/4" OD tubing with no sharp bends or kinks that could restrict pilot signal flow.
• Install an upstream MD4 5-micron filter or equivalent to protect the main body valve seat and diaphragm. Connect directly to the MD4 manifold without intervening fittings.
• Filter the pilot signal supply air with a minimum 5-micron filter at the pilot regulator inlet. Contaminated pilot air can block the pilot port in the main body.
• Ensure main body inlet pressure does not exceed 300 psig (21 bar).
• For modular MD4 manifold installation, follow ROSS Controls MD4 assembly procedures: verify module alignment, apply specified tie-rod torque, and confirm port sealing before applying supply pressure.
• Maintain ambient temperature within 40 to 175 F (4 to 79 C). The Series standard Nitrile seals support the full 175 F operating range.
• Verify gauge ports: install a gauge in the front or rear 1/4" NPT port at the main body to monitor actual outlet pressure. Plug the unused gauge port with a 1/4" NPT plug.
• Set the remote pilot regulator to the desired working pressure. Confirm the series main body outlet pressure matches the pilot set point using a calibrated gauge at the main body.
• For non-relieving applications, verify that downstream circuit design accounts for the hold behavior: no venting occurs when pilot set point is raised. Provide adequate downstream safety relief if required by circuit safety analysis.
• Test the complete pilot system: increase and decrease pilot set point over the full operating range, confirming main body outlet tracks pilot output accurately and self-relieving (or non-relieving) behavior is as expected.

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 MD4 remote pilot system design is available through ROSS Controls USA at (800) 438-7677.

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

Visit rosscontrols.com for Series documentation, MD4 manifold assembly guides, pilot system design resources, and distributor locator services.

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