MD4 Series Port Sizes 3/8" to 3/4"; Flow to 220 scfm (6230 l/min)

Product Overview

The ROSS Controls MD4 Series is a family of modular pressure regulators covering port sizes from 3/8" to 3/4" with a maximum flow capacity of 220 scfm (6230 l/min). The MD4 is the highest-flow modular regulator in the ROSS FRL line, providing a 42% flow increase over the Full-Size Series in the same 3/4" port size range.

Both piston and diaphragm construction are available in the MD4 Series. Piston construction is selected when maximum flow through the 3/4" port is the primary design criterion. Diaphragm construction provides faster downstream pressure response and more consistent regulation under variable flow demand. Both options are self-relieving as standard, with non-relieving configurations available by special order.

The MD4 Series uses a configurable model numbering system allowing selection of adjustment type (knob 52K or T-Handle 52T), adjustment range (0 to 20 psig through 0 to 175 psig), flow option (standard or reverse flow), port size and thread (NPT or G), and cap color (Black 2 or Yellow Y). This flexibility accommodates diverse machine design requirements without stocking multiple fixed configurations.

Maximum inlet pressure is 300 psig (21 bar) with outlet adjustable up to 175 psig (12 bar) using appropriate springs. The zinc body with nylon dome and acetal knob construction is rated for 40 to 175 degrees F (4 to 79 degrees C) ambient temperature. A 1/4 NPT gauge port on front and rear accommodates gauge installation from either side of the body.

Key Engineering Features

• Maximum Flow 220 scfm (6230 l/min) - Highest flow capacity of any modular regulator in the ROSS FRL line, supporting large-bore cylinders, high-demand circuits, and multiple simultaneous actuator operations.
• Piston and Diaphragm Construction - Piston construction maximizes air flow; diaphragm construction provides faster downstream pressure response and higher regulation precision.
• Port Sizes 3/8" to 3/4" - Covers the full range of mid-to-large port sizes, bridging between smaller modular regulators and the inline High-Capacity Series.
• Configurable Model Numbering - Adjustment type, adjustment range, flow option, port size, thread type, and cap color are all selectable, reducing special-order requirements for diverse applications.
• Reverse Flow Option - Available for weld gun and downstream pressure release applications, with standard (S) or reverse (R) flow selectable in the model number configuration.
• Modular Mounting - Connects directly to MD4 Series FRL filters and lubricators without additional fittings, forming high-flow integrated air preparation assemblies.
• Maximum Inlet Pressure 300 psig (21 bar) - Rated for high-pressure supply systems, consistent with the MD3 and Full-Size Series in the ROSS modular FRL platform.
• Four Adjustment Ranges - 0 to 175 psig (A), 0 to 125 psig (B), 0 to 50 psig (C), and 0 to 20 psig (D) options available to match application pressure requirements precisely.
• Removable Locking Key - Secures set point after commissioning to prevent unauthorized adjustment. Reinstall to permit future set point changes.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Heavy Automation and Press Operations

• Large-bore pneumatic cylinder supply circuits where 220 scfm flow capacity prevents downstream pressure drop during rapid full-stroke cycling.
• Pneumatic press and stamping machine supply where high flow at regulated pressure maintains consistent press force across high-cycle operation.
• Transfer machine pneumatic circuits supplying multiple simultaneous actuators across multiple stations from a single regulated 3/4" modular source.
• Pneumatic power unit supply circuits where regulated air at high flow rates drives multiple downstream actuators and control circuits.

Welding and Fabrication

• High-throughput resistance welding lines requiring both weld pressure regulation and rapid inter-weld exhaust at 3/4" port sizes using the MD4 reverse flow option.
• Robotic welding cell main air supply preparation where modular MD4 filter-regulator assemblies provide centralized high-flow regulated air.
• Large projection welding fixture circuits requiring sustained high flow to maintain consistent electrode force across extended production runs.
• Welding robot base supply lines where 3/4" modular assemblies prepare air for multiple robot stations simultaneously.

Automotive Manufacturing

• Body shop main air circuits supplying entire workstations from single modular MD4 filter-regulator-lubricator assemblies at 3/4" supply.
• Engine assembly line torque tool supply where high flow rates at regulated pressure maintain consistent fastening torque across multiple simultaneous tool operations.
• Paint line actuator supply circuits using the elevated 175 degrees F temperature rating in warm oven environments.
• Vehicle testing station pneumatic supply where 220 scfm capacity handles large-diameter test fixture actuators.

Material Handling and Warehousing

• High-speed pneumatic conveyor switching actuator supply where large-bore cylinders require high flow rates at regulated pressure for rapid stroke actuation.
• Pneumatic palletizer and depalletizer circuits requiring regulated 3/4" air at the high flow rates needed to drive multiple gripper and lift actuators simultaneously.
• Sortation system diverter actuator supply where consistent regulated pressure across high-cycle operations is critical to system reliability.

Ordering and Model Number Configuration

Related Products & Accessories

• 116 Full-Size Series Pressure Regulators - Modular diaphragm regulators, port sizes 1/4" to 3/4", flow to 155 scfm. https://www.rosscontrols.com/en/series/116-full-size-series
• MD3 Series Pressure Regulators - Modular diaphragm regulators, port sizes 1/4" to 1/2", flow to 120 scfm, outlet to 200 psig. https://www.rosscontrols.com/en/series/115-md3-series
• 118 High-Capacity Series Pressure Regulators - Inline piston regulators for very high flow at port sizes 3/4" to 1-1/2", flow to 800 scfm. https://www.rosscontrols.com/en/series/118-high-capacity-series
• ROSS FRL Filters MD4 Series - MD4 Series filters for modular assembly with MD4 Series regulators. https://www.rosscontrols.com/en/categories/36-air-preparation-frls

Frequently Asked Questions (FAQ)

Q: What port sizes are available for the MD4 Series?

A: The MD4 Series is available in 3/8", 1/2", and 3/4" port sizes in both NPTF and G (BSPP) thread forms.

Q: What is the maximum flow capacity?

A: The MD4 Series has a maximum flow capacity of 220 scfm (6230 l/min), which is 42% higher than the Full-Size Series and the highest flow capacity of any modular regulator in the ROSS FRL line.

Q: Should I choose piston or diaphragm construction for the MD4?

A: Choose piston construction when maximum air flow through the 3/4" port is the primary requirement. Choose diaphragm construction when faster downstream pressure response and more precise regulation under variable flow demand are required. Both are self-relieving as standard.

Q: What are the adjustment range options?

A: Four adjustment ranges are available: 0 to 175 psig (A), 0 to 125 psig (B), 0 to 50 psig (C), and 0 to 20 psig (D). Select the range that covers the desired set point while providing adequate resolution for fine adjustment.

Q: How does the configurable model number work?

A: The MD4 model number is assembled by selecting options: adjustment type (52K or 52T), adjustment range (A through D), flow option (R or S), port size, thread form, gauge option, and cap color. Consult the model number builder table to assemble the correct model number for the application.

Q: What is the reverse flow option?

A: The reverse flow option (R in the flow option position) provides regulated pressure in the inlet-to-outlet direction and quick exhaust in the outlet-to-inlet direction. This is the standard selection for weld gun circuits requiring rapid inter-weld downstream pressure release.

Q: What is the maximum inlet pressure?

A: The maximum inlet pressure is 300 psig (21 bar), consistent with the MD3 and Full-Size Series.

Q: What outlet pressures can the MD4 regulate to?

A: Up to 175 psig (12 bar) with the 0 to 175 psig spring (range A). Optional springs cover other ranges. The 0 to 20 psig range (D) provides the finest resolution for low-pressure applications.

Q: Is the MD4 self-relieving?

A: Yes. The MD4 is self-relieving as standard. Non-relieving configurations are available by consulting ROSS Controls.

Q: What gauge options are available?

A: Six gauge configurations are offered: without gauge, with 0 to 200 psig gauge, and with 0 to 60 psig gauge, each available with or without panel mount nut for through-panel gauge installation.

Q: What cap color options are available?

A: Black (code 2) and Yellow (code Y) cap colors are available. Cap color can be used to visually differentiate pressure zones in multi-regulator installations.

Q: How does the MD4 compare to the Full-Size Series?

A: The MD4 covers the same 3/4" maximum port size as the Full-Size Series but provides 42% higher flow (220 vs. 155 scfm). The MD4 also adds piston construction option and a wider adjustment range selection. Select MD4 when higher flow or configurable model numbering are required.

Q: What is the ambient temperature range?

A: The MD4 Series is rated for 40 to 175 degrees F (4 to 79 degrees C), the same as the MD3 and Full-Size Series.

Installation & Maintenance Guidelines

• Install the MD4 Series with the inlet port connected to the supply side and the outlet connected to the downstream circuit. Do not reverse flow through a standard flow model.
• For modular assemblies, align all MD4 Series interface connections properly before pressurizing to prevent leakage at interface faces.
• Apply thread sealant only to male port thread connections. Keep sealant clear of the first two threads to prevent internal contamination.
• For dome removal clearance, provide at least 0.625 inches (16 mm) above the dome. For cap removal, allow at least 0.50 inches (13 mm) below the cap.
• Set the outlet pressure by rotating the adjustment knob or T-Handle clockwise to increase and counterclockwise to decrease pressure.
• Monitor the selected gauge (if installed) during adjustment to verify the outlet pressure reaches the desired set point.
• Remove the locking key or lock the locking knob after final set point confirmation to prevent unauthorized adjustment.
• For reverse flow models, verify both regulated forward pressure and reverse exhaust functions after installation.
• Do not exceed 300 psig (21 bar) inlet pressure.
• For panel mounting, use a 2-1/16 inch (52 mm) hole. Confirm the gauge is accessible for routine inspection from the normal maintenance position.
• After initial pressurization, check all connections for leaks using soapy water or an appropriate leak detection solution.
• Ensure upstream filtration is in place. Hard particulate can damage the nitrile seals and brass valve seat, causing regulated pressure drift over time.

Warranty & Global Support

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

Technical support is available through ROSS Controls USA at (800) 438-7677 or by visiting rosscontrols.com.

For product configuration, dimensional drawings, modular assembly documentation, and catalog downloads, visit the ROSS Controls MD4 Series product page at rosscontrols.com or contact ROSS Controls directly.

Download Catalog: https://www.rosscontrols.com/en/series/117-md4-series