MD4 Series Port Sizes 3/8" to 3/4"; Flow to 205 scfm (5806 l/min)

Product Overview

The ROSS Controls MD4 Series is a high-flow modular Filter Regulator Lubricator (FRL) combination product line for 3/8" to 3/4" port size compressed air systems. The MD4 Series delivers combined filtration, pressure regulation, and lubrication with maximum flow capacity up to 205 scfm (5806 l/min), providing substantially higher flow than standard full-size FRL combinations at the same 3/4" port dimension.

The MD4 Series is the high-performance counterpart to the Full-Size Series within the ROSS Controls FRL product range, designed specifically for applications where 3/8" to 3/4" port circuits must support peak pneumatic demand beyond the capacity of full-size FRL combinations. This includes high-speed production equipment, multi-actuator machine systems, and centralized air preparation stations serving extensive pneumatic distribution headers.

The filter component offers three bowl configurations: a polycarbonate plastic bowl with steel shatterguard, an aluminum bowl with a clear nylon sight glass, and an extended aluminum lubricator bowl with sight glass. Drain options include internal automatic drain, manual drain, and electronic drain, providing the same complete condensate management flexibility as the MD3 Series at a higher flow class. The self-relieving diaphragm-type regulator features dual gauge ports for simultaneous inlet and outlet pressure monitoring.

The MD4 Series is the preferred selection for plant-level centralized FRL stations, major machine air inlet preparation with 3/4" supply ports, and any application where the compressed air demand exceeds the flow ceiling of standard full-size FRL combinations.

Key Engineering Features

• High Flow Capacity to 205 scfm at 3/4" Port - Delivers up to 205 scfm (5806 l/min) at 3/4" port size, providing 49% higher flow capacity than the Full-Size Series at the same port dimension, enabling the MD4 to serve demanding high-cycle production environments without requiring a larger supply port size.
• Three Bowl Material and Capacity Options - Available with polycarbonate bowl with steel shatterguard, aluminum bowl with clear nylon sight glass, and extended aluminum lubricator bowl with sight glass, providing configuration flexibility across operating environments and condensate volume requirements.
• Electronic Drain Option - Electronic drain provides timed or demand-triggered condensate expulsion to minimize compressed air waste compared to continuous float-type automatic drains, particularly beneficial in high-flow applications with variable condensate generation.
• Four Drain Configurations - Internal automatic drain, manual drain, and electronic drain options cover all condensate management strategies from continuous unattended automatic drainage to programmed electronic expulsion.
• Diaphragm-Type Regulator with Dual Gauge Ports - Self-relieving diaphragm-type regulator provides high-sensitivity pressure control with two gauge ports for simultaneous connection of inlet and outlet pressure gauges, enabling differential pressure monitoring across the regulator.
• Non-Relieving Regulator Option - Non-relieving regulator option for applications where downstream pressure must be retained when the regulator set point is reduced below the current circuit pressure.
• Modular Side-by-Side Assembly - Modular mounting allows individual filter, regulator, and lubricator units to be assembled side-by-side into a compact FRL station using MD4 Series connection hardware.
• Extended Aluminum Lubricator Bowl - The extended aluminum lubricator bowl option provides increased oil reservoir capacity for high-flow applications with higher lubricant consumption rates, extending the refill interval.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

High-Demand Production Lines and Machine Centers

• Main machine air preparation on high-cycle production equipment with 3/4" supply circuits where simultaneous actuation of multiple cylinders, grippers, and transfer mechanisms creates peak demand exceeding 138 scfm.
• Centralized FRL station on production line pneumatic distribution manifolds with 3/4" supply headers serving downstream branch circuits to multiple machine stations.
• Automated assembly systems with robotic stations, pick-and-place units, and pneumatic conveyors sharing a common 3/4" supply that requires the MD4 Series high-flow FRL to maintain regulated pressure during peak demand cycles.
• Multi-spindle machining centers and transfer machines with pneumatic workholding, tool change, coolant purge, and chip clearing circuits simultaneously consuming compressed air at peak rates exceeding full-size FRL capacity.

Automotive Manufacturing

• Automotive body shop welding and assembly line main air preparation at 3/4" supply circuits serving banks of welding robots, pneumatic fixture clamps, and part transfer mechanisms with simultaneous high-flow demand.
• Vehicle final assembly line pneumatic tool supply including multiple torque tools, riveters, and pneumatic assembly aids sharing a common FRL station requiring MD4 Series flow capacity.
• Paint shop pneumatic spray booth air preparation with air motors, mixing systems, and pneumatic actuators for booth doors and product transport requiring high-flow filtered, regulated, and lubricated air.
• Engine assembly test cells and dynamometer facilities with pneumatic simulation, loading, and measurement systems requiring reliable high-flow air preparation at the main supply inlet.

Plastics and Rubber Processing

• Injection molding machine air preparation serving mold open/close, ejector, and hot runner pneumatic circuits from a single 3/4" MD4 FRL station during simultaneous actuation of multiple pneumatic functions.
• Blow molding and extrusion blow molding machine pneumatic circuits with high-flow preform handling, mold clamping, and product ejection systems requiring the flow capacity of the MD4 Series FRL.
• Rubber processing and calendering equipment with pneumatic press, material feed, and take-up systems operating from a main 3/4" supply FRL station requiring consistent high-flow filtered and regulated air.
• Thermoforming machine pneumatic systems including forming pressure, plug assist, and trim press circuits sharing a common high-flow MD4 FRL supply.

Metals Processing and Fabrication

• Metal stamping and blanking press lines with pneumatic die cushion, material feed automation, and scrap handling requiring the MD4 Series high-flow FRL at the press air supply inlet.
• Tube and pipe bending machine pneumatic circuits with mandrel pull, clamp, and wipe die actuation systems requiring high-flow regulated and lubricated air from a 3/4" MD4 FRL station.
• Welding and cutting system pneumatic supply circuits with high-consumption compressed air circuits for positioning, torch cooling, and material handling requiring MD4 Series flow capacity.
• Roll forming and coil processing line pneumatic systems with high-demand press drives, side trimmer actuators, and stackers requiring centralized high-flow FRL preparation at the line supply inlet.

Food, Beverage, and Consumer Products

• High-speed beverage filling and packaging lines with multiple pneumatic circuits including filling heads, cap feeders, label applicators, and case packers sharing a 3/4" FRL station requiring MD4 flow capacity.
• Baking and confectionery high-speed production equipment with depositing, cutting, and cooling circuits at high pneumatic demand requiring the 205 scfm capacity of the MD4 Series FRL.
• Consumer products manufacturing including cosmetics, household goods, and personal care product lines with high-speed pneumatic assembly and packaging requiring central high-flow FRL stations.

Compressed Air System Energy Management

• Applications where the electronic drain option contributes to compressed air energy conservation by replacing continuous float drains with demand-triggered condensate expulsion on high-flow 3/4" circuits.
• Plant air preparation stations where dual gauge ports on the MD4 regulator enable ongoing monitoring of supply versus regulated pressure differential for preventive maintenance of supply pressure adequacy and filter loading condition.
• Facilities implementing ISO 50001 compressed air energy management programs where monitoring and minimizing compressed air waste at FRL stations requires electronic drain capability at high-flow air preparation points.

Ordering and Model Number Configuration

The MD4 Series FRL components are ordered individually as filter, regulator, or lubricator units and assembled into modular combinations using MD4 Series connection hardware. Specify port size, bowl material, drain type, and regulator function. Contact ROSS Controls at (800) 438-7677 or visit rosscontrols.com for complete ordering information.

Port sizes available: 3/8", 1/2", and 3/4" NPT.

Filter bowl material: polycarbonate with steel shatterguard (psig maximum), aluminum with nylon sight glass (200 psig maximum), or extended aluminum lubricator bowl with sight glass.

Drain options: internal automatic drain, manual drain, or electronic drain. Electronic drain is recommended for high-flow applications where compressed air conservation is required.

Regulator type: diaphragm-type. Self-relieving (standard) or non-relieving option.

Two gauge ports standard on regulator for simultaneous inlet and outlet pressure monitoring.

For complete catalog part numbers, dimensional drawings, and assembly configurations, visit rosscontrols.com or contact ROSS Controls technical sales.

Accessories

MD4 Series Modular Connection Hardware

MD4 Series modular bracket and connection hardware assembles filter, regulator, and lubricator units into a compact side-by-side modular FRL station with single supply and outlet ports.

Electronic Drain Controllers

Timer-based and demand-sensing electronic drain controllers for MD4 Series filter units with electronic drain connections, enabling programmed or sensor-triggered condensate expulsion.

Replacement Filter Elements

Replacement filter elements for the MD4 Series filter units in 5-micron and 40-micron particulate grades.

Pressure Gauges

Replacement and additional pressure gauges for MD4 Series regulator units for inlet and outlet gauge port connections.

Related Products & Accessories

• 149 Full-Size Series FRL Combination - Full-size modular FRL combination for 1/4" to 3/4" port sizes with flow to 138 scfm (3906 l/min). https://www.rosscontrols.com/en/series/149-full-size-series
• 151 High Capacity FRL Combination - High-capacity inline FRL combination for 3/4" to 1-1/2" port sizes with flow to 495 scfm (14018 l/min). https://www.rosscontrols.com/en/series/151-high-capacity
• MD4 Series Filter - Individual MD4 Series filter component for 3/8" to 3/4" port sizes, flow to 204 scfm (5777 l/min). https://www.rosscontrols.com/en/series/73-md4-series
• MD3 Series FRL Combination - MD3 modular FRL combination for 1/4" to 1/2" port sizes with flow to 110 scfm (3115 l/min). https://www.rosscontrols.com/en/series/148-md3-series
• Flow Controls - ROSS flow control valves for pneumatic actuator speed regulation downstream of FRL assemblies. https://www.rosscontrols.com/en/series/261-flow-controls

Frequently Asked Questions (FAQ)

Q: What is the maximum flow capacity of the MD4 Series FRL?

A: The MD4 Series FRL combination delivers maximum flow of 205 scfm (5806 l/min) at port sizes from 3/8" to 3/4".

Q: What port sizes are available?

A: The MD4 Series is available in 3/8", 1/2", and 3/4" NPT port sizes.

Q: How does the MD4 Series differ from the Full-Size Series (149)?

A: The MD4 Series provides significantly higher flow capacity at 205 scfm versus 138 scfm for the Full-Size Series, both at 3/4" port size. The MD4 has a smaller port size range starting at 3/8" versus 1/4" for the Full-Size. The MD4 features dual gauge ports and three bowl options (including extended aluminum lubricator bowl) compared to two bowl options and single gauge port on the Full-Size Series. The MD4 is the choice when flow demand exceeds Full-Size Series capacity.

Q: What is the extended aluminum lubricator bowl?

A: The extended aluminum lubricator bowl is a larger capacity aluminum bowl designed for the lubricator unit. The larger oil reservoir reduces the refill frequency in high-flow applications where lubricant consumption is higher. The clear nylon sight glass on the bowl allows oil level monitoring without opening the system.

Q: Why are two gauge ports provided on the MD4 regulator?

A: The dual gauge ports allow simultaneous connection of an inlet pressure gauge and an outlet pressure gauge. This enables the technician to monitor both supply pressure and regulated output pressure at the FRL station simultaneously, facilitating diagnosis of supply pressure shortfalls, monitoring regulator differential pressure, and verifying filter loading through pressure drop analysis.

Q: When is the electronic drain preferred over automatic or manual drain?

A: Electronic drain is preferred when compressed air conservation is a priority (minimizing air waste from continuous float drain operation), when condensate generation is intermittent and a continuous float drain would remain partially open wasting air, or in remote or automated installations where manual drain service is impractical. Timer-based electronic drains cycle at user-defined intervals; demand-sensing models trigger only when condensate level reaches the sensor threshold.

Q: What is the maximum operating pressure?

A: Maximum operating pressure is psig (10 bar) with polycarbonate bowls and 200 psig (14 bar) with aluminum bowls.

Q: What temperature range is the MD4 Series rated for?

A: Polycarbonate bowl units are rated for 40 to 125 degrees F (4 to 52 degrees C). Aluminum bowl units are rated for 40 to degrees F (4 to 66 degrees C).

Q: What type of regulator is used in the MD4 Series?

A: The MD4 Series uses a diaphragm-type regulator. Self-relieving is standard; non-relieving is available as an option.

Q: How should the MD4 FRL assembly be oriented?

A: Mount with the bowls in the downward (vertical) position to allow condensate to collect at the drain and the lubricator to operate with proper oil level orientation.

Q: Can individual MD4 components be purchased separately?

A: Yes. The filter, regulator, and lubricator are each available as individual components and can be assembled into any combination using MD4 Series modular connection hardware.

Q: What type of lubricant should be used in the MD4 lubricator?

A: Use petroleum-based oil with ISO 32 viscosity or lighter. Avoid synthetic oils, phosphate ester-based fluids, or oils with incompatible additives. Consult the ROSS Controls installation instructions for the specific lubricant specification for the MD4 Series lubricator.

Q: Where can I find catalog part numbers and technical data?

A: Complete catalog part numbers, dimensional drawings, and technical data are available at rosscontrols.com. Contact ROSS Controls at (800) 438-7677 for configuration assistance.

Installation & Maintenance Guidelines

• Mount the MD4 Series FRL assembly with the bowls in the downward (vertical) position for proper condensate collection and lubricator oil level maintenance.
• Install components in the correct sequence: filter (inlet) - regulator (middle) - lubricator (outlet).
• Align the flow direction arrow on each unit body with the compressed air flow direction before making port connections.
• Apply thread sealant to all NPT port connections and tighten to the torque values in the ROSS Controls installation instructions for the MD4 Series.
• Pressurize gradually and verify all connections and bowl seals with an approved leak detection solution after installation.
• Connect inlet and outlet pressure gauges to the dual gauge ports on the regulator if simultaneous supply and regulated pressure monitoring is required.
• Set regulated output pressure by unlocking the adjustment knob, rotating to the target reading on the outlet gauge, and locking the knob at the set point.
• Fill the lubricator bowl with recommended ISO 32 or lighter petroleum-based oil to the maximum fill level. Adjust the delivery rate via the needle valve.
• For electronic drain models, configure the timer interval or demand sensor threshold per the application condensate volume and the drain controller instructions.
• Verify modular connection hardware between all adjacent units is fully tightened and seated to prevent internal air leakage.
• Establish a maintenance schedule for filter element replacement based on differential pressure threshold and application contamination level.
• Always depressurize and isolate the FRL assembly before removing bowls for element replacement or lubricator refill access.

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 and product configuration assistance is available through ROSS Controls at (800) 438-7677 or rosscontrols.com.

Global support is available through ROSS offices in the USA (Ferndale, Michigan headquarters), Canada, Brazil, Germany, France, United Kingdom, India, China, and Japan.

For complete technical data, dimensional drawings, and ordering information for the MD4 Series FRL combination, visit rosscontrols.com or contact ROSS Controls technical sales.