MD4 Series Port Sizes 3/8" to 3/4"; Flow to 204 scfm (5777 l/min)

Product Overview

The ROSS Controls MD4 Series is a family of modular and inline air preparation filters engineered for port sizes 3/8 inch through 3/4 inch (NPT or G/BSPP) with maximum particulate filter flow of 204 scfm (5,777 l/min). The MD4 is the larger-bore companion to the MD3 Series, covering the 3/8-to-3/4-inch port size range where the MD3's 1/4-to-1/2-inch ports are undersized. Together, the MD3 and MD4 provide a consistent, feature-aligned modular filter platform for 1/4-inch through 3/4-inch pneumatic systems.

The MD4 Series encompasses particulate filters, coalescing filters, oil vapor removal (adsorbing) filters, and clean air packages combining all three stages. Particulate filters use 5-micron polyethylene (standard) or 40-micron sintered bronze elements. Coalescing filter variants with borosilicate glass fiber elements in standard (9-oz / 266-ml) or extended (15-oz / 443-ml) bowls remove oil aerosols to 0.3-micron or 0.01-micron levels. Adsorbing filter elements use activated carbon for hydrocarbon vapor removal. Clean air packages integrate two or three filtration stages into a single modular assembly.

The MD4 uses a 9-oz polycarbonate bowl with steel shatterguard (standard) or aluminum bowl with nylon sight glass. Multiple drain options include automatic, manual, internal float, less-drain fitting (1/4 NPT female), and electronic drain. L-O-X lockout valve integration is available on the inlet or outlet side with standard or EEZ-ON soft-start function. The piston-type regulator in MD4 filter/regulator models supports outlet pressure adjustment to 125 psig (8.6 bar) with a removable locking key to prevent tampering.

For systems engineers specifying air preparation at 3/8-to-3/4-inch port sizes where higher flow, advanced multi-stage filtration, energy isolation integration, or clean air packages are required, the MD4 provides the most complete catalog-standard solution in the ROSS FRL product line for this port size range.

Key Engineering Features

• High Flow to 204 scfm at 3/8 to 3/4 Inch Ports - Delivers 204 scfm (5,777 l/min) flow capacity at 100 psig, making the MD4 Series suitable for high-demand pneumatic systems at 3/4-inch supply headers including production line mains, machine tool supply headers, and robot cell supply rails.
• L-O-X Lockout Valve Integration - MD4 units can be ordered with integral L-O-X lockout valves on the inlet or outlet side, with standard or EEZ-ON soft-start function. This creates a combined filtration and OSHA-compliant energy isolation assembly at the point of air use.
• Clean Air Package Option (Two and Three Stage) - MD4 clean air packages combine a 5-micron particulate filter, 0.3-micron or 0.01-micron coalescing filter, and optional activated carbon adsorbing stage in a single modular assembly delivering ISO 8573-1 Class 1 air quality.
• Electronic Drain Option - In addition to manual, automatic, float, and less-drain fitting options, the MD4 Series supports an electronic drain for timed automated condensate purging. Electronic drains are preferred in applications where automatic float drain response may be too slow or where drain timing must be controlled.
• Polycarbonate Bowl with Steel Shatterguard - Standard 9-oz (266-ml) polycarbonate bowl includes a steel shatterguard for personnel protection against bowl fragmentation. Transparent bowl provides visual condensate monitoring.
• Aluminum Bowl with Sight Glass - Aluminum bowl (9-oz standard, 15-oz extended) option extends upper operating temperature to 175 F (79 C) and maximum inlet pressure to 200 psig (14 bar). Extended aluminum bowl provides 15-oz (450-ml) capacity for coalescing and adsorbing filter stages.
• Piston-Type Regulator with Removable Locking Key - MD4 filter/regulator models use a piston-type regulator adjustable to 125 psig (8.6 bar). The removable locking key prevents unauthorized pressure adjustment in production applications.
• Multiple Differential Gauge Ranges - Gauge options in 0-50 psig, 0-125 psig, 0-175 psig, and 0-200 psig ranges, including panel mount nut configurations, allow matching gauge scale to application pressure range and enable condition-based element replacement decisions.
• Reverse Flow Configuration Available - MD4 units with reverse flow are available for installations where supply and process plumbing directions are inverted relative to standard.
• NPT and G (BSPP) Thread Options - Both NPT and G (BSPP) thread types are standard catalog selections for compatibility with North American and international machine designs.
• Stainless Steel Option with L-O-X - MD4 filter/regulators combined with L-O-X lockout valves are available in stainless steel construction for food processing, pharmaceutical, and corrosion-resistant applications.

Technical Specifications

General Specifications

Temperature Ratings

Temperature ratings depend on bowl material. Polycarbonate bowl has a lower upper limit than aluminum bowl.

Important: Polycarbonate bowls are incompatible with solvents, ketones, chlorinated hydrocarbons, and other aggressive chemicals. Select aluminum bowl for elevated temperature or chemical exposure environments. Filter/regulator models with aluminum bowl and optional spring support outlet pressure to 175 psig (12 bar).

Flow Performance Data

Flow performance at 100 psig inlet pressure, new element. Coalescing and adsorbing filter flows reflect standard bowl configurations. Extended bowl provides same flow with greater condensate holding capacity.

Certifications & Compliance

Typical Applications & Industries

Industrial Automation and Robotics

• Main supply air preparation for robot cells and automation lines at 3/4-inch supply headers, where 204 scfm capacity at consistent quality serves multiple robots, servo pneumatics, and high-cycle actuator groups simultaneously.
• Clean air preparation (coalescing or clean air package) for proportional valve circuits, servo pneumatic systems, and precision motion actuators where oil-free air prevents valve contamination and ensures repeatable performance.
• L-O-X lockout valve integration at robot cell air preparation points for OSHA-compliant energy isolation during tooling changes, maintenance, and robot programming activities.
• MD4 clean air package (3-stage) for semiconductor manufacturing, flat panel display production, and other high-cleanliness automation where ISO 8573-1 Class 1 air quality is required at the machine supply point.

Machine Tools and Precision Manufacturing

• Main supply air preparation for large CNC machining centers, multi-spindle turning centers, and precision grinding machines at 3/4-inch supply ports where 204 scfm capacity supports simultaneous operation of spindle purge, tool change, workholding, and coolant system actuators.
• Air preparation for air-bearing spindles, coordinate measuring machines (CMMs), and precision measurement equipment where coalescing filtration prevents oil aerosol contamination on precision surfaces and bearing elements.
• Clean air preparation for precision machining of optical components, medical implants, and aerospace parts where particulate and oil contamination from compressed air can produce surface defects.
• MD4 with L-O-X EEZ-ON for machine tool supply where controlled soft-start re-pressurization after lockout prevents hydraulic shock to workholding cylinders and precision tooling during startup.

Food, Beverage, and Pharmaceutical Manufacturing

• MD4 clean air package at 3/4-inch supply headers for food packaging lines, bottling operations, and canning systems where multi-stage filtration delivers oil-free, particulate-free air to actuators, air jets, and blow-off systems with potential product contact.
• Pharmaceutical cleanroom compressed air supply where MD4 clean air packages (with 0.01-micron coalescing and activated carbon adsorbing stages) meet GMP air purity requirements at the point of use.
• Stainless steel MD4 filter/regulator with L-O-X for food processing and pharmaceutical applications requiring corrosion-resistant construction, CIP-compatible materials, and OSHA energy isolation compliance.
• Adsorbing filter stage in MD4 clean air package for removal of compressor lube oil vapors that pass through standard and coalescing filter stages, essential for food contact and pharmaceutical clean room air quality.

Process and Utility Applications

• Instrument air preparation at 3/4-inch supply mains in process facilities where MD4 filters with piston-type regulators supply pneumatic valve positioners and actuator groups at stable outlet pressure from 20 to 125 psig.
• Compressed air preparation for pneumatic actuators on large process control valves, diaphragm valves, and isolation valves at 3/4-inch supply connections in petrochemical, chemical processing, and water treatment plants.
• Clean air supply for purge-and-pressurization systems in ATEX or NEC Class I Division 1 hazardous area enclosures where MD4 coalescing filtration prevents oil contamination of enclosure interiors.
• Air preparation for high-performance air-operated diaphragm pumps in chemical transfer and process fluid handling where 5-micron filtration protects pump actuator mechanisms from particulate damage at 3/4-inch supply connections.

Ordering and Model Number Configuration

The ROSS MD4 Series uses a structured alphanumeric configuration code system, similar to the MD3 Series but with different port size and element codes. Each position in the model number specifies a configuration choice. Consult the ROSS FRL catalog for the complete How-to-Order table.

For G (BSPP) threads, specify B in the thread position of the configuration code.

L-O-X lockout valve integration specifies the side (inlet or outlet) and whether EEZ-ON soft-start function is included.

Filter/regulator models include a piston-type regulator with adjustment range codes A through J plus reverse flow variants; specify the appropriate range code for the application.

Clean air packages use the MD4 CAP order code series combining filter, coalescing, and optional adsorbing stages; consult the ROSS FRL catalog for full configuration.

Stainless steel MD4 with L-O-X available; contact ROSS Controls for model number.

Panel mounting requires a 2.05-inch (52.1 mm) hole.

Accessories

Replacement Filter Elements

ROSS replacement elements for MD4 Series. Elements are specific to MD4 and are not interchangeable with MD3 or other series elements.

L-O-X Lockout Valves

Integrated L-O-X lockout valves are available for MD4 units on inlet or outlet side with standard or EEZ-ON soft-start function. Padlockable for OSHA 29 CFR 1910.147 compliance. Stainless steel L-O-X with MD4 filter/regulator available for food and pharmaceutical applications. Consult ROSS Controls for lockout valve model number selection.

Differential Pressure Gauges

Gauge ranges available: 0 to 50 psig (0 to 3.4 bar), 0 to 125 psig (0 to 8.6 bar), 0 to 175 psig (0 to 12 bar), and 0 to 200 psig (0 to 14 bar). Panel mount nut options available. Gauges mount at 1/4 NPT gauge ports on front and rear faces of unit.

Related Products & Accessories

• MD3 Series Air Preparation Filters - MD3 modular filters for 1/4 to 1/2 port sizes with flow to 92 scfm and the same L-O-X integration and clean air package options as MD4. https://www.rosscontrols.com/en/series/72-md3-series
• Full-Size Series Air Preparation Filters - Established modular and inline filters for 1/4 to 3/4 port sizes with flow to 155 scfm. https://www.rosscontrols.com/en/series/70-full-size-series
• High Capacity Series Air Preparation Filters - Inline filters for 3/4 to 2-inch port sizes with flow to 1,000 scfm for main supply headers above MD4 capacity. https://www.rosscontrols.com/en/series/71-high-capacity-series
• L-O-X Lockout Valves (15 Series) - Stand-alone OSHA-compliant pneumatic lockout valves for energy isolation at supply headers and machine inlets. https://www.rosscontrols.com/en/series/1287-lockout-valves-15-series
• MD4 Series Clean Air Packaging (FRL) - MD4 Series filter, coalescing filter, regulator, and lubricator clean air packages in standard configured assemblies. https://www.rosscontrols.com/en/series/73-md4-series

Frequently Asked Questions (FAQ)

Q: What is the relationship between the MD4 Series and the MD3 Series?

A: The MD3 and MD4 are the same-generation modular filter platform with aligned feature sets, but different port size coverage. The MD3 covers 1/4 to 1/2 inch with 92 scfm particulate filter capacity. The MD4 covers 3/8 to 3/4 inch with 204 scfm particulate filter capacity. Both support L-O-X lockout valve integration, clean air packages, multiple drain options, and the same order configuration code system. A system can use MD3 at smaller sub-circuits and MD4 at larger headers for a consistent platform throughout.

Q: How does the MD4 Series compare to the Full-Size Series at 3/4-inch ports?

A: At 3/4-inch ports, the MD4 provides 204 scfm versus 155 scfm for the Full-Size Series. The MD4 also offers diaphragm-type regulator variants, more drain options (including electronic drain), L-O-X lockout integration, and clean air packages. The Full-Size Series is the established design offering OEM continuity; the MD4 is the advanced design for new machine specifications requiring higher flow or expanded configuration options.

Q: What filtration levels are available in the MD4 Series?

A: Particulate filter models offer 5-micron polyethylene (standard, R-A115-106PE5) and 40-micron sintered bronze (R-A115-106PE3) elements. Coalescing variants use 0.3-micron (R-A115-117E8, standard bowl) and 0.01-micron (R-A115-118E8, extended bowl) borosilicate glass fiber elements. Adsorbing filter variants use activated carbon elements (R-A115-117E9 standard bowl, R-A115-118E9 extended bowl) for hydrocarbon vapor removal.

Q: What is an electronic drain and when should it be specified?

A: The electronic drain option replaces the float or mechanical automatic drain with a solenoid-operated drain valve controlled by an external timer or PLC signal. Electronic drains are specified when automatic float drain response is too slow for high condensate generation rates, when drain timing must be precisely controlled to match process cycles, or when remote monitoring and control of the drain function is required for predictive maintenance systems.

Q: What is the maximum inlet pressure for MD4 units?

A: Polycarbonate bowl models are rated to 150 psig (10 bar). Aluminum bowl models are rated to 200 psig (14 bar). Filter/regulator models with the optional spring provide outlet pressure adjustment to 175 psig (12 bar) with the aluminum metal bowl. All drain types except manual have minimum pressure requirements; verify supply pressure before commissioning.

Q: Can the MD4 Series be ordered with integrated L-O-X lockout valves?

A: Yes. MD4 units can be configured with L-O-X lockout valves on the inlet side (lockout upstream of filter), outlet side, or with L-O-X plus EEZ-ON soft-start on either side. The EEZ-ON option provides controlled re-pressurization after lockout release, protecting actuators and cylinders from pressure surge on startup. Stainless steel versions with L-O-X are available for food and pharmaceutical environments.

Q: What is a clean air package (CAP) and how does it differ from a standard filter?

A: An MD4 clean air package (CAP) is a pre-configured modular assembly integrating a 5-micron particulate filter, 0.3-micron or 0.01-micron coalescing filter, and optionally an activated carbon adsorbing stage on a common manifold with a single inlet and outlet. The CAP delivers ISO 8573-1 Class 1 compressed air quality in a single modular assembly at 3/8 to 3/4 inch port size, eliminating the need to individually select, size, purchase, and connect three separate filter stages.

Q: What bowl options are available and how do they differ?

A: The standard 9-oz (266-ml) polycarbonate bowl with steel shatterguard provides transparent liquid level monitoring and personnel protection. The 9-oz aluminum bowl with nylon sight glass extends upper temperature to 175 F and maximum pressure to 200 psig. The 15-oz (443-450 ml) extended aluminum bowl on coalescing and adsorbing filter stages provides additional condensate holding capacity, extending the interval between drain cycles for high-condensate applications.

Q: What is the bowl clearance requirement for the MD4 Series?

A: Standard bowl clearance below the unit is 3.1 inches (79 mm). Extended bowl clearance is 6.1 inches (155 mm). Ensure adequate vertical clearance below the unit for bowl removal during element replacement. For clean air packages with multiple stages, measure overall assembly height and required bowl clearance before specifying installation location.

Q: What replacement element is standard for MD4 particulate filters?

A: The standard 5-micron polyethylene replacement element is R-A115-106PE5. This element is specific to the MD4 and is not interchangeable with MD3 (R-A60F-03PE5) or other series elements. Always verify the element part number against the specific MD4 model before ordering replacements to prevent installation errors.

Q: Is the regulator outlet pressure adjustable and lockable?

A: Yes. MD4 filter/regulator models include a piston-type regulator adjustable from near zero to the selected maximum outlet pressure (ranges available: 0 to 20, 0 to 50, 0 to 125, 0 to 175 psig). A removable locking key is standard; removing the key prevents unauthorized pressure adjustment in production or safety-sensitive applications.

Q: What are the panel mounting requirements?

A: The MD4 requires a 2.05-inch (52.1 mm) diameter hole for panel mounting. This is slightly larger than the MD3's panel mount hole. The unit includes mounting hardware for panel installation with the gauge face and regulator knob accessible from the front face.

Installation & Maintenance Guidelines

• Mount with bowl pointing down for all drain types. Vertical orientation is required for automatic drain, float drain, and electronic drain operation, and optimizes manual drain condensate collection.
• Install upstream isolation shutoff valves to allow element replacement and service without depressurizing the entire supply line or connected equipment.
• Always install a 5-micron particulate filter upstream of coalescing and adsorbing filter stages. Liquid water entering a coalescing element saturates the glass fiber media and destroys coalescing efficiency.
• For L-O-X lockout valve integration, verify padlock shackle diameter compatibility with facility lockout padlocks before installation. Test padlock insertion and removal before commissioning.
• For electronic drain models, connect the solenoid drain valve to the external timer or PLC output per the wiring diagram. Set drain open time to achieve complete condensate removal without excessive air loss (typically 0.5 to 2 seconds per cycle). Adjust drain frequency based on observed condensate accumulation rate.
• Add 1.21 in (31 mm) to dimension C when installing the optional differential gauge. Verify this additional depth is available in the installation space before mounting.
• Ensure bowl clearance below the unit: 3.1 in (79 mm) for standard bowl, 6.1 in (155 mm) for extended bowl. Insufficient clearance prevents bowl removal for element replacement.
• For less-drain fitting models, route the 1/4 NPT drain line to an appropriate condensate collection or disposal point with adequate slope to prevent back-pressure at the drain fitting.
• Do not exceed maximum inlet pressure for bowl type selected: 150 psig for polycarbonate, 200 psig for aluminum. Regularly inspect the polycarbonate shatterguard for cracks or impact damage.
• After initial installation, gradually pressurize the system and inspect all port connections, module-to-module seals, and drain fittings for leaks before placing equipment into service.

Warranty & Global Support

ROSS Controls provides a one-year warranty on all MD4 Series products, covering defects in material and workmanship from the date of purchase.

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

Contact ROSS Controls USA at (800) 438-7677 or visit rosscontrols.com for product configuration assistance, technical support, and distributor locator services.

For complete dimensional drawings, flow curves, and ordering configuration details for all MD4 Series variants, visit the ROSS Controls MD4 Series product page at rosscontrols.com or download the ROSS FRL catalog.

Download Catalog: https://www.rosscontrols.com/en/series/73-md4-series