MD4 Series Port Sizes 3/8 to 3/4; Flow to 158 scfm (4475 l/min)

Product Overview

The ROSS Controls MD4 Coalescing Filter is engineered for high-demand pneumatic systems requiring aerosol removal at flow rates to 158 scfm (4475 l/min) in port sizes from 3/8 to 3/4. The MD4 Series occupies the flow range between the mid-size MD3 Series and the High-Capacity Series, addressing the needs of large machine air preparation circuits, compressed air distribution sub-mains, and high-flow FRL assembly requirements that exceed the capacity of 1/2-port coalescing filters.

The MD4 Series delivers a comprehensive filtration platform with coalescing filter variants in 0.3-micron and 0.01-micron element ratings, 5-micron and 40-micron general-purpose particulate filter variants, and an Oil Vapor Removal (Adsorbing) Filter using an activated carbon element. This platform-level product family allows the engineer to specify all filtration stages from the same modular product line, maintaining consistent physical dimensions, coupling compatibility, and maintenance procedures across particulate, coalescing, and adsorbing filter stages.

Bowl options include a high-strength polycarbonate bowl with a steel shatterguard for visual inspection at operating pressures up to 150 psig (10 bar), and an aluminum bowl with clear nylon sight glass for higher-pressure service to 200 psig (14 bar) and temperatures to 175 degrees F (80 degrees C). Extended aluminum bowls provide additional liquid storage for high condensate-generating systems. Multiple drain configurations including manual, automatic internal float, and automatic external drain provide flexibility to match system condensate management requirements.

For connected factory applications, the MD4 Series offers a reed switch-equipped differential pressure gauge option that generates a remote element-change signal, integrating with PLC systems and CMMS platforms for automated maintenance scheduling. This capability supports predictive maintenance strategies in Industry 4.0 manufacturing environments.

Key Engineering Features

• Flow to 158 scfm (4475 l/min) - Highest flow capacity among ROSS coalescing filters in the 3/8 to 3/4 port size range, supporting large machine circuits, multi-actuator manifolds, and distribution sub-main air preparation at lower pressure drop than smaller series.
• 0.3-Micron and 0.01-Micron Element Options - Borosilicate glass-fiber coalescing elements available in 0.3-micron for general industrial aerosol removal and 0.01-micron for near oil-free air quality suitable for instrumentation and sensitive process applications.
• Oil Vapor Removal (Adsorbing) Filter Variant - Activated carbon adsorbing filter in the MD4 platform removes residual hydrocarbon vapor after the coalescing stage, achieving comprehensive oil removal across both aerosol and vapor phases in the same modular form factor.
• Multiple Drain Configurations - Manual drain, automatic internal float drain, and automatic external drain options available for precise condensate management matching the condensate volume and maintenance schedule of each installation.
• Polycarbonate and Aluminum Bowl Options - High-strength polycarbonate bowl with steel shatterguard supports visual inspection at up to 150 psig (10 bar); aluminum bowl with clear nylon sight glass covers pressures to 200 psig (14 bar) and temperatures to 175 degrees F (80 degrees C).
• Differential Pressure Gauge with Reed Switch Option - Standard differential pressure gauge enables visual element condition monitoring. Optional reed switch differential gauge generates a remote element-change signal for PLC integration and automated maintenance alerting.
• Modular and Inline Mounting - Full modular compatibility with MD4 Series regulators and lubricators via porting block coupling kits; inline pipe-threaded installation also supported for direct line integration.
• Extended Bowl Option - Extended aluminum bowl version increases condensate storage capacity from 9 oz (270 ml) to 15 oz (450 ml) for extended drain intervals in high-humidity or high-condensate environments.
• Die-Cast Zinc Body - Zinc die-cast body provides high structural rigidity, precise modular port block sealing surfaces, and reliable thread integrity for 3/8 to 3/4 port threaded connections.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Large Machine and Process Equipment

• Air preparation for large-format pneumatic machine centers serving 20 to 50 actuators at a single point-of-use drop, where the 3/4 port and 158 scfm capacity handle aggregate demand while minimizing pressure drop in the distribution system.
• Compressed air sub-main filtration in manufacturing plants where individual machine groups are served by a dedicated coalescing filter protecting the local distribution circuit from oil carryover generated by the main compressor system.
• Air preparation for large-bore pneumatic cylinders, diaphragm actuators, and pneumatic presses where the high flow rate is required to meet the rapid cylinder fill demand of large-volume actuators.

Automotive and Heavy Manufacturing

• Transfer press and stamping line pneumatic air preparation where 3/4 port connections and flows exceeding 100 scfm are typical, and contaminated air accelerates wear in reciprocating air tools, cylinders, and control valves.
• Engine assembly and powertrain manufacturing air preparation for torque tools, pneumatic presses, and air-driven test fixtures where both high flow and clean air are simultaneously required.
• Chassis and final assembly line air preparation where heavy cycle rates and large actuator volumes create peak air demand exceeding the capacity of mid-size coalescing filter series.

Food, Beverage, and Pharmaceutical

• High-flow air preparation in large-capacity filling, packaging, and pasteurization equipment where 3/4 port connections service multiple pneumatic sub-circuits from a single air preparation station.
• Compressed air supply to clean-in-place (CIP) actuated valves and pneumatic agitation systems in food and beverage processing where oil-contaminated air would create food safety violations.
• Multi-stage air purification in pharmaceutical manufacturing using the MD4 coalescing filter followed by the activated carbon adsorber to achieve ISO 8573-1 Class 1 oil content at high flow rates.

Packaging and Logistics

• High-speed palletizing, stretch wrapping, and container handling systems where large pneumatic grippers, clamps, and rotary actuators require high-flow, clean-air preparation that mid-size filters cannot deliver.
• Air preparation for pneumatic conveyors, blow-off stations, and sortation systems in distribution centers where 3/4 port drops serve clusters of pneumatic components along conveyor lines.

Oil, Gas, and Chemical Processing

• Instrument air preparation at process skids and control panels where 3/4 port drops supply multiple positioners, solenoid valves, and pneumatic instruments, and air quality specifications require sub-micron aerosol removal.
• Compressed air preparation for pneumatically operated process control valves and safety instrumented system actuators where clean, dry air is a process safety requirement and the 200 psig metal bowl rating covers high-pressure instrument air systems.

Ordering and Model Number Configuration

Bowl code: 53P = Polycarbonate (9 oz / 270 ml); 53M = Standard metal/aluminum (9 oz / 270 ml); 53E = Extended metal filter bowl (9 oz / 270 ml) with extended lubricator bowl (15 oz / 450 ml) in FRL combinations.

Element rating: specify at time of order (0.3 micron standard; 0.01 micron optional).

Drain options: manual, automatic internal float, and automatic external drain available. Specify drain type by model number suffix code.

Reed switch differential gauge option available for PLC integration; specify at time of order.

Port size suffix codes: 3/8 = size code 3; 1/2 = size code 4; 3/4 = size code 5. Consult ROSS Controls for complete model number structure.

For BSPP (G) thread ports, consult ROSS Controls for applicable model number prefix.

Related Products & Accessories

• MD3 Series Coalescing Filter - Lower-flow MD3 coalescing filter for 1/4 to 1/2 port sizes at up to 125 scfm, with the same modular platform architecture as the MD4. https://www.rosscontrols.com/en/series/81-md3-series
• 84 High-Capacity Series Coalescing Filter - Very high flow coalescing filter for 1-1/4 to 2 port sizes with flow to 1000 scfm for large main air supply filtration. https://www.rosscontrols.com/en/series/84-high-capacity-series
• MD4 Series Standard Filters - 5-micron and 40-micron general purpose filters in the MD4 modular platform for upstream pre-filtration. https://www.rosscontrols.com/en/categories/40-filters
• MD4 Series Regulators and Lubricators - Pressure regulators and lubricators in the MD4 modular assembly platform compatible with the series coalescing filter. https://www.rosscontrols.com/en/categories/44-filter-regulator-and-lubricator
• Coalescing Filter Element R-A115-117 - 0.3-micron borosilicate glass-fiber replacement element for the MD4 Series standard bowl coalescing filter. https://www.rosscontrols.com/en/series/83-md4-series

Frequently Asked Questions (FAQ)

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

A: Maximum flow is 158 scfm (4475 l/min) at 100 psig (6.9 bar) inlet pressure. This is the highest flow rating among ROSS coalescing filters in the 3/8 to 3/4 port size range, exceeding the 125 scfm of the MD3 Series and the 100 scfm of the Full-Size and Mid-Size Series.

Q: How does the MD4 differ from the MD3 Series?

A: The MD4 Series is sized for 3/8 to 3/4 port connections and achieves 158 scfm maximum flow, while the MD3 Series covers 1/4 to 1/2 port sizes at up to 125 scfm. Both use the same modular platform with compatible bowl types, element configurations, and accessory compatibility within their respective size families. The MD4 is the appropriate choice when the system pipe size is 3/8 to 3/4, requiring greater flow capacity than the MD3 can deliver.

Q: What bowl capacity is available?

A: The standard polycarbonate and standard aluminum bowls hold 9 oz (270 ml). The extended aluminum bowl holds 15 oz (450 ml). The extended bowl reduces the frequency of manual drain operation in high-humidity or high condensate-generating systems.

Q: Is the Oil Vapor Removal filter available in the MD4 Series?

A: Yes. The MD4 platform includes an activated carbon adsorbing filter variant for residual hydrocarbon vapor removal downstream of the 0.01-micron coalescing stage. When installed in series, the coalescing filter removes aerosol oil and the activated carbon adsorber removes vapor-phase hydrocarbons, achieving comprehensive oil removal for sensitive applications.

Q: What is the maximum pressure rating for the MD4 Series metal bowl?

A: The aluminum (metal) bowl is rated at 200 psig (14 bar) for both automatic and manual drain configurations, covering the majority of industrial instrument air and utility compressed air systems.

Q: Can the reed switch on the differential gauge trigger a PLC alarm?

A: Yes. The optional reed switch differential pressure gauge includes a magnetic reed switch that activates when the element differential pressure reaches the element-change threshold. This switch provides a dry contact output that can be wired directly to a PLC digital input to generate an element-change alarm or work order in a CMMS system.

Q: Which replacement elements are used in the MD4 Series?

A: For standard bowl: order R-A115-117 (0.3 micron) or R-A115-117E8 (0.01 micron). For extended bowl: order R-A115-118 (0.3 micron) or R-A115-118E8 (0.01 micron). Standard and extended bowl elements have different lengths and cannot be interchanged.

Q: Is the MD4 suitable for outdoor installations?

A: The MD4 Series can be installed outdoors within the rated ambient temperature range. Specify the metal bowl option for temperatures above 125 degrees F (52 degrees C) or below 40 degrees F (4 degrees C) when liquid freeze protection is required. For cold climates, verify upstream air dryer dew point is adequate to prevent ice formation in the bowl and element.

Q: Does the MD4 support modular FRL assembly?

A: Yes. The MD4 Series is the coalescing filter component within the ROSS MD4 modular FRL assembly system. It connects directly to MD4 Series regulators and lubricators using compatible porting blocks and coupling kits, forming a compact integrated FRL station without intermediate pipe fittings.

Q: What drain types are available for the MD4?

A: Three drain configurations are available: manual drain (operator-controlled), automatic internal float drain (continuous automatic), and automatic external drain. The appropriate drain type depends on condensate accumulation rate, maintenance access, and whether the system can tolerate periodic drain-open events that create brief downstream pressure pulses.

Q: What seals are used in the MD4 Series?

A: Seals are Nitrile elastomer, compatible with compressed air and petroleum-based compressor oils across the full rated temperature range. The bowl ring is nylon. For applications requiring seal materials other than Nitrile, contact ROSS Controls for special material options.

Q: What is the weight of the MD4 filter with different bowl options?

A: With the polycarbonate or standard aluminum bowl, the MD4 coalescing filter weighs approximately 2.13 lb (0.97 kg). With the extended aluminum bowl, weight increases to approximately 2.31 lb (1.05 kg). These weights are for the filter unit alone; FRL modular assemblies add the regulator and lubricator weights.

Installation & Maintenance Guidelines

• Install vertically with bowl pointing downward. The MD4 Series requires proper gravity drainage orientation due to the higher condensate volumes generated at the larger flow rates and port sizes served.
• For automatic drain models, ensure minimum system pressure of 30 psig (2 bar) at the filter inlet for reliable automatic drain activation. Monitor for condensate accumulation at initial startup to verify the drain is operating.
• Provide upstream 5-micron or 40-micron pre-filtration before the MD4 coalescing filter to remove solid particulate contamination that would prematurely load the coalescing element.
• In modular FRL assemblies, use ROSS MD4 coupling kits and porting blocks and apply the specified bolt torque. At the higher flow rates served by the MD4, joint leakage from under-torqued couplings becomes more significant.
• Monitor the differential pressure gauge during initial operation to establish the element change interval. In high-flow systems, flow velocity through the element is higher, which can cause faster element loading in contaminated air environments.
• For extended bowl installations, verify that the additional bowl length does not conflict with floor-level obstructions, maintenance access panels, or adjacent piping below the filter assembly.
• When specifying the reed switch differential gauge for PLC integration, confirm the switch voltage and current ratings match the PLC digital input module specifications before wiring.
• Depressurize the filter and isolate from the compressed air supply before element or bowl service. The higher pressure ratings of the metal bowl models mean stored energy is greater than in smaller series; ensure zero pressure before opening.

Warranty & Global Support

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

Global technical support is available through ROSS 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 (1-800-GET-ROSS) or visit rosscontrols.com for product configuration, technical support, and distributor locator services.

Technical service is available at 1-888-TEK-ROSS for application engineering support and replacement parts identification.

Download Catalog: https://www.rosscontrols.com/en/series/83-md4-series