MD3 Series Port Sizes 1/4 to 1/2; Flow to 125 scfm (3540 l/min)

Product Overview

The ROSS Controls MD3 Coalescing Filter is an advanced air preparation unit engineered for mid-to-high flow pneumatic systems requiring superior aerosol removal across port sizes 1/4 to 1/2. With a maximum flow rating of 125 scfm (3540 l/min), the MD3 Series exceeds the capacity of standard mid-size coalescing filters while maintaining the compact modular form factor that allows direct assembly with MD3 Series regulators and lubricators.

The MD3 Series provides a comprehensive filtration platform within the ROSS air preparation product family. Coalescing filter variants are available in 0.3-micron and 0.01-micron element ratings. The same platform supports 5-micron and 40-micron general-purpose particulate filters, providing a consistent form factor for all filtration stages in a multi-stage air preparation train. An Oil Vapor Removal (Adsorbing) Filter variant using an activated carbon element is also part of the MD3 Series, covering applications where residual hydrocarbon vapor must be removed after the coalescing stage.

Bowl options for the MD3 Series include a high-strength polycarbonate plastic bowl with a steel shatterguard for visual condensate inspection at lower pressures, and an aluminum bowl with a clear nylon sight glass for higher pressure and temperature applications. An extended metal bowl further increases liquid capacity for high-condensate-generating systems. Drain options include manual, automatic internal float, and automatic external drain configurations.

The integral differential pressure gauge on coalescing filter configurations provides real-time element condition monitoring. Multiple gauge options are available, including reed switch-equipped differential gauges that can transmit an element-change signal to a PLC or maintenance system, enabling automated maintenance scheduling in Industry 4.0 connected factory environments.

Key Engineering Features

• Flow to 125 scfm (3540 l/min) - Highest flow capacity in the 1/4 to 1/2 port size range among ROSS mid-size coalescing filters, supporting larger pneumatic systems and multi-actuator machine circuits without excessive pressure drop.
• 0.3-Micron and 0.01-Micron Coalescing Element Options - Borosilicate glass-fiber elements available in both standard 0.3-micron and ultra-fine 0.01-micron ratings, covering general industrial to near oil-free air quality requirements within the same product platform.
• Oil Vapor Removal Filter Variant - The MD3 Series platform supports an activated carbon adsorbing filter variant for complete oil vapor removal downstream of the coalescing stage, enabling ISO 8573-1 Class 1 hydrocarbon content in a compact modular assembly.
• Multiple Drain Options - Manual drain, automatic internal float drain, and automatic external drain options available, providing flexibility to match drain mechanism to system condensate volume and maintenance access constraints.
• Polycarbonate and Metal Bowl Options - Polycarbonate bowl with nylon shatterguard for visual inspection at up to 150 psig (10 bar); aluminum bowl with clear nylon sight glass for pressures to 200 psig (14 bar) and temperatures to 175 degrees F (80 degrees C).
• Modular and Inline Mounting - Full modular compatibility with MD3 Series regulators and lubricators for compact FRL assembly; inline pipe-threaded mounting also available for direct line installation without a modular base.
• Differential Pressure Gauge with Reed Switch Option - Standard differential pressure gauge monitors element loading continuously. Optional reed switch differential gauge enables remote element-change signals to PLC systems for automated maintenance alerts.
• Extended Bowl Option - Extended aluminum bowl increases liquid storage capacity, reducing drain frequency in high-humidity environments and extending maintenance intervals for the automatic drain mechanism.
• Die-Cast Zinc Body - Zinc die-cast body provides high structural rigidity and precise port thread engagement, maintaining reliable sealing and alignment in modular assemblies across the rated pressure range.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Industrial Automation and Machine Building

• Air preparation for pneumatic valve islands and manifolds serving 10 to 30 actuators on automated assembly, welding, and material handling machines where the 125 scfm capacity handles aggregate demand at a single main drop point.
• Modular FRL stations on CNC machining centers, robotic cells, and automated test stands where the MD3 platform provides coalescing filtration, pressure regulation, and lubrication in a compact integrated assembly.
• Air preparation for servo-pneumatic positioning systems and precision cylinder applications where consistent air quality directly affects positioning repeatability and eliminates contamination-driven valve and seal failures.

Automotive Manufacturing

• Body shop pneumatic circuit air preparation where resistance welders, nut runners, and pneumatic transfer presses draw high instantaneous air flows, and oil-contaminated air would accelerate wear in reciprocating pneumatic tools.
• Paint shop and coating line air supplies where aerosol oil from compressed air systems must be removed upstream of application equipment to prevent fish-eye and adhesion defects in painted surfaces.

Food, Beverage, and Pharmaceutical Processing

• Multi-stage air preparation for filling and packaging machines in food processing facilities, with the coalescing filter followed by an MD3 activated carbon adsorber to achieve the combination of aerosol and vapor removal required for food contact zone air purity.
• Pharmaceutical manufacturing equipment supplies where the dual 0.01-micron coalescing and activated carbon adsorbing stages in the MD3 platform together achieve ISO 8573-1 Class 1 oil content required by validation protocols.

Packaging and Material Handling

• High-speed packaging machine air preparation in bottling, cartoning, form-fill-seal, and palletizing applications where the 125 scfm capacity supports the aggregate air demand of multi-actuator high-cycle packaging cells.
• Pneumatic conveying and blow-molding system air preparation where clean, dry air prevents product contamination and reduces wear in conveying nozzles, air knives, and blow-molding valves.

General Industrial and OEM

• Compressed air point-of-use coalescing filtration at machine air drops in multi-tenant manufacturing facilities where the main compressed air supply quality cannot be guaranteed, and each machine must provide its own air preparation stage.
• Air preparation for pneumatic tools and tool balancers in assembly operations where aerosol oil removal is required to prevent contamination of sensitive assembly processes while also maintaining adequate lubricant levels in the tool.

Ordering and Model Number Configuration

Bowl code: 50P = Polycarbonate (5.1 oz / 151 ml); 50M = Standard metal/aluminum (6 oz / 177 ml); 50E = Extended metal bowl.

Element code: C = 0.3-micron coalescing; D = 0.01-micron coalescing.

Drain options: manual, automatic internal, and automatic external are available. Consult ROSS Controls for specific model number suffix codes.

Reed switch differential gauge option available for automated maintenance alert integration. Specify at time of order.

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

Accessories including coupling kits, mounting brackets, and modular porting blocks are ordered separately.

Related Products & Accessories

• 80 Mid-Size Series Coalescing Filter - Mid-size coalescing filter with flow to 100 scfm for 1/4 to 1/2 port sizes with differential pressure gauge and aluminum bowl. https://www.rosscontrols.com/en/series/80-mid-size-series
• 82 Full-Size Series Coalescing Filter - Full-size coalescing filter for 1/4 to 1/2 port sizes with flow to 100 scfm, polycarbonate bowl with shatterguard, and metal bowl options. https://www.rosscontrols.com/en/series/82-full-size-series
• MD3 Series Standard Filters - 5-micron and 40-micron general-purpose filters in the MD3 modular form factor for upstream pre-filtration ahead of the coalescing stage. https://www.rosscontrols.com/en/categories/40-filters
• MD3 Series Regulators and Lubricators - Compatible pressure regulators and lubricators in the MD3 modular assembly platform for complete FRL air preparation stations. https://www.rosscontrols.com/en/categories/44-filter-regulator-and-lubricator
• Clean Air Packaging MD3 Series - MD3 Series clean air packaging combining coalescing filter and activated carbon adsorbing filter for oil-free and vapor-free air. https://www.rosscontrols.com/en/series/87-md3-series

Frequently Asked Questions (FAQ)

Q: How does the MD3 Series differ from the standard Mid-Size (80 Series) coalescing filter?

A: The MD3 Series offers higher flow capacity at 125 scfm versus 100 scfm for the Mid-Size (80 Series), achieved through an optimized internal flow path and larger element area. The MD3 also offers polycarbonate bowl options (not available on the 80 Series aluminum-only bowl), a broader drain type selection including external automatic drain, and higher metal bowl pressure ratings up to 250 psig (17 bar) on manual drain models. The MD3 platform also supports an activated carbon adsorbing filter variant for oil vapor removal.

Q: What is the maximum inlet pressure for the MD3 Series?

A: Manual drain models with the metal bowl are rated up to 250 psig (17 bar). Automatic drain models with the metal bowl are rated to 200 psig (14 bar). Polycarbonate bowl models are rated to 150 psig (10 bar) for manual drain and require a minimum of 30 psig (2 bar) for automatic drain activation.

Q: What is the Oil Vapor Removal (Adsorbing) filter option?

A: The MD3 platform includes an activated carbon adsorbing filter variant that captures hydrocarbon vapor remaining after the coalescing stage. When installed in series after the 0.01-micron coalescing filter, the activated carbon unit achieves near Class 1 oil content per ISO 8573-1. This combination is required in food processing, pharmaceutical, and electronics manufacturing where vapor-phase hydrocarbon contamination is as problematic as aerosol oil.

Q: What drain types are available for the MD3 Series?

A: Four drain configurations are available: manual drain (operator-controlled purge), automatic internal float drain (continuous automatic liquid removal), and automatic external drain. The manual drain is required for the adsorbing filter variant. The automatic internal and external drain options are applicable to coalescing filter models. Consult ROSS Controls for the specific model number suffix for each drain type.

Q: Is the polycarbonate bowl safe at the maximum rated pressure?

A: Yes. The polycarbonate bowl with nylon shatterguard is rated for operation up to 150 psig (10 bar) with automatic drain and 150 psig with manual drain. The shatterguard retains bowl fragments in the event of an impact or overpressure incident, providing an additional safety margin. Do not use the polycarbonate bowl above the rated pressure.

Q: What is the reed switch differential gauge and when should I specify it?

A: The reed switch differential gauge functions as the standard differential pressure gauge but includes a built-in reed switch that closes (or opens) when the differential pressure across the element reaches a set threshold. The switch signal can be wired to a PLC digital input or a maintenance annunciator to generate an automated element-change alert. Specify this option when integrating the MD3 into a connected machine or facility CMMS where remote maintenance notification is required.

Q: Which replacement element model should I order?

A: The correct element model depends on the bowl type: polycarbonate bowl uses R-A60F-23 (0.3 micron) or R-A60F-23E8 (0.01 micron); standard metal bowl uses R-A60F-29 (0.3 micron) or R-A60F-29E8 (0.01 micron); extended metal bowl uses R-A60F-32 (0.3 micron) or R-A60F-32E8 (0.01 micron). Elements are not interchangeable between bowl types.

Q: What body and seal materials are used in the MD3 Series?

A: The body is die-cast zinc. Seals are Nitrile elastomer. The polycarbonate bowl includes a nylon shatterguard; the standard and extended metal bowls are aluminum with a clear nylon sight glass.

Q: Can the MD3 Series coalescing filter be field-converted between automatic and manual drain?

A: Drain type conversion in the field is generally not supported as the drain mechanism is integral to the bowl assembly. If a different drain configuration is required, it is more practical to order the appropriate factory-configured model. Consult ROSS Controls for specific field conversion options and compatibility.

Q: What is the minimum pressure for automatic drain operation?

A: The automatic internal float drain requires a minimum inlet pressure of 30 psig (2 bar) to operate correctly. Below this pressure, the float mechanism may not open the drain valve fully, allowing condensate to accumulate in the bowl. For systems operating below 30 psig, specify the manual drain option.

Q: Is the MD3 compatible with the ROSS MD3 modular FRL assembly system?

A: Yes. The MD3 coalescing filter is a core component of the ROSS MD3 Series modular FRL system. It connects directly to MD3 Series regulators and lubricators using standard coupling kits and porting blocks, forming an integrated air preparation assembly without intermediate pipe fittings or adapters.

Q: What are the typical lead times for MD3 Series coalescing filters?

A: Standard manufacturing lead times for quantities of 10 or fewer units are typically 3 to 4 weeks. Contact ROSS Controls at (800) 438-7677 for specific availability and delivery schedules for larger quantities or special configurations.

Installation & Maintenance Guidelines

• Mount the filter vertically with the bowl pointing downward. Gravity drainage is essential for proper condensate collection; do not install horizontally or inverted.
• For automatic drain models requiring a minimum operating pressure, ensure inlet pressure is maintained above 30 psig (2 bar) to activate the automatic float drain. Below this threshold, the drain may not open and the bowl can overflow.
• Install a 5-micron rated general purpose filter upstream of the coalescing filter to remove bulk solid particulate contamination and maximize coalescing element service life.
• When assembling in modular configuration with MD3 regulators and lubricators, use ROSS-supplied coupling kits and porting blocks. Apply the specified torque to all coupling bolts to ensure leak-free joints.
• Monitor the differential pressure gauge regularly during initial operation. Establish the element service interval based on the observed differential pressure rise rate, then replace the element when the gauge indicates the service threshold.
• If specifying the reed switch differential gauge option, verify that the electrical circuit connected to the reed switch is rated for the switch current and voltage specifications provided by ROSS Controls.
• For the polycarbonate bowl option, do not use aromatic hydrocarbon solvents, ketones, or esters for cleaning. These chemicals attack polycarbonate and can cause bowl crazing or brittle failure under pressure.
• For the extended bowl option, note that the increased length extends below the standard mounting envelope. Verify clearance below the filter assembly before installation.
• Depressurize and isolate the filter before performing element replacement or bowl service. Verify zero pressure before removing the bowl to avoid uncontrolled release of stored system pressure.

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/81-md3-series