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

Product Overview

The ROSS Controls MD3 Series Clean Air Package is a factory-configured three-stage compressed air filtration assembly that delivers the highest levels of air purity achievable in a modular filter-based system. Each assembly combines a 5-micron particulate filter, a coalescing filter (0.3-micron or 0.01-micron), and an activated carbon adsorbing filter in a single modular unit covering port sizes from 1/4 to 1/2 inch, with maximum flow capacity of 125 scfm (3,540 l/min). The result is compressed air with residual oil content of no more than 0.01 mg/m3, meeting ISO 8573-1 Class 1 oil purity standards.

The Clean Air Package MD3 Series is the pre-engineered solution for applications where individual filter selection, sizing, and integration would otherwise require separate engineering effort. ROSS Controls pre-assembles and configures the three-stage filter stack on a single modular body with shared mounting hardware, eliminating the need to independently select, order, and connect individual filter units. Optional L-O-X lockout valves can be integrated directly into the modular assembly at the inlet for compliant energy isolation during element maintenance.

The Clean Air Package is designed around the same MD3 filter bodies used in the individual adsorbing and coalescing filter lines, maintaining full parts interchangeability for replacement elements across the product family. The coalescing filter in the Clean Air Package is equipped with a differential pressure gauge that indicates when the coalescing element needs replacement, providing a clear, visual maintenance indicator without additional instrumentation.

Bowl options include polycarbonate with steel shatterguard for standard pressure and temperature conditions, metal aluminum for high-pressure or elevated-temperature environments, and extended metal aluminum for applications requiring up to 50 percent greater flow through the adsorbing stage. All three stages share consistent modular geometry for a compact installation footprint.

Key Engineering Features

• Adsorbing Filter with Activated Carbon Element - Third-stage activated carbon element removes oil vapors, hydrocarbon vapors, and odors that pass through upstream particulate and coalescing filtration, producing air virtually free of oil and hydrocarbons.
• Three-Stage Filtration in One Assembly - Particulate filter (5-micron), coalescing filter (0.3-micron or 0.01-micron), and adsorbing filter are pre-configured in a single modular assembly, eliminating separate component selection and inter-unit pipe fittings.
• Differential Pressure Gauge on Coalescing Filter - Coalescing filter stage includes a differential pressure gauge that provides a visual indication when the coalescing element is loaded and requires replacement, supporting proactive maintenance without external instrumentation.
• Modular Mounting - All three filter stages connect modularly on a shared body, providing a compact assembly with consistent porting, shared tie rod hardware, and direct connection to other ROSS MD3 FRL components.
• Multiple Bowl Options - Polycarbonate with steel shatterguard (standard), metal aluminum, and extended metal aluminum bowls address different pressure, temperature, and flow requirements across the three filter stages.
• Automatic or Manual Drain Options - Particulate and coalescing filters support automatic or manual drain options. The adsorbing filter uses a manual drain. Automatic drains on the first two stages ensure continuous condensate removal without operator intervention.
• Optional L-O-X Lockout Valve Integration - L-O-X energy isolation lockout valve can be integrated directly into the Clean Air Package modular assembly at the inlet, providing compliant lockout/tagout capability during filter element maintenance per OSHA requirements.
• ISO 8573-1 Class 1 Oil Purity - The three-stage combination with 0.01-micron coalescing and activated carbon adsorbing delivers outlet air quality with residual oil no greater than 0.01 mg/m3, equivalent to the highest oil purity class in ISO 8573-1.
• Port Sizes 1/4 to 1/2 in NPT and BSPP - Available in 1/4, 3/8, and 1/2 inch port sizes in NPT (NPTF) or BSPP (G) thread for compatibility with the widest range of compressed air systems in the MD3 flow range.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Food and Beverage Processing

• Product-contact compressed air in food packaging machinery, bottle blowing, filling, capping, and labeling operations where regulatory requirements (FDA, USDA, food safety management systems) prohibit detectable oil contamination and require clean air at all product contact points.
• Ingredient handling and metered dosing systems in bakery, dairy, confectionery, and condiment production where pneumatically operated valves, cylinders, and diaphragm pumps supply compressed air to process zones containing open product.
• Brewery, winery, and beverage carbonation systems where compressed air used to transfer, mix, or pressurize product lines must be free of hydrocarbon odors and oil contamination that would affect product flavor profiles.
• Aseptic packaging and ultra-high-temperature (UHT) processing lines where the highest air purity class (0.01 mg/m3 residual oil) is required to maintain sterile conditions in packaging zones.
• Bulk powder conveying for flour, sugar, spice, and nutritional supplement handling where pneumatic conveying air contacts the product directly and must meet food-grade air quality standards.

Pharmaceutical and Biotechnology Manufacturing

• Compressed air in tablet coating, fluid bed drying, granulation, and blending operations where compressed air contacts active pharmaceutical ingredients or in-process materials and must meet current Good Manufacturing Practice (cGMP) requirements for instrument-quality air.
• Sterile manufacturing and aseptic filling operations where compressed air for pneumatic actuators, integrity test systems, and environmental monitoring equipment must be validated to ISO 8573-1 Class 1 oil purity to prevent product contamination.
• Biopharmaceutical fermentation and downstream processing where compressed air for sparging, vessel pressurization, and transfer operations must be free of hydrocarbons that could inhibit biological cultures or contaminate protein products.
• Medical device assembly clean rooms where compressed air for robotic assembly, vision system purging, and test fixtures must meet clean room air quality standards and regulatory requirements for device manufacturing.

Electronics and Semiconductor Manufacturing

• Wafer fab compressed air systems where pneumatically actuated equipment handles substrates in Class 10 and Class 100 clean rooms, and any oil contamination would cause immediate yield losses through particle deposition or chemical interference with photolithography processes.
• SMT assembly and solder reflow lines where compressed air for pick-and-place machines, solder paste dispensing, and selective soldering must be free of hydrocarbons to prevent flux contamination, non-wet solder joints, and component adhesion failures.
• Flat panel display manufacturing where large-area glass substrate handling equipment requires sustained high-purity compressed air to prevent hydrocarbon deposits on display surfaces during TFT and OLED deposition processes.
• Precision optical assembly where compressed air for component handling and lens cleaning operations must be oil-free to prevent surface contamination that would degrade optical transmission or coating adhesion.

Automotive and Aerospace

• Automotive paint booth air supply where compressed air for atomizing spray guns must be free of oil contamination to prevent fish-eye defects, adhesion failures, and coating surface defects in primer and topcoat application.
• Aerospace composite layup and bonding operations where compressed air contacting uncured prepreg materials, adhesive films, and surface preparation zones must be oil-free to ensure full structural bond strength.
• Aircraft interior manufacturing where compressed air for automated fastener installation, sealant dispensing, and cabin component assembly must meet aerospace supplier quality requirements for clean air.
• Automotive final assembly operations where compressed air for torque tools, adhesive systems, and robotic assemblers must not contaminate painted surfaces, glass, or interior trim components.

Precision Instrumentation

• Instrument air supply for DCS and PLC-controlled pneumatic loop components including positioners, I/P converters, and smart valve controllers where clean air prevents fouling of pilot orifices, diaphragm seals, and feedback nozzles in control valves.
• Analytical laboratory instrument supply lines where compressed air as carrier gas, sample blanket gas, or detector supply gas must be free of hydrocarbons that would create false peaks in gas chromatography, spectroscopy, or mass spectrometry analyses.
• Coordinate measuring machine (CMM) air bearing spindles and precision rotary axes where the air bearing clearance is measured in microns and any oil contamination would alter bearing performance and dimensional measurement accuracy.

Breathing Air and Respiratory Protection

• OSHA Grade D breathing air supply systems in industrial facilities where workers use compressed air-fed respirators for abrasive blasting, spray painting, chemical handling, and confined space entry. The MD3 Clean Air Package removes oil and hydrocarbon vapors to levels below the OSHA and NIOSH requirements for breathing air quality.
• Supplied-air respirator (SAR) distribution systems in painting, welding, and chemical plant operations where compressed air purity is a workplace safety requirement for respiratory health protection of workers.

Ordering and Model Number Configuration

The MD3 Clean Air Package model number is configured by selecting bowl size, bowl drain type, pipe size, cap color, differential pressure gauge option, coalescing element grade, and optional lockout valve.

Select coalescing element grade A (0.3-micron) for general clean air applications; select grade B (0.01-micron) for the most stringent purity requirements including food contact and pharmaceutical applications.

The lockout valve option integrates directly into the modular assembly and eliminates the need for a separate energy isolation device upstream of the filter assembly during maintenance.

For BSPP (G) threads, use pipe size codes B (1/4), C (3/8), or D (1/2).

The extended bowl option (bowl size 3) uses the R-A60F-32E9 element in the adsorbing stage for up to 50 percent greater flow capacity.

When ordering with float drain, verify that inlet pressure will remain above 30 psig (2 bar), which is required for float drain activation.

Related Products & Accessories

• MD3 Series Adsorbing Filters (Series 85) - Individual adsorbing filter units in the MD3 body size for applications where only the activated carbon adsorbing stage is needed. https://www.rosscontrols.com/en/series/85-md3-series
• MD4 Clean Air Package (Series 88) - Higher-flow Clean Air Package in the MD4 body size for port sizes 3/8 to 3/4 inch with flow to 158 scfm. https://www.rosscontrols.com/en/series/88-md4-series
• Adsorbing Filter Elements MD3 and MD4 - Replacement activated carbon cartridges for MD3 and MD4 adsorbing filter stages in standard and extended bowl sizes. https://www.rosscontrols.com/en/series/2012-adsorbing-filter-element
• Silencers and Reclassifiers (Series 89) - Inline sintered bronze reclassifiers and silencers for exhaust noise reduction and oil mist separation. https://www.rosscontrols.com/en/series/89-silencers-reclassifiers

Frequently Asked Questions (FAQ)

Q: What filtration stages are included in the MD3 Clean Air Package?

A: The MD3 Clean Air Package includes three filter stages: a 5-micron particulate filter (Stage 1), a coalescing filter at either 0.3-micron or 0.01-micron rating (Stage 2), and an activated carbon adsorbing filter (Stage 3). All three stages are assembled into a single modular unit.

Q: What air purity level does the MD3 Clean Air Package achieve?

A: When configured with the 0.01-micron coalescing element, the MD3 Clean Air Package delivers outlet air with residual oil content of no more than 0.01 mg/m3, equivalent to ISO 8573-1 Class 1 oil purity, which is the highest classification for oil in compressed air systems.

Q: What is the difference between the 0.3-micron and 0.01-micron coalescing element options?

A: The 0.3-micron coalescing element (grade A) removes oil aerosols and submicron particles down to 0.3 micron. The 0.01-micron coalescing element (grade B) provides more thorough removal of fine oil mist aerosols at a lower level. For food contact, pharmaceutical, and electronics applications where the highest air purity is required, specify the 0.01-micron element. For general industrial clean air applications, 0.3-micron is appropriate.

Q: Why is the differential pressure gauge on the coalescing filter and not on the adsorbing filter?

A: Coalescing filter elements load progressively with captured oil and particles, causing measurable pressure drop increase that directly correlates with element exhaustion. This makes differential pressure an accurate and reliable maintenance indicator for coalescing filters. Activated carbon adsorbing elements do not restrict flow progressively in the same way, so differential pressure is not a reliable exhaustion indicator for the adsorbing stage.

Q: Can the L-O-X lockout valve be added to an existing MD3 Clean Air Package?

A: Yes. The L-O-X lockout valve is a modular accessory that integrates directly into the MD3 Clean Air Package assembly at the inlet. This allows energy isolation for filter element maintenance without requiring a separate lockout device upstream. Contact ROSS Controls for the lockout valve model number corresponding to the specific Clean Air Package configuration.

Q: What is the maximum operating pressure for the MD3 Clean Air Package?

A: For polycarbonate bowls with automatic drain, the maximum inlet pressure is 150 psig (10 bar). For metal aluminum bowls with automatic drain, the maximum is 200 psig (14 bar). For metal bowls with manual drain, the maximum pressure is 250 psig (17 bar). The lowest-rated bowl type in the assembly sets the maximum pressure for the complete assembly.

Q: Do automatic drains require a minimum pressure to operate?

A: Yes. Automatic drains on the particulate and coalescing filter stages require a minimum inlet pressure of 30 psig (2 bar) for polycarbonate bowls and 30 psig (2 bar) for metal bowls to operate correctly. Systems operating below 30 psig should use manual drain models.

Q: Can I build the same functionality from individual filter components?

A: Yes. The MD3 Clean Air Package provides the same filtration performance as three separately ordered MD3 filter units (particulate, coalescing, adsorbing) assembled in series. The Clean Air Package is a pre-engineered and pre-configured version that eliminates the need to select and order each component individually and to specify the inter-unit connections.

Q: What replacement elements are required for the three stages?

A: Stage 1 particulate filter uses R-A60F-03PE5 (5-micron polyethylene). Stage 2 coalescing filter uses R-A60F-23 (0.3-micron) or R-A60F-23E8 (0.01-micron). Stage 3 adsorbing filter uses R-A60F-29E9 (standard bowl) or R-A60F-32E9 (extended bowl). Each stage requires a different element on a schedule appropriate to inlet contamination levels.

Q: How should I schedule element replacements for the three stages?

A: Replace the Stage 2 coalescing element when the differential pressure gauge indicates the element is loaded. Replace the Stage 1 particulate element at the same interval or more frequently in high-particulate environments. Replace the Stage 3 adsorbing element on a time or volume-based schedule since it does not provide a differential pressure indicator. Outlet air quality testing confirms adsorbing element performance.

Q: Is the MD3 Clean Air Package available in BSPP threads for metric pipe systems?

A: Yes. BSPP (G) thread versions are available in 1/4 G, 3/8 G, and 1/2 G configurations using pipe size codes B, C, and D in the model number.

Q: What does ROSS Controls mean by ISO 8573-1 Class 1 oil purity?

A: ISO 8573-1 is the international standard for compressed air quality. Class 1 is the highest purity classification for oil content, specifying no more than 0.01 mg/m3 of total oil (aerosol, liquid, and vapor). The MD3 Clean Air Package configured with a 0.01-micron coalescing element meets this specification, making it suitable for the most stringent industrial air quality applications.

Q: Can the MD3 Clean Air Package be panel mounted?

A: Panel mounting hardware is available as an accessory for MD3 Series filters. Specify the panel mount nut option in the gauge code when ordering, which provides a mounting nut for installation through a 2-1/16 inch (52 mm) panel mounting hole.

Installation & Maintenance Guidelines

• Install the MD3 Clean Air Package with the flow direction matching the directional arrow on the filter body. Air enters the particulate filter first, flows through the coalescing filter, and exits through the adsorbing filter.
• Mount the assembly in the vertical position with bowls facing downward to facilitate condensate collection in the bowls and effective automatic drain operation.
• Ensure that the inlet compressed air supply is not lubricated. Never introduce oil-lubricated air upstream of the Clean Air Package. Lubricators, if required downstream of the Clean Air Package for actuator lubrication, must be installed after the filter assembly.
• For automatic drain models, verify that inlet pressure remains above 30 psig (2 bar) for correct drain operation. Below this threshold, use manual drain models.
• The coalescing filter differential pressure gauge requires periodic monitoring. Replace the coalescing element when the gauge indicates the element is loaded per the element replacement pressure drop limit.
• Replace the adsorbing element on a scheduled basis. Schedule is determined by system air flow volume and inlet hydrocarbon concentration. Do not wait for performance degradation as the only replacement trigger.
• When integrating the optional L-O-X lockout valve, verify that the lockout valve model corresponds to the inlet pressure and pipe size of the Clean Air Package, and that lockout/tagout procedures are updated to include the lockout valve location.
• After initial installation or after element replacement, run the system for a minimum of 10 minutes before allowing outlet air to contact sensitive process equipment or products, to allow the system to reach steady-state operation.
• In high-vibration installation environments, secure the filter assembly with bracket hardware to prevent vibration-induced loosening of modular connections and bowl retaining rings.
• Verify that the bowl removal clearances (add 3.1 inches / 79 mm for standard bowl; add 6.1 inches / 155 mm for extended bowl) are maintained in the installation space to allow element replacement without removing the assembly from the system.

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 +1-248-764-1800 or visit rosscontrols.com for product configuration, technical support, and distributor locator services.

For complete technical data, dimensional drawings, and ordering information, visit the ROSS Controls MD3 Clean Air Package product page or contact ROSS Controls at (800) 438-7677.

Download Catalog: https://www.rosscontrols.com/en/series/87-md3-series