MD3 Series Port Sizes 1/4" to 1/2"; Flow to 110 scfm (3115 l/min)

Product Overview

The ROSS Controls MD3 Series Integrated Filter/Regulator consolidates air filtration and pressure regulation into a single modular assembly with a unique combination of features distinguishing it from standard integrated FR products. The diaphragm-type regulator design provides higher outlet pressure capability (to 200 psig / 14 bar) than piston-type regulators, with excellent sensitivity to small pressure variations, making the MD3 Series suitable for both standard industrial automation and higher-pressure circuit requirements.

A key differentiating feature of the MD3 Series is the optional integrated L-O-X Lockout Valve, which can be added directly to the assembly for energy isolation during maintenance without requiring separate lockout hardware in the pneumatic supply line. Two gauge ports (front and rear) provide installation flexibility for pressure monitoring. A pressure adjustment locking key is standard, preventing unauthorized pressure changes after commissioning.

Bowl material options include a polycarbonate plastic bowl with nylon shatterguard or an aluminum bowl with clear nylon sight glass. Five filter element configurations are available including 5-micron and 20-micron sintered bronze elements in addition to the standard 5-micron polyethylene element, providing filtration options matched to contamination level, element durability, and service interval requirements. Float drain and manual drain configurations are available.

The MD3 Series configurable ordering system allows engineers to specify bowl material, filter element rating and type, drain configuration, port size, lockout valve option, gauge range, and reverse flow capability from a structured part number system. This flexibility makes the MD3 Series a versatile platform across a wide range of mid-size pneumatic air preparation requirements.

Key Engineering Features

• Diaphragm-Type Regulator to 200 psig (14 bar) - Diaphragm regulator design provides higher outlet pressure capability than standard piston-type units, supporting high-pressure pneumatic circuits up to 200 psig (14 bar) while delivering excellent pressure sensitivity and regulation accuracy.
• Optional L-O-X Lockout Valve Integration - An L-O-X Lockout Valve can be added directly to the MD3 assembly at either the outlet or inlet, providing integrated OSHA-compliant lockout/tagout energy isolation without requiring separate lockout components in the pneumatic supply line.
• Pressure Adjustment Locking Key - Removable locking key prevents unauthorized pressure changes after the set point is established. Essential for production environments where consistent actuator force or process pressure is critical to product quality or machine safety.
• Two Gauge Ports (Front and Rear) - Independent gauge ports on both front and rear of the unit allow the pressure gauge to be positioned for optimal visibility regardless of installation orientation or panel layout.
• Multiple Filter Element Options - Five element configurations including 5-micron polyethylene, 5-micron sintered bronze, 20-micron sintered bronze, and 40-micron sintered bronze provide filtration matched to contamination level and service interval requirements.
• Configurable Part Number System - Structured ordering code allows specification of bowl material, filter element type, drain type, port size (NPT or BSPP), lockout valve option, gauge range, and reverse flow configuration, enabling precise unit configuration for each application.
• Polycarbonate Bowl with Nylon Shatterguard - Standard 5.1-oz (151 ml) polycarbonate bowl provides visual condensate inspection; nylon shatterguard provides mechanical protection and fragment containment.
• Aluminum Bowl with Clear Nylon Sight Glass - 6-oz (177 ml) aluminum bowl extends maximum operating pressure to 250 psig (manual drain) and upper temperature rating to 175 degrees F (80 degrees C). Clear nylon sight glass maintains condensate visibility.
• Self-Relieving or Non-Relieving Options - Standard self-relieving diaphragm regulator allows downstream pressure bleed-off when set point is reduced. Non-relieving option available for circuits requiring downstream pressure retention after supply shut-off.
• Modular Mounting with Panel Mounting Support - Modular design supports assembly with ROSS lubricators and filter units. Panel mounting requires a 2-1/16 inch (52 mm) hole for enclosure-mounted installations.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Machine Safety and Energy Isolation

• Pneumatic machine air preparation with integrated L-O-X lockout valve providing OSHA-compliant energy isolation during maintenance without requiring separate lockout plumbing, combining air quality conditioning and lockout/tagout compliance in a single compact assembly.
• Multi-machine manufacturing cells where each machine drop includes an MD3 Series with integrated lockout, allowing maintenance personnel to lock out individual machines at the air preparation point without affecting adjacent equipment in the cell.
• Automated equipment requiring both high-pressure (to 200 psig) supply conditioning and lockout capability, where the MD3 with metal bowl and L-O-X option provides both functions in a modular, space-efficient configuration.
• Equipment with machine guarding where the integrated lockout valve enables the guard to be locked in place and air isolated at the FR point, providing a clear, documented energy isolation point for the pneumatic circuit.

High-Pressure Pneumatic Systems

• Pneumatic pressing, clamping, and forming equipment operating at pressures above 100 psig where the diaphragm regulator's 200 psig outlet capability and high inlet pressure rating with metal bowl (250 psig manual drain) accommodate high-force pneumatic circuit requirements.
• Test stand pneumatic supply circuits where precise high-pressure regulation and the dual gauge port configuration allow accurate pressure monitoring during automated test sequences.
• Pneumatic press-fitting and assembly equipment where consistent regulated pressure at up to 200 psig ensures repeatable insertion force across production batches and minimizes variation in press-fit quality.

Process Industry and Chemical

• Chemical plant instrument air preparation where the sintered bronze filter element options provide greater durability in high-contamination environments and the aluminum bowl resists chemical exposure from cleaning and process chemicals.
• Pharmaceutical and food processing equipment where the combination of high filtration quality (5-micron sintered bronze element option), tamper-resistant pressure setting, and energy isolation capability supports both air quality and safety compliance requirements.
• Oil and gas processing facility pneumatic instrument air conditioning where the MD3 Series with metal bowl and high inlet pressure capability supports the higher-pressure compressed air systems common in process plant environments.

General Industrial Automation

• Mid-size pneumatic actuator circuits in automated production equipment where the diaphragm regulator provides superior pressure droop performance compared to piston regulators, maintaining more consistent downstream pressure under varying flow demand.
• Modular FRL assemblies combining MD3 Series filter/regulator with ROSS lubricators and lockout valves for complete air preparation systems that provide clean conditioned air, precise pressure control, and energy isolation in a single modular train.
• Pneumatic circuit supply conditioning for equipment serving multiple operators simultaneously, where the tamper-resistant locking key prevents each operator from adjusting supply pressure and the integrated lockout supports per-station energy isolation.

Ordering and Model Number Configuration

The MD3 Series uses a configurable part number system. Build the model number by selecting from the available option codes below. Contact ROSS Controls at (800) 438-7677 for assistance configuring the correct model number for your application.

Base code for the standard polycarbonate bowl configuration begins with MD3 53P; metal bowl configurations begin with MD3 53M.

Specify the filter element code (A, B, E, or F), drain type (M or F), port size code, cap color code, and gauge option to complete the model number.

For lockout valve configurations, add the lockout code (2, 3, or 4) to the model number. Metal bowl must be specified for configurations requiring inlet pressure above 150 psig.

Stainless steel filter/regulator and L-O-X lockout valve combinations are available; contact ROSS Controls for stainless steel configuration model numbers.

For reverse flow configurations (reverse flow allows downstream equipment to back-feed regulated pressure), specify the appropriate reverse flow gauge option code.

Accessories

L-O-X Lockout Valve Add-On

The ROSS L-O-X Lockout Valve can be added directly to the MD3 Series assembly, providing integrated OSHA-compliant lockout/tagout energy isolation at the filter/regulator point. Available in outlet lockout, inlet with reverse flow, and EEZ-ON outlet configurations. Contact ROSS Controls for L-O-X model numbers and configurations compatible with the MD3 Series.

Replacement Filter Elements

Four element options are available for the MD3 Series: 5-micron polyethylene (R-A60F-03PE5), 5-micron sintered bronze (R-A60F-03E5), 20-micron sintered bronze (R-A60F-03E4), and 40-micron sintered bronze (R-A60F-03E3). Sintered bronze elements are reusable and more durable in high-condensate or abrasive contamination environments.

External Drain and Differential Gauge Options

External bowl drain connections and differential pressure gauge options are available for the MD3 Series. External drains allow remote condensate discharge to a central drain system. Differential pressure gauges provide direct indication of filter element loading. Refer to ROSS Controls accessories catalog or contact ROSS at (800) 438-7677 for model numbers.

Related Products & Accessories

• MD4 Series Integrated Filter/Regulator - Full-size version of the MD4 diaphragm-type integrated FR with L-O-X option, port sizes 3/8" to 3/4", flow to 230 scfm. https://www.rosscontrols.com/en/series/75-md4-series
• 65 Mid-Size Series Integrated Filter/Regulator - Mid-size modular integrated FR with piston regulator and tamper-resistant knob, port sizes 1/4" to 1/2", flow to 105 scfm. https://www.rosscontrols.com/en/series/65-mid-size-series
• 132 Mid-Size Series Integrated Filter/Regulator - Modular integrated FR with piston regulator, polycarbonate or zinc bowl, port sizes 1/4" to 1/2", flow to 100 scfm. https://www.rosscontrols.com/en/series/132-mid-size-series
• 74 Full-Size Integrated Filter/Regulator - Modular integrated FR with piston regulator, locking key, external drain option, port sizes 1/4" to 3/4", flow to 180 scfm. https://www.rosscontrols.com/en/series/74-full-size-series
• ROSS L-O-X Lockout Valves - Standalone and integrated ROSS L-O-X lockout valves for OSHA-compliant pneumatic energy isolation. https://www.rosscontrols.com/en/categories/lockout-valves

Frequently Asked Questions (FAQ)

Q: What makes the MD3 Series different from standard mid-size filter/regulators?

A: The MD3 Series offers several differentiating features: a diaphragm-type regulator capable of outlet pressures to 200 psig (14 bar) vs. 100 psig for most piston-type mid-size units; an optional integrated L-O-X Lockout Valve for energy isolation; five filter element options including sintered bronze elements; a configurable part number system allowing precise specification; and two gauge ports for flexible pressure monitoring. These features make the MD3 suitable for higher-pressure circuits, machine safety applications, and demanding contamination environments.

Q: What is the maximum outlet pressure of the MD3 Series?

A: The diaphragm-type regulator is adjustable up to 200 psig (14 bar). This is significantly higher than the 100 psig maximum of most competing mid-size piston-type integrated FRs and accommodates high-pressure pneumatic clamping, pressing, and test circuits.

Q: What is the maximum inlet operating pressure?

A: With a polycarbonate bowl and auto drain configuration, maximum inlet pressure is 150 psig (10 bar). With a metal bowl, maximum inlet pressure is 200 psig (14 bar) for auto drain and 250 psig (17 bar) for manual drain configurations. The metal bowl with manual drain is the highest-pressure configuration in the MD3 line.

Q: How does the integrated L-O-X Lockout Valve work?

A: The L-O-X Lockout Valve integrates directly with the MD3 assembly, providing a hasp-type lockout point where a padlock can be applied to physically lock the valve in the exhaust (de-energized) position during maintenance. This provides OSHA 29 CFR 1910.147-compliant pneumatic energy isolation at the filter/regulator assembly itself, eliminating the need for a separate lockout device in the supply line.

Q: What filter element options are available?

A: Five element options are available: 5-micron polyethylene (standard, model R-A60F-03PE5), 5-micron sintered bronze (R-A60F-03E5), 20-micron sintered bronze (R-A60F-03E4), and 40-micron sintered bronze (R-A60F-03E3). Sintered bronze elements provide greater mechanical durability and can be cleaned and reused, making them cost-effective in high-contamination environments.

Q: Why does the MD3 use a diaphragm regulator instead of a piston regulator?

A: Diaphragm regulators offer several advantages over piston types in certain applications: better pressure sensitivity (response to small pressure differentials), lower hysteresis, and higher outlet pressure capability. They are particularly well suited for applications requiring precise pressure control and for high-pressure circuits. The tradeoff is that diaphragm regulators generally have slightly lower flow capacity for a given body size compared to piston designs.

Q: What is the difference between self-relieving and non-relieving regulator options?

A: Self-relieving regulators allow excess downstream pressure to bleed back through the regulator when the set point is reduced, eliminating the need for manual downstream venting during pressure adjustments. Non-relieving regulators block this backflow path, retaining downstream pressure after supply shut-off. Select non-relieving for circuits where downstream pressure must be held after supply isolation, such as pneumatic clamps that must remain engaged during shutdown sequences.

Q: What bowl options are available?

A: The polycarbonate bowl (5.1 oz / 151 ml) with nylon shatterguard is rated to 150 psig and 125 degrees F. The aluminum metal bowl (6 oz / 177 ml) with clear nylon sight glass extends maximum operating pressure to 250 psig (manual drain) and upper temperature limit to 175 degrees F (80 degrees C). Select the metal bowl for high-pressure, high-temperature, or chemically aggressive environments.

Q: Can a stainless steel version be ordered?

A: Yes. Stainless steel filter/regulator and L-O-X lockout valve combination units are available. Contact ROSS Controls at (800) 438-7677 for stainless steel configuration model numbers, which are appropriate for corrosive environments, washdown applications, and food/pharmaceutical process equipment.

Q: How do I build an MD3 model number?

A: The MD3 model number is built from a structured code: MD3 [Bowl Code] [Element Code] [Drain Code] [Port Code] [Cap Color Code] [Gauge Code]. For example: MD3 53P B M 2 2 B = Polycarbonate bowl, 5-micron PE element, manual drain, 1/4 NPTF port, standard cap, 0-200 psig gauge. Contact ROSS Controls at (800) 438-7677 for assistance with configurations including lockout valves or non-standard options.

Q: What is the panel mounting hole size?

A: The MD3 Series requires a 2-1/16 inch (52 mm) diameter hole for panel mounting. Allow adequate clearance for bowl removal after installation.

Q: What is the warranty?

A: ROSS Controls provides a one-year warranty on all products covering defects in material and workmanship from the date of purchase. Contact ROSS Controls USA at (800) 438-7677 for technical support or warranty claims.

Installation & Maintenance Guidelines

• Mount with the bowl oriented downward for proper condensate collection and drain operation.
• For auto (float) drain configurations, ensure the drain outlet is clear and not subjected to back pressure that would prevent condensate discharge.
• For manual drain models, drain condensate regularly based on air system humidity and observed accumulation rates.
• Do not exceed rated inlet pressures: 150 psig for polycarbonate bowl auto drain, 200 psig for metal bowl auto drain, 250 psig for metal bowl manual drain.
• Set the regulated outlet pressure before locking the adjustment. Remove the locking key after setting and store in a secure location accessible to authorized personnel.
• When installing with an integrated L-O-X lockout valve, verify the lockout valve is in the OPEN position and not locked before pressurizing the system for the first time.
• Replace the filter element when pressure drop across the unit exceeds acceptable limits or on a scheduled maintenance interval.
• Use thread sealant or PTFE tape on NPTF connections; apply sparingly to prevent contamination of the air circuit.
• When panel mounting, use the specified 2-1/16 inch (52 mm) hole and ensure adequate bowl removal clearance.
• For modular FRL assembly with a lubricator, follow ROSS modular assembly instructions to ensure proper interface sealing.

Warranty & Global Support

ROSS Controls provides a one-year warranty on all products, covering defects in material and workmanship from the 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 or visit rosscontrols.com for product configuration, technical support, and distributor locator services.

For complete technical data, dimensional drawings, and product configurator access, visit the ROSS Controls MD3 Series product page or contact ROSS Controls directly.

Download Catalog: https://www.rosscontrols.com/en/series/66-md3-series