MD3 Series Port Sizes 1/4" to 1/2"; Flow to 100 scfm (2832 l/min)

Product Overview

The ROSS Controls MD3 Series is a Filter/Regulator and Lubricator combo that consolidates filtration, pressure regulation, and sight-feed lubrication in a single modular assembly for pneumatic systems operating at port sizes from 1/4" to 1/2" with flow requirements up to 100 scfm (2832 l/min). The MD3 Series distinguishes itself within the ROSS FRL combo product line through its diaphragm-type regulator with dual gauge ports, providing enhanced pressure monitoring flexibility, and its expanded drain selection including manual, float, and electronic drain options.

The MD3 Series filter section is available with polycarbonate plastic bowls fitted with steel shatterguards for visual condensate monitoring with impact protection, aluminum bowls with clear sight glass for higher-pressure and temperature applications, or extended aluminum lubricator bowls with sight glass for increased oil capacity. These bowl options address a range of environmental conditions from standard indoor manufacturing to more demanding industrial environments.

The diaphragm-type regulator in the MD3 Series provides low hysteresis and precise output pressure control, making this series well suited for applications where finely controlled downstream pressure is required, including pneumatic instrumentation, positioner supplies, and precision assembly equipment. Both self-relieving and non-relieving configurations are available. Two gauge ports are provided on the regulator body to allow pressure gauge mounting on either side of the assembly for installation flexibility.

The integrated sight-feed lubricator delivers oil drops into the compressed air stream through a transparent dome, giving operators a direct visual confirmation that lubrication is occurring. This is particularly valuable in automated production environments where lubrication verification is part of a routine operator check. The modular construction allows the MD3 Series to be assembled in configurations ranging from standalone filter/regulator/lubricator to complex multi-function treatment trains.

Key Engineering Features

• Diaphragm-Type Regulator with Dual Gauge Ports - Low-hysteresis diaphragm regulator provides precise output pressure control; two gauge ports allow pressure gauge mounting on either side of the assembly for installation flexibility.
• Sight-Feed Lubricator - Oil delivery is visible through a transparent sight dome, enabling operators to confirm lubrication is occurring and adjust the oil feed rate without instrumentation.
• Modular Mounting - Designed for modular assembly, allowing individual sections to be replaced, serviced, or reconfigured without removing the entire assembly from the compressed air piping.
• Three Drain Options - Manual drain, float (automatic) drain, and electronic drain are available, providing the widest selection of condensate management strategies to match application requirements.
• Multiple Bowl Options - Polycarbonate with steel shatterguard, aluminum with clear sight glass, or extended aluminum with sight glass, to match environmental conditions and capacity requirements.
• Self-Relieving or Non-Relieving Regulator - Self-relieving configuration allows rapid downstream pressure reduction when set point is lowered; non-relieving retains downstream pressure for closed systems.
• Filter and Regulator Consolidated - Filter and regulator are integrated in a single assembly section, eliminating external pipe connections between filter and regulator and reducing potential leak points.
• Standard Pressure Gauge - A pressure gauge is included for continuous monitoring of regulated output pressure. Dual gauge ports provide installation flexibility for right-hand or left-hand gauge orientation.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Precision Assembly and Instrumentation

• Pneumatic instrumentation supply circuits requiring fine pressure control from a low-hysteresis diaphragm regulator, where the dual gauge port feature allows pressure monitoring at the most accessible side of the installation.
• Precision assembly fixtures for aerospace, defense, and electronics components where tight pressure tolerance reduces variability in pneumatic actuator force output.
• Pneumatic positioner supply lines where the diaphragm regulator's stable output pressure maintains accurate valve positioning across varying flow demand.
• Test and calibration equipment requiring stable, clean, regulated, and lubricated compressed air with verified pressure readings from the integral gauge.

Automated Manufacturing and Robotics

• Automated assembly cell air preparation stations where electronic drain provides fully automated condensate management with no operator intervention, supporting lights-out manufacturing operations.
• Industrial robot air preparation panels with the extended aluminum lubricator bowl providing increased oil reservoir capacity for extended production runs without refilling.
• Machine tool air preparation with diaphragm regulator delivering consistent regulated pressure to spindle air purge, workholding, and ATC actuators.

Chemical, Oil and Gas, and Petrochemical

• Process plant compressed air preparation for pneumatic control valve actuators and positioners requiring stable regulated pressure and reliable condensate removal via float or electronic drain.
• Offshore and field installation panels where the aluminum bowl extended capacity and electronic drain reduce the frequency of manual maintenance interventions.
• Analyzer and instrument air preparation systems where the diaphragm regulator provides stable, low-hysteresis pressure for sensitive process instruments.

Packaging and Consumer Goods Manufacturing

• High-speed packaging machinery with 100 scfm air demand requiring reliable FRL conditioning with automatic float drain to prevent moisture ingestion during continuous operation.
• Consumer goods assembly lines requiring modular air preparation that can be quickly serviced during scheduled maintenance windows with minimal line disruption.
• Cosmetics and personal care product filling lines with strict cleanliness requirements for pneumatic actuating air.

Plastics and Rubber Processing

• Injection molding machine pneumatic circuits requiring modular FRL conditioning with diaphragm regulators for stable pressure to mold core pull and injection actuators.
• Extrusion and thermoforming equipment air preparation where consistent regulated pressure and lubrication protect high-cycle pneumatic actuators from premature wear.

Utilities and Building Automation

• Building automation compressed air systems for pneumatic HVAC actuators and zone controls requiring reliable air preparation with automatic float drain to handle condensation in outdoor or semi-outdoor installations.
• Utility plant compressed air preparation for instrument and control air headers supplying multiple pneumatic field devices from a single modular FRL station.

Ordering and Model Number Configuration

The ROSS MD3 Series FRL combo is configured by selecting port size, bowl material, drain type, and regulator function. Contact ROSS Controls at (800) 438-7677 or visit rosscontrols.com for configuration assistance and model number generation.

Specify port size, bowl material, drain type (manual, float, or electronic), and regulator function (self-relieving or non-relieving) when ordering.

NPT thread is standard. G (BSPP) thread may be available; confirm with ROSS Controls at time of order.

The electronic drain option requires a 24 VDC or 110 VAC power supply for the drain solenoid. Confirm power source compatibility prior to order.

The extended aluminum lubricator bowl provides increased oil capacity for longer service intervals between refills.

For applications not requiring lubrication, refer to the ROSS Controls MD3 Series filter/regulator.

Accessories

Panel and Pipe Mounting Brackets

Mounting hardware for panel, pipe, and wall mounting of the MD3 Series modular assembly is available from ROSS Controls. Contact ROSS Controls for compatible bracket model numbers.

Replacement Filter Elements

Replacement filter elements in 5-micron and 40-micron grades maintain rated filtration efficiency in the MD3 Series filter section. Replace on schedule or when elevated differential pressure is observed.

Electronic Drain Power Supplies and Cables

Compatible power supply cables and connector accessories are available for the electronic drain option. Confirm compatibility with ROSS Controls at time of order.

Replacement Bowls and Seals

Replacement polycarbonate and aluminum bowls with associated seals are available as service parts for the MD3 Series.

Related Products & Accessories

• MD3 Series Filter/Regulator - Standalone MD3 Series filter/regulator for applications not requiring downstream lubrication. https://www.rosscontrols.com/en/series/72-md3-series
• 141 Mid-Size Series FRL Combo - Mid-Size Series FRL combo with piston regulator for same port range at similar flow capacity. https://www.rosscontrols.com/en/series/141-mid-size-series
• MD4 Series FRL Combo - MD4 Series FRL combo for port sizes 3/8" to 3/4" with higher flow up to 205 scfm. https://www.rosscontrols.com/en/series/144-md4-series
• 143 Full-Size Series FRL Combo - Full-Size FRL combo for port sizes 1/4" to 3/4" and flow up to 140 scfm. https://www.rosscontrols.com/en/series/143-full-size-series
• 139 Bantam Series FRL Combo - Bantam Series FRL combo for smaller port sizes 1/8" and 1/4". https://www.rosscontrols.com/en/series/139-bantam-series

Frequently Asked Questions (FAQ)

Q: What distinguishes the MD3 Series from the 141 Mid-Size Series FRL combo?

A: The key differences are the regulator type and drain options. The MD3 Series uses a diaphragm-type regulator for lower hysteresis and finer pressure control, while the Mid-Size Series uses a piston-type regulator. The MD3 Series also offers three drain options (manual, float, and electronic) versus two (automatic and manual) for the Mid-Size Series, and provides two gauge ports for installation flexibility.

Q: What port sizes are available?

A: The MD3 Series is available in 1/4", 3/8", and 1/2" port sizes.

Q: What is the maximum rated flow?

A: The MD3 Series handles up to 100 scfm (2832 l/min).

Q: What are the three drain options?

A: Manual drain requires the operator to open the drain valve to expel condensate. Float drain (automatic) uses a float-actuated valve that opens automatically when condensate reaches a set level. Electronic drain uses an electrically actuated solenoid valve that opens on a timed or demand basis, requiring a 24 VDC or 110 VAC power supply.

Q: Why does the MD3 Series have two gauge ports?

A: Two gauge ports allow the pressure gauge to be installed on either the left or right side of the regulator body. This accommodates installations where space constraints or panel layouts dictate gauge position, and allows the unused port to be plugged.

Q: What are the bowl material options?

A: Options include polycarbonate with steel shatterguard (150 psig / 125 degrees F), aluminum with clear sight glass (200 psig / 175 degrees F), and extended aluminum with sight glass (200 psig / 175 degrees F, with increased oil capacity). The aluminum bowl is required for applications exceeding 125 degrees F or 150 psig.

Q: What is a diaphragm-type regulator and when is it preferred?

A: A diaphragm-type regulator uses a flexible diaphragm as the sensing element rather than a piston. This design provides lower hysteresis and higher sensitivity to pressure changes, making it preferred for precision pressure control applications such as instrumentation supply, positioner feeds, and test equipment.

Q: What lubricant is compatible with the sight-feed lubricator?

A: Use petroleum-based oil with ISO 32 viscosity or lighter. Avoid synthetic ester-based and phosphate-ester lubricants, which are incompatible with the nitrile seals used throughout the assembly.

Q: How do I set the regulated pressure?

A: Pull the regulator adjustment knob upward to release the lock. Turn clockwise to increase pressure or counterclockwise to decrease. Monitor the reading on the pressure gauge and push the knob down to lock when the desired pressure is reached.

Q: Is the extended aluminum bowl compatible with all MD3 Series filter sections?

A: The extended aluminum lubricator bowl is a lubricator section option. Confirm bowl and section compatibility with ROSS Controls to ensure proper assembly with the selected filter/regulator section.

Q: Can the electronic drain operate autonomously?

A: Yes. The electronic drain operates on a configurable timer or demand signal, providing fully automated condensate removal without manual operator intervention. This makes the electronic drain the preferred option for unmanned or lights-out production environments.

Q: How often should the filter element be replaced?

A: Replace the filter element on a scheduled interval or when differential pressure across the filter increases noticeably above baseline, indicating element saturation. In high-particulate environments, intervals may be shorter.

Q: Can the modular sections be reconfigured after installation?

A: Yes. The modular design of the MD3 Series allows individual sections to be replaced or reconfigured without dismantling the entire assembly. Contact ROSS Controls to confirm section compatibility and replacement procedures.

Q: Where can I get product documentation?

A: Catalogs, data sheets, and installation instructions for the MD3 Series are available at rosscontrols.com. Call ROSS Controls at (800) 438-7677 for configuration assistance.

Installation & Maintenance Guidelines

• Install the assembly with bowls oriented downward for proper condensate collection and drainage.
• Align the flow direction arrow on the assembly body with the compressed air supply flow direction.
• Position the assembly to provide unobstructed access to the bowl drains, lubricator fill, sight dome, gauge, and regulator adjustment knob.
• Apply thread sealant to pipe port connections and tighten to the manufacturer-specified torque. Do not overtighten polycarbonate or shatterguard assemblies.
• Confirm inlet pressure does not exceed 150 psig for polycarbonate bowls or 200 psig for aluminum bowls.
• Verify ambient and air temperature remain within the rated range for the selected bowl material.
• For electronic drain installations, wire the drain solenoid to the appropriate 24 VDC or 110 VAC power supply and configure the timer or demand signal as required.
• Fill the lubricator bowl with petroleum-based ISO 32 or lighter oil before first use.
• Pressurize slowly after installation and check all connections, bowl seals, and drain valve with leak detection solution.
• Set regulated output pressure: pull knob up to unlock, rotate to desired gauge reading, push down to lock.
• Observe the sight dome after start-up to confirm oil is feeding at the intended rate.
• Inspect and drain the filter bowl at each maintenance interval. Verify float drain operation or electronic drain cycle is functioning correctly.
• Replace the filter element on schedule or when elevated differential pressure is observed.

Warranty & Global Support

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

Technical support is available through ROSS Controls USA at (800) 438-7677 or by visiting rosscontrols.com.

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

Contact ROSS Controls at (800) 438-7677 or visit rosscontrols.com for product configuration, replacement parts, and distributor referral.

Download Catalog: https://www.rosscontrols.com/en/documents