MD3 Series Port Sizes 1/4" to 1/2"; Flow to 150 scfm (4248 l/min)

Product Overview

The ROSS Controls MD3 Series is an advanced modular sight-feed lubricator engineered for pneumatic systems requiring high flow capacity, precise oil monitoring, and flexible bowl volume configuration in 1/4 to 1/2 inch port applications. With a maximum flow of 150 scfm (4,248 l/min), the MD3 Series handles demanding medium-to-high flow pneumatic circuits while maintaining the compact, modular form factor required for FRL station integration.

The MD3 Series distinguishes itself with a transparent dome that shows the oil being dispensed in real time. Rather than simply counting drops as in earlier sight-feed designs, the transparent dome design of the MD3 allows maintenance personnel to observe the oil delivery visually in the dome window, providing an immediate, unambiguous indication of lubricant flow. This makes field verification faster and more reliable, particularly in noisy or high-activity production environments.

The external adjusting knob of the MD3 Series is designed to be removable, providing a convenient two-state tamper protection approach. With the knob installed, authorized personnel can adjust oil delivery at any time. Removing the knob eliminates the interface for adjustment entirely, creating true tamper resistance for installations where lubrication settings must not be changed between scheduled maintenance events.

Bowl options for the MD3 Series include a 5.1-oz (151-ml) polycarbonate bowl with nylon shatterguard, a 6-oz (177-ml) aluminum bowl, and an extended 10-oz (295-ml) aluminum bowl for applications requiring longer intervals between oil refills. The metal bowl option achieves a maximum operating pressure of 250 psig (17 bar), the highest rating in the ROSS mid-range lubricator lineup.

Key Engineering Features

• Transparent Dome Oil Monitoring - The transparent dome on top of the lubricator body allows direct visual observation of oil being dispensed into the airstream. Confirms active lubrication delivery at a glance without sight glass counting or special instruments.
• Removable External Adjusting Knob for Tamper Resistance - External adjusting knob regulates oil delivery rate and can be physically removed from the lubricator to prevent any unauthorized adjustment. When the knob is absent, the delivery rate is locked at the last set position.
• Extended Metal Bowl Option - Optional 10-oz (295-ml) extended metal bowl provides increased oil reservoir capacity for high-consumption applications or locations where frequent access for refilling is difficult. Standard 5.1-oz (151-ml) polycarbonate and 6-oz (177-ml) aluminum bowls also available.
• High Pressure Metal Bowl Rating - Aluminum bowl option is rated to a maximum of 250 psig (17 bar), making the MD3 Series suitable for higher-pressure systems where polycarbonate bowl limits of 150 psig would be exceeded.
• Modular or Inline Mounting - Compatible with modular FRL assembly configurations or standalone inline installation. ROSS MD3 Series filters and regulators match the MD3 lubricator for complete modular FRL station construction.
• Quick-Fill Cap Option - Available quick-fill cap allows pressurized oil refilling without bowl removal or system shutdown, reducing maintenance time and production interruption.
• Zinc Body Construction - Zinc die-cast body provides structural rigidity, corrosion resistance, and elevated pressure and temperature performance compared to polymer-body alternatives in the same flow range.
• Nitrile Seals - Standard nitrile seals provide petroleum oil compatibility. Polycarbonate bowl models rated to 125 F (52 C); metal bowl models rated to 175 F (80 C) ambient and media temperature.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

High-Cycle Automation and Assembly

• High-speed pneumatic actuator banks on automotive body assembly lines cycling at 30 to 120 cycles per minute, where 150 scfm flow capacity handles simultaneous multi-cylinder operation and the extended metal bowl reduces the frequency of oil refilling during continuous production.
• Robotic welding cell pneumatic clamping and gun actuator circuits, where the transparent dome provides immediate visual verification of lubrication delivery during cell commissioning and periodic maintenance audits.
• Transfer machine pneumatic indexing and clamping circuits, where the removable knob tamper protection ensures that once lube delivery is optimized at commissioning, production personnel cannot inadvertently alter settings.

Compressed Air Systems Above Standard Pressure

• Pneumatic circuits operating at inlet pressures between 150 and 250 psig (10 to 17 bar), where the MD3 aluminum bowl option provides the only modular lubricator in this port size range rated for these elevated pressures.
• High-pressure pneumatic clamping systems for machining fixtures, where clamp actuation at 200+ psig requires components rated above the standard 150 psig polycarbonate bowl limit of smaller series lubricators.
• Hydraulic accumulator charging circuits and pressure intensifier systems using compressed air as the driving medium, where system pressures regularly exceed 150 psig during charging cycles.

Plastics Processing and Injection Molding

• Large injection molding machine core and ejector pneumatic circuits, where 3/8 and 1/2 inch supply lines at 80 to 150 scfm require MD3 capacity, and the extended bowl option reduces oil refill frequency during 24-hour continuous production runs.
• Blow molding machine pneumatic clamping, pre-blow, and final blow circuits, where sight-feed monitoring allows operators to confirm lube delivery is active before starting a production batch.
• Thermoforming and vacuum forming machine pneumatic forming box, trim, and part handling circuits, where the zinc body and metal bowl combination provides the durability needed in heated machine environments.

Mining and Heavy Industry

• Pneumatic drill and hammer air supply lines at underground mining operations, where high-cycle vibrating equipment demands consistent lubrication, and the extended metal bowl provides the reservoir capacity needed for remote or hard-to-access installations.
• Rock drill lubricators in quarry operations where 1/2 inch air supply at over 100 psig is standard, and the MD3 metal bowl rating to 250 psig handles peak compressor output pressure surges.
• Pneumatic scaling hammers and chipping equipment in construction and demolition applications, where the transparent dome confirms the tool is receiving lubricant after reconnecting the air supply at the start of each shift.

Wood Products and Furniture Manufacturing

• Pneumatic nailer banks and stapler supply circuits in furniture manufacturing, where multiple tools drawing from a 1/2 inch header require a lubricator rated above 100 scfm to prevent flow restriction.
• CNC routing and machining center pneumatic toolchanger and workholding circuits, where modular MD3 FRL stations are installed at each machine to provide clean, regulated, lubricated air at the point of use.
• Wood component clamping presses and gluing line pneumatic actuators, where the transparent dome allows quick visual checks during production without interrupting the glue cure cycle.

Aerospace Ground Support and MRO

• Aircraft maintenance pneumatic tooling supply in MRO hangar environments, where 1/4 to 1/2 inch air drops supplying impact wrenches, riveters, and drill motors benefit from modular FRL stations with MD3 lubricators that can be serviced as a module.
• Ground support equipment pneumatic systems on airport ramps, where outdoor exposure and variable temperatures require the metal bowl option for its wider temperature range and resistance to UV and chemical degradation compared to polycarbonate.
• Pneumatic test stands for aircraft component testing, where consistent, calibrated lubrication delivery confirmed by transparent dome monitoring is required for repeatable test conditions.

Ordering and Model Number Configuration

The MD3 Series uses a structured configurable model number. An example: MD3 51P Q C 2 2 specifies a polycarbonate 5.1-oz bowl, quick-fill cap, 3/8 G thread port, black cap.

NPT thread models use numeric port codes (2, 3, 4). G (BSPP) thread models use letter codes (B, C, D).

Extended metal bowl (51E) is rated to 250 psig (17 bar) and 175 F (80 C). Standard polycarbonate (51P) is rated to 150 psig (10 bar) and 125 F (52 C).

Quick-fill cap (Q) is recommended for applications where oil refilling must occur without system shutdown.

Accessories

MD3 Series Filters

ROSS MD3 Series modular filters with 5-micron elements for 1/4 to 1/2 inch ports. Available with polycarbonate or metal bowls matching MD3 lubricator bowl families. Automatic or manual drain options.

MD3 Series Regulators

Modular piston-type regulators for 1/4 to 1/2 inch ports in MD3 Series FRL assemblies. Adjustable pressure range and lockout valve options available.

Extended Metal Bowl

10-oz (295-ml) extended metal bowl provides additional reservoir capacity for high-consumption applications or remote locations. Bowl removal clearance: 6.1 inches (155 mm). Rated to 250 psig (17 bar).

Related Products & Accessories

• 106 Mid-Size Series Lubricators - Modular sight-feed lubricators for 1/4 to 1/2 inch ports with zinc shatterguard bowl. Flow to 110 scfm. External tamper-resistant adjustment. https://www.rosscontrols.com/en/series/106-mid-size-series
• 108 Full-Size Series Lubricators - Modular or inline sight-feed and wick-feed lubricators for 1/4 to 3/4 inch ports. 8-oz bowl capacity. Flow to 140 scfm. https://www.rosscontrols.com/en/series/108-full-size-series
• MD4 Series Lubricators - Modular sight-feed lubricators with transparent dome for 3/8 to 3/4 inch ports. Extended bowl option. Flow to 205 scfm. https://www.rosscontrols.com/en/series/109-md4-series
• 110 High-Capacity Series Lubricators - Inline sight-feed and wick-feed lubricators for 3/4 to 1-1/2 inch ports. Flow to 500 scfm. Multiple bowl capacity options. https://www.rosscontrols.com/en/series/110-high-capacity-series

Frequently Asked Questions (FAQ)

Q: What makes the MD3 Series different from the standard Mid-Size Series (106)?

A: The MD3 Series offers higher maximum flow (150 scfm vs 110 scfm), a higher maximum operating pressure on the metal bowl option (250 psig vs 200 psig), a transparent dome for direct oil drop observation (versus sight-feed dome on Mid-Size), and a removable external knob that creates true tamper resistance when removed. The MD3 also offers an extended 10-oz metal bowl option that the standard Mid-Size Series does not.

Q: How does the transparent dome differ from a standard sight-feed dome?

A: The MD3 transparent dome provides a wider, clearer window for observing oil being dispensed into the airstream. The design allows personnel to see the oil delivery process in the dome itself rather than only counting drops at a narrow sight glass. This makes it easier to confirm active lubrication, particularly in production environments with poor lighting or where the lubricator is installed at height or in a confined location.

Q: What is the advantage of the removable adjusting knob?

A: The removable knob provides two operating modes. With the knob installed, authorized personnel can adjust oil delivery by turning the knob. With the knob removed, there is no physical interface for adjustment, creating tamper-resistant protection that cannot be defeated without a replacement knob. This is more robust than a tamper-resistant knob design, which can sometimes be turned with pliers or tools.

Q: What is the maximum operating pressure for MD3 Series metal bowl models?

A: The aluminum metal bowl models for the MD3 Series are rated to 250 psig (17 bar), which is the highest pressure rating in the ROSS mid-range lubricator lineup. This enables MD3 Series lubricators to be used in systems operating above the 150 to 200 psig range supported by polycarbonate or standard zinc bowl lubricators in the same port size range.

Q: When should I specify the extended metal bowl?

A: Specify the extended 10-oz (295-ml) aluminum bowl when the application has high air consumption rates that would exhaust a standard 5.1 to 6 oz bowl too quickly, when the lubricator is installed in a location that is difficult to access frequently for refilling, or when a shift-length or longer operation is required without maintenance interruption. The extended bowl adds approximately 3 inches (76 mm) to the overall height.

Q: Can the MD3 Series lubricator be combined with MD3 Series filters and regulators?

A: Yes. The MD3 Series is designed as a modular system where the lubricator, filter, and regulator components join directly. ROSS MD3 Series filters with 5-micron elements and piston-type or diaphragm-type MD3 regulators are available for 1/4 to 1/2 inch port sizes and mount to form a complete FRL station.

Q: What is the bowl removal clearance for the MD3 Series?

A: Standard bowl removal requires approximately 3.1 inches (79 mm) of clearance below the lubricator body. The extended metal bowl requires approximately 6.1 inches (155 mm). Verify this clearance exists in the installation space before mounting, particularly in panel or enclosure installations.

Q: Is the transparent dome covered by the standard cartridge replacement?

A: Yes. All working parts of the MD3 Series, including the sight dome, are contained in a field-replaceable cartridge. Replacement cartridges are available through ROSS Controls and authorized distributors.

Q: What flow rate is required for the MD3 to deliver oil reliably?

A: While the MD3 catalog does not publish a specific minimum flow, the sight-feed mechanism requires a minimum pressure differential to draw oil. A practical minimum of approximately 2 to 5 scfm at rated inlet pressure is typical for sight-feed lubricators of this type. For very low-flow applications below these levels, select the 105 Miniature Series low-flow model.

Q: What oil viscosity is recommended for the MD3 Series?

A: Use petroleum-based oil with ISO 32 viscosity or lighter and an aniline point between 180 F and 220 F. Standard pneumatic tool oil meeting ANSI/ASTM specifications for pneumatic tool lubrication is appropriate. Avoid phosphate-ester additives and synthetic fluids incompatible with nitrile seals.

Q: Are both NPT and BSPP threads available for the MD3?

A: Yes. NPTF threads are specified using numeric port codes (2 = 1/4, 3 = 3/8, 4 = 1/2). G (BSPP) threads use letter codes in the model number (B = 1/4 G, C = 3/8 G, D = 1/2 G).

Q: Can the MD3 lubricator be ordered with a lockout valve?

A: Yes. When ordering complete MD3 FRL assembly models, a lockout valve (L-O-X or EEZ-ON lockout valve) can be integrated into the assembly. Consult the ROSS FRL combination units catalog for the specific configuration codes, or contact ROSS technical support at (800) 438-7677.

Installation & Maintenance Guidelines

• Install the MD3 lubricator downstream of the filter and regulator in the air treatment sequence. Lubricating unfiltered air introduces contaminants into the oil reservoir and can foul the transparent dome.
• Mount with the bowl in the downward vertical position. Do not install in the inverted orientation.
• Verify bowl removal clearance before installation: 3.1 inches (79 mm) for standard bowls, 6.1 inches (155 mm) for extended bowls.
• For modular FRL assembly, join components following ROSS module assembly instructions. Confirm O-ring seals are properly seated before applying tie bolt torque.
• Do not exceed the rated operating pressure for the selected bowl: 150 psig (10 bar) for polycarbonate, 250 psig (17 bar) for aluminum metal bowl.
• After installation, confirm oil delivery by observing the transparent dome. Adjust the external knob to achieve the desired drop rate at actual operating flow conditions.
• Remove the external adjusting knob after setting to activate tamper-resistant mode in installations where lubrication settings must not be altered between scheduled maintenance.
• Use only petroleum-based lubricant with ISO 32 viscosity or lighter. Do not use incompatible oils or additives.
• Inspect the transparent dome periodically for cloudiness, oil deposits, or physical damage. Replace the dome or cartridge assembly if visibility is impaired.

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

Download Catalog: https://www.rosscontrols.com/en/documents/198/ROSS_FRL_Combination_Units_Filter_Regulator_Lubricator.pdf