MD4 Series Port Sizes 3/8" to 3/4"; Flow to 205 scfm (5806 l/min)

Product Overview

The ROSS Controls MD4 Series is the highest-flow modular lubricator in the ROSS standard lineup, engineered for pneumatic systems requiring 3/8 to 3/4 inch port sizes at flow capacities up to 205 scfm (5,806 l/min). The MD4 Series is the larger counterpart to the MD3 Series, extending the transparent dome sight-feed design and removable adjusting knob architecture to the higher flow demands of 3/4 inch main air headers and high-capacity pneumatic circuits.

Like the MD3, the MD4 Series uses a transparent dome design that allows direct visual observation of oil being dispensed into the compressed air supply. This feature enables maintenance personnel to confirm active lubrication at a glance during production, during commissioning of new equipment, and at scheduled maintenance checkpoints. The dome approach is superior to single-drop counting sight glasses for confirming that the lubricator is actively delivering oil, particularly at higher flow rates.

The external adjusting knob on MD4 models is engineered to be removable. With the knob installed, qualified maintenance personnel can calibrate oil delivery rate to match equipment requirements. With the knob removed, the delivery rate is maintained at the last set position and the adjustment interface is absent, making the lubricator tamper-resistant without any additional hardware.

Three bowl options cover the range of volume requirements: a 9-oz (266-ml) polycarbonate bowl with steel shatterguard for standard applications, a 9-oz aluminum bowl with nylon sight glass for elevated pressure and temperature conditions, and a 15-oz (443-ml) extended aluminum bowl for applications requiring maximum reservoir capacity between refills. All working parts are contained in a field-replaceable cartridge.

Key Engineering Features

• Transparent Dome for Direct Oil Delivery Monitoring - Transparent nylon dome enables direct visual observation of oil being dispensed into the airstream, providing immediate confirmation of active lubrication without drop counting or instrumentation.
• Removable External Adjusting Knob - Oil delivery rate is adjustable via external knob. Knob removal locks the current setting and eliminates the adjustment interface, creating a robust tamper-resistant configuration for installations requiring fixed lubrication delivery.
• Extended Metal Bowl Option - 15-oz (443-ml) extended aluminum bowl with nylon sight glass provides the maximum reservoir capacity in the MD4 lineup for high-consumption applications or locations with infrequent maintenance access.
• Highest Flow Modular Lubricator - At 205 scfm, the MD4 Series provides the highest flow capacity in the ROSS modular lubricator lineup, making it the appropriate choice for 3/4 inch supply headers and high-volume pneumatic circuits.
• Modular or Inline Mounting - Compatible with ROSS MD4 Series filter and regulator components for complete modular FRL assembly, or mountable inline in existing pipework as a standalone lubricator.
• Quick-Fill Cap Option - Available quick-fill cap allows pressurized oil replenishment without removing the bowl or stopping the air supply. Particularly valuable on high-flow production lines where maintenance shutdowns are costly.
• Polycarbonate or Aluminum Bowl - 9-oz polycarbonate bowl with steel shatterguard rated to 150 psig (10 bar) and 125 F (52 C). 9-oz aluminum bowl rated to 200 psig (14 bar) and 175 F (80 C). Extended 15-oz aluminum bowl also rated to 200 psig.
• Replaceable Cartridge Design - All internal working parts are contained in a single replaceable cartridge assembly, allowing field service without special tools and minimizing downtime during scheduled maintenance.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

High-Volume Pneumatic Supply Systems

• Main compressed air supply headers at 3/4 inch serving multiple downstream circuits in automotive assembly plants, where 200 scfm flow capacity supports simultaneous operation of multiple tool stations without pressure drop restriction at the lubricator.
• Central FRL station 3/4 inch main air outlets in machine shop environments, where the MD4 modular assembly provides a complete filter-regulator-lubricator station at the machine header before distribution to individual tool drops.
• High-bay manufacturing facility pneumatic tool supply buses, where a single MD4 lubricator in the main 3/4 inch supply header provides lubrication for all downstream tools and actuators, simplifying the lubrication maintenance program.

Heavy Pneumatic Tooling and Construction

• Pneumatic rock drills, down-the-hole hammers, and rotary drill air supplies in mining and quarry operations, where 3/4 inch supply lines at high flow rates require MD4 capacity and the metal bowl handles higher operating temperatures near compressor discharge.
• Demolition hammers, breakers, and scarifiers in construction applications, where high-cycle vibrating equipment demands consistent lubrication delivery and the extended metal bowl provides reservoir capacity for extended shifts without refilling.
• Pile driving pneumatic hammer supply lines, where the MD4's 205 scfm capacity matches the air demand of large pneumatic hammers and transparent dome monitoring confirms lube delivery to the hammer mechanism.

Automotive Manufacturing - Large Actuator Circuits

• Pneumatic press clamping and transfer system main supply headers in automotive body-in-white operations, where multi-cylinder simultaneous actuation requires lubricator flow capacity above the MD3 and Full-Size Series range.
• Spot welding gun pneumatic actuation circuits on robotic welding lines, where 3/4 inch supply at over 150 scfm feeds electrode opening and closing cylinders, and the transparent dome confirms lubrication during welding cell commissioning.
• Automotive assembly conveyor system pneumatic actuators for carrier transfers, accumulation zones, and part positioners, where modular MD4 FRL stations at conveyor junction points provide protected, regulated, lubricated air for high-cycle actuators.

Steel and Metal Processing

• Rolling mill pneumatic actuator circuits for strip tension, roll gap, and side trimmer pneumatic controls, where 3/4 inch supply headers at elevated pressures benefit from the MD4 metal bowl rated to 200 psig.
• Coil handling and steel service center pneumatic equipment, where heavy pneumatic cylinders on coil cars, peelers, and threading tables demand high-flow lubrication that MD4 capacity provides at 3/4 inch header sizes.
• Continuous casting pneumatic mold oscillation and withdrawal roll controls, where the transparent dome monitoring feature enables process engineers to verify lubricant delivery during continuous casting sequences without stopping the process.

Rubber and Tire Manufacturing

• Tire building machine pneumatic actuator circuits, where bladder inflation, bead placement, and stitching operation pneumatic systems operate at high flow rates requiring MD4 capacity at 1/2 and 3/4 inch supply sizes.
• Rubber calendering line pneumatic roll gap and strip tension actuators, where high ambient temperature environments near calender rolls require zinc body and aluminum bowl construction rated to 175 F (80 C).
• Vulcanizing press pneumatic circuits for opening, closing, and bladder inflation actuators, where extended metal bowls reduce maintenance interruptions during continuous production vulcanizing campaigns.

Petrochemical and Oil Refinery

• Process plant pneumatic control valve actuators in refineries and chemical plants, where 3/4 inch instrument air supply circuits at elevated pressures up to 200 psig require the MD4 aluminum bowl option for pressure compliance.
• Wellhead pneumatic actuator supply systems at oil and gas production facilities, where modular FRL stations provide clean, regulated, lubricated air for surface-controlled subsurface safety valve (SCSSV) actuation pneumatic supply.
• Compressor station pneumatic valve and actuator air supply in pipeline operations, where high-flow demand at 3/4 inch supply headers and outdoor installation conditions favor the aluminum bowl MD4 for its temperature and pressure range.

Ordering and Model Number Configuration

The MD4 Series uses a configurable model number. An example: MD4 51P S B 3 2 specifies a polycarbonate 9-oz bowl, fill port, 3/8 G thread port, black cap. Substitute fill method, port, and bowl codes as needed.

NPT thread models use numeric port codes (3, 4, 5). G (BSPP) thread models use letter codes (C, D, E).

Standard polycarbonate bowl (51P) is rated to 150 psig (10 bar) and 125 F (52 C). Aluminum bowl (51M, 51E) is rated to 200 psig (14 bar) and 175 F (80 C).

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

Accessories

MD4 Series Filters

ROSS MD4 Series modular filters for 3/8 to 3/4 inch ports with 5-micron or 40-micron filter elements. Available with polycarbonate or aluminum bowls, automatic or manual drain. Mount directly to MD4 Series lubricators and regulators.

MD4 Series Regulators

Modular piston-type regulators for 3/8 to 3/4 inch ports in MD4 Series FRL assemblies. Adjustable pressure with optional lockout valve (L-O-X or EEZ-ON) for energy isolation during maintenance.

Extended Metal Bowl

15-oz (443-ml) extended aluminum bowl with two nylon sight glass windows provides maximum oil reservoir capacity. Bowl removal clearance: 6.1 inches (155 mm). Rated to 200 psig (14 bar) and 175 F (80 C).

Related Products & Accessories

• MD3 Series Lubricators - Modular sight-feed lubricators for 1/4 to 1/2 inch ports. Transparent dome, removable knob, extended bowl. 250 psig metal bowl rating. Flow to 150 scfm. https://www.rosscontrols.com/en/series/107-md3-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. Flow to 140 scfm. https://www.rosscontrols.com/en/series/108-full-size-series
• 110 High-Capacity Series Lubricators - Inline sight-feed and wick-feed lubricators for 3/4 to 1-1/2 inch ports. Multiple bowl size options. Flow to 500 scfm. https://www.rosscontrols.com/en/series/110-high-capacity-series
• 106 Mid-Size Series Lubricators - Modular sight-feed lubricators for 1/4 to 1/2 inch ports. 4-oz bowl. Flow to 110 scfm. https://www.rosscontrols.com/en/series/106-mid-size-series

Frequently Asked Questions (FAQ)

Q: What is the difference between the MD4 Series and the MD3 Series?

A: The MD4 Series covers larger port sizes (3/8 to 3/4 inch vs 1/4 to 1/2 inch for MD3) and delivers higher maximum flow (205 scfm vs 150 scfm). Both series use the transparent dome sight-feed design and removable external adjusting knob. The MD4 uses a 9-oz bowl versus the MD3's 5.1 to 6 oz bowl, and the MD4 extended bowl is 15 oz versus 10 oz for the MD3. The MD3 aluminum bowl is rated to 250 psig while the MD4 metal bowl is rated to 200 psig.

Q: What is the maximum flow capacity of the MD4 Series?

A: The MD4 Series is rated for a maximum flow of 205 scfm (5,806 l/min), making it the highest-flow modular lubricator in the ROSS standard lineup. This capacity supports 3/4 inch supply headers serving high-volume pneumatic circuits in demanding industrial applications.

Q: When should I specify the extended metal bowl?

A: Specify the extended 15-oz (443-ml) aluminum bowl when: the application consumes oil at a rate that exhausts the standard 9-oz bowl faster than the maintenance schedule allows, the lubricator is installed in a location with difficult access requiring maximum time between refills, or production runs longer than the standard bowl capacity will support without maintenance interruption. Extended bowl removal requires 6.1 inches (155 mm) of clearance versus 3.1 inches for the standard bowl.

Q: Can the MD4 lubricator be used in a modular FRL assembly?

A: Yes. The MD4 Series is designed for modular assembly with ROSS MD4 Series filters and regulators. The modular construction allows the filter, regulator, and lubricator to be joined without separate pipe fittings between components, reducing the number of potential leak points and simplifying the FRL station.

Q: What operating pressure is the MD4 metal bowl rated for?

A: The aluminum metal bowl (51M and 51E) is rated to 200 psig (14 bar). The polycarbonate bowl (51P) is rated to 150 psig (10 bar). For applications requiring pressures above 200 psig in this port size range, consult ROSS technical support for alternative configurations.

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

A: A standard sight glass provides a narrow window for counting drops. The MD4 transparent dome provides a broader, clearer view area that makes it easier to observe the oil delivery process, particularly at the higher flow rates common in 3/4 inch circuits. The dome design also makes it easier to see whether oil is flowing continuously versus intermittently, giving maintenance personnel a better qualitative assessment of lubricator performance.

Q: What is the difference between tamper-resistant and tamper-proof adjustment?

A: Tamper-resistant (as used on the MD4 with the knob removed) means the adjustment mechanism is protected from casual or accidental changes. With the knob removed, there is no accessible interface to change the setting. Tamper-proof (as used on the 105 Miniature Series) means the adjustment is internal and requires disassembly to change. The MD4's removable knob approach gives more flexibility because the knob can be reattached when authorized adjustments are needed.

Q: Are quick-fill cap models available for the MD4?

A: Yes. Quick-fill cap models are available for all MD4 configurations by selecting fill method Q in the model number. The quick-fill cap allows pressurized oil refilling without removing the bowl or interrupting the air supply.

Q: What is the bowl removal clearance for the MD4?

A: Standard 9-oz bowl removal requires approximately 3.1 inches (79 mm) of clearance below the lubricator body. The extended 15-oz bowl requires approximately 6.1 inches (155 mm). Plan for these clearances before installing in a panel, enclosure, or overhead position.

Q: What lubricant is recommended for the MD4 Series?

A: Use petroleum-based lubricant with ISO 32 viscosity or lighter and an aniline point between 180 F and 220 F. Standard pneumatic tool oil grades meeting these criteria are appropriate for MD4 Series applications. Do not use synthetic fluids, phosphate-ester fluids, or lubricants with additives incompatible with nitrile seals.

Q: Can the MD4 Series handle compressed air at elevated temperatures near compressor discharge?

A: The aluminum bowl MD4 is rated to 175 F (80 C) media temperature. If the compressed air temperature at the lubricator inlet exceeds 175 F, the air must be cooled (aftercooler, dryer, or sufficient pipe run) before reaching the lubricator. Do not install polycarbonate bowl models (rated to 125 F) in locations where compressed air temperature exceeds this limit.

Q: Is the MD4 Series available with both NPT and BSPP threads?

A: Yes. NPTF threads are specified using numeric port codes (3 = 3/8, 4 = 1/2, 5 = 3/4). G (BSPP) threads use letter codes in the model number (C = 3/8 G, D = 1/2 G, E = 3/4 G).

Installation & Maintenance Guidelines

• Install the lubricator downstream of the filter and regulator in the air treatment sequence. Lubricating contaminated air degrades wick and cartridge service life.
• Mount with the bowl in the downward vertical position for correct sight dome alignment and oil reservoir operation.
• Verify bowl removal clearance before installation: 3.1 inches (79 mm) for 9-oz standard bowls, 6.1 inches (155 mm) for 15-oz extended bowls.
• For modular FRL assembly with MD4 Series filters and regulators, follow ROSS module assembly instructions for O-ring seating and tie bolt torque specifications.
• Confirm system pressure does not exceed 150 psig for polycarbonate bowl or 200 psig for aluminum bowl under all operating and upset conditions.
• After installation, observe the transparent dome at operating conditions to confirm oil delivery. Adjust the external knob as needed to achieve target delivery rate.
• After adjustment, remove the external knob to activate tamper-resistant mode if required by site maintenance policy.
• Use only petroleum-based ISO 32 viscosity or lighter lubricant with aniline point between 180 F and 220 F.
• For high-ambient temperature installations (above 125 F), confirm the aluminum bowl option (51M or 51E) is specified.
• Inspect the transparent dome and bowl periodically for signs of degradation, contamination, or physical damage.

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