Mid-Size Series Port Sizes 1/4" to 1/2"; Flow to 75 scfm (2124 l/min)

Actual product may differ from above image. Product details should be verified before purchase.

Modular or inline mounting
High-strength polycarbonate plastic filter bowl with zinc shatterguard, or zinc bowl
Internal automatic drain, or manual drain

Air Preparation Filters Mid-Size Series Product Overview

Within our Mid-Size Series Air Preparation Filters, you'll find robust filtration solutions tailored to a range of applications. These filters offer 5- and 40-micron filtration levels to effectively remove particulate matter from your air systems. For more precise filtration, our Coalescing Filters come in 0.3- and 0.01-micron options. Our Oil Vapor Removal (Adsorbing) Filters are designed to eliminate oil and hydrocarbon vapors, maintaining the purity of your air supply. To ensure easy maintenance, we provide a selection of Filter Drains, including manual, automatic, internal float, and automatic external drains. With modular and in-line mounting options, these filters can be adapted to your specific space and system requirements. Choose between metal and High Strength polycarbonate bowl materials to suit different environmental conditions. To monitor and control your filtration processes with precision, we offer several Differential Gauge options. The Mid-Size Series Air Preparation Filters provide a versatile and reliable solution for diverse filtration needs.

Please refer to the side and below for links to easily navigate and Air Preparation Filters Mid-Size Series catalogs, installation instructions, and technical data. Additionally, you have the option to filter through all available options to discover the Air Preparation Filters Mid-Size Series, variant that meets your requirements.

Series Overview ❯

Product Overview

The ROSS Controls Mid-Size Series is a family of modular and inline air preparation filters engineered for port sizes 1/4 inch through 1/2 inch (NPT or G/BSPP) with maximum particulate filter flow of 75 scfm (2,124 l/min). The Mid-Size Series provides the core filtration tier in ROSS FRL assemblies serving medium-sized pneumatic systems, bridging the performance gap between the compact Miniature/Bantam filters and the higher-flow MD3, Full-Size, and MD4 series.

The Mid-Size Series encompasses particulate filters, coalescing filters, and oil vapor removal filter options. Particulate filters remove solid contaminants to 5-micron (standard polyethylene element), 20-micron, or 40-micron (optional sintered bronze) levels. Coalescing filters using borosilicate glass fiber elements remove oil aerosols to 0.3-micron (standard) or 0.01-micron (high-efficiency) levels. Oil vapor removal (adsorbing) filters use activated carbon technology to capture hydrocarbon vapors that pass through standard and coalescing elements.

Both modular and inline mounting options are supported. Modular mounting enables assembly of multi-unit filtration and regulation stations on port kits or manifolds, creating compact FRL assemblies with a single pipe inlet and outlet. Inline mounting installs the filter directly in a pipeline. Drain options include internal automatic drain and manual drain, with an optional internal float drain available on select configurations.

The Mid-Size Series bowl uses high-strength polycarbonate with a zinc shatterguard for protection against bowl fragmentation in the event of an impact, or a zinc metal bowl with optional clear nylon sight glass for higher temperature and pressure applications. This series is the recommended starting point for general-purpose industrial pneumatic systems requiring reliable filtration at 1/4-inch through 1/2-inch port sizes.

Key Engineering Features

Modular and Inline Mounting Options - Supports both modular manifold station assembly and direct pipeline (inline) installation, providing configuration flexibility for central FRL stations or point-of-use inline installations.
5- and 40-Micron Particulate Filtration - Standard 5-micron polyethylene element removes fine particulates and condensate droplets. Optional 40-micron sintered bronze element provides coarser cut prefiltration for high-contamination upstream supply lines.
Coalescing Filter Option (0.3 and 0.01 Micron) - Coalescing variants using borosilicate glass fiber elements aggregate and drain sub-micron oil aerosols. The 0.3-micron element satisfies ISO 8573-1 Class 2 oil; the 0.01-micron element meets Class 1 for sensitive downstream equipment.
Oil Vapor Removal (Adsorbing) Filter Option - Activated carbon adsorbing filter elements capture oil and hydrocarbon vapors that pass through particulate and coalescing elements, essential for applications requiring oil-free air at the vapor phase.
High-Strength Polycarbonate with Zinc Shatterguard - Standard polycarbonate bowl includes a zinc shatterguard ring that retains bowl fragments in the event of impact failure, protecting personnel and equipment from projectile hazard.
Zinc Metal Bowl Option with Sight Glass - Zinc metal bowl extends upper operating temperature to 175 F (79 C) and maximum pressure to 200 psig (14 bar). Clear nylon sight glass allows visual liquid level monitoring without the transparency limitation of opaque metal bowls.
Internal Automatic Drain and Manual Drain Options - Internal automatic drain provides continuous condensate purging without operator intervention. Manual drain provides operator-controlled purging. Internal float drain option available (consult ROSS) for applications with high condensate accumulation rates.
4-Ounce Bowl Capacity - 4-oz (120-ml) bowl provides greater condensate holding volume than Bantam or Miniature Series units, reducing drain frequency on systems with moderate-to-high condensate generation rates.
Differential Gauge Options Available - Optional differential pressure gauges indicate element loading status, allowing data-driven element replacement decisions rather than time-based replacement intervals.
NPT and G (BSPP) Thread Availability - Both NPT and G (BSPP) thread types are catalog-standard, supporting installations on North American and international machine designs without adapter fittings.

Technical Specifications

General Specifications

Parameter	Specification
Series	Mid-Size Series (ROSS FRL)
Product Type	Modular and Inline Air Preparation Filters (particulate, coalescing, adsorbing)
Port Sizes	1/4", 3/8", 1/2" (NPT or G/BSPP)
Maximum Flow (Particulate Filter, 5 µm)	75 scfm (2,124 l/min)
Maximum Flow (Coalescing Filter, 0.3/0.01 µm)	100 scfm (2,832 l/min) (standard bowl); 85 scfm noted in some configurations
Filtration Levels	5 µm (polyethylene, standard); 20 µm and 40 µm (sintered bronze, optional); 0.3 µm and 0.01 µm (borosilicate glass fiber, coalescing variants); Activated carbon (adsorbing variant)
Bowl Capacity	4 oz (120 ml) standard; 10 oz (300 ml) extended coalescing bowl
Bowl Materials	Polycarbonate with zinc shatterguard (standard); Zinc with clear nylon sight glass (metal bowl option)
Drain Types	Internal automatic; Manual; Internal float (consult ROSS)
Mounting	Modular (manifold/port kit) or Inline
Port Thread Types	NPTF (NPT); G (BSPP)
Flow Media	Compressed air
Body Material	Zinc
Seal Material	Nitrile
Standard Particulate Element	5 µm Polyethylene (Part No. 936K77)
Standard Coalescing Element	0.3 µm Borosilicate Glass Fiber

Temperature Ratings

Temperature ratings are determined by bowl material selection. Polycarbonate bowl has a lower upper limit; zinc (metal) bowl permits higher temperature operation.

Configuration	Ambient Temperature	Media Temperature
Polycarbonate Bowl (Particulate Filter, Auto or Manual Drain)	40 to 125 F (4 to 52 C)	40 to 125 F (4 to 52 C)
Zinc Bowl (Particulate Filter, Auto or Manual Drain)	40 to 175 F (4 to 79 C)	40 to 175 F (4 to 79 C)
Aluminum Bowl (Coalescing Filter, Auto or Manual Drain)	40 to 175 F (4 to 79 C)	40 to 175 F (4 to 79 C)

Important: Do not use polycarbonate bowls in environments with solvents, strong cleaning agents, or other chemicals incompatible with polycarbonate. Select the zinc metal bowl option for elevated temperature service or chemical exposure environments.

Flow Performance Data

Flow performance at 100 psig inlet pressure, new element. Coalescing filter maximum flow may differ between standard and extended bowl configurations.

Port Size	Filter Type	Max Flow	Bowl Capacity
1/4"	Particulate (5 µm)	75 scfm (2,124 l/min)	4 oz (120 ml)
3/8"	Particulate (5 µm)	75 scfm (2,124 l/min)	4 oz (120 ml)
1/2"	Particulate (5 µm)	75 scfm (2,124 l/min)	4 oz (120 ml)
1/4" to 1/2"	Coalescing (0.3/0.01 µm)	100 scfm (2,832 l/min) std / 85 scfm loaded	6 oz (180 ml) std, 10 oz (300 ml) ext

Certifications & Compliance

Certification/Standard	Detail
Thread Standards	NPT (NPTF) per ANSI B1.20.1; G (BSPP) per ISO 228. Both available as standard catalog models.
Material Compliance	Nitrile seals, polyethylene and sintered bronze filter elements are compatible with compressed air service. Zinc body with shatterguard polycarbonate bowl provides protection against bowl failure.
Pressure Vessel Design	Polycarbonate bowl with zinc shatterguard rated to 150 psig (10 bar); zinc metal bowl rated to 200 psig (14 bar). Coalescing aluminum bowl rated to 150 psig.
ISO Air Quality	5-micron particulate filter addresses ISO 8573-1 Class 3-5 particulate. 0.3-micron coalescing element addresses Class 2 oil. 0.01-micron element addresses Class 1 oil. Activated carbon adsorber addresses hydrocarbon vapor content.

Typical Applications & Industries

General Industrial Pneumatics and Factory Automation

Central air preparation stations for pneumatic distribution headers serving multiple machine tools, robots, or automation systems where 1/4-inch to 1/2-inch port sizes are the supply line standard.
Pneumatic cylinder and actuator supply circuits on conveyors, transfer lines, indexing systems, and automated assembly equipment requiring reliable particulate-free air at moderate flow rates.
Pneumatic valve and solenoid-operated valve supply conditioning where 5-micron filtration removes particulates that would otherwise accumulate on valve seats, seals, and orifices.
Air preparation for pneumatic grippers, rotary actuators, rodless cylinders, and multi-axis actuator systems in factory automation cells requiring clean air at consistent pressure.
Compressed air supply to pneumatic tools at production workstations including impact wrenches, drills, grinders, and sanders where filtered air protects tool internals and extends service intervals.

Automotive Manufacturing and Assembly

Body shop pneumatic circuits including spot weld gun cylinders, part clamp and locate actuators, and transfer bar systems where consistent air quality reduces weld quality variation and cylinder maintenance.
Paint shop air preparation for pneumatic actuators in paint booth environments where clean, dry air prevents contamination of paint lines and spray atomization equipment.
Assembly line torque tool supply headers where 1/2-inch port filters supply regulated clean air to multiple nutrunner and torque wrench tool drops along the assembly line.
Engine assembly pneumatic circuits for cylinder bore cleaning air, valve seat seating actuators, and automated assembly press systems requiring reliable pneumatic performance.

Food and Beverage Processing

Air preparation ahead of pneumatic actuators on filling machines, capping heads, labeling systems, and conveyor diverters where moderate flow at 1/4-inch to 1/2-inch ports is required.
Coalescing filter (0.3 or 0.01 micron) installation ahead of air jets, air knives, and product blow-off systems that may have incidental product contact, meeting food-grade air purity requirements.
Air preparation for pneumatic product handling on packaging lines including pick-and-place, vacuum cup circuits, and pneumatic pushers in bakery, dairy, meat, and beverage applications.
Compressed air supply conditioning in clean-in-place (CIP) and sanitation environments where polycarbonate bowls are protected by the zinc shatterguard against incidental impacts from cleaning tools.

Process Industries and Utilities

Instrument air supply conditioning for pneumatic valve positioners, control valve operators, and pneumatic transmitters in process plant environments at 1/4-inch to 1/2-inch supply port sizes.
Compressed air preparation for pneumatic sampling systems and purge-and-pressurization air supply in hazardous area enclosures where clean, dry air at controlled pressure is required.
Air preparation for pneumatic actuators on process valves, dampers, and louvers in power generation, water treatment, and chemical plant environments.
Coalescing filter application ahead of critical pneumatic instruments in refinery and petrochemical environments where oil carryover from reciprocating compressors would degrade instrument reliability.

Ordering and Model Number Configuration

The ROSS Mid-Size Series uses a structured model number system that encodes port size, bowl type, drain type, and mounting configuration. Prefix C is added for G (BSPP) thread models. Coalescing and adsorbing filter variants have separate model number series.

MID-SIZE SERIES EXAMPLE MODEL NUMBERS (Particulate Filter, Modular):

Modular, Auto Drain, Polycarbonate Bowl:

1/4" NPTF: 5021B2007

3/8" NPTF: 5021B3027

1/2" NPTF: 5021B4007

Modular, Auto Drain, Metal (Zinc) Bowl:

1/4" NPTF: 5022B2007

3/8" NPTF: 5022B3027

1/2" NPTF: 5022B4007

Modular, Manual Drain, Polycarbonate Bowl:

1/4" NPTF: 5011B2007

3/8" NPTF: 5011B3027

1/2" NPTF: 5011B4007

Modular, Manual Drain, Metal (Zinc) Bowl:

1/4" NPTF: 5012B2007

3/8" NPTF: 5012B3027

1/2" NPTF: 5012B4007

For G (BSPP) threads: add prefix C (e.g., C5021B2007)

REPLACEMENT ELEMENTS:

936K77 = 5 µm Polyethylene (standard)

R-KA60F-03E5 = 5 µm Sintered Bronze

R-KA60F-03E4 = 20 µm Sintered Bronze

R-KA60F-03E3 = 40 µm Sintered Bronze

For G (BSPP) threads, add the prefix C to the model number (e.g., C5021B2007 for 1/4-inch G, auto drain, polycarbonate).

Coalescing filter model numbers use a separate configuration string; consult ROSS Controls for coalescing model selection.

Internal float drain option is available; contact ROSS Controls for the applicable model number.

The 936K77 (5-micron) replacement element is specific to the Mid-Size Series and is not interchangeable with Bantam/Miniature 933K77 elements.

Differential pressure gauge options are available for element condition monitoring; consult ROSS Controls for model number designations.

Accessories

Replacement Filter Elements

ROSS replacement filter elements for the Mid-Size Series. Note: Mid-Size elements (936K77 series) are not interchangeable with Bantam/Miniature Series elements.

Element Rating	Material	Model Number
5 µm (standard particulate)	Polyethylene	936K77
5 µm (optional particulate)	Sintered Bronze	R-KA60F-03E5
20 µm (optional particulate)	Sintered Bronze	R-KA60F-03E4
40 µm (optional particulate)	Sintered Bronze	R-KA60F-03E3

Differential Pressure Gauges

Optional differential pressure gauges available to indicate filter element loading. The gauge measures pressure drop across the filter element and alerts the user when element replacement is required, enabling condition-based maintenance rather than fixed-interval replacement.

Frequently Asked Questions (FAQ)

Q: What is the maximum flow capacity of the Mid-Size Series?

A: The particulate filter models provide flow to 75 scfm (2,124 l/min) through the standard 5-micron polyethylene element at 100 psig inlet pressure. Coalescing filter variants using borosilicate glass fiber elements provide up to 100 scfm (2,832 l/min) at 100 psig. These values are for new elements; flow decreases as elements load with particulate.

Q: What port sizes does the Mid-Size Series support?

A: The Mid-Size Series is available in 1/4-inch, 3/8-inch, and 1/2-inch port sizes in both NPT (NPTF) and G (BSPP) thread types. For 1/8 and 1/4-inch port applications with lower flow requirements, the Bantam or Miniature Series is the appropriate smaller-body choice.

Q: What is the difference between the Mid-Size Series and the MD3 Series?

A: Both cover 1/4 to 1/2 port sizes, but the MD3 Series is the newer, higher-flow design providing 92 scfm versus the Mid-Size's 75 scfm. The MD3 also supports diaphragm-type regulator configuration, a wider array of drain options, and integration with L-O-X lockout valves in a combined assembly. The MD3 is the preferred selection for new machine designs; the Mid-Size is the established, proven design for OEM continuity applications.

Q: What filtration levels are available?

A: Particulate filter models offer 5-micron polyethylene (standard), 20-micron sintered bronze, and 40-micron sintered bronze elements. Coalescing filter variants use 0.3-micron borosilicate glass fiber (standard) and 0.01-micron (high-efficiency) elements. Oil vapor adsorbing filter variants use activated carbon elements for hydrocarbon vapor removal.

Q: Does the polycarbonate bowl include shatter protection?

A: Yes. The Mid-Size Series polycarbonate bowl includes a zinc shatterguard that encases the lower portion of the bowl. This retains bowl fragments in the event of bowl impact failure, protecting personnel and nearby equipment from the projectile hazard associated with unprotected plastic bowls under pressure.

Q: What is the maximum operating temperature?

A: Polycarbonate bowl models are rated to 125 F (52 C) ambient and media temperature. Zinc metal bowl models extend the upper rating to 175 F (79 C). Coalescing filter aluminum bowl models are also rated to 175 F (79 C).

Q: What is the maximum inlet pressure?

A: Polycarbonate bowl models are rated to 150 psig (10 bar) maximum inlet. Zinc metal bowl models are rated to 200 psig (14 bar). Automatic drain models require a minimum inlet pressure of approximately 30 psig for the automatic drain mechanism to function.

Q: Can the Mid-Size Series be configured for modular or inline installation?

A: Yes. The Mid-Size Series supports both modular manifold station assembly and direct inline pipeline installation. The modular configuration uses ROSS port kits to connect multiple filter, regulator, and lubricator units with a single inlet and outlet connection. The inline configuration mounts directly in the pipeline.

Q: What replacement element is standard for Mid-Size Series particulate filters?

A: The standard replacement element is 936K77 (5-micron polyethylene). This is distinct from the 933K77 used in the Bantam and Miniature Series. The Mid-Size element is physically larger to accommodate the greater bowl capacity and flow rating.

Q: Is a differential pressure gauge available to indicate element replacement timing?

A: Yes. Optional differential pressure gauges are available for Mid-Size Series filters. The gauge measures pressure drop across the element; when the differential pressure reaches the replacement threshold (typically 10 psig), the element is due for replacement. This enables condition-based rather than fixed-interval maintenance.

Q: What is the bowl capacity of the Mid-Size Series?

A: The standard particulate filter bowl holds 4 oz (120 ml) of condensate. Coalescing filter standard bowls hold 6 oz (180 ml); extended bowls for the coalescing variant hold 10 oz (300 ml). The larger bowl capacity compared to the Bantam/Miniature Series reduces drain frequency in systems with higher condensate generation.

Q: Are BSPP (G) thread models available as standard catalog items?

A: Yes. For G (BSPP) thread models, add the prefix C to the NPT model number. For example, C5021B2007 is the 1/4-inch G thread, auto drain, polycarbonate bowl modular particulate filter.

Installation & Maintenance Guidelines

Mount with flow direction matching the inlet/outlet port markings. Vertical installation with bowl pointing down is preferred for automatic drain efficiency and condensate collection.
Install an isolation shutoff valve upstream of the filter to enable element replacement and service without full system depressurization.
In systems with significant pipe scale, compressor oil carryover, or high moisture content, consider installing a coarser prefiltration stage (40-micron) upstream of the 5-micron filter to extend primary element service life.
For coalescing filter installations, always install a 5-micron particulate prefilter upstream. Liquid water entering a coalescing element saturates the glass fiber media and reduces coalescing efficiency significantly.
Automatic drain models require minimum inlet pressure of approximately 30 psig for the float mechanism to function correctly. Verify supply pressure before commissioning.
Manual drain models: drain accumulated condensate before the liquid level reaches the bottom of the filter element. Liquid carryover through the element will degrade downstream equipment and shorten element life.
Replace particulate elements when differential pressure across the filter element reaches 10 psig (0.7 bar). Using a differential pressure gauge accessory is recommended for condition-based element management.
Torque threaded port connections wrench-tight without over-tightening. Over-torquing NPT fittings in the zinc body can damage port threads and compromise joint integrity.
Do not expose polycarbonate bowls to solvents, ketones, chlorinated hydrocarbons, or other chemicals incompatible with polycarbonate. Select the zinc metal bowl if chemical exposure is possible.
Verify shatterguard installation is secure before pressurization. The zinc shatterguard ring must be properly seated on the bowl before the bowl is threaded onto the body.

Warranty & Global Support

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

Global technical support is available through ROSS Controls 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 selection assistance, technical support, and distributor locator services.

For complete dimensional drawings, flow curves, and catalog data for the Mid-Size Series, visit the ROSS Controls product page at rosscontrols.com or download the ROSS FRL catalog.

Download Catalog: https://www.rosscontrols.com/en/series/76-mid-size-series