Miniature Series Port Sizes 1/8 & 1/4; Flow to 10 scfm (283 l/min)

Product Overview

The ROSS Controls Miniature Coalescing Filter delivers precision aerosol removal in a compact inline package for 1/8 and 1/4 port compressed air systems. Rated for flow to 10 scfm (283 l/min), the series uses a borosilicate glass-fiber coalescing element to capture liquid water, oil aerosols, and sub-micron particulate contamination that standard 5-micron filters cannot remove, protecting pneumatic instruments, miniature cylinders, and sensitive solenoid valves from contamination-related failure.

The Miniature Series distinguishes itself from the Bantam Series by its aluminum body construction, which provides greater rigidity and thread strength for inline pipe-threaded installations. Available with a high-strength polycarbonate plastic bowl or a metal bowl, the series covers a range of pressure and temperature requirements while maintaining the compact physical envelope demanded by space-constrained installations.

Two filter element options satisfy different air quality targets: the standard 0.3-micron borosilicate glass-fiber element removes bulk aerosols for general industrial applications, while the optional 0.01-micron element achieves near oil-free air quality approaching ISO 8573-1 Class 1 for instrumentation and food-grade service. Both automatic and manual drain options are available, allowing the designer to match the drain mechanism to the condensate volume and maintenance access of the application.

The Series integrates cleanly into pneumatic systems alongside ROSS Miniature Series regulators and lubricators, making it a straightforward selection for engineers building air preparation stations for small-bore pneumatic lines in panel-mounted, machine-mounted, or inline piping installations.

Key Engineering Features

• 0.3-Micron Borosilicate Glass-Fiber Element - Standard element coalesces sub-micron liquid droplets and aerosol oil, protecting downstream components from contamination caused by compressor oil carryover and condensed water vapor.
• Optional 0.01-Micron Ultra-Fine Element - Upgrades the series to near oil-free service, reducing aerosol oil content to trace levels suitable for instrumentation, food processing, and electronics applications.
• Aluminum Body Construction - Die-cast aluminum body provides greater structural rigidity and thread engagement strength compared to plastic bodies, ensuring durable inline pipe connection without deformation over time.
• Inline Mounting Design - Threaded inline body design installs directly in the compressed air line without requiring a manifold or modular base, simplifying installation in retrofit and space-constrained systems.
• Polycarbonate or Metal Bowl Options - High-strength polycarbonate bowl supports visual condensate-level inspection at up to 150 psig (10 bar); metal (aluminum) bowl extends the pressure rating to 200 psig (14 bar) and temperature to 150 degrees F (66 degrees C).
• Automatic or Manual Drain - Internal automatic float drain continuously expels collected liquid without operator attention; manual drain gives the operator direct control over purging frequency and volume.
• Compact Physical Envelope - With body dimension A of 1.6 inches (41 mm), the series fits in confined machine frames and panel-mounted air preparation stations alongside other Miniature Series components.
• Nitrile Seals for Compressed Air Service - Standard Nitrile elastomer seals provide reliable performance with compressed air and petroleum-based compressor oils across the rated operating temperature range.
• 2-oz (60 ml) Bowl Capacity - Adequate condensate storage for low-to-moderate humidity applications; for high condensate-generating systems, the automatic drain option prevents bowl overflow and downstream liquid carryover.

Technical Specifications

General Specifications

Certifications & Compliance

Typical Applications & Industries

Instrumentation and Analytical Equipment

• Pneumatic instrument air supply to pressure transmitters, positioners, and pneumatic controllers where residual oil or moisture from the compressor would cause calibration drift, stiction, or corrosion of precision internals.
• Laboratory gas handling systems requiring clean, dry compressed air for analytical instruments, mass spectrometers, and chromatography equipment where oil contamination would compromise measurement accuracy.
• Control valve actuator supplies in process plants where clean air is critical for reliable diaphragm actuator operation and predictable valve stem positioning.

Electronics and Semiconductor Manufacturing

• Compressed air supplies for pick-and-place machines, PCB handling, and chip bonding equipment where oil-free air is required to prevent contamination of solder paste, adhesives, and semiconductor surfaces.
• Air bearing and spindle supplies in precision machining and inspection equipment where even trace oil in the air supply would contaminate the bearing surface and cause premature failure.

Food and Beverage Processing

• Actuator and conveyor pneumatic supplies in food processing facilities where oil-contaminated air could contact food products directly or indirectly through packaging, filling, or sealing operations.
• Pneumatic conveying systems for granular or powdered food ingredients where air quality must meet food safety standards and excess moisture would cause product clumping or spoilage.

Automotive and General Industrial

• Air preparation for pneumatic test fixtures, leak detectors, and gauging systems in automotive assembly plants where consistent, dry air prevents false test readings caused by humidity or oil vapor.
• Retrofit coalescing filtration on existing compressed air lines in facilities that have identified oil carryover from aging compressors as a cause of pneumatic component failures.
• Compact machine air preparation stations in OEM equipment where the inline form factor and small envelope fit within a restricted machine enclosure alongside the pneumatic actuators and valves being served.

Ordering and Model Number Configuration

For BSPP (G) thread ports, consult ROSS Controls for model number prefix conventions applicable to the Miniature Series.

Standard element rating is 0.3 micron. The 0.01-micron element (model R-A-10F-16E8) is ordered separately as a replacement element or specified at time of order.

Automatic drain models require a minimum inlet pressure of approximately 30 psig (2 bar) to activate the float mechanism.

Accessories including mounting brackets and coupling kits for modular assemblies are ordered separately from ROSS Controls.

Related Products & Accessories

• 78 Bantam Series Coalescing Filter - Smaller form factor coalescing filter with modular assembly capability, threaded ports, and quick-connect tube fittings for tubing up to 10 mm OD. https://www.rosscontrols.com/en/series/78-bantam-series
• 80 Mid-Size Series Coalescing Filter - Higher-flow coalescing filter for 1/4 to 1/2 port sizes with differential pressure gauge and aluminum bowl with sight glass. https://www.rosscontrols.com/en/series/80-mid-size-series
• Miniature Series Standard Filters - 5-micron and 40-micron particulate filters in the Miniature form factor for upstream pre-filtration ahead of the coalescing stage. https://www.rosscontrols.com/en/categories/40-filters
• Miniature Series Regulators - Compact inline pressure regulators for 1/8 and 1/4 port pneumatic systems in the Miniature Series form factor. https://www.rosscontrols.com/en/categories/42-regulators
• Coalescing Filter Element 945K77 - 0.3-micron borosilicate glass-fiber replacement element for Bantam and Miniature Series coalescing filters. https://www.rosscontrols.com/en/series_variants/512517-945k77

Frequently Asked Questions (FAQ)

Q: What is the flow capacity of the series Miniature coalescing filter?

A: The Series is rated for maximum flow of 10 scfm (283 l/min) at 100 psig (6.9 bar) inlet pressure. Actual flow through the filter will decrease as the element loads with contamination or as inlet pressure decreases.

Q: How does the Miniature Series differ from the Bantam Series coalescing filter?

A: The primary differences are the body material and mounting style. The Miniature Series uses an aluminum body and is designed for inline pipe-threaded mounting, providing greater structural rigidity. The 78 Bantam Series uses an acetal body and supports both inline and modular assembly mounting with threaded or quick-connect tube fittings. The Bantam also accommodates tube fitting sizes up to 10 mm OD that are not available in the Miniature Series.

Q: What bowl material should I specify for higher operating pressures?

A: Specify the metal (aluminum) bowl for operating pressures from 150 to 200 psig (10 to 14 bar) or for ambient temperatures from 125 to 150 degrees F (52 to 66 degrees C). The polycarbonate bowl is limited to 150 psig (10 bar) and 125 degrees F (52 degrees C).

Q: Does the series include a differential pressure indicator?

A: The Series Miniature coalescing filter does not include a differential pressure gauge or indicator in the standard configuration. For differential pressure monitoring, consider the 80 Mid-Size Series or larger ROSS coalescing filter series, which include integral differential pressure gauges.

Q: Which replacement element model should I order?

A: Order model 945K77 for the standard 0.3-micron element or R-A-10F-16E8 for the 0.01-micron ultra-fine element. Both elements are borosilicate glass fiber and fit the standard bowl configuration of the series.

Q: What is the bowl liquid capacity?

A: The bowl capacity is 2 oz (60 ml). For systems with high condensate generation (high humidity environments or wet air compressors), the automatic drain option is strongly recommended to prevent bowl overflow and downstream liquid carry-over.

Q: Can the Miniature Series coalescing filter handle oil mist from a lubricated compressor?

A: Yes. The borosilicate glass-fiber coalescing element is specifically designed to capture aerosol oil droplets including those from reciprocating and rotary screw compressors with lubricant injection. The 0.3-micron element removes the majority of aerosol oil; the 0.01-micron element removes additional trace aerosols for oil-sensitive applications.

Q: Is the automatic drain self-cleaning?

A: The internal float drain operates automatically based on the liquid level in the bowl. It is not self-cleaning in the sense of backflushing the element, but the float mechanism itself requires minimal maintenance under normal operating conditions. The element should be replaced when differential pressure or flow performance degrades.

Q: What are the temperature limits for the polycarbonate bowl?

A: The polycarbonate bowl is rated for 40 to 125 degrees F (4 to 52 degrees C) ambient and media temperature. For applications above 125 degrees F, specify the metal bowl, which extends the temperature limit to 150 degrees F (66 degrees C).

Q: Can the series be used in outdoor installations?

A: The Series can be used outdoors provided the installation environment is within the rated ambient temperature range for the bowl type selected, and that the compressed air supply is dried to prevent ice formation at low temperatures. For temperatures below 40 degrees F (4 degrees C), specify the metal bowl and verify the upstream air dryer dew point is adequate.

Q: Is the flow direction fixed for inline installation?

A: Yes. The Series has a defined flow direction (inlet to outlet) that must be respected during installation. The directional arrow on the body indicates the flow direction. Installing with reversed flow will prevent proper drainage and may reduce filtration efficiency.

Q: What warranty does ROSS Controls provide on the series?

A: ROSS Controls provides a one-year warranty covering defects in material and workmanship from the date of purchase. Contact ROSS at (800) 438-7677 for warranty service, replacement parts, or technical support.

Installation & Maintenance Guidelines

• Install the filter with the bowl pointing downward to allow gravity drainage of collected liquid to the bowl drain point. Horizontal or inverted mounting prevents proper drainage and will cause liquid carryover into the downstream system.
• Provide upstream coarse filtration (5-micron or better) before the coalescing filter to remove bulk particulate matter and prevent premature loading of the coalescing element.
• Verify the rated pressure for the bowl type selected: up to 150 psig (10 bar) for polycarbonate and up to 200 psig (14 bar) for metal bowl. Operating above the rated pressure risks bowl failure.
• Ensure system pressure at the filter inlet meets the minimum pressure for automatic drain activation (approximately 30 psig / 2 bar) when specifying the automatic drain option.
• Depressurize the filter completely before performing element replacement or bowl removal. Do not rely on upstream isolation alone; verify zero pressure at the filter before opening.
• Use only OEM replacement elements (945K77 for 0.3 micron; R-A-10F-16E8 for 0.01 micron) to maintain rated filtration efficiency. Non-OEM elements may not provide the same sealing and filtration performance.
• Inspect the element at each scheduled maintenance interval. Heavy liquid loading visible in the bowl or a measurable pressure drop increase across the filter are indicators that element replacement is needed.
• For outdoor or cold-environment installations, specify the metal bowl option and ensure the compressed air supply is dried to a dew point at least 18 degrees F (10 degrees C) below the minimum expected ambient temperature to prevent ice formation.

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 (1-800-GET-ROSS) or visit rosscontrols.com for product configuration, technical support, and distributor locator services.

Technical service is available at 1-888-TEK-ROSS for application engineering support and replacement parts identification.

Download Catalog: https://www.rosscontrols.com/en/series/79-miniature-series