Miniature Precision Series Port Sizes 1/8" & 1/4"; Flow to 40 scfm (1133 l/min)

Product Overview

The ROSS Controls is a family of compact inline precision pressure regulators engineered for applications demanding accurate, repeatable output pressure in a minimal footprint. Available in 1/8" and 1/4" port sizes, these miniature units deliver flow to 40 scfm (1133 l/min) while maintaining regulated pressures from 0 to 100 psig (0 to 7 bar) against an inlet supply of up to 300 psig (21 bar).

Precision regulators differ fundamentally from standard industrial regulators through a combination of a small valve seat and an oversized diaphragm sensing area. This geometry allows the diaphragm to detect and correct even minor deviations in downstream pressure before they become perceptible to downstream equipment. The result is pressure settings held to within 3 psig (0.2 bar) across varying flow demand, a characteristic critical for pneumatic torque tools, instrumentation air supplies, and sensitive process control systems.

The Series uses diaphragm construction exclusively in these miniature bodies, providing the high sensitivity and fast response required for low-flow precision applications. The self-relieving design allows downstream pressure to exhaust back through the regulator body when set point is lowered, eliminating the need for a separate downstream relief valve in most installations. Both NPTF and G (BSPP) thread options are available, enabling worldwide application compatibility.

For engineers specifying air pressure control in confined panel spaces, instrument enclosures, or at individual pneumatic tool stations, the series provides ROSS Controls' proven precision performance in one of the smallest available package sizes, with front and rear 1/8" NPT gauge ports for in-line pressure verification without breaking the main circuit.

Key Engineering Features

• Diaphragm Construction with Large Sensing Area - Combines a small valve seat with an oversized diaphragm to achieve high sensitivity to downstream pressure deviations, maintaining set pressure within 3 psig (0.2 bar) across variable flow demand.
• Self-Relieving Design - Allows excess downstream pressure to vent through the regulator body when set point is reduced, eliminating the requirement for a separate downstream relief device in most circuit configurations.
• Compact Miniature Footprint - Body dimensions of 1.8" x 3.4" x 0.4" (44 x 86 x 10 mm) at 0.38 lb (0.16 kg) makes the series suitable for tight panel installations, instrument enclosures, and individual tool stations.
• High Inlet Pressure Rating - Accepts supply pressures up to 300 psig (21 bar), accommodating high-pressure header systems while regulating down to precise working pressures for sensitive downstream equipment.
• Dual Gauge Port Orientation - Front and rear 1/8" NPT gauge ports allow pressure gauge installation in either orientation to suit panel layout without requiring additional fittings or tee connections.
• Panel Mount Capability - Compatible with 1-3/16" (30 mm) panel cutout for flush-mount installation in control panels or enclosure doors, securing the regulator in a fixed, accessible position.
• NPTF and G Thread Options - Available in both NPTF (American) and G (BSPP/ISO) thread standards, enabling integration into North American and international pneumatic systems with a single product family.
• Aluminum Body Construction - Aluminum body with Acetal dome and knob provides corrosion resistance and lightweight design suitable for instrument air and dry compressed air service.
• Nitrile Seals Standard - Nitrile (Buna-N) seals are standard, offering reliable performance with clean and filtered compressed air at temperatures from 40 to 125 F (4 to 52 C).
• Tamper-Resistance Option - The removable adjusting knob can be withdrawn after setting, providing a degree of tamper resistance to prevent unauthorized pressure adjustment in production environments.

Technical Specifications

General Specifications

Temperature Ratings

Temperature limits apply to both the ambient environment and the compressed air media passing through the regulator.

Flow Performance Data

Flow performance data measured at 91 psig (6.3 bar) inlet pressure. Maximum rated flow is 40 scfm (1133 l/min) at full open position.

Certifications & Compliance

Typical Applications & Industries

Pneumatic Tool and Torque Control

• Individual nutrunner and torque wrench supply regulators at assembly stations, where precise outlet pressure directly controls torque output on threaded fasteners. The 3 psig accuracy band ensures torque repeatability within specification limits.
• Pneumatic screwdriver supply conditioning on electronics assembly lines where consistent air pressure prevents over-torquing delicate circuit board connectors and enclosure fasteners.
• Drill feed pressure control on multi-spindle drilling heads, holding feed rate and cutting force within narrow process windows to maintain consistent hole quality.
• Grinder and die grinder speed control via air pressure regulation at individual workstation drops, maintaining consistent material removal rates in deburring and finishing operations.
• Impact wrench staging where a precision upstream regulator pre-conditions supply before a downstream tool regulator to provide two-stage pressure control in high-torque assembly.

Instrument Air and Sensing Systems

• Pneumatic instrument supply regulators for I/P (current to pressure) transducers and positioners requiring stable, low-noise supply air in the 15 to 60 psig range.
• Reference pressure supply for differential pressure transmitters and pressure switches where supply stability directly affects calibration accuracy and measurement repeatability.
• Sample conditioning system supply pressure for gas analyzer panels, where the compact footprint allows integration inside analyzer enclosures without consuming excessive space.
• Pilot signal supply conditioning for larger pneumatic control valves when the pilot signal must be maintained at a precise reference pressure independent of header supply fluctuations.
• Test bench reference pressure supply for calibrating pressure gauges, transmitters, and sensors against a stable, repeatable reference source.

Panel and Enclosure Integration

• Control panel compressed air supply regulators for purge and pressurization systems (Type Z, Type X) on electrical enclosures in hazardous locations, controlling purge air flow and enclosure pressure.
• Pneumatic logic and control system supply conditioning for legacy pneumatic PLC and sequencer systems requiring stable pilot air at standard instrument pressures (typically 20 psig).
• Actuator supply pressure control in compact machine modules where panel real estate is at a premium and standard-size regulators cannot be accommodated.
• Brake and clutch air supply regulators on printing presses and converting equipment where precise, repeatable release pressure ensures consistent tension control.
• Proportional control air supply for miniature pneumatic cylinders in packaging and labeling machinery where the compact regulator mounts directly adjacent to the actuator.

Laboratory and Medical Device Manufacturing

• Laboratory gas pressure control for bench-top pneumatic fixtures, clamping devices, and actuated test stands requiring accurate, stable air pressure within a laboratory environment.
• Medical device assembly pressure control for crimping, pressing, and bonding operations where force is applied through calibrated air pressure to delicate components.
• Pharmaceutical packaging machinery precision air supply for blister packaging and sealing equipment where head pressure consistency controls seal integrity.
• Research and development test fixture supply conditioning where repeatable pressure is critical to experimental validity and result reproducibility.

Ordering and Model Number Configuration

The ROSS uses a structured model number. Standard models are available in 1/8" and 1/4" port sizes with NPTF or G (BSPP) thread, in the standard 0-50 psig pressure range. For additional pressure ranges (0-10, 0-20, 0-60 psig), consult ROSS Controls directly.

Standard pressure range is 0-50 psig (0-3.4 bar). For 0-10, 0-20, or 0-60 psig ranges, contact ROSS Controls for special order configurations.

G (BSPP) thread models are identified by the prefix C before the model number (e.g., C5212C1006).

Pressure gauge is not included standard; gauge ports (1/8" NPT) are provided front and rear. Gauges are available as accessories from ROSS Controls.

Panel mounting requires a 1-3/16" (30 mm) diameter cutout. Panel mount nut is available as an accessory.

Standard Model Numbers

Accessories

Pressure Gauges

ROSS Controls offers 0 to 160 psig (0 to 11 bar) pressure gauges compatible with the 1/8" NPT gauge ports on the series. Gauges mount front or rear to suit panel orientation requirements.

Panel Mount Nut

A panel mount nut accessory is available for flush-mounting the series in a 1-3/16" (30 mm) panel cutout, securing the regulator body firmly for operator access.

Downstream Filters

ROSS Controls FRL filters are available as modular upstream companions to the series precision regulator, providing 5, 20, or 40 micron particulate removal to protect the regulator seat and downstream instrumentation.

Related Products & Accessories

• 121 Series Full-Size Precision Regulator - Modular precision regulator for 1/4" to 3/4" port sizes, flow to 155 scfm, for higher-flow precision applications. https://www.rosscontrols.com/en/series/121-full-size-precision-series
• 122 Series MD4 Precision Regulator - Modular MD4-platform precision regulator for 3/8" to 3/4" ports, flow to 170 scfm, for FRL manifold integration. https://www.rosscontrols.com/en/series/122-md4-precision-series
• 123 Series High-Capacity Precision Regulator - Inline high-capacity precision regulator for 3/4" to 1-1/2" ports, flow to 800 scfm, for large-volume precision air supply. https://www.rosscontrols.com/en/series/123-high-capacity-precision-series
• 127 Series Miniature Relief Valves - Inline relief valves in 1/8" and 1/4" port sizes for overpressure protection of small pneumatic circuits. https://www.rosscontrols.com/en/series/127-miniature-series
• ROSS FRL Filters (Miniature Series) - Miniature modular filters for upstream air preparation, removing particulates and moisture before the precision regulator. https://www.rosscontrols.com/en/categories/filters
• ROSS FRL Lubricators (Miniature Series) - Miniature lubricators for downstream oil-mist introduction to pneumatic tools and actuators following the precision regulator. https://www.rosscontrols.com/en/categories/lubricators

Frequently Asked Questions (FAQ)

Q: What distinguishes a precision regulator from a standard pressure regulator?

A: A precision regulator uses a small valve seat combined with a large diaphragm sensing area, which amplifies the diaphragm's response to downstream pressure changes. This geometry produces tighter pressure regulation: ROSS units hold set pressure within 3 psig (0.2 bar) across varying demand, whereas standard regulators may allow 5 to 15 psig variation at the same conditions.

Q: What is the maximum inlet supply pressure the series can accept?

A: The Series accepts inlet supply pressures up to 300 psig (21 bar). The outlet pressure is adjustable from 0 to 100 psig (0 to 7 bar), providing a substantial pressure reduction ratio for high-pressure header systems feeding instrument or tool air circuits.

Q: What does self-relieving mean and why does it matter?

A: Self-relieving means the regulator vents downstream pressure back through the regulator body when the set point is reduced below existing downstream pressure. Without this feature, a non-relieving regulator would trap downstream pressure above the new set point until the system consumed it. Self-relieving design simplifies circuit design by eliminating the need for a separate downstream relief valve in most applications.

Q: What flow capacity does the series provide?

A: The Series delivers flow up to 40 scfm (1133 l/min). This is designed for low-flow instrument air, pneumatic tool supply at individual stations, and sensing system applications. For higher-flow precision requirements, the 121 Series (155 scfm), 122 Series (170 scfm), or 123 Series (800 scfm) should be evaluated.

Q: Can the series be used with lubricator oil downstream?

A: The Series uses Nitrile seals, which are compatible with petroleum-based air line lubricants at standard ISO 32 viscosity. When lubricators are used in the FRL system, the lubricator should be positioned downstream of the precision regulator to prevent oil-laden air from entering the regulator diaphragm chamber.

Q: Is the series suitable for vacuum service?

A: No. The Series is designed for compressed air pressure regulation above atmospheric. For vacuum regulation or control, consult ROSS Controls for the appropriate vacuum-rated product family.

Q: What are the gauge port sizes and how are they used?

A: The Series has 1/8" NPT gauge ports located both front and rear of the body. A standard pressure gauge (0-160 psig / 0-11 bar) can be threaded into either port. The opposite port should be plugged when not in use. Having both front and rear ports allows gauge installation in the most accessible direction for the specific panel layout.

Q: What thread standards are available?

A: The Series is available in NPTF (American National Taper Pipe Thread, dryseal) standard for North American installations, and G (BSPP, per ISO 228-1) for international and European applications. G-thread models are identified by the prefix C in the model number (e.g., C5212C1006).

Q: What pressure ranges are available beyond the standard 0-50 psig?

A: The standard catalog pressure range is 0-50 psig (0-3.4 bar). Additional ranges including 0-10 psig (0-0.7 bar), 0-20 psig (0-1.4 bar), and 0-60 psig (0-4.1 bar) are available by consulting ROSS Controls directly. These special-range configurations use different internal spring assemblies selected for optimum diaphragm sensitivity at the target pressure range.

Q: How does the series mount in a control panel?

A: The Series is designed for panel mounting through a 1-3/16" (30 mm) diameter circular cutout. A panel mount nut (available as an accessory) threads onto the regulator body from the rear of the panel to secure it in place. The regulator body depth (1.8" / 44 mm without gauge) must be accommodated behind the panel surface.

Q: What filtration is recommended upstream of the series?

A: A minimum of 5-micron particulate filtration is recommended upstream of any precision regulator to protect the small valve seat from particle contamination that could cause leakage or erratic regulation. ROSS Controls offers miniature FRL filters designed as modular companions to the series.

Q: What is the operating temperature range?

A: The Series with standard Nitrile seals operates from 40 F to 125 F (4 C to 52 C) for both ambient and media (air) temperatures. This covers the majority of indoor industrial, laboratory, and climate-controlled applications. For higher-temperature environments, consult ROSS Controls for seal material options.

Installation & Maintenance Guidelines

• Install an upstream 5-micron particulate filter to protect the precision regulator valve seat from contaminants that cause seat leakage and erratic regulation.
• Mount the regulator with the adjusting knob accessible for operator set point adjustment. Panel mounting using the 1-3/16" (30 mm) cutout and panel mount nut is recommended for fixed installations.
• Supply clean, dry, filtered compressed air. The Series is not rated for lubricated air service upstream of the diaphragm chamber.
• Ensure inlet supply pressure does not exceed 300 psig (21 bar). Operating above maximum inlet pressure may damage the diaphragm and internal components.
• Install a pressure gauge in either the front or rear 1/8" NPT gauge port to allow monitoring of the regulated outlet pressure. Plug the unused gauge port.
• Turn the adjusting knob clockwise to increase outlet pressure and counterclockwise to decrease it. The self-relieving function will vent excess downstream pressure when set point is lowered.
• Do not use pipe thread sealant tape (PTFE tape) beyond the thread engagement on the small NPTF ports. Excess tape can enter the valve seat area and cause seat leakage.
• Verify the regulated outlet pressure with a calibrated reference gauge before placing the system into production service.
• Keep ambient temperature within 40 to 125 F (4 to 52 C). Temperatures outside this range may affect diaphragm flexibility, seal integrity, and regulation accuracy.
• If tamper resistance is required, remove the adjusting knob after setting the desired pressure. Retain the knob for future set point adjustments.

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 for the series and all ROSS FRL products is available through ROSS Controls USA headquarters in Ferndale, Michigan, and through ROSS offices in Canada, Brazil, Germany, France, United Kingdom, India, China, and Japan.

Contact ROSS Controls USA at (800) 438-7677 or visit rosscontrols.com for product configuration assistance, technical documentation, and authorized distributor locations.

Replacement parts, seal kits, and service documentation for the series are available through ROSS Controls and its authorized distributor network.

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