FRL Combination Units
Filters
ARO-Flo FRL Combination Units: 2-Piece and 3-Piece
An FRL combination unit puts the three stages of air preparation into one pre-assembled set: a filter to remove water, dirt and oil, a regulator to hold a steady pressure, and a lubricator to add oil mist for the equipment that needs it. Ordering one assembly instead of three parts means one part number, matched components and a quicker installation. This page carries 49 ARO-Flo FRL units across four series, from 1/8" to 1" NPT, in 2-piece and 3-piece configurations, with polycarbonate or metal bowls and manual or automatic drains.
2-Piece or 3-Piece FRL?
| Configuration | What is in it | Strengths | On this page |
|---|---|---|---|
A piggyback filter regulator plus a lubricator |
Shorter assembly with fewer joints, for tight spaces |
22 units, 1/8" to 1" |
|
A separate filter, regulator and lubricator |
Each stage can be serviced on its own, and flow ratings are similar to or higher than a 2-piece of the same size |
27 units, 1/8" to 1" |
Sizing an FRL by Flow
Air passes through every stage of the unit, so a combination's flow rating is lower than any single component of the same port size. Size by the rating of the complete unit, shown on each product, against the air the equipment draws. Examples of 3-piece units in each series:
ARO-Flo 3000
3/4" and 1" ports
C38461-810, 1" 3-piece: 101 SCFM
High-demand branches, metal bowls only
Check the unit, not the parts
The 1/2" 2000 Series particulate filter on its own is rated at 197 SCFM, while the complete 1/2" 3-piece C38341-810 is rated at 71 SCFM. If the equipment draws more than the unit's rating, step up a size or series.
Options in Every Size
- Bowls Polycarbonate with guard (150 psi, 23°F to 125°F) in the 1000 to 2000 Series, or metal (250 psi, 23°F to 175°F) in every series. Choose metal wherever synthetic oils, ester-based compressor oils or solvents could reach the bowls.
- Drains Manual, or automatic on the filter bowl to empty collected water without an operator.
- Mounting A T-bracket wall mount is standard on every combination unit. Panel nuts are ordered separately.
- Modular build The stages are joined with ARO-Flo modular connectors, so a unit can be taken apart for service with a minimum of tools, even with fixed piping.
Reading an FRL part number
In C38341-811, the fourth digit is the series (1 = 1000 up to 4 = 3000) and the fifth the port size (1 = 1/8" up to 6 = 1"). After the dash: 6 = 2-piece or 8 = 3-piece, then the bowl (0 = polycarbonate, 1 = metal) and the drain (0 = manual, 1 = automatic). So C38341-811 is a 2000 Series 1/2" 3-piece unit with metal bowls and automatic drain.
Setting Up an FRL
ARO's installation and maintenance guidance for ARO-Flo units, in the order you will need it:
- Install filter, regulator, lubricator in that order, with air flowing in the direction of the arrows
- Take the supply from the top of the main air line, with drip leg drains at the low points
- Mount close to the equipment, bowls pointing down
- Before first start-up, back the regulator knob off fully, then raise the pressure gradually
- Fill the lubricator with non-detergent oil such as ARO 29665, and start at one drop per minute for each 10 SCFM of flow
- Replace the filter element when the pressure drop reaches 10 psi
Frequently Asked Questions
What is an FRL unit?
FRL stands for filter, regulator and lubricator, the three stages of compressed air preparation. The filter removes water, dirt and oil, the regulator sets a steady pressure, and the lubricator adds a controlled oil mist for equipment that needs it. An FRL combination unit delivers all three pre-assembled, ready to install in the air line ahead of the equipment.
What is the difference between a 2-piece and a 3-piece FRL?
A 3-piece unit (F+R+L) has a separate filter, regulator and lubricator. A 2-piece unit (F/R+L) has a piggyback filter regulator, which combines the filter and regulator in one body, plus a lubricator, so the assembly is shorter. Both have a 5 micron filter element. On this page there are 22 two-piece and 27 three-piece units, from 1/8" to 1" NPT.
Why does an FRL flow less than a filter of the same port size?
Air passes through every stage of a combination unit, and each stage costs some pressure, so the whole assembly is rated lower than any single component of the same size. As listed on this shop, the 1/2" 2000 Series particulate filter is rated at 197 SCFM, while the 1/2" 3-piece C38341-810 is rated at 71 SCFM. Size the unit by its own rating, not by the rating of its parts.
Is a mounting bracket or panel nut included with an FRL unit?
A T-bracket wall mount is standard on all ARO-Flo combination units. Panel nuts are not included and are ordered separately: 104416 for the 1000 Series, 104417 for the 1500 Series, 104418 for the 2000 Series and 104419 for the 3000 Series.
Can I add a coalescing filter to an FRL?
Yes. The combination units here use 5 micron filter elements. Where oil aerosols must be removed, add a separate 0.3 micron coalescing filter after the unit's filter and before the lubricator, so it protects the regulator and equipment without stripping out the oil the lubricator adds. ARO-Flo units are modular, so stages can be added within the same series.
Complete Air Preparation in One Order
An FRL unit is the simplest way to get the full sequence right: matched components, assembled in the correct order, sized together. Install one at each point of use and the equipment behind it gets clean air, at a steady pressure, with the oil it needs.
Order the FRL units above. Where the equipment does not need oil, a piggyback filter regulator does the first two jobs on its own. Individual compressed air filters, air pressure regulators and air line lubricators are available for custom arrangements. Application selections are on the industry pages for car wash, food & beverage, packaging and general manufacturing.
Need help sizing an FRL?
Talk to ARO about flow, configuration or supplying several machines. Monday to Friday, 08:00 am to 5:00 pm CST.