Use-point placement takes priority over the image’s receiver-proximity note; 10–15 m is an illustrative branch length.
Quick answer
Install a point-of-use FRL at the machine's air inlet or on the branch supplying the equipment it protects, upstream of the relevant control valves and actuators. Follow the marked airflow direction, mount bowl-type components in their specified orientation, and leave room to drain and service them. Use the sequence filter → regulator → lubricator, with the lubricator included only when the downstream equipment requires added oil.
The best position lets you check pressure near the working load without burying the filter bowl behind a panel. A convenient mounting surface alone is not enough: branch restrictions, different pressure requirements and poor service access can make an otherwise correct assembly difficult to use.
Start with the correct FRL connection sequence
For the local air-preparation section, the basic arrangement is:
Compressed-air supply → filter → regulator → lubricator, if required → downstream controls and equipment.
The filter removes particles and separated liquid within its design capability before air reaches the regulator. The regulator establishes the downstream pressure setting. The lubricator adds a controlled oil mist to the air going to equipment that requires it. Putting the lubricator ahead of the filter can cause the filter to remove some of the oil you intended to deliver.
This is a functional sequence, not a complete machine safety circuit. Isolation, exhaust and other protective devices must follow the machine's design. A combined filter-regulator performs two of the functions in one assembly.
If the equipment specifies operation without added airline oil, use the required filtration and regulation without automatically adding a lubricator. Keep an oil-lubricated branch separate from equipment that requires air without added oil. Where branches share upstream piping, account for possible oil backflow and the specified prevention arrangement. A downstream shutoff does not remove oil already introduced into shared piping.
Filtration also needs to match the equipment's air-quality requirements. Our guide to pneumatic air filter micron ratings explains the difference between particle capture and moisture treatment.
Centralized or point-of-use: which layout fits the branches?
When several loads can share air preparation
A shared unit can serve equipment with compatible air-quality, lubrication and pressure requirements, provided its flow capacity and the downstream distribution support the combined demand. This reduces the number of bowls, elements and adjustment points to maintain.
The difficulty appears when one outlet serves loads with different operating patterns. Consider an FRL supplying branches 15–20 m away. A gauge at the FRL measures local outlet pressure; it does not establish what reaches each distant machine while several loads operate together. Check the branches before concluding that the FRL itself is the restriction.
When separate branch regulation helps
Consider neighboring stations requiring 0.5 MPa and 0.7 MPa, respectively. One common regulated outlet cannot independently maintain both settings. Branch regulators can establish separate setpoints where the upstream supply provides enough pressure and flow, including the required pressure margin across each regulator.
Separate branches also make it easier to keep added oil out of equipment that does not need it. The tradeoff is additional components, joints and service points. Point-of-use preparation is useful when it solves a specific branch requirement; it does not mean every cylinder needs its own complete FRL.
How far should the FRL be from the equipment?
Keep the treated-air run practical and avoid unnecessary restrictions. Distance matters together with the pipe's internal bore, fittings, valves, flow rate and simultaneous demand. There is no single distance at which all FRLs stop working properly.
For a layout review, consider a 10–15 m branch using nominal 3/8–1/2-inch piping. That combination is a reason to examine pressure loss during operation, not a universal maximum run length. Nominal pipe size alone does not tell you the actual internal bore or the restriction through connectors.
Moving the regulator closer may help establish a more useful local setting, but it cannot restore pressure already lost through an inadequate upstream supply path. Compare measurements under the same operating demand before changing the layout.
Two other effects deserve attention:
- Water can form after the filter. A particulate filter with liquid separation does not remove water vapor. If downstream air cools below its pressure dew point, condensation can occur again. Local filtration can collect liquid reaching that location; it does not replace necessary drying.
- Oil delivery depends on the complete downstream run. Lubricator type, airflow, line geometry and the equipment's requirements affect delivery. Check the specified installation arrangement rather than treating 10–15 m as a guaranteed oil-mist travel distance.
Flexible tubing adds another routing concern. A short run with a tight bend can restrict flow more than its length suggests. Check moving sections through their full travel, using our pneumatic tubing troubleshooting guide where needed.
Leave room for drainage, adjustment and bowl removal
Check the inlet and outlet markings before connecting the assembly. Mount bowl-type filters and lubricators vertically with their bowls down where the model instructions require it. Do not rotate an assembly sideways simply to fit a narrow cabinet.
Use suitable mounting brackets and support the connected piping so the FRL is not carrying its weight or being pulled out of alignment. Keep it away from avoidable impact, excessive vibration, heat and chemical exposure beyond its material ratings.
Service space must accommodate the actual removal path. Consider 50–80 mm below the bowl as a layout allowance to check against the selected unit's drawing, not a guaranteed clearance for every model. With less than 30 mm, even reaching the drain or removing a bowl may become awkward. Some designs need substantially more room to release, lower or turn the bowl.
Before fixing the mounting position, check whether someone can:
- Read the gauge and bowl level without removing a guard or reaching into moving machinery.
- Adjust and lock the regulator as intended.
- Reach the drain and route discharge to a suitable collection point.
- Remove the bowl, guard and element using the required service procedure.
- Inspect and refill the lubricator where one is fitted.
The drain arrangement affects access too. Manual, semi-automatic and automatic filter drains have different operating behaviors; an automatic drain still needs an accessible, unobstructed discharge path.
Common FRL installation mistakes and what to check
Use symptoms as starting points for inspection. A slow cylinder, water downstream or unstable pressure can have several causes.
| Installation mistake | Possible result | What to check or change |
|---|---|---|
| Connecting against the marked airflow direction | Incorrect regulation, drainage or component operation | Compare the actual piping with inlet/outlet markings and the assembly instructions. |
| Mounting a bowl-type unit in an unsupported orientation | Poor liquid collection, drainage or oil delivery | Restore the specified orientation and use suitable supports. |
| Sharing one regulated outlet across branches needing different pressures | One branch is over-supplied or another falls short | Separate the pressure requirements; check supply capacity and pressure during combined demand. |
| Mounting the bowl directly above an obstruction | Routine drainage or element service requires extra dismantling | Check the complete bowl-removal path and relocate the unit or obstruction. |
| Putting a lubricator upstream of a shared oil-free branch | Added oil reaches equipment that should not receive it | Separate the branches before oil injection and address existing oil contamination. |
A joint that leaks after installation also deserves its own inspection. Correct FRL placement cannot compensate for incompatible threads, damaged seals or poorly supported connections. See our guide to pneumatic fittings and leak prevention. The U.S. Department of Energy's guidance on minimizing compressed-air leaks also identifies fittings, connections and air-preparation components as places to inspect.
Check the installation while the equipment is working
Before changing connections or removing bowls, follow the machine's energy-control procedure: isolate the supply, prevent unexpected re-energization, release or restrain stored energy, and verify the isolated condition. A regulator is not an isolation device, and a zero reading on one gauge does not prove every trapped section is depressurized. U.S. requirements for relevant servicing tasks are covered in OSHA's hazardous-energy control standard.
After installation, restore air under the machine's approved commissioning procedure and check:
- Connections: inspect joints for leakage using an approved method; do not tighten or disconnect pressurized joints.
- Regulation: set and lock the required outlet pressure using the unit's instructions, including the specified method for reducing a setting.
- Operating pressure: compare pressure at the FRL outlet and at the equipment during a representative cycle, including expected simultaneous demand.
- Drainage: confirm the discharge route is unobstructed and the drain operates under its specified conditions.
- Lubrication, where required: verify the specified oil, adjustment and delivery checks under operating airflow.
If the FRL outlet remains adequate but pressure at the equipment falls, inspect the downstream path. If both readings fall, investigate the supply and restrictions through the preparation assembly. These observations help locate the problem; they do not identify a failed component on their own.
Record the initial operating readings as a maintenance baseline. The FRL maintenance checklist covers follow-up checks for drainage, pressure behavior and lubrication.
AIRZOE air-preparation products
For point-of-use air preparation, explore AIRZOE's AF2000-02 air filter and water separator, AR2000-02 air pressure regulator, and filter-regulator-lubricator combination.
AIRZOE's current filtering products are rated 5 μm. The linked pages provide details for the individual components and assemblies; the installation examples above are not AIRZOE model-specific pressure, distance or clearance ratings.
Frequently asked questions
Can an FRL go inside a control cabinet?
Yes, if the unit's environmental requirements, ventilation needs, access and drainage arrangement can be met. Keep discharge away from electrical equipment and leave the full bowl-removal space. Mounting outside may make routine checks easier, but the assembly still needs protection from impact and unsuitable exposure.
Can several cylinders share one FRL?
Yes, when the air-quality and lubrication requirements are compatible and the assembly and piping support the cylinders' combined demand. Evaluate overlapping strokes rather than sizing from one cylinder's consumption alone. Different required pressures may call for separate branch regulation.
Does the regulator isolate the machine when turned down?
Do not use it as the machine's isolation device. A regulator controls pressure, and its relieving behavior varies by design. Use the designated isolation and exhaust arrangement, then verify stored-energy control before servicing.
Can a downstream filter remove oil added by a lubricator?
Do not rely on a standard particulate filter to restore an oil-free branch. Removing oil aerosol may require suitable coalescing treatment, while oil vapor is a separate treatment problem. Keep equipment that requires air without added oil on a separate branch before lubrication.