An HDA two-piece FRL still provides filtration, pressure regulation and lubrication. It combines a filter-regulator with a lubricator (FR+L). The three-piece version uses separate filter, regulator and lubricator units (F+R+L). Choose between them by the machine's air requirements, installation envelope and service plan, then confirm the complete ordering code. Two pieces does not mean two functions or oil-free air.
The quick comparison: what changes between two and three pieces?
Three-piece HDAC: one HDAF filter, one HDAR regulator and one HDAL lubricator, providing F+R+L. Two-piece HDAC-A: one HDAW filter-regulator and one HDAL lubricator, providing FR+L. Both arrangements retain the lubricator and a condensate collection bowl in the filtration stage. The key difference is whether filtration and regulation occupy separate modules. This terminology agrees with common FRL manufacturer usage. [1, 2]
| Configuration | Documented modules | Functions | Lubrication decision |
|---|---|---|---|
| HDAC three-piece | HDAF filter + HDAR regulator + HDAL lubricator | F + R + L in separate modules | Includes a lubricator; confirm the equipment needs added oil. |
| HDAC-A two-piece | HDAW filter-regulator + HDAL lubricator | Combined F + R, followed by L | Also includes lubrication; two housings do not mean two functions. |
| HDAW without HDAL | Combined filter and regulator | F + R in one unit | No lubricator in this unit; this alone does not establish an outlet-air purity class. |
How XMC identifies the two arrangements
Printed page 48 of the XMC catalogue dated 21 June 2025 covers HDAC20-40 three-piece combinations. Page 50 covers HDAC20-40A two-piece combinations and shows the letter A after the body size in the ordering code. For example, HDAC30-03 denotes the three-piece family with a 3/8 port, while HDAC30A-03 identifies the two-piece family with a 3/8 port before additional options are specified. Use the ordering diagram and complete code; the family label alone does not settle gauge, drain or bowl configuration. [1]
Start with the downstream lubrication requirement
Decide whether the connected equipment requires externally lubricated air before choosing an FRL assembly. Both HDAC configurations add a lubricator to the branch. If the equipment specifies non-lubricated air, discuss a filter-regulator arrangement such as HDAW, without HDAL, against the rest of the air-quality requirements. Do not select a two-piece HDAC-A on the assumption that the lubricator has been removed. For mixed requirements, identify the lubricated and non-lubricated branches in the circuit review.
Compare installed dimensions and service clearance
Combining filtration and regulation removes one separate module, which can help when arranging an air-preparation station. Confirm the actual assembly drawing instead of assuming a fixed percentage of space saving. Compare overall width, height, bracket position, gauge projection, adjustment access and room below each bowl for maintenance. A layout that fits between two panels may still be unsuitable if a technician cannot see the oil level, operate the drain or remove the bowl safely.
Match airflow before choosing by port size
A matching pipe connection does not prove that an assembly will meet demand at an acceptable pressure drop. Provide the lowest operating demand, peak flow, inlet pressure, required outlet pressure and machine duty cycle. The HDA combination tables list minimum oil mist flow of 15 L/min for body size 20, 40 L/min for size 30 and 50 L/min for size 40. These are lubrication thresholds, not maximum assembly flow ratings. The same low-demand question applies to both two-piece and three-piece versions. [1]
Compare specifications on the same basis
The two combination tables list a maximum working pressure of 1.0 MPa, a regulating range of 0.05-0.85 MPa, ambient and fluid temperatures of 5-60 degrees Celsius, and vertical installation within plus or minus 5 degrees. They list 25 micrometres as the standard filter rating, with 5 and 50 micrometre options. [1] These shared nominal values do not establish identical pressure-drop curves, outlet stability or service life. Confirm performance for the selected size and operating point; an additional physical module is not evidence of better air quality.
Include the drain and bowl in the comparison
The catalogue distinguishes manual draining on body size 20 from air-shutoff draining on sizes 30 and 40, with automatic draining available as specified. Its ordering diagrams use D for the automatic-drain option. [1] Do not equate drainage on depressurization with automatic condensate removal during continuous operation. Record how often the machine is depressurized, who checks the bowl and how discharge will be collected. Confirm the exact drain option, pressure requirements and bowl configuration with XMC for either assembly.
Consider how the station will be maintained
Three separate functional modules make the filter, regulator and lubricator distinct items in the maintenance plan. A two-piece station combines the filter and regulator in one module. Check the actual replacement parts, coupling arrangement, isolation procedure and service access for the proposed configuration. Do not assume that any module can be exchanged while pressurized, or that using the same port size makes different product families interchangeable. Compare the quoted assembly and spare parts together.
A practical selection example and RFQ checklist
For a tool branch that requires oil and has limited mounting space, an HDAC30A arrangement is a candidate for review. For a machine with an established maintenance layout for separate filtration and regulation modules, an HDAC30 arrangement may be a better layout match. Neither example is a final selection without operating data. Send the required functions, complete model or current label, connection size and thread requirement, flow range, pressures, duty cycle, mounting envelope, filter rating, gauge preference, drain requirement and bowl environment with your inquiry.
| Purchasing situation | Candidate arrangement to review | Conditions to confirm before quotation |
|---|---|---|
| Tool branch needs added oil and mounting space is limited | HDAC-A two-piece FR+L | Actual assembly drawing, bowl/service access, lowest and peak demand, and permitted pressure loss. |
| Existing machine uses separate filtration, regulation and lubrication modules | HDAC three-piece F+R+L | Full existing code, drawing, coupling and mounting details, and identified replacement parts; do not assume identical fit. |
| Equipment specifies non-lubricated air | Review the required treatment without HDAL, such as an HDAW configuration | Actual particle, water and oil requirements, flow/pressure conditions, drain and bowl options; no outlet-purity guarantee inferred. |
Catalogue references and comparison scope
XMC configuration and specification facts above follow printed pages 48–51, 52, 54, 56 and 58 of the 21 June 2025 catalogue. The comparison and quotation tables organize those functions and buyer inputs; they do not establish an interchangeable assembly, measured installation result or outlet-air purity. Use the linked sizing and installation guides for those separate decisions.
Questions buyers ask.
Does a two-piece FRL have no lubricator?
The HDA two-piece FR+L arrangement includes an HDAL lubricator. Filtration and regulation are combined in the HDAW unit. Check the functional symbols, not just the number of housings.
Is a three-piece FRL always better than a two-piece FRL?
No. Select the required functions, verify pressure and flow performance, and compare installation and maintenance needs. The number of modules alone does not establish superior performance.
Are HDAW30 + HDAL30 and HDAC30A related?
HDAW30 + HDAL30 describes the filter-regulator-plus-lubricator arrangement represented by the HDAC30A two-piece family. Confirm the complete port, gauge, drain and bowl options before treating two quoted assemblies as identical.
Can I replace an HDAC30 with an HDAC30A without checking the installation?
Check dimensions, mounting, connection requirements, flow performance and selected options first. A shared body-size number does not make the assemblies dimensionally identical.
Technical references
- [1] XMC product catalogue, edition 21 June 2025: printed pages 48–51, HDAC and HDAC-A combinations; page 52, HDAF filters; page 54, HDAR regulators; page 56, HDAL lubricators; page 58, HDAW filter-regulators. Original catalogue tables and diagrams visually rechecked 23 October 2026.
- [2] ARO, 2-Piece FRLs Combination: general F+R+L and F/R+L terminology only. ARO specifications do not establish XMC performance or interchangeability. https://www.arozone.com/en/filters-regulators-and-lubricators/2-piece-units/
Put the guide to work.
Choose the relevant XMC series, download its product PDF and include the application details with your inquiry.