Use an HDAF air filter when the requirement is particle filtration at its specified grade. Review HDAFM mist separation when fine oil droplets are also a concern, together with the required upstream filtration. A 5 μm filter grade does not establish oil-removal performance, and HDAFM’s 0.3 μm rating alone does not prove an outlet oil-purity class. If the requirement concerns water vapour or oil vapour, assess the appropriate drying or vapour-treatment stage separately.
First identify what is in the air
A buyer reporting dirty air may mean rust particles, liquid condensate, a fine oil aerosol or vapour. These descriptions lead to different equipment choices. Parker's air-treatment guide separates particulate removal, coalescing filtration for aerosols, drying for water vapour and adsorption for oil vapour. [3] Start an inquiry with the observed problem and the required outlet-air specification. An oily surface alone cannot establish the concentration, physical form or origin of the contamination. For a specified purity requirement, use an appropriate air-quality test instead of judging the air only by appearance.
| Requirement | Treatment to investigate | Selection question |
|---|---|---|
| Solid particles | A suitably rated particulate filter | What particle grade and removal performance does the equipment require? |
| Oil aerosol or fine liquid droplets | A suitable mist-separation or coalescing stage | What outlet contamination limit must the selected assembly meet? |
| Water vapour | Drying selected for the required pressure dew point | How cold can the downstream piping become? |
| Oil vapour | A suitable vapour-removal stage | Is aerosol removal alone sufficient for the stated requirement? |
Why changing to 5 μm may not answer the oil question
The HDAF catalogue lists 25 μm as standard, with 5 μm and 50 μm options. [1] Those choices describe the listed filter grade. They are not a statement that the outlet is oil-free, dry or sterile. If a machine specification calls for a defined oil limit, asking only for the smallest micron number leaves a gap in the purchase specification. Ask for the relevant treatment function, performance evidence and test conditions. An element-grade requirement and an oil-removal requirement may both apply; one does not automatically replace the other.
Compare the XMC HDAF and HDAFM ranges
HDAF is the ordinary filter family within the HDA range. HDAFM30 and HDAFM40 are separately listed as mist separators, with a 0.3 μm filter precision and initially filtered compressed air as the working medium. [1][2] The table below transcribes the relevant catalogue choices. It does not establish a complete outlet-air purity class or make the two product families interchangeable.
| Range | Listed filtration | Available port sizes | What to confirm |
|---|---|---|---|
| HDAF20 | 25 μm standard; 5 or 50 μm optional | 1/8 or 1/4 inch | Required particle grade, flow and drain configuration |
| HDAF30 | 25 μm standard; 5 or 50 μm optional | 1/4 or 3/8 inch | Required particle grade, flow and drain configuration |
| HDAF40 | 25 μm standard; 5 or 50 μm optional | 3/8 or 1/2 inch | Required particle grade, flow and drain configuration |
| HDAFM30 | 0.3 μm | 1/4 or 3/8 inch | Upstream filtration, treatment performance and operating flow |
| HDAFM40 | 0.3 μm | 3/8 or 1/2 inch | Upstream filtration, treatment performance and operating flow |
Check the flow conditions behind the model choice
Printed page 60 lists maximum air-processing values of 450 L/min for HDAFM30 and 1,100 L/min for HDAFM40. The accompanying note specifies 0.7 MPa inlet pressure, 20 °C and 65% atmospheric relative humidity; it also says capacity varies with inlet pressure and warns of oil carryover if the maximum processing flow is exceeded. [2] Treat these as conditional catalogue references, not unconditional machine ratings. Provide peak demand, its measurement basis and the minimum pressure available while the machine operates. A shared 3/8-inch connection does not settle whether HDAFM30 or HDAFM40 suits the circuit.
| Catalogue model | Maximum air-processing reference | Shared note and selection limit |
|---|---|---|
| HDAFM30 | 450 L/min | 0.7 MPa inlet, 20 °C, 65% atmospheric relative humidity |
| HDAFM40 | 1,100 L/min | Capacity changes with inlet pressure; confirm actual operating conditions |
| Both sizes | 0.3 μm listed filtration | Exceeding maximum processing flow can cause oil carryover |
Do you need both an air filter and a mist separator?
The HDAFM catalogue specifies initially filtered compressed air, so include its upstream filter in the selection review. [2] HDAF and HDAFM are not automatically alternatives: one arrangement may require particle filtration followed by suitable mist treatment. Confirm the prefiltration grade, flow and outlet quality with XMC; the label “0.3 μm” does not authorize removing the existing upstream stage. Mark each unit and flow direction on a circuit sketch, identify the drain option and check service access. A combined filter-regulator such as HDAW adds regulation, but does not by its name establish the oil-mist performance of HDAFM.
Keep intentional lubrication separate from oil removal
Check whether the downstream equipment requires added lubricant, permits it or prohibits it. A lubricator deliberately introduces oil, so its location matters when evaluating the oil condition at a later measurement point. Festo's air-preparation guidance treats lubrication as an application-dependent choice. [4] Draw the actual circuit and mark the inspection point before concluding that an upstream separator has failed. For mixed equipment requirements, ask the machine designer to review the branches rather than assuming one treatment and lubrication arrangement serves every air user.
A sizing example: the same 3/8-inch port, a different decision
Suppose a proposed circuit has 500 L/min peak demand, expressed on the same basis and at the conditions used for the catalogue processing reference. This is already above HDAFM30’s listed 450 L/min maximum, even though its 3/8-inch port fits the piping. HDAFM40’s 1,100 L/min reference makes it a candidate for further review, not a confirmed selection: check minimum inlet pressure, pressure drop, prefiltration and the required outlet oil limit. If the flow bases or conditions differ, first obtain a comparable rating. This is a hypothetical sizing comparison, not a tested installation or an oil-removal guarantee.
What to send with an HDAF or HDAFM inquiry
Send the equipment’s particle, water and oil requirements separately, along with the location at which they must be met. Include existing model labels and a circuit sketch, minimum operating inlet pressure, peak flow with reference conditions, inlet temperature, port thread and size, drain preference, space and quantity. If the specification gives a purity class or total-oil limit, include the full wording and requested test evidence. Ask XMC to confirm the complete configuration and any additional treatment needed, so a component quote addresses the actual air-quality requirement.
Catalogue and technical references
XMC model facts come from the 21 June 2025 catalogue. Other manufacturers’ references explain general treatment functions; their efficiencies, service limits and certifications are not assigned to XMC products. The 500 L/min comparison is hypothetical and does not certify a treatment result.
Questions buyers ask.
Does a 5 micron pneumatic filter guarantee oil-free air?
No. That grade alone does not specify outlet oil-aerosol or oil-vapour performance. Define the required air quality and confirm the treatment arrangement against it.
Is an oil-mist separator the same as an oil-vapour filter?
No. Aerosols are fine liquid droplets; vapour is in the gas phase. A requirement covering oil vapour needs a separate treatment review rather than an assumption based on mist filtration.
What filtration precision does XMC list for HDAFM30 and HDAFM40?
The reviewed catalogue lists 0.3 μm for both. It also specifies initially filtered compressed air and model-dependent flow conditions. That number alone is not an outlet purity-class certification.
Can I remove the upstream filter when adding HDAFM?
Do not remove it just because HDAFM has a finer listed grade. The HDAFM catalogue specifies initially filtered compressed air. Confirm the required prefiltration and complete arrangement with XMC before changing the installed stages.
Can HDAFM30 and HDAFM40 be selected by port size alone?
No. Both offer 3/8-inch connections, but their catalogue processing capacities differ. Supply actual pressure, peak flow and the treatment requirement for a model-specific selection.
Can a mist separator replace a compressed-air dryer?
Do not assume so. Controlling water vapour and pressure dew point is a drying requirement. Confirm it separately from particle or oil-mist filtration.
Technical references
- [1] XMC Huayi catalogue, 21 June 2025, printed pages 52–53: HDAF element choices, ports and flow graphs; page 52 visually rechecked 10 October 2026.
- [2] XMC Huayi catalogue, 21 June 2025, printed page 60: HDAFM30/40 specifications and flow-reference note; visually rechecked 10 October 2026.
- [3] Parker, Compressed Air Treatment, November 2021: distinctions between particle, aerosol and vapour treatment; rechecked 10 October 2026.
- [4] Festo, Compressed air preparation in pneumatics, 2015: separate treatment and lubrication functions; rechecked 10 October 2026.
Put the guide to work.
Choose the relevant XMC series, download its product PDF and include the application details with your inquiry.