Ingersoll Rand 99273906 Air Filter Element | M37 Compressor Intake

Product Overview

99273906 is the intake air filter element for the Ingersoll Rand M37 screw air compressor. It seats inside the air filter housing at the intake, upstream of the inlet valve, and forms the first filtration barrier for the entire compressed-air system. As the machine draws in ambient air, dust, grit, fibre, water mist and oil mist are captured by the media before reaching the airend — surface filtration holds larger particles, depth filtration retains finer ones.

Filter condition directly affects airend service life. Hard particles that pass an exhausted or damaged element accelerate rotor and bearing wear and contaminate the separator element, oil filter and lubricant, shortening all three at once. A heavily loaded element also restricts intake volume, reducing delivered air and raising energy consumption; in extreme cases oil carry-over can lead to airend seizure. Replacing the intake filter on schedule remains the lowest-cost protection for the airend.

Core Specifications

• Part number: 99273906
• Product name: Air Filter Element
• Application: Ingersoll Rand M37 screw air compressor
• Machine free air delivery: 6 m³/min @ 0.7 MPa
• Element outer diameter: 270 mm
• Element height: 120 mm
• Effective filtration area: approx. 1.3 m²
• Filtration rating: 2–10 μm
• Filtration efficiency: ≥98% for particles ≥5 μm
• Initial pressure drop: approx. 0.5–1.0 kPa
• Alarm resistance: 6.0–6.5 kPa
• Recommended replacement interval: approx. 2,000 hours (adjust to site conditions)

Technical Parameters

Filtration Performance

• Filtration rating: 2–10 μm (industry range; published data varies between 2–10, 3–12, 5–10 and 10–15 μm — mainstream overlap shown)
• Filtration efficiency: ≥98% for particles ≥5 μm
• Filter class: HVAC classification (EN 779 G/M/F) does not apply. Intake air filters are characterised under ISO 5011 by filtration efficiency, intake resistance and dust holding capacity together.
• Dust holding capacity: approx. 380 g (calculated from 1.3 m² effective area at a typical 300 g/m² for wood-pulp media)
• Beta ratio (β value): not applicable to intake air filters. β values belong to hydraulic and lube filter testing under ISO 16889 multi-pass; a β value quoted for an air filter is normally copied from a hydraulic filter datasheet.

Flow and Resistance

• Rated air flow: matched to M37 free air delivery of 6 m³/min @ 0.7 MPa
• Face velocity: approx. 0.077 m/s (calculated; within the normal 0.05–0.15 m/s band for intake filters)
• Initial pressure drop: approx. 0.5–1.0 kPa (calculated)
• Operating differential range: approx. 1.0–6.0 kPa (calculated, from new-element resistance to alarm point)
• Alarm / final resistance: 6.0–6.5 kPa (calculated from typical machine differential indicator setting; confirm against the specific unit)
• Pressure drop vs. energy: each 1 kPa of intake resistance adds roughly 1% to machine energy consumption (calculated; see below)

Pressure drop and energy (calculated). At 0.7 MPa gauge discharge and 101.3 kPa atmospheric reference, intake resistance raises the compression ratio:

• 0 kPa (new element): ratio 7.91 — baseline
• 2 kPa: ratio 8.07 — +2.0%
• 4 kPa: ratio 8.24 — +4.1%
• 6 kPa (near alarm): ratio 8.41 — +6.3%

Engineering implication: across one element life (0 to 6 kPa) machine energy consumption climbs by roughly 6%. On a 37 kW unit running 6,000 hours per year, the later part of the element's life carries a measurable power penalty. The saving from running a loaded element is far smaller than the extra electricity paid — the engineering reason OEMs fit a differential alarm.

Dimensions and Installation

• Overall size: 270 mm OD x 120 mm height
• Construction: pleated (folded media wrap)
• Effective filtration area: approx. 1.3 m² (calculated from 270 mm OD / 200 mm ID / 35 mm pleat depth / approx. 154 pleats; approx. 1.7 m² if ID is 165 mm)
• Pleat count: approx. 150
• Pleat pitch: approx. 4.8 mm (calculated: 738 mm mean circumference ÷ 150 pleats)
• Mounting interface: end-cap located, matched to the M37 air filter assembly
• Sealing: axial face seal (typical for this element type; confirm against the physical part)

Sourcing note. When cross-checking a replacement, 270 mm OD and 120 mm height are the two most direct dimensions to compare. The ML37 / MU37 in the same series uses 39588777 (130 mm OD x 250 mm height) — the size difference is large and the two are not interchangeable.

Materials

• Media: imported wood-pulp filter paper (industry practice: US HV or Ahlstrom media)
• Media basis weight: approx. 130 g/m² (calculated; typical air-filter paper range is 100–150 g/m²)
• Inner and outer support: galvanised steel perforated cage, approx. 0.6 mm sheet, open area ≥45% (calculated; common practice for comparable elements)
• End caps: metal end caps (galvanised steel) with polyurethane bonding (calculated; no plastic end caps noted for this series)
• Seal: NBR rubber seal (calculated; standard for compressor intake parts, oil and temperature resistant, −30 to +100 °C)
• Bonding: polyurethane (PU) hot-melt adhesive (calculated; standard media-to-cap/cage process)

Operating Tolerance

• Operating temperature: −10 to +100 °C
• Relative humidity: ≤80% RH, no condensation. Wood-pulp media loses strength and efficiency when wet; condensing conditions require upstream moisture removal.
• Burst strength: approx. 200–400 kPa media burst (per ISO 2758 paper burst test; calculated, typical air-filter paper range)
• Collapse resistance: element designed for differential ≥10 kPa (calculated; approx. 50% safety margin over the 6.5 kPa alarm)
• Special functions: no flame-retardant, anti-static or moisture-proof rating noted for this part number

Service Life and Maintenance

• Service life: approx. 2,000 hours (industry value, consistent across sources)
• Practical replacement interval: shorten to under 1,000 hours in dusty, sandy or humid environments; follow the differential alarm
• Storage shelf life: approx. 2–3 years unopened, dry and ventilated storage (calculated; moisture or direct sunlight shortens this significantly)

Standards

• Applicable product standard: ISO 5011 (intake air cleaners for internal combustion engines and compressors — performance testing), evaluating filtration efficiency, intake resistance and dust holding capacity
• Frequently cited test standards: ISO 2941 / 2942 / 2943 / 3723 / 3724 / 3968
• Applicability note: the ISO 29xx / 37xx series are general test methods for hydraulic fluid power filter elements (collapse/burst, structural integrity, material compatibility, axial load, flow fatigue, pressure drop vs. flow). If a supplier can only offer hydraulic filter standards, request ISO 5011 data or the OEM specification sheet.

Standard Installation and Maintenance Steps

Single-person task; allow roughly 20–30 minutes.

1. Stop, isolate and depressurise. Press emergency stop or stop button, switch off main power and apply lockout/tagout. Open the receiver drain valve to release system pressure and wait for the separator tank gauge to read zero. Criterion: gauge at 0 with no residual air flow sound.
2. Locate and open the air filter housing. On the M37 the filter assembly sits at the intake end. Release the housing clamp or end-cover bolts and remove the cover. Criterion: cover undistorted, clamp not seized; free a seized clamp before dismantling further.
3. Remove the old element and inspect it. Pull the element straight out and check dust distribution and media condition. Criterion: replace immediately if media is torn, perforated, end caps are debonded or the seal face is flattened — even before the interval is reached. Black oily sludge on the outer surface indicates abnormal oil mist in the intake; check the upstream environment.
4. Clean the housing interior thoroughly. Wipe the inner wall and base with a lint-free cloth. Do not blast compressed air into the housing — this drives dust into the intake passage. Criterion: no loose dust on the inner wall, seal face flat and free of debris.
5. Verify the new element. Compare old and new: 270 mm OD, 120 mm height, face seal intact with no gaps, media undamaged. Criterion: all three dimensions and the visual check must match. If any item fails, do not install — re-confirm the part number.
6. Fit the new element and refit the cover. Lower the element vertically into the housing, confirm it is fully seated and the seal face is flush with no trapped material. Refit the cover and tighten clamps or bolts evenly in a diagonal sequence. Criterion: even gap between cover and housing, no visible skew.
7. Start-up check. Restore power and run the machine 5–10 minutes. Criterion: no abnormal whistle or intake noise (unusual noise usually means the seal is not compressed or the element is not seated); the air filter differential indicator sits in the green zone.

The one hard rule: never start the machine before the element is seated. Running with no element or an uncompressed seal lets unfiltered air straight into the airend — irreversible wear can occur in a short time.

FAQ

Are 99273906 and 39588777 interchangeable?
No. 39588777 is for the ML37 / MU37 and measures 130 mm OD x 250 mm height; 99273906 is for the M37 at 270 mm OD x 120 mm height. The size difference is more than double and the two cannot physically fit the same housing. Always cross-check by machine model plus part number.

How often should it be replaced?
Approximately 2,000 hours under standard conditions, but this is not a fixed deadline. In heavy dust (cement, foundry, woodworking, mining) shorten to under 1,000 hours; in clean environments with low running hours it may be extended. The most reliable trigger is the air filter differential indicator — replace when it reaches the alarm point.

What happens if it is not replaced?
Failure propagates through the system and has a clear economic cost. As the element loads, intake resistance rises; by compression-ratio calculation, going from 0 to 6 kPa adds roughly 6.3% to machine energy consumption. If the media tears or the seal fails, unfiltered air reaches the airend and dust contaminates the rotors, bearings, separator element, oil filter and lubricant together — repair cost moves from the price of one filter to the scale of an airend overhaul.

How do I know it needs changing?
Three signals: the differential indicator enters the alarm zone (approx. 6.0–6.5 kPa); on shutdown the element shows media fully covered in dust with pleats no longer visible; or the machine shows falling delivered air with rising current / energy consumption. Any one signal means replace.

Can the element be cleaned and reused?
Not recommended. This is a pleated paper element designed as a single-use part. Reverse blowing with compressed air only removes surface dust; fine particles trapped in the depth of the media cannot be cleared, and the air pressure can easily fracture fibres or distort pleat spacing, creating invisible channels that let unfiltered air pass. Reuse leaves the element looking clean but functionally failed — the risk outweighs the benefit.

What else should be checked when changing the air filter?
Check that the differential indicator still responds (it should return after being pressed and reset), that the intake hose is free of cracks or loosening, that the housing seal is not aged, and that the inlet valve operates correctly. These parts work together; replacing only the element without checking the surrounding items often leads to a further intake fault in a short time.

Is this a genuine part?
The 99273906 described on this page is an Ingersoll Rand OEM part number. When ordering, confirm by the part number itself — it is the one identifier that cannot be confused. Do not order solely on a "fits M37" claim or visual similarity.

Do all M-series machines use the same air filter?
No. Air filter specifications differ across the Ingersoll Rand M series: M22 uses 39588470 (130 mm OD), M37 uses 99273906 (270 mm OD), M55 uses 39708466 (278 mm OD), ML37 uses 39588777. The same series does not mean the same element — verify model by model.

What is the most common installation mistake?
Two: trapping material on the seal face or pressing the cover down before the element is fully seated, which causes leakage; and tightening cover bolts in a single-side sequence, which skews the cover. The correct method is to confirm seating, then tighten evenly in a diagonal cross pattern in stages.

Are there storage requirements for a new element?
Yes. Wood-pulp media swells and distorts when damp, reducing efficiency, and the metal cage corrodes. Store on indoor shelving in a dry, ventilated area, off the floor and away from walls, away from water and oil. Use within 2–3 years unopened, following first-in-first-out; long-term stockpiling is not recommended.

Compatible Machine Models

• M37 — 6 m³/min @ 0.7 MPa — 99273906 — 270 mm x 120 mm
• M22 — 3 m³/min @ 0.7 MPa — 39588470 — 130 mm x 151 mm
• M55 — 10 m³/min @ 0.7 MPa — 39708466 — 278 mm x 125 mm
• ML37 / MU37 — 6 m³/min @ 0.7 MPa — 39588777 — 130 mm x 250 mm
• 30S — 3 m³/min @ 0.7 MPa — 42855429 — 130 mm x 123 mm
• 50S — 6 m³/min @ 0.7 MPa — 42855411 — 216 mm x 318 mm
• 75S — 10 m³/min @ 0.7 MPa — 42855403 — 278 mm x 251 mm

How to read this list

• This page covers 99273906 for the M37. The other rows are same-series references only, provided to help you avoid a mis-purchase.
• ML37 / MU37 and M37 both deliver 6 m³/min, yet the air filter part numbers and dimensions are entirely different — equal air delivery does not mean a shared element. This is the most common confusion in the series.
• If your machine nameplate model is not listed, send a photo of the nameplate and the full model code. We will confirm by reverse part-number lookup before you order.

Machine generation note. The Ingersoll Rand M37 exists in more than one production generation. The 99273906 described here belongs to earlier M37 machines. Newer M37-75 series units (covered by the SL/SM37-75KW operation and parts manual) use a different part-number system. If your machine is a recent build, confirm against the parts manual supplied with the unit, or contact us with the machine serial number. In practice the safest confirmation is still to read the part number from the old element itself.

Related Components

The M37 intake and lubrication system includes seven parts maintained on a similar cycle to the air filter. Listed below by location, function and inspection point. For specific part numbers, refer to the machine parts manual.

• Oil filter element — in the main oil circuit between cooler and airend — removes wear debris and sludge from the lubricant, protecting bearings and rotors — replace together with the air filter; check the housing seal face for weeping afterwards.
• Separator element — inside the separator tank — separates oil mist from compressed air and returns oil, controlling oil carry-over — when replacing, check the oil return line for blockage (poor return directly causes high oil carry-over).
• Air filter differential indicator — on the air filter assembly — indicates element loading and replacement timing — should return after being pressed and reset; a reading that never moves means it has failed and should be replaced.
• Coolant filter element — in the coolant return circuit between cooler and filter — keeps coolant clean and prevents scale and debris build-up — replace together with the oil filter.
• Thermostatic control valve element — between cooler and filter — controls coolant flow through the cooler to maintain airend operating temperature — if the machine runs cold long-term or alarms on high temperature, check the thermostatic valve first.
• Breather filter — on the separator tank — balances tank pressure and prevents external dust entering the oil circuit — inspect on the same cycle as the air filter; shorten the interval in dusty environments.
• Intake hose and housing seal — between the air filter assembly and the airend — keeps the intake path leak-free with no unfiltered air bypass — check for cracks, ageing and loose clamps; bypass leakage is as harmful as running with no element.

Recommended kit replacement. On dusty sites, replace air filter, oil filter and separator element together to avoid staggered maintenance cycles and repeated shutdowns. Schedule the coolant filter element and thermostatic valve element on their own intervals.