Ingersoll Rand 99273906 Air Filter Element | M37 Compressor Inlet Filter

Product Overview

99273906 is the genuine Ingersoll Rand inlet air filter element for the M37 rotary screw air compressor. It installs inside the air filter housing at the compressor intake, upstream of the inlet valve, and serves as the first filtration barrier for the entire compressed-air system.

As the machine draws in ambient air, dust, grit, fibres, water mist and oil mist are captured by the filter media before reaching the airend — surface filtration stops larger particles while depth filtration retains finer ones. Only clean air is allowed into the rotor meshing zone.

Filter condition directly affects airend service life. Unfiltered air accelerates rotor and bearing wear and contaminates the downstream separator element, oil filter and lubricant, shortening the life of all three at once. A heavily blocked element reduces intake volume, lowering discharge capacity and raising energy consumption; in extreme cases oil carry-over can lead to airend seizure. Replacing the air filter on schedule is therefore the lowest-cost protection available for the airend.

Key Specifications

Item	Value
Part number	99273906
Description	Air Filter Element
Compatible model	Ingersoll Rand M37 rotary screw compressor
Machine discharge capacity	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. 2000 hours (adjust to operating conditions)

Technical Parameters

Filtration Performance

Parameter	Value / Notes
Filtration rating	2–10 μm
Filtration efficiency	≥98% for particles ≥5 μm
Filter class	Air filter elements are not classified under ventilation filter systems (EN 779 G/M/F). Performance is characterised per ISO 5011 by filtration efficiency, intake resistance and dust holding capacity.
Dust holding capacity	Approx. 380 g (estimated from 1.3 m² effective area × typical 300 g/m² for wood-pulp filter paper)
Beta ratio (β value)	Not applicable to air filter elements. β values are determined per ISO 16889 multi-pass testing for hydraulic and lubricating oil filters.

Flow and Resistance

Parameter	Value / Notes
Rated air flow	Matched to M37 discharge capacity of 6 m³/min @ 0.7 MPa
Filtration face velocity	Approx. 0.077 m/s (6 m³/min ÷ 1.3 m²; within the typical 0.05–0.15 m/s range for air filters)
Initial pressure drop	Approx. 0.5–1.0 kPa
Operating differential range	Approx. 1.0–6.0 kPa
Alarm / final resistance	6.0–6.5 kPa (per the machine's air filter differential indicator; confirm against the specific unit)
Pressure drop vs. energy	Each 1 kPa increase in intake resistance raises machine energy consumption by approximately 1%

Pressure drop and energy consumption: Based on an M37 discharge pressure of 0.7 MPa (gauge) and atmospheric pressure of 101.3 kPa, intake resistance raises the compression ratio. At 0 kPa (new element) the ratio is 7.91; at 2 kPa it is 8.07 (+2.0%); at 4 kPa it is 8.24 (+4.1%); at 6 kPa (near alarm) it is 8.41 (+6.3%). A filter element run from new to alarm therefore adds roughly 6% to machine energy consumption over its service life. For a 37 kW machine running 6000 hours per year, the extra electricity cost in the latter part of the filter's life exceeds the cost of the filter itself — which is the engineering rationale behind the factory-set differential alarm.

Dimensions and Installation

Parameter	Value / Notes
Dimensions	270 mm OD × 120 mm height
Construction	Pleated (folded filter paper)
Effective filtration area	Approx. 1.3 m² (based on 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 spacing	Approx. 4.8 mm
Mounting interface	End-cap located, matched to the M37 air filter assembly
Sealing	Face seal (axial compression)

Procurement note: When cross-checking replacements, 270 mm OD and 120 mm height are the two most direct dimensions to compare. The ML37 / MU37 models in the same series use 39588777 (130 mm OD × 250 mm height) — the dimensional difference is substantial and the two are not interchangeable.

Material Composition

Parameter	Value / Notes
Filter media	Imported wood-pulp filter paper (industry-common US HV or Ahlstrom media)
Media grammage	Approx. 130 g/m²
Inner / outer support	Galvanised steel perforated cage, approx. 0.6 mm thickness, ≥45% open area
End caps	Metal end caps (galvanised steel) with polyurethane adhesive
Seal	NBR seal ring, oil and temperature resistant −30 to +100 °C
Bonding	Polyurethane (PU) hot-melt adhesive

Operating Tolerance

Parameter	Value / Notes
Operating temperature	−10 to +100 °C
Relative humidity	≤80% RH, no condensation
Burst strength	Approx. 200–400 kPa (per ISO 2758 paper burst testing)
Collapse pressure	Design differential ≥10 kPa (approx. 50% safety margin over the 6.5 kPa alarm value)
Special functions	No flame-retardant, anti-static or moisture-proof ratings specified for this model

Service Life and Maintenance

Parameter	Value / Notes
Service life	Approx. 2000 hours
Actual replacement interval	Reduce to under 1000 hours in dusty, sandy or humid environments; follow the differential alarm
Shelf life	Approx. 2–3 years unopened, in dry, ventilated storage

Applicable Standards

Item	Details
Product standard	ISO 5011 — inlet air cleaners for internal combustion engines and compressors; performance evaluated by filtration efficiency, intake resistance and dust holding capacity
Commonly referenced test standards	ISO 2941 / 2942 / 2943 / 3723 / 3724 / 3968
Standard applicability note	The ISO 29xx / 37xx series are general test methods for hydraulic filter elements (collapse/burst, structural integrity, material compatibility, axial load, flow fatigue, pressure drop vs. flow). Where a supplier can only provide hydraulic filter standards, request ISO 5011 data or the OEM specification sheet.

Installation and Maintenance Steps

Single-person operation, approximately 20–30 minutes.

1. Shut down, isolate and depressurise. Press emergency stop or stop button, disconnect main power and apply lockout/tagout. Open the receiver tank 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 noise.
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 undeformed, clamp not seized; treat a seized clamp before removal.
3. Remove the old element and inspect its condition. Pull the element out vertically and check dust distribution and media condition. Criterion: replace immediately if the media is torn, perforated, the end cap is debonded or the seal face is flattened — even if the interval has not been reached. Black oily sludge on the outer surface indicates abnormal oil mist in the intake and the upstream environment should be checked.
4. Clean the housing interior thoroughly. Wipe the inner wall and base with a lint-free cloth. Do not blow compressed air hard 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, seal strip complete with no gaps, media undamaged. Criterion: all three dimensions and the visual check pass; if any item does not match, do not install — re-check the part number.
6. Fit the new element and refit the cover. Place the element vertically into the housing, confirm it is fully seated at the base and the seal face contacts without trapped material. Refit the cover and tighten the clamp 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 for 5–10 minutes. Criterion: no abnormal whistling or intake noise (unusual noise usually means the seal is not compressed or the element is not seated); the air filter differential indicator reads in the green zone.

The one hard rule: never start the machine before the element is seated. Running without an element, or with an uncompressed seal, sends unfiltered air straight into the airend and can cause irreversible wear in a short time.

FAQ

Are 99273906 and 39588777 interchangeable?
No. 39588777 is for ML37 / MU37 models with a 130 mm OD × 250 mm height element; 99273906 is for the M37 with a 270 mm OD × 120 mm height element. The dimensions differ by more than double and the two cannot physically fit the same housing. Always cross-check by model plus part number.

How often should it be replaced?
About 2000 hours under standard conditions, but this is not a fixed deadline. In high-dust environments (cement, foundry, woodworking, mining) shorten to under 1000 hours; clean environments with short running hours may allow longer. The most reliable method is to follow the air filter differential indicator and replace at 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 with dust, intake resistance rises; based on compression ratio, resistance increasing from 0 to 6 kPa raises machine energy consumption by about 6.3%. If the media tears or the seal fails, unfiltered air enters the airend and dust contaminates the rotors, bearings, separator element, oil filter and lubricant — repair cost escalates from the price of one filter to the level of an airend overhaul.

How do I know it needs replacing?
Three signals: the differential indicator enters the alarm zone (about 6.0–6.5 kPa); after shutdown the element shows a media surface fully covered in dust with no visible pleats; or the machine shows falling discharge capacity with rising current/energy consumption. Any one signal warrants replacement.

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

What else should be checked when changing the air filter?
Check the differential indicator for correct reset response, the intake hose for cracks or looseness, the housing seal ring for ageing, and the inlet valve for correct operation. These parts work together with the air filter; replacing only the element without checking the surroundings often leads to recurring intake problems.

Is this a genuine part?
The 99273906 described here is an Ingersoll Rand OEM part number. Always order by the part number itself — it is the only unambiguous identifier. Do not order on the basis of "fits M37" or visual similarity alone.

Do all M-series models use the same air filter?
No. Air filter specifications differ across the M series: M22 uses 39588470 (130 mm OD), M37 uses 99273906 (270 mm OD), M55 uses 39708466 (278 mm OD), and ML37 uses 39588777. Being in the same series does not mean the same element — cross-check each model individually.

What is the most common installation mistake?
Two: compressing the cover with material trapped at the seal face or with the element not fully seated, causing leakage; and tightening cover bolts in a one-sided sequence, causing uneven load and skew. The correct method is to confirm seating first, then tighten evenly in a diagonal cross pattern in stages.

Are there storage requirements for new elements?
Yes. Moisture causes the filter paper to swell and deform and reduces filtration efficiency, while the metal cage can corrode. Store on shelving in a dry, ventilated indoor area, off the floor and away from walls, water and oil. Use within 2–3 years while unopened. Follow first-in, first-out and avoid long-term stockpiling.

Compatible Models

No.	Model	Discharge capacity	Air filter part no.	Element OD × height
1	M37	6 m³/min @ 0.7 MPa	99273906	270 mm × 120 mm
2	M22	3 m³/min @ 0.7 MPa	39588470	130 mm × 151 mm
3	M55	10 m³/min @ 0.7 MPa	39708466	278 mm × 125 mm
4	ML37 / MU37	6 m³/min @ 0.7 MPa	39588777	130 mm × 250 mm
5	30S	3 m³/min @ 0.7 MPa	42855429	130 mm × 123 mm
6	50S	6 m³/min @ 0.7 MPa	42855411	216 mm × 318 mm
7	75S	10 m³/min @ 0.7 MPa	42855403	278 mm × 251 mm

How to read the table

• This page covers 99273906, row 1 (M37); the other rows are included only as same-series references to help avoid mis-purchase.
• Row 4 (ML37 / MU37) and row 1 (M37) both have 6 m³/min discharge capacity, but the air filter part numbers and dimensions are completely different — identical discharge capacity does not mean a shared element, and this is the most easily confused point in the series.
• If your machine nameplate model is not listed, provide a photo of the nameplate and the full model number so we can reverse-look-up the part number before ordering.

Model generation note

The Ingersoll Rand M37 exists in different production generations. The 99273906 described here is the inlet filter for earlier M37 models. Newer M37-75 series machines (covered by the SL/SM37-75KW operation and parts manual) use a different part-number system. If your machine is a recent build, verify against the parts manual supplied with the unit or contact us with the machine serial number. In practice the most reliable confirmation is to read the part number directly from the old element.

Related Components

Seven components in the M37 intake and lubrication system are maintained on the same cycle as the air filter. They are listed below by location, function and inspection point; for specific part numbers refer to the machine parts manual.

Component	Location	Function	Inspection point
Oil filter element	Main oil circuit, between cooler and airend	Removes wear debris and sludge from lubricant, protecting bearings and rotors	Replace together with the air filter; check the housing seal face for oil seepage after replacement
Separator element	Inside the separator tank	Separates oil mist from compressed air and returns oil, controlling oil carry-over	Check the oil return line for blockage at replacement — poor return directly causes excessive oil carry-over
Air filter differential indicator	On the air filter assembly	Indicates element blockage and signals replacement timing	Should reset correctly when pressed; a reading that never moves indicates failure and the indicator should be replaced
Coolant filter element	Coolant circuit, between cooler and filter	Keeps coolant clean and prevents scale and debris build-up	Replace together with the oil filter element
Thermostatic control valve element	Between cooler and filter	Controls coolant flow through the cooler to maintain airend operating temperature	If the machine runs cold or gives high-temperature alarms, 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 ring	Between air filter assembly and airend	Ensures an leak-free intake path with no unfiltered air bypass	Check for cracks, ageing and loose clamps — bypass leakage is as harmful as running without an element

Recommended replacement grouping: At dusty sites, replace the air filter, oil filter element and separator element together to avoid staggered maintenance intervals and repeated downtime. The coolant filter element and thermostatic valve element follow their own service schedules.