Ingersoll Rand 99273906 Air Filter Element | M37 Compressor Inlet Filter

Product Overview

99273906 is the inlet air filter element for the Ingersoll Rand 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.

During operation, ambient air is drawn in and dust, sand, fibers, water mist and oil mist are captured by the filter media before reaching the airend — surface filtration intercepts coarse particles while depth filtration adsorbs fine particles. Only clean air is allowed into the rotor meshing zone.

The condition of this element directly affects airend service life. Unfiltered air entering the screw airend accelerates rotor and bearing wear and contaminates the downstream separator element, oil filter and lubricant, shortening all three simultaneously. Severe blockage reduces intake volume, lowering discharge capacity and raising energy consumption; in extreme cases oil carryover can cause the airend to seize. 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
Applicable Model	Ingersoll Rand M37 rotary screw compressor
Discharge Capacity	6 m³/min @ 0.7 MPa
Outer Diameter	270 mm
Height	120 mm
Effective Filter 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 per operating conditions)

Technical Parameters

Filtration Performance

Parameter	Value / Notes
Filtration Rating	2–10 μm
Filtration Efficiency	≥98% (for particles ≥5 μm)
Filter Class	Evaluated per ISO 5011 using filtration efficiency, intake resistance and dust holding capacity; EN 779 G/M/F classification does not apply to compressor intake filters
Dust Holding Capacity	Approx. 380 g (estimated: 1.3 m² effective area × 300 g/m² typical wood pulp media capacity)
Beta Ratio (β)	Not applicable — β values apply to hydraulic and lubrication filters per ISO 16889 multi-pass testing, not to air filter elements

Flow and Resistance

Parameter	Value / Notes
Rated Air Flow	Matched to M37 discharge capacity: 6 m³/min @ 0.7 MPa
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 Pressure Differential Range	Approx. 1.0–6.0 kPa (from new element initial resistance to alarm resistance)
Alarm / Final Resistance	6.0–6.5 kPa (per the compressor air filter differential pressure indicator setting; refer to the machine for exact value)
Pressure Drop vs. Energy Consumption	Each 1 kPa increase in intake resistance raises compressor energy consumption by approximately 1%

At a discharge pressure of 0.7 MPa (gauge) and atmospheric pressure of 101.3 kPa, intake resistance raises the compression ratio. Going from a new element (0 kPa) to near-alarm condition (6 kPa), energy consumption increases by approximately 6.3%. For a 37 kW compressor running 6,000 hours per year, this represents significant additional power draw during the latter part of the filter's service life. Continuing to run a clogged element costs far more in electricity than the filter itself — this is the engineering basis for the OEM differential pressure alarm setting.

Dimensions and Installation

Parameter	Value / Notes
Dimensions	Outer diameter 270 mm × height 120 mm
Construction	Pleated (folded filter paper)
Effective Filter Area	Approx. 1.3 m² (calculated from OD 270 mm / ID 200 mm / pleat depth 35 mm / approx. 154 pleats; approx. 1.7 m² if ID is 165 mm)
Pleat Count	Approx. 150
Pleat Spacing	Approx. 4.8 mm (average circumference 738 mm ÷ 150 pleats)
Installation Interface	End-cap located, matched to M37 air filter assembly
Sealing	End-face seal (axial compression)

Procurement note: When cross-referencing replacement parts, outer diameter 270 mm and height 120 mm are the two most direct comparison dimensions. 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 Construction

Parameter	Value / Notes
Filter Media	Imported wood pulp filter paper (industry-common US HV or Korean Ahlstrom media)
Media Weight	Approx. 130 g/m² (median of typical 100–150 g/m² range for air filter paper)
Inner/Outer Support	Galvanized steel perforated cage, approx. 0.6 mm thickness, ≥45% open area
End Caps	Metal end caps (galvanized steel) with polyurethane adhesive
Seal	Nitrile rubber (NBR) seal ring, oil and temperature resistant −30 to +100 °C
Adhesive	Polyurethane (PU) hot-melt adhesive

Operating Conditions

Parameter	Value / Notes
Operating Temperature	−10 to +100 °C
Relative Humidity	≤80% RH, no condensation
Bursting Strength	Approx. 200–400 kPa (per ISO 2758 paper bursting strength test)
Collapse Pressure Resistance	≥10 kPa design differential pressure (approx. 50% safety margin over the 6.5 kPa alarm value)
Special Features	No flame-retardant, anti-static or moisture-proof ratings specified for this model

Service Life and Maintenance

Parameter	Value / Notes
Service Life	Approx. 2,000 hours under standard conditions
Actual Replacement Interval	Reduce to under 1,000 hours in dusty, sandy or humid environments; replace when the differential pressure indicator alarms
Shelf Life	Approx. 2–3 years (unopened, dry and ventilated storage)

Applicable Standards

Item	Details
Product Standard	ISO 5011 (Inlet air cleaning equipment for internal combustion engines and compressors — performance testing), evaluated on 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 fluid power filter elements (collapse/burst resistance, structural integrity, material compatibility, axial load, flow fatigue, pressure drop vs. flow characteristics). If a supplier can only provide hydraulic filter standards, request ISO 5011 or OEM specification sheets.

Installation and Maintenance Procedure

Single-person operation, approximately 20–30 minutes.

1. Shut down, disconnect power and relieve pressure
   Press emergency stop or shutdown, disconnect main power and apply lockout/tagout. Open the receiver tank drain valve to release system pressure and wait for the separator tank pressure gauge to read zero. Criterion: gauge reads 0 and no residual air flow is audible.

2. Locate and open the air filter housing
   The M37 filter assembly is at the intake end of the unit. Loosen the housing clamp or end-cover bolts and remove the cover. Criterion: cover is not deformed and clamp is not seized; if the clamp is seized, address it before removal.

3. Remove the old element and inspect its condition
   Pull the old element straight out and observe dust distribution and media condition. Criterion: if the media shows tears, holes, end-cap debonding or a flattened sealing face, replace immediately even if the service interval has not been reached; if the outer surface has black oil sludge, intake oil mist is abnormal and the upstream environment should be checked.

4. Thoroughly clean the housing interior
   Wipe the inner walls and bottom with a lint-free cloth. Do not blow compressed air directly into the housing (this drives dust into the intake passage). Criterion: no loose dust on inner walls, sealing surface flat and free of debris.

5. Verify the new element
   Compare old and new: outer diameter 270 mm, height 120 mm, end-face seal intact with no gaps, media undamaged. Criterion: all three dimensions and appearance match; if any item does not match, do not install — recheck the part number.

6. Install the new element and reassemble the cover
   Place the new element vertically into the housing, confirm it is fully seated at the bottom and the sealing face is properly aligned with no trapped material. Reinstall the cover and tighten the clamp or bolts evenly in a diagonal sequence. Criterion: even gap between cover and housing with no visible skew.

7. Start-up check
   Restore power and run the compressor for 5–10 minutes. Criterion: no abnormal whistling or intake air noise (unusual noise usually indicates the seal is not compressed or the element is not seated); the air filter differential pressure indicator is in the green zone.

The one absolute rule: Never start the compressor before the element is seated. Running with no element or with an uncompressed seal allows unfiltered air directly into the airend, causing irreversible wear in a short time.

Frequently Asked Questions

Are 99273906 and 39588777 interchangeable?
No. 39588777 is for ML37 / MU37 models with a 130 mm outer diameter and 250 mm height; 99273906 is for M37 with a 270 mm outer diameter and 120 mm height. The dimensional difference is more than double and they cannot physically fit the same housing. Always cross-check by both model and part number.

How often should it be replaced?
Approximately 2,000 hours under standard conditions. However, this is not a fixed deadline: in high-dust environments (cement, foundry, woodworking, mining) reduce to under 1,000 hours; in clean environments with low running hours it may be extended. The most reliable method is to replace when the differential pressure indicator alarms.

What happens if I don't replace it?
Failure is a chain reaction with a clear economic cost. As dust accumulates, intake resistance rises; based on compression ratio calculations, going from 0 to 6 kPa increases energy consumption by approximately 6.3%. Once the media tears or the seal fails, unfiltered air enters the airend directly, contaminating the screw rotors, bearings, separator element, oil filter and lubricant simultaneously — repair cost escalates from the price of one filter to the level of an airend overhaul.

How do I know it's time to replace?
Three signals: the differential pressure indicator enters the alarm zone (approx. 6.0–6.5 kPa); visual inspection after shutdown shows the media surface completely covered with dust and no visible pleat pattern; the compressor shows reduced discharge capacity with increased current/energy consumption. Any one signal warrants replacement.

Can the element be cleaned and reused?
Not recommended. These are pleated paper elements designed as single-use items. Blowing compressed air from inside out only removes surface dust; deeply trapped fine particles cannot be removed. Back-blow pressure can also rupture media fibers or deform pleat spacing, creating invisible channels that allow unfiltered air to pass. A cleaned element is "visually clean but functionally failed" — the risk outweighs any benefit.

What else should be checked when replacing the air filter?
Check the differential pressure indicator for responsiveness (does it return properly after reset), intake hoses for cracks or looseness, housing seal rings for aging, and inlet valve operation. These components work together with the air filter; replacing only the element without checking the surrounding parts can quickly lead to recurring intake problems.

Is this a genuine OEM part?
99273906 is the Ingersoll Rand OEM part number. When ordering, always verify by the part number itself — it is the only unambiguous identifier. Do not order based solely on "fits M37" or visual similarity.

Do M37 and other M-series models use the same air filter?
No. Ingersoll Rand M-series air filter specifications differ by model: M22 uses 39588470 (130 mm OD), M37 uses 99273906 (270 mm OD), M55 uses 39708466 (278 mm OD), ML37 uses 39588777. Same series does not mean same filter — each model must be verified individually.

What is the most common installation error?
Two: first, trapped material on the sealing face or incomplete seating before tightening the cover, causing seal leakage; second, tightening cover bolts in a single-side sequence, causing uneven stress and skew. The correct method is to confirm seating, then tighten evenly in a diagonal cross pattern in multiple passes.

Are there storage requirements for new elements?
Yes. Moisture causes filter paper to swell and deform, reducing filtration efficiency, and the metal cage will corrode. Store on indoor shelving in a dry, ventilated area, away from walls and floors, away from water and oil. Use within 2–3 years while unopened. Follow first-in-first-out principles; long-term stockpiling is not recommended.

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 this table

• The product on this page, 99273906, corresponds to row 1, M37. Other rows are provided as same-series cross-reference to help prevent mis-ordering.
• 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 — same discharge capacity does not mean interchangeable filters. This is the most common point of confusion in this series.
• If your compressor nameplate model is not listed above, provide a photo of the nameplate and the full model number; we will cross-reference by part number and confirm before ordering.

Note on model generations

The Ingersoll Rand M37 exists in different production generations. The 99273906 described on this page is the intake filter for earlier M37 models. Newer M37-75 series units (corresponding to the SL/SM37-75KW operation and parts manual) use a different part number system in their parts manual. If your unit is a recent model, verify against the parts manual supplied with the machine, or contact us to confirm by serial number. In practice, the most reliable verification method remains reading the part number directly from the old filter element.

Related Components

There are 7 components in the M37 intake and lubrication system maintained on the same cycle as the air filter. Listed below by location, function and inspection points; refer to the machine parts manual for specific part numbers.

Component	Location	Function	Inspection Points
Oil Filter Element	Main oil circuit, between cooler and airend	Removes wear debris and sludge from lubricant, protecting bearings and rotors	Replace together with air filter; check housing seal face for oil seepage after replacement
Separator Element	Inside separator tank	Separates oil mist from compressed air and returns oil, controlling oil carryover	Check oil return line for blockage during replacement (poor return directly causes excessive oil carryover)
Air Filter Differential Pressure Indicator	On air filter assembly	Indicates element blockage level and replacement timing	Should return properly after reset; if the reading never moves, it has failed and should be replaced
Coolant Filter Element	Coolant circuit, between cooler and filter	Keeps coolant clean, preventing scale and debris accumulation	Replace together with oil filter element
Thermostatic Control Valve Element	Between cooler and filter	Controls coolant flow through the cooler to maintain airend operating temperature	If the unit runs cold long-term or gives high-temperature alarms, check the thermostatic valve first
Breather Filter	On separator tank	Balances tank pressure and prevents external dust from 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 the intake path is leak-free with no unfiltered air bypass	Check for cracks, aging, loose clamps — bypass leakage is as harmful as running with no filter

Recommended kit replacement: In dusty sites, replace the air filter, oil filter element and separator element together to avoid staggered maintenance intervals and repeated downtime. Schedule the coolant filter element and thermostatic valve element according to their own service intervals.