Ingersoll Rand 99273906 Air Filter Element | M37 Compressor Intake

Product Overview

99273906 is the intake air filter element for Ingersoll Rand M37 screw air compressors. Mounted inside the air filter housing at the compressor inlet, upstream of the inlet valve, it is the first filtration barrier for the entire compressed air system. As the machine draws in ambient air, dust, sand, fibers, water mist and oil mist are captured by the filter media before reaching the airend — surface filtration intercepts large 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. When unfiltered air enters the screw airend, hard particles accelerate rotor and bearing wear while contaminating the downstream oil 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 carry-over can cause airend seizure. Replacing the air filter on schedule is therefore the lowest-cost protection measure for the airend.

Core Specifications

Item	Value
Part Number	99273906
Name	Air Filter Element
Application	Ingersoll Rand M37 screw air compressor
Unit Discharge Capacity	6 m³/min @ 0.7 MPa
Filter OD	270 mm
Filter 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 by operating conditions)

Technical Parameters

Filtration Performance

Parameter	Value / Notes	Data Type
Filtration Rating	2–10 μm	Industry value (sources cite 2–10, 3–12, 5–10, 10–15 μm; mainstream overlap taken)
Filtration Efficiency	≥98% for particles ≥5 μm	Industry value
Filter Class	HVAC filter classification (EN 779 G/M/F) does not apply; air filters are characterized per ISO 5011 by efficiency + intake resistance + dust holding capacity	Technical note
Dust Holding Capacity	Approx. 380 g	Calculated (1.3 m² effective area × 300 g/m² typical capacity for wood-pulp filter paper)
Beta Ratio (β)	Not applicable to air filters	Not applicable — see note below

Note on Beta Ratio: β value is a hydraulic and lubricating oil filter metric determined per ISO 16889 multi-pass test, characterizing filtration ratio at different particle sizes. Air filters are not characterized by β value; per ISO 5011 they are evaluated by filtration efficiency + intake resistance + dust holding capacity. A β value appearing in an air filter specification is typically miscopied from a hydraulic filter datasheet.

Flow and Resistance

Parameter	Value / Notes	Data Type
Rated Air Flow	Matches M37 discharge capacity 6 m³/min @ 0.7 MPa	Multi-source (unit parameters)
Filtration Face Velocity	Approx. 0.077 m/s	Calculated (6 m³/min ÷ 1.3 m², within typical 0.05–0.15 m/s air filter range)
Initial Pressure Drop	Approx. 0.5–1.0 kPa	Calculated (based on face velocity and wood-pulp paper resistance characteristics)
Operating Differential Range	Approx. 1.0–6.0 kPa	Calculated (full range from new element initial resistance to alarm resistance)
Alarm / Final Resistance	6.0–6.5 kPa	Calculated (per unit air filter differential indicator alarm setting; refer to machine specifications)
Pressure Drop vs. Energy	Each 1 kPa increase in intake resistance raises unit energy consumption by approx. 1%	Calculated — see below

Quantitative Relationship Between Pressure Drop and Energy (Calculated)

Based on M37 discharge pressure of 0.7 MPa (gauge) and atmospheric pressure of 101.3 kPa, intake resistance raises the compression ratio:

Intake Resistance	Compression Ratio	Relative Energy Increase
0 kPa (new element)	7.91	Baseline
2 kPa	8.07	+2.0%
4 kPa	8.24	+4.1%
6 kPa (near alarm)	8.41	+6.3%

Engineering Implication: As an element ages from new to alarm (0 → 6 kPa), unit energy consumption rises by approximately 6% over the interval. For a 37 kW unit running 6000 hours per year, this represents continuous excess power draw during the latter portion of element life. The savings from extending a clogged element's service life are far less than the additional electricity cost — this is the engineering basis for the OEM pressure differential alarm setting.

Dimensions and Installation

Parameter	Value / Notes	Data Type
Dimensions	OD 270 mm × H 120 mm	Multi-source consistent
Construction	Pleated (folded filter paper wound)	Industry value
Effective Filtration Area	Approx. 1.3 m²	Calculated (OD 270 / ID 200 / pleat depth 35 mm / approx. 154 pleats; approx. 1.7 m² if ID is 165 mm)
Pleat Count	Approx. 150 pleats	Calculated
Pleat Spacing	Approx. 4.8 mm	Calculated (average circumference 738 mm ÷ 150 pleats)
Mounting Interface	End cap positioning, matched to M37 air filter assembly	Based on machine compatibility
Sealing	Face seal (axial compression)	Calculated (common for this air filter construction; refer to actual part)

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

Material Composition

Parameter	Value / Notes	Data Type
Filter Media	Imported wood-pulp filter paper (industry commonly uses US HV or Korean Ahlstrom paper)	Industry value
Media Weight	Approx. 130 g/m²	Calculated (midpoint of typical 100–150 g/m² for air filter paper)
Inner/Outer Support	Galvanized steel perforated cage, approx. 0.6 mm thickness, open area ≥45%	Calculated (common practice for comparable products)
End Caps	Metal end caps (galvanized steel) + polyurethane adhesive	Calculated (no plastic end cap specified for this series)
Seal	Nitrile rubber (NBR) seal ring	Calculated (common material for compressor intake parts, oil and temperature resistant −30 to +100 °C)
Adhesive	Polyurethane (PU) hot-melt adhesive	Calculated (common process for bonding media to end caps/cage)

Operating Tolerance

Parameter	Value / Notes	Data Type
Operating Temperature	−10 to +100 °C	Industry value
Relative Humidity	≤80% RH, no condensation	Calculated (wood-pulp paper loses strength and efficiency when damp; condensation conditions require upstream water removal)
Bursting Strength	Filter paper bursting strength approx. 200–400 kPa (per ISO 2758 paper bursting strength test)	Calculated (typical range for air filter paper)
Collapse Resistance	Element design differential pressure resistance ≥10 kPa	Calculated (approx. 50% safety margin over 6.5 kPa alarm value)
Special Functions	No flame-retardant, anti-static or moisture-proof markings specified for this model	—

Service Life and Maintenance

Parameter	Value / Notes	Data Type
Service Life	Approx. 2000 hours	Industry value (multi-source consistent)
Actual Replacement Interval	Reduce to under 1000 hours in dusty, sandy or humid environments; follow differential pressure alarm	Engineering recommendation
Shelf Life	Approx. 2–3 years (unopened, dry and ventilated conditions)	Calculated (typical validity for filter paper and adhesive under controlled storage; moisture or sunlight exposure significantly shortens this)

Standards

Item	Content
Applicable Product Standard	ISO 5011 (Inlet air cleaning equipment for internal combustion engines and compressors — performance testing), evaluated by filtration efficiency, intake resistance and dust holding capacity
Commonly Cited Test Standards	ISO 2941 / 2942 / 2943 / 3723 / 3724 / 3968
Standard Applicability Note	The above ISO 29xx / 37xx series are actually general test methods for hydraulic fluid power filter elements (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 the OEM specification sheet as a supplement.

Standard Maintenance and Installation Procedure

Single-person operation, approx. 20–30 minutes.

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

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 cap bolts and remove the end cap. Criterion: end cap not deformed, clamp 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 damage, perforation, end cap debonding or compressed seal face, replace immediately even if the interval has not been reached; if the outer surface has black oil sludge, intake oil mist is abnormal — check the upstream environment.

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

5. Verify the new element
   Compare old and new: OD 270 mm, H 120 mm, face seal strip intact without gaps, media undamaged. Criterion: all three dimensions and appearance match; if any item does not match, do not install — re-verify the part number.

6. Install the new element and refit the end cap
   Place the new element vertically into the housing, confirm it is fully seated at the bottom and the seal face fits without trapped material. Refit the end cap and tighten the clamp or bolts evenly in a diagonal sequence. Criterion: uniform gap between end cap and housing, no visible misalignment.

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

The single iron rule of installation: Never start the unit before the element is seated. Starting without an element or with an uncompressed seal allows completely unfiltered air into the airend, causing irreversible wear in a short time.

Frequently Asked Questions

Are 99273906 and 39588777 interchangeable?
No. 39588777 corresponds to ML37 / MU37 models with element OD 130 mm and H 250 mm; 99273906 corresponds to M37 with OD 270 mm and H 120 mm. The dimensions differ by more than double and they physically cannot fit the same housing. When purchasing, verify by both machine model and part number.

How often should it be replaced?
Approximately 2000 hours under standard conditions. However, this is not a hard deadline: in high-dust environments (cement, foundry, woodworking, mining sites) reduce to under 1000 hours; clean environments with short running hours may allow extension. 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 is a chain reaction with a clear economic calculation. As the element accumulates dust, intake resistance rises — based on compression ratio calculations, resistance increasing from 0 to 6 kPa raises unit energy consumption by approximately 6.3%. Once the media is damaged or the seal fails, unfiltered air enters the airend directly, and dust contaminates the screw rotors, bearings, oil separator element, oil filter and lubricant simultaneously — repair costs escalate from the price of one filter to the magnitude of an airend overhaul.

How do I know it needs replacement?
Three signals: first, the differential indicator enters the alarm zone (approx. 6.0–6.5 kPa); second, visual inspection after shutdown shows the media surface completely covered with dust, with original pleat pattern no longer visible; third, discharge capacity drops while current/energy consumption rises. Replace upon any of these signals.

Can the element be cleaned and reused?
Not recommended. This type of pleated paper element is designed as a single-use item. Blowing compressed air from inside out only removes surface dust; deeply trapped fine particles cannot be removed, and blow-back pressure can easily fracture media fibers or deform pleat spacing, creating invisible channels that allow unfiltered air to pass. Continued use after cleaning represents a 'looks clean, actually failed' condition — the risk exceeds the benefit.

What else should be checked when replacing the air filter?
Recommended simultaneous checks: whether the air filter differential indicator is still responsive (does it return properly after reset), intake hose for cracks or looseness, housing seal ring for aging, inlet valve for proper operation. These components work together with the air filter; replacing only the element without checking the surroundings can easily lead to recurring intake issues in a short time.

Is this element a genuine OEM part?
The 99273906 described on this page is an Ingersoll Rand OEM part number. When purchasing, verify by the part number itself — the part number is the only unambiguous identity marker; 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 across models: M22 uses 39588470 (OD 130 mm), M37 uses 99273906 (OD 270 mm), M55 uses 39708466 (OD 278 mm), ML37 uses 39588777. Being in the same series does not mean the same filter — verify model by model.

What are the most error-prone steps during installation?
Two: first, compressing the end cap with trapped material or without full seating, causing seal leakage; second, tightening end cap bolts in a one-sided sequence, causing uneven force and misalignment. The correct method is to confirm seating, then tighten evenly in a diagonal cross pattern in multiple passes.

Are there storage requirements for a new element?
Yes. Filter paper expands and deforms when damp, reducing filtration efficiency; the metal cage rusts when damp. Store on indoor shelves in a dry, ventilated area, avoid contact with walls or floors, keep away from water and oil contamination, and use within 2–3 years in unopened condition. Follow first-in-first-out for unopened packaging; long-term stockpiling is not recommended.

Compatible Machine Models

No.	Model	Unit Discharge Capacity	Air Filter Part No.	Element OD × H
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

Reading the table

• This page's product 99273906 corresponds to row 1, M37; other rows are provided for same-series comparison to help you avoid mis-purchase.
• Row 4 ML37 / MU37 and row 1 M37 both have 6 m³/min discharge capacity, but air filter part numbers and dimensions are completely different — same discharge capacity does not mean interchangeable filter. This is the most easily confused point in this series.
• If your unit's nameplate model is not in the table above, please provide a photo of the unit nameplate and complete model; we will confirm by reverse part number lookup before ordering.

Note on machine generations

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

Related Components

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

Component	Location	Function	Inspection Points
Oil Filter Element	Main oil circuit, between cooler and airend	Filters wear debris and sludge from lubricant, protecting bearings and rotors	Replace with air filter; check housing seal face for oil seepage after replacement
Oil Separator Element	Inside oil separator tank	Separates oil mist from compressed air and returns oil, controlling discharge oil content	Check oil return line for blockage during replacement (poor return directly causes excessive discharge oil content)
Air Filter Differential Indicator	On air filter assembly	Indicates element blockage level, prompting replacement timing	Should return properly after reset; if reading does not change long-term, it has failed and should be replaced
Coolant Filter Element	Coolant circuit, between cooler and filter	Keeps coolant clean, preventing scale and wear debris deposits	Replace with oil filter
Thermostatic Control Valve Element	Between cooler and filter	Controls whether coolant passes through cooler, maintaining airend operating temperature	If unit runs cold long-term or has high-temperature alarm, check thermostatic valve first
Breather Filter	On oil separator tank	Balances tank pressure, preventing external dust from entering oil circuit	Check on same cycle as air filter; shorten interval in dusty environments
Intake Hose and Housing Seal Ring	Between air filter assembly and airend	Ensures intake path has no leakage or unfiltered air bypass	Check for cracks, aging, loose clamps — bypass leakage is as harmful as no filter installed

Recommended companion replacement: In high-dust sites, replace air filter + oil filter + oil separator element together to avoid maintenance cycle misalignment and repeated downtime. Schedule coolant filter and thermostatic valve element on their own cycles.