Ingersoll Rand 99273906 Air Filter Element for M37 Air Compressors

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Product Overview

99273906 is the intake air filter element for the Ingersoll Rand M37 screw air compressor. It is mounted inside the air filter housing at the compressor intake, upstream of the inlet valve, and forms the first filtration barrier for the entire compressed air system.

During operation, ambient air is drawn in and dust, grit, fibers, water mist, and oil mist are intercepted by the media before reaching the airend. Surface filtration captures coarse particles; depth filtration adsorbs fine particles. Only clean air is allowed into the rotor meshing zone.

Filter condition 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 clogging reduces intake volume, lowers discharge capacity, and raises energy consumption. In extreme cases, oil carry-over can cause airend seizure. Replacing the air filter on schedule is 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
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 per operating conditions)

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Basic Parameters

Parameter	Detail
Part Number	99273906
Brand	Ingersoll Rand
Product Name	Air Filter Element
Product Category	Intake Filtration (Air Filter)
Compatible Machine	M37 screw air compressor (see Section 6)
Unit Discharge Capacity	6 m³/min @ 0.7 MPa
Installation Position	Inside the intake air filter assembly, upstream of the inlet valve
Replacement Interval	Approx. 2,000 hours

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Technical Specifications

1. Filtration Performance (Core Indicators)

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

Regarding Beta Ratio: β values are indicators for hydraulic and lubricating oil filters, determined per ISO 16889 multi-pass testing, characterizing filtration ratio at different particle sizes. Air filter elements are not characterized by β values; they are evaluated per ISO 5011 using filtration efficiency + intake resistance + dust holding capacity. If a β value appears in an air filter specification, it is typically copied incorrectly from a hydraulic filter datasheet.

2. Flow and Resistance Parameters

Parameter	Value / Note	Data Basis
Rated Air Flow	Matches M37 unit discharge 6 m³/min @ 0.7 MPa	Multiple sources (unit parameters)
Face Velocity	Approx. 0.077 m/s	Estimated (6 m³/min ÷ 1.3 m², within the normal 0.05–0.15 m/s range for air filters)
Initial Pressure Drop	Approx. 0.5–1.0 kPa	Estimated (based on face velocity and wood-pulp media resistance characteristics)
Operating Differential Pressure Range	Approx. 1.0–6.0 kPa	Estimated (full range from new element initial resistance to alarm resistance)
Alarm / Final Resistance	6.0–6.5 kPa	Estimated (based on unit air filter differential pressure indicator alarm setting; refer to the specific machine)
Pressure Drop vs. Energy Consumption	Each 1 kPa increase in intake resistance raises unit energy consumption by approx. 1%	Estimated; calculation shown below

Quantitative Relationship Between Pressure Drop and Energy Consumption (Estimated)

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 vs. Baseline
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 a filter element goes from new to alarm condition (0 → 6 kPa), unit energy consumption rises by approximately 6% over the interval. For a 37 kW unit running 6,000 hours per year, this represents continuous excess power draw during the latter part of the filter's life. The savings from continuing to use a clogged filter are far less than the additional electricity cost — this is the engineering basis for the OEM differential pressure alarm setting.

3. Structural Dimensions and Installation Parameters

Parameter	Value / Note	Data Basis
Dimensions	Outer diameter 270 mm × height 120 mm	Consistent across multiple sources
Construction	Pleated (folded media wrapped)	Industry value
Effective Filtration Area	Approx. 1.3 m²	Estimated (based on OD 270 / ID 200 / pleat depth 35 mm / approx. 154 pleats; if ID is 165 mm, approx. 1.7 m²)
Number of Pleats	Approx. 150	Estimated
Pleat Spacing	Approx. 4.8 mm	Estimated (average circumference 738 mm ÷ 150 pleats)
Mounting Interface	End-cap located, matched to M37 air filter assembly	Based on machine compatibility
Sealing Method	End-face seal (axial compression)	Estimated (standard for this air filter construction; refer to actual product)

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 (outer diameter 130 mm × height 250 mm); the dimensional difference is substantial and the two are not interchangeable.

4. Material Composition

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

5. Operating Condition Tolerance

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

6. Service Life and Maintenance Parameters

Parameter	Value / Note	Data Basis
Service Life	Approx. 2,000 hours	Industry value (consistent across multiple sources)
Actual Replacement Interval	Reduce to under 1,000 hours in dusty, sandy, or humid environments; follow differential pressure alarm	Engineering recommendation
Shelf Life	Approx. 2–3 years (unopened, dry, ventilated conditions)	Estimated (typical shelf life for filter paper and adhesives under controlled storage; moisture or direct sunlight significantly shortens it)

7. Applicable Standards

Item	Detail
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 (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 the OEM specification sheet as a supplement.

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Standard Maintenance and Installation Steps

Personnel: single-person operation; working time approx. 20–30 minutes.

1. Shut down, disconnect power, and depressurize
   Press the emergency stop or shutdown button, cut the main power supply, and apply lockout/tagout. Open the air receiver drain valve to release system pressure and wait for the pressure gauge on the separator tank to read 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-cover bolts and remove the end cover. Criterion: end cover 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 a compressed seal 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 housing inner walls and bottom with a lint-free cloth. Do not blow compressed air directly into the housing interior (it will drive 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 parts: outer diameter 270 mm, height 120 mm, end-face seal strip complete without gaps, media undamaged. Criterion: all three dimensions and visual checks pass; if any item does not match, do not install — re-verify the part number.

6. Install the new element and reassemble the end cover
   Place the new element vertically into the housing, confirm it is fully seated at the bottom and the seal face is properly aligned without trapped material. Reinstall the end cover and tighten the clamp or bolts evenly in a diagonal sequence. Criterion: uniform gap between end cover and housing, no visible skew.

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 indicates the seal is not compressed or the element is not seated); air filter differential pressure indicator in the green zone.

Single Most Important Installation Rule: Never start the unit before the element is properly seated. Starting with no element or an uncompressed seal allows unfiltered air to enter the airend directly, causing irreversible wear in a short time.

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Frequently Asked Questions

Are 99273906 and 39588777 interchangeable?
No. 39588777 corresponds to ML37 / MU37 models, with element outer diameter 130 mm and height 250 mm; 99273906 corresponds to M37, with outer diameter 270 mm and height 120 mm. The dimensional difference is more than double, and they physically cannot fit the same housing. When ordering, verify by both machine model and part number.

How often should it be replaced?
Approximately 2,000 hours under standard conditions. However, this is not a rigid deadline: in high-dust environments (cement, foundry, woodworking, mining sites), shorten to under 1,000 hours; in clean environments with short running hours, it may be extended appropriately. The most reliable method is to follow the air filter differential pressure indicator and replace when it reaches the alarm position.

What happens if it is not replaced?
Failure propagates through a chain, with a clear economic calculation. As dust accumulates, intake resistance rises; based on compression ratio estimates, when resistance increases from 0 to 6 kPa, unit energy consumption increases by approximately 6.3%. Once the media is damaged or the seal fails, unfiltered air enters the airend directly, and dust contaminates the screw rotor, bearings, separator element, oil filter, and lubricant simultaneously — repair costs escalate from the price of one filter element to the scale of an airend overhaul.

How do I know it is time to replace?
Three signals: first, the differential pressure indicator enters the alarm zone (approx. 6.0–6.5 kPa); second, after shutdown, visual inspection of the element shows the media surface fully covered with dust and the original pleat pattern no longer visible; third, the unit shows reduced discharge capacity with increased current/energy consumption. Replace when any signal appears.

Can the element be cleaned and reused?
Not recommended. This type of element is a pleated paper filter designed as a single-use item. Blowing compressed air from inside out only removes surface dust; fine particles trapped in the depth cannot be removed. Additionally, back-blow pressure easily causes media fiber breakage or pleat deformation, creating invisible channels that allow unfiltered air to pass through. Continuing to use a cleaned element represents a "looks clean, actually failed" condition, with risk exceeding benefit.

What else should be checked when replacing the air filter?
Recommended simultaneous checks: whether the air filter differential pressure indicator is still responsive (does it return properly after pressing to reset), whether the intake hose has cracks or is loose, whether the housing seal ring is aged, and whether the inlet valve operates normally. These components work together with the air filter; replacing only the element without checking the surrounding parts can easily lead to recurring intake issues in a short time.

Is this element a genuine part?
The 99273906 described on this page is an Ingersoll Rand OEM part number. When ordering, rely on the part number itself — it 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. Air filter specifications differ across Ingersoll Rand M-series models: M22 uses 39588470 (outer diameter 130 mm), M37 uses 99273906 (outer diameter 270 mm), M55 uses 39708466 (outer diameter 278 mm), and ML37 uses 39588777. Being in the same series does not mean the same filter element; each must be verified by machine model.

What is the most error-prone step during installation?
Two: first, compressing the end cover with trapped material on the seal face or without full seating, causing a poor seal and air leakage; second, tightening end cover bolts in a single-side sequence, causing uneven load 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. Filter paper absorbs moisture, expands, deforms, and loses filtration efficiency; metal supports corrode when damp. Store on indoor shelving in a dry, ventilated area, away from walls and floors, and away from water and oil contamination. In unopened condition, use within 2–3 years. Follow first-in-first-out rotation for unopened packaging; long-term stockpiling is not recommended.

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Compatible Machine Models

No.	Model	Unit 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

Reading the Table

• The product on this page, 99273906, corresponds to row 1, M37. The other rows are provided as same-series model references to help you 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 — the same discharge capacity does not mean a common filter element. This is the most easily confused point in this series.
• If your unit's nameplate model is not in the table above, provide a photo of the unit nameplate and the complete model number. We will confirm by reverse lookup from the part number before you order.

Note on Machine Generations

Ingersoll Rand M37 units exist in different production generations. The 99273906 described on this page is the intake filter element for early M37 models. Newer M37-75 series units (corresponding to the SL/SM37-75KW operation parts manual) 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 directly from the old filter element.

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Related Components

There are 7 components in the M37 intake and lubrication system maintained on the same cycle as the air filter. They are listed below by location — function — inspection point. For specific part numbers, refer to the parts manual for your unit.

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 air filter; after replacement, check housing seal face for oil seepage
Separator Element	Inside the separator tank	Separates oil mist from compressed air and returns oil, controlling oil carry-over in discharge	During replacement, simultaneously check the oil return line for blockage (poor oil return directly causes excessive oil carry-over)
Air Filter Differential Pressure Indicator	On the air filter assembly	Indicates filter clogging level and signals replacement timing	Should return properly after pressing to reset; if the reading does not change over time, 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 together with oil filter
Thermostatic Control Valve Element	Between cooler and filter	Controls whether coolant passes through the cooler, maintaining airend operating temperature	If the unit runs cold for extended periods or triggers high-temperature alarms, check the thermostatic valve first
Breather Filter	On the separator tank	Balances tank pressure, preventing external dust from entering the oil circuit	Check 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, and loose clamps — bypass leakage is as harmful as running without a filter element

Recommended Group Replacement: At dusty sites, we recommend replacing the air filter + oil filter + separator element as a group to avoid staggered maintenance intervals and repeated downtime. Schedule the coolant filter and thermostatic valve element according to their own intervals.