Ingersoll Rand M37 Air Filter Element 99273906

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1. Product Overview

99273906 is the intake air filter element for the Ingersoll Rand M37 rotary screw air compressor. It is installed 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 intercepted by the filter media before reaching the airend — surface filtration captures large particles while depth filtration adsorbs fine particles. Only clean air is allowed into the rotor meshing zone.

The condition of this filter element directly affects the service life of the airend. Hard particles entering the screw airend accelerate wear on rotors and bearings, while also contaminating the downstream oil separator, oil filter, and lubricant, shortening their service life simultaneously. Severe clogging reduces intake volume, lowering discharge capacity and increasing energy consumption; in extreme cases, oil carryover can cause airend seizure. Therefore, replacing the air filter on schedule is the lowest-cost protection measure for the airend.

Key Specifications at a Glance

Item	Value
Part Number	99273906
Product Name	Air Filter Element
Compatible Model	Ingersoll Rand M37 rotary screw compressor
Unit Discharge Capacity	6 m³/min @ 0.7 MPa
Outer Diameter	270 mm
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 Pressure Drop	6.0–6.5 kPa
Recommended Replacement Interval	Approx. 2,000 hours (adjust based on operating conditions)

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2. Basic Parameters

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

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3. Technical Specifications

3.1 Filtration Performance (Core Metrics)

Parameter	Value / Description	Data Type
Filtration Rating	2–10 μm	Industry value (overlapping range from various sources)
Filtration Efficiency	≥98% (for particles ≥5 μm)	Industry value
Filter Class	Not applicable to EN 779 G/M/F classification; air filters are characterized per ISO 5011 by efficiency, intake resistance, and 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 filters	Not applicable — see note below

Note on Beta Ratio: The beta ratio is a metric for hydraulic and lubricating oil filters, determined by ISO 16889 multi-pass testing. Air filters are not characterized by beta ratio; they are evaluated per ISO 5011 using filtration efficiency + intake resistance + dust-holding capacity. If a beta ratio appears in an air filter specification, it is typically copied incorrectly from a hydraulic filter datasheet.

3.2 Flow and Resistance Parameters

Parameter	Value / Description	Data Type
Rated Air Flow	Matches M37 unit discharge 6 m³/min @ 0.7 MPa	Multi-source (unit parameter)
Filtration Face Velocity	Approx. 0.077 m/s	Estimated (6 m³/min ÷ 1.3 m², within typical air filter range of 0.05–0.15 m/s)
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 (per unit air filter differential pressure indicator alarm setting; refer to unit manual)
Pressure Drop vs. Energy Consumption	Each 1 kPa increase in intake resistance increases 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 progresses from new to alarm condition (0 → 6 kPa), unit energy consumption gradually rises by approximately 6%. For a 37 kW unit running 6,000 hours per year, this represents continuous excess power consumption during the latter stage of filter life. The cost saved by continuing to use a clogged filter is far less than the additional electricity cost — this is the engineering basis for the factory-set differential pressure alarm.

3.3 Structural Dimensions and Installation Parameters

Parameter	Value / Description	Data Type
Dimensions	OD 270 mm × H 120 mm	Multi-source consistent
Structure	Pleated (folded media wound)	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 positioning, matches M37 air filter assembly	Based on model compatibility
Sealing Type	End face seal (axial compression)	Estimated (common for this air filter structure; refer to actual product)

Procurement Tip: When verifying replacement parts, OD 270 mm and height 120 mm are the two most direct dimensions to compare. The ML37 / MU37 models in the same series use 39588777 (OD 130 mm × H 250 mm) — dimensions differ significantly and the two are not interchangeable.

3.4 Material Composition

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

3.5 Operating Condition Tolerance

Parameter	Value / Description	Data Type
Operating Temperature	−10 to +100 °C	Industry value
Relative Humidity	≤80% RH, no condensation	Estimated (wood pulp media loses strength and efficiency when wet; condensation requires upstream moisture 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 Pressure Resistance	Element design pressure differential resistance ≥10 kPa	Estimated (approx. 50% safety margin over 6.5 kPa alarm value)
Special Features	No flame retardant, anti-static, or moisture-proof special ratings noted for this model	—

3.6 Service Life and Maintenance Parameters

Parameter	Value / Description	Data Type
Service Life	Approx. 2,000 hours	Industry value (multi-source consistent)
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 and ventilated storage)	Estimated (typical shelf life for filter paper and adhesives under controlled storage; moisture or sunlight exposure significantly reduces life)

3.7 Applicable Standards

Item	Detail
Applicable Product Standard	ISO 5011 (Inlet air cleaning equipment for internal combustion engines and compressors — performance testing), evaluating filtration efficiency, intake resistance, and dust-holding capacity
Commonly Referenced 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 transmission filter elements (burst resistance, structural integrity, material compatibility, axial load, flow fatigue, pressure drop vs. flow characteristics). When procuring, if a supplier can only provide hydraulic filter standards, request ISO 5011 or the original manufacturer specification sheet.

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4. Standard Maintenance and Installation Steps

Units: Single-person operation, approximately 20–30 minutes.

1. Shut down, disconnect power, and depressurize
   Press the 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 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 located 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 sealing surface, replace immediately even if the replacement interval has not been reached; if the outer surface has black oil sludge, intake oil mist is abnormal and upstream conditions 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 (this would blow 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 parts: OD 270 mm, height 120 mm, end face seal complete 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 reassemble the end cap
   Place the new element vertically into the housing, confirming it is fully seated at the bottom and the sealing surface is in contact without trapped material. Reinstall 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 inspection
   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.

The Single Iron Rule of Installation: 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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5. Frequently Asked Questions

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

How often should it be replaced?
Approximately 2,000 hours under standard conditions. However, this is not a hard deadline: in high-dust environments (cement, foundry, woodworking, mining sites), reduce to under 1,000 hours; in clean environments with short operating 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 I don't replace it?
Failure is a chain reaction with clear economic consequences. As dust accumulates, intake resistance rises; based on compression ratio calculations, resistance increasing from 0 to 6 kPa increases 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, 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 when to replace it?
Three signals: first, the differential pressure indicator enters the alarm zone (approx. 6.0–6.5 kPa); second, visual inspection after shutdown shows the media surface completely covered with dust and no visible pleat pattern; third, the unit shows reduced discharge capacity with increased current/energy consumption. Any one signal indicates replacement is due.

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; deeply trapped fine particles cannot be removed. Additionally, back-blowing pressure can easily cause media fiber breakage or pleat deformation, creating invisible channels that allow unfiltered air to pass through. Continuing to use a cleaned element creates a "looks clean, actually failed" condition with risks exceeding benefits.

What else should I check when replacing the air filter?
Recommended simultaneous checks: air filter differential pressure indicator responsiveness (does it return properly after reset), intake hose for cracks or looseness, housing seal ring for aging, and inlet valve operation. These components work together with the air filter; replacing only the element without checking surrounding parts 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 procuring, verify by the part number itself — the part number 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 models have different air filter specifications: 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 element — each model must be verified individually.

What is the most error-prone step during installation?
Two things: first, trapped material on the sealing surface or incomplete seating before tightening the end cap, causing seal leakage; second, tightening end cap bolts in a single-side 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 new elements?
Yes. Moisture causes filter paper to expand and deform, reducing filtration efficiency, and moisture causes the metal support to rust. Store on shelves in a dry, ventilated indoor area, avoid wall contact and floor placement, keep away from water and oil contamination, and use within 2–3 years in unopened condition. Follow first-in-first-out principles for unopened packaging; long-term stockpiling is not recommended.

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6. Compatible 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

How to Read This Table

• The product on this page, 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 the air filter part numbers and dimensions are completely different — same discharge capacity does not mean interchangeable elements. 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 the complete 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 belongs to the intake filter of 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 unit, or contact us to confirm by unit serial number. In practice, the most reliable verification method remains reading the part number directly from the old filter element.

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7. Related Components

The M37 intake and lubrication system has 7 components maintained on the same cycle as the air filter. Listed below by "location — function — 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 together with air filter; after replacement, check housing sealing surface for oil seepage
Oil Separator Element	Inside oil separator tank	Separates oil mist from compressed air and returns oil, controlling oil carryover	During replacement, also check oil return line for blockage (poor oil return directly causes excessive oil carryover)
Air Filter Differential Pressure Indicator	On air filter assembly	Indicates element clogging level, signaling replacement timing	Should return properly after reset; if reading remains unchanged for extended periods, 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 element
Thermostatic Control Valve Element	Between cooler and filter	Controls whether coolant passes through cooler, maintaining airend operating temperature	If unit runs cold for extended periods or has high-temperature alarms, check thermostatic valve first
Breather Filter	On oil separator tank	Balances tank pressure, preventing external dust from entering oil circuit	Inspect on same cycle as air filter; reduce interval in dusty environments
Intake Hose and Housing Seal Ring	Between air filter assembly and airend	Ensures intake passage is leak-free with no unfiltered air bypass	Check for cracks, aging, loose clamps — bypass leakage is as harmful as no filter element installed

Recommended Replacement Grouping: In dusty sites, we recommend replacing air filter + oil filter + oil separator as a set to avoid maintenance cycle misalignment and repeated downtime from single-component replacement. Coolant filter and thermostatic valve element should be scheduled separately according to their own intervals.