Ingersoll Rand 99273906 Air Filter Element | M37 Compressor Inlet Filter

Product Overview

The Ingersoll Rand 99273906 is the 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, serving as the first filtration barrier for the entire compressed air system.

As ambient air is drawn in, 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.

Filter condition directly affects airend service life. Unfiltered air entering the screw airend accelerates rotor and bearing wear, and simultaneously contaminates the downstream oil separator, oil filter, and lubricant, shortening all three in step. Severe clogging reduces intake volume, lowering discharge capacity and raising energy consumption; in extreme cases, oil carryover can cause the airend to seize. Timely air filter replacement is therefore the lowest-cost protection measure for the airend.

Key Specifications

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
Filter Outside Diameter	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 Differential Pressure	6.0–6.5 kPa
Recommended Replacement Interval	Approx. 2000 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	Air filter elements are characterized per ISO 5011 by filtration efficiency, intake resistance, and dust holding capacity — not by EN 779 ventilation filter classes.
Dust Holding Capacity	Approx. 380 g
Beta Ratio (β)	Not applicable to air filter elements. Beta ratio is a hydraulic/lubricating oil filter metric per ISO 16889 multi-pass testing. Air filters are evaluated per ISO 5011.

Flow and Resistance

Parameter	Value / Notes
Rated Air Flow	Matches M37 discharge capacity of 6 m³/min @ 0.7 MPa
Filtration Face Velocity	Approx. 0.077 m/s
Initial Pressure Drop	Approx. 0.5–1.0 kPa
Operating Differential Pressure Range	Approx. 1.0–6.0 kPa
Alarm / Final Pressure Drop	6.0–6.5 kPa
Pressure Drop vs. Energy Consumption	Approximately 1% energy increase per 1 kPa rise in intake resistance

Engineering Note: As a filter element loads from new to alarm condition (0 → 6 kPa), compressor energy consumption rises by approximately 6%. For a 37 kW unit running 6,000 hours per year, this represents continuous excess power draw during the latter part of filter life. The cost of replacing a clogged filter is far lower than the added electricity cost — this is the engineering basis for the OEM differential pressure alarm setting.

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
Pleat Count	Approx. 150 pleats
Pleat Spacing	Approx. 4.8 mm
Mounting Interface	End-cap located, matched to M37 air filter assembly
Sealing Method	Face seal (axial compression)

Procurement Tip: When cross-referencing replacement parts, 270 mm OD and 120 mm height are the two most direct comparison dimensions. The ML37 / MU37 models in the same series use 39588777 (130 mm OD × 250 mm height) — a significant dimensional difference. These two parts are not interchangeable.

Materials of Construction

Parameter	Value / Notes
Filter Media	Imported wood pulp filter paper (industry-standard HV or Ahlstrom media)
Media Basis Weight	Approx. 130 g/m²
Inner/Outer Support	Galvanized steel perforated cage, approx. 0.6 mm thickness, ≥45% open area
End Caps	Metal end caps (galvanized steel) + polyurethane adhesive
Seal	NBR (nitrile rubber) seal ring
Bonding	Polyurethane (PU) hot-melt adhesive

Operating Conditions

Parameter	Value / Notes
Operating Temperature	−10 to +100 °C
Relative Humidity	≤80% RH, no condensation
Burst Strength	Approx. 200–400 kPa (per ISO 2758)
Collapse Pressure	Design differential pressure ≥10 kPa
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 differential pressure alarm
Shelf Life	Approx. 2–3 years (unopened, dry, ventilated storage)

Applicable Standards

Item	Details
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 ISO 29xx / 37xx series are hydraulic filter element test methods (burst resistance, structural integrity, material compatibility, axial load, flow fatigue, pressure drop vs. flow). If a supplier can only provide hydraulic filter standards, request ISO 5011 or OEM specification sheets.

Standard Maintenance and Installation Steps

Single-person operation, approximately 20–30 minutes.

1. Shutdown, Lockout, and Depressurization
   Press emergency stop or shutdown button, disconnect main power, and apply lockout/tagout. Open the receiver tank 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 is audible.

2. Locate and Open the Air Filter Housing
   The M37 filter assembly is located at the compressor intake end. Loosen the housing clamp or end-cover bolts and remove the cover. Criterion: cover is not deformed, clamp is not seized. If the clamp is seized, address it before removal.

3. Remove the Old Filter 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 compressed sealing surfaces, replace immediately even if the service interval has not been reached. If the outer surface carries black oil sludge, intake oil mist is abnormal — inspect the upstream environment.

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 interior (this drives dust into the intake passage). Criterion: no loose dust on inner walls, sealing surfaces flat and free of debris.

5. Verify the New Filter Element
   Compare old and new parts: 270 mm OD, 120 mm height, intact face seal without gaps, undamaged media. 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 Cover
   Place the new element vertically into the housing, confirming full seating at the bottom and proper seal contact without trapped material. Reinstall the cover and tighten clamps or bolts evenly in a diagonal sequence. Criterion: uniform gap between cover and housing, no visible skew.

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

Installation Iron Rule: Never start the compressor before the filter element is fully seated. Operating without a filter element or with an uncompressed seal allows unfiltered air to enter the airend directly, causing irreversible wear in a short time.

Frequently Asked Questions

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

How often should it be replaced?
Approximately 2000 hours under standard conditions. However, this is not a hard deadline: dusty environments (cement, foundry, woodworking, mining) should be reduced to under 1000 hours; clean environments with short running hours may extend it. 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 a clear economic cost. As the filter loads, intake resistance rises. Based on compression ratio calculations, resistance increasing from 0 to 6 kPa raises compressor energy consumption by approximately 6.3%. Once the media tears 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 a filter element to the scale of an airend overhaul.

How do I know it's time to replace?
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 fully covered with dust and original pleat pattern no longer visible; third, the compressor shows reduced discharge capacity with increased current/energy consumption. Any one signal indicates replacement is due.

Can the filter element be cleaned and reused?
Not recommended. This 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. Moreover, reverse blowing pressure easily causes media fiber breakage or pleat deformation, creating invisible channels that allow unfiltered air to bypass. Continued use after cleaning represents a "looks clean, actually failed" condition — the risk outweighs the benefit.

What else should be checked 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 inspecting surrounding parts can lead to recurring intake issues in a short time.

Is this filter element a genuine part?
The 99273906 described on this page is an Ingersoll Rand OEM part number. When purchasing, always reference 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 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. The same series does not mean the same filter element — verify model by model.

What are the most error-prone installation steps?
Two: first, trapped material on the sealing surface or incomplete seating before tightening the cover, causing seal leakage; second, tightening cover bolts in a single-side sequence, causing uneven cover 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 filter elements?
Yes. Moisture causes filter paper to swell and deform, reducing filtration efficiency; the metal cage will corrode if exposed to moisture. Store on indoor shelving in a dry, ventilated area, away from walls and floors, away from water and oil contamination. Use within 2–3 years unopened. Follow FIFO principles and avoid long-term stockpiling.

Compatible Models

No.	Model	Discharge Capacity	Air Filter Part No.	Filter 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

• This page's product 99273906 corresponds to Row 1, M37. Other rows are for same-series model comparison only, 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 filter elements. This is the most easily confused point in this series.
• If your compressor nameplate model is not listed above, please provide a nameplate photo and complete model number. We will reverse-look-up by part number to confirm before ordering.

Model Generation Note

The Ingersoll Rand M37 exists in different production generations. The 99273906 described on this page belongs to the earlier M37 model's intake filter. 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 shipped with the unit, or contact us to confirm by unit serial number. In practice, the most reliable confirmation method is still to read the part number from the old filter element itself.

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's 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 sealing surface for oil seepage after replacement
Oil Separator Element	Inside oil 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 filter clogging level, signals replacement timing	Should return properly after reset; if reading never changes, it has failed and should be replaced
Coolant Filter Element	Coolant circuit, between cooler and filter	Keeps coolant clean, prevents scale and wear debris deposits	Replace with oil filter
Thermostatic Control Valve Element	Between cooler and filter	Controls coolant flow through cooler, maintaining airend operating temperature	If unit runs cold long-term or shows high-temperature alarm, check thermostatic valve first
Breather Filter	On oil separator tank	Balances tank pressure, prevents external dust from entering oil circuit	Inspect 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 is leak-free with no unfiltered air bypass	Check for cracks, aging, loose clamps — bypass leakage is as harmful as no filter element

Recommended Replacement Bundling: In dusty sites, we recommend replacing air filter + oil filter + oil separator element together to avoid maintenance cycle misalignment and repeated downtime. Coolant filter and thermostatic valve element follow their own service intervals.