Ingersoll Rand 99273906 Air Filter Element | M37 OEM Intake Filter

Product Overview

99273906 is the intake air filter element for the Ingersoll Rand M37 screw air compressor. It mounts 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. As the machine draws in outside air, dust, sand, fibers, water mist, and oil mist are retained by the filter media before reaching the airend — surface filtration captures coarse particles, depth filtration adsorbs fine particles. Only clean air is allowed into the rotor mesh zone.

The condition of this element directly affects airend service life. Hard particles entering the screw airend accelerate rotor and bearing wear and contaminate the downstream separator element, oil filter, and lubricant, shortening all three service lives together. When the element is severely clogged, intake volume drops, discharge volume falls, and energy consumption rises; in extreme cases oil carryover can lead to airend seizure. Replacing the air filter on schedule is therefore the lowest-cost airend protection measure available.

Core Specifications

Item	Value
Part Number	99273906
Product Name	Air Filter Element
Compatible Machine	Ingersoll Rand M37 screw air compressor
Unit Discharge Volume	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 to 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 characterised per ISO 5011 by filtration efficiency, intake resistance, and dust holding capacity — not by the EN 779 G/M/F ventilation filter classification
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 value)	Not applicable to air filter elements; β values are determined per ISO 16889 multi-pass testing for hydraulic and lube oil filters

Flow and Resistance

Parameter	Value / Notes
Rated Air Flow	Matched to M37 discharge volume of 6 m³/min @ 0.7 MPa
Filtration Face Velocity	Approx. 0.077 m/s (calculated: 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 (calculated from face velocity and wood-pulp paper resistance characteristics)
Operating Differential Pressure Range	Approx. 1.0–6.0 kPa (from new-element initial resistance to alarm resistance)
Alarm / Terminal Resistance	6.0–6.5 kPa (per the unit's air filter differential pressure indicator setting; confirm against the specific machine)
Pressure Drop vs. Energy	Each 1 kPa increase in intake resistance raises unit energy consumption by approximately 1% (calculated; see table below)

Quantified pressure drop vs. energy relationship (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 condition (0 → 6 kPa), unit 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 the element's life. The cost of continuing to run a clogged element far exceeds the cost of a replacement element — this is the engineering basis for the factory pressure-drop alarm setting.

Dimensions and Installation

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

Procurement note: When cross-checking replacement parts, 270 mm OD and 120 mm height are the two most direct comparison dimensions. The same-series ML37 / MU37 machines use 39588777 (130 mm OD × 250 mm height) — the dimensional difference is substantial and the two are not interchangeable.

Materials of Construction

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

Operating Tolerance

Parameter	Value / Notes
Operating Temperature	−10 to +100 °C
Relative Humidity	≤80% RH, no condensation
Burst Strength	Filter paper burst strength approx. 200–400 kPa (per ISO 2758 paper burst test)
Collapse Resistance	Element designed for differential pressure ≥10 kPa (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 (industry standard, consistent across sources)
Actual Replacement Interval	Reduce to under 1,000 hours in dusty, sandy, or humid environments; always follow the differential pressure alarm
Shelf Life	Approx. 2–3 years when unopened and stored in dry, ventilated conditions

Applicable Standards

Item	Content
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 ISO 29xx / 37xx series are actually general test methods for hydraulic fluid power filters (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 the original manufacturer specification sheet.

Standard Maintenance and Installation Procedure

Single-person operation, approximately 20–30 minutes.

1. Shut down, isolate power, and release pressure
   Press the emergency stop or stop button, disconnect the main power supply, 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 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 cover. Criterion: cover free of deformation, 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 tears, perforations, end-cap debonding, or a flattened seal face, replace immediately even if the service interval has not been reached. If the outer surface is coated with black oil sludge, intake oil mist is abnormal — inspect the upstream environment.

4. Thoroughly clean the housing interior
   Wipe the housing interior and base 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 interior walls, seal face flat and free of debris.

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

6. Install the new element and refit the cover
   Place the new element vertically into the housing, confirming it is fully seated at the bottom and the seal face is in contact without trapped material. Refit the cover and tighten the clamp or bolts evenly in a diagonal sequence. Criterion: even gap between 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 means the seal is not compressed or the element is not seated); air filter differential pressure indicator in the green zone.

The single most important installation rule: Never start the unit before the element is seated. Running with no element or 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 machines with a 130 mm OD × 250 mm height element; 99273906 is for M37 with 270 mm OD × 120 mm height. The dimensions differ by more than a factor of two and they cannot physically fit the same housing. Always cross-check by machine model plus part number.

How often should it be replaced?
Approximately 2,000 hours under standard conditions. This is not a hard 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. The most reliable approach is to follow the air filter differential pressure indicator and replace at the alarm point.

What happens if it is not replaced?
Failure propagates through the system and has a clear economic cost. 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 tears or the seal fails, unfiltered air enters the airend directly and dust contaminates the screw rotors, bearings, separator element, oil filter, and lubricant simultaneously — repair cost escalates from the price of one filter element to the scale of an airend overhaul.

How do I know it needs replacing?
Three signals: the differential pressure indicator enters the alarm zone (approx. 6.0–6.5 kPa); visual inspection after shutdown shows the media surface fully covered with dust and the original pleat pattern no longer visible; discharge volume drops while current/energy consumption rises. Any one signal warrants replacement.

Can the element be cleaned and reused?
Not recommended. This is a pleated paper element designed as a single-use item. Blowing compressed air from inside out only removes surface dust; deeply trapped fine particles cannot be removed. Back-blowing pressure can also fracture the paper fibers or deform pleat spacing, creating invisible channels that allow unfiltered air to pass. Cleaning and reusing results in a "looks clean, actually failed" condition with more risk than benefit.

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

Is this a genuine part?
The 99273906 described on this page is an Ingersoll Rand original part number. Always confirm the part number itself — it is the only identifier that cannot be confused. Do not order based solely on "fits M37" or visual similarity.

Do M37 and other M-series machines use the same air filter?
No. Air filter specifications differ across the Ingersoll Rand M series: M22 uses 39588470 (130 mm OD), M37 uses 99273906 (270 mm OD), M55 uses 39708466 (278 mm OD), and ML37 uses 39588777. Being in the same series does not mean the same element — verify each by machine model.

What is the most common installation error?
Two: trapping material on the seal face or not fully seating the element before tightening the cover, causing a seal leak; and tightening cover bolts in a one-sided sequence, causing uneven force and skew. The correct method is to confirm seating, then tighten evenly in a diagonal cross pattern in stages.

Are there storage requirements for new elements?
Yes. Moisture causes the filter paper to swell and deform, reducing filtration efficiency, and the metal cage can corrode. Store on indoor shelving in a dry, ventilated area, away from walls and floors, water sources, and oil contamination. Use within 2–3 years in unopened packaging. Follow first-in-first-out and avoid long-term stockpiling.

Compatible Machine Models

No.	Model	Discharge Volume	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 listed only as same-series cross-references to help you avoid mis-purchase.
• Row 4 (ML37 / MU37) and row 1 (M37) both have 6 m³/min discharge volume, but the air filter part numbers and dimensions are completely different — same discharge volume does not mean interchangeable elements. This is the most easily confused point in this series.
• If your machine nameplate model is not in the table above, provide a photo of the machine nameplate and the full model number. We will reverse-look-up by part number and confirm before ordering.

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

Related Components

Seven components in the M37 intake and lubrication system are maintained on the same cycle as the air filter. They are listed below by location, function, and inspection point. For specific part numbers, refer to the machine's parts manual.

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; check housing seal face for oil seepage after replacement
Separator Element	Inside the oil separator tank	Separates oil mist from compressed air and returns oil, controlling discharge oil content	Check the oil return line for blockage during replacement (poor return flow directly causes excessive discharge oil content)
Air Filter Differential Pressure Indicator	On the air filter assembly	Indicates element clogging level and signals replacement timing	Should return normally after pressing 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 wear debris deposits	Replace together with the 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 long-term or gives high-temperature alarms, check the thermostatic valve first
Breather Filter	On the oil 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, and loose clamps — bypass leakage is as harmful as running without an element

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