Ingersoll Rand 99273906 Air Filter Element | M37 Compressor Intake

Product Overview

99273906 is the intake air filter element for Ingersoll Rand M37 rotary screw air compressors. It mounts inside the air filter housing at the compressor inlet, upstream of the inlet valve, and serves as the first filtration barrier for the entire compressed-air system. As ambient air is drawn in, dust, grit, fibers, water mist and oil mist are captured by the media before reaching the airend — surface filtration arrests larger particles while depth filtration retains finer contaminants.

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 in step. A severely clogged element restricts intake volume, reducing discharge capacity and raising energy consumption; in extreme cases oil carry-over can lead to airend seizure. Timely replacement is the lowest-cost protection available for the airend.

Core Specifications

• Part number: 99273906
• Application: Ingersoll Rand M37 rotary screw compressor
• Discharge capacity: 6 m³/min @ 0.7 MPa
• Element outside 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 differential pressure: 6.0–6.5 kPa
• Recommended replacement interval: approx. 2000 hours, adjusted for operating conditions

Technical Parameters

Filtration Performance

• Filtration rating: 2–10 μm (industry range; published values vary between 2–10, 3–12, 5–10 and 10–15 μm — the mainstream overlap is quoted here)
• Filtration efficiency: ≥98% for particles ≥5 μm (industry value)
• Filter classification: Intake air filter elements are not classified under ventilation filter systems such as EN 779 G/M/F classes. Per ISO 5011, performance is characterized by filtration efficiency, intake resistance and dust holding capacity.
• Dust holding capacity: approx. 380 g (calculated from 1.3 m² effective area × typical 300 g/m² capacity for wood-pulp filter paper)
• Beta ratio: Not applicable to air filter elements. Beta ratio is a hydraulic and lubricating oil filter metric determined by ISO 16889 multi-pass testing. Air filter performance is evaluated under ISO 5011 by efficiency, intake resistance and dust holding capacity.

Flow and Resistance

• Rated air flow: matched to M37 discharge capacity 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 media resistance characteristics)
• Operating differential range: approx. 1.0–6.0 kPa (from new-element initial resistance to alarm resistance)
• Alarm / final resistance: 6.0–6.5 kPa (calculated from the compressor's air filter differential pressure indicator setting; refer to the machine for the exact value)
• Pressure drop vs. energy: each 1 kPa increase in intake resistance raises compressor energy consumption by approximately 1% (calculated — see below)

Quantified relationship between pressure drop and energy consumption (calculated): With M37 discharge pressure at 0.7 MPa (gauge) and atmospheric pressure at 101.3 kPa, intake resistance raises the compression ratio:

• 0 kPa (new element): compression ratio 7.91 — baseline
• 2 kPa: compression ratio 8.07 — +2.0%
• 4 kPa: compression ratio 8.24 — +4.1%
• 6 kPa (near alarm): compression ratio 8.41 — +6.3%

Engineering implication: as an element progresses from new to alarm condition (0 → 6 kPa), compressor energy consumption rises by roughly 6%. For a 37 kW unit running 6000 hours per year, this represents sustained excess power draw during the latter part of the element's service life. The electricity saved by continuing to run a clogged element far exceeds the cost of a replacement element — which is the engineering rationale behind the OEM differential pressure alarm.

Dimensions and Installation

• Dimensions: 270 mm outside diameter × 120 mm height (consistent across sources)
• Construction: pleated (folded filter paper wrap)
• Effective filtration area: approx. 1.3 m² (calculated from 270 mm OD / 200 mm ID / 35 mm pleat depth / approx. 154 pleats; approx. 1.7 m² if the inner diameter is 165 mm)
• Pleat count: approx. 150 pleats (calculated)
• Pleat spacing: approx. 4.8 mm (calculated: mean circumference 738 mm ÷ 150 pleats)
• Mounting interface: end-cap located, matched to the M37 air filter assembly
• Sealing: face seal (axial compression) — typical for this element type; confirm against the physical part

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

Materials

• Media: imported wood-pulp filter paper (industry-common US HV or Ahlstrom media)
• Media basis weight: approx. 130 g/m² (calculated — midpoint of the typical 100–150 g/m² range for air filter paper)
• Inner and outer support: galvanized steel perforated cage, approx. 0.6 mm sheet thickness, ≥45% open area (calculated — standard practice for comparable products)
• End caps: metal end caps (galvanized steel) with polyurethane adhesive (calculated — no plastic end caps noted for this series)
• Seal: nitrile rubber (NBR) seal ring (calculated — standard material for compressor intake parts, oil and temperature resistant from −30 to +100 °C)
• Bonding: polyurethane (PU) hot-melt adhesive (calculated — standard process for bonding media to end caps and cage)

Operating Condition Tolerance

• Operating temperature: −10 to +100 °C (industry value)
• Relative humidity: ≤80% RH, no condensation (calculated — wood-pulp media loses strength and efficiency when damp; condensation conditions require upstream moisture removal)
• Burst strength: media burst strength approx. 200–400 kPa per ISO 2758 paper burst testing (calculated — typical range for air filter paper)
• Collapse resistance: element designed for differential pressure ≥10 kPa (calculated — approx. 50% safety margin above the 6.5 kPa alarm value)
• Special functions: no flame-retardant, anti-static or moisture-proof ratings noted for this model

Service Life and Maintenance

• Service life: approx. 2000 hours (industry value, consistent across sources)
• Actual replacement interval: shorten to under 1000 hours in dusty, sandy or humid environments; always defer to the differential pressure alarm
• Shelf life: approx. 2–3 years unopened, in dry, ventilated storage (calculated — typical validity for filter paper and adhesives under controlled storage; moisture or direct sunlight significantly shortens this)

Applicable Standards

• 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 cited test standards: ISO 2941 / 2942 / 2943 / 3723 / 3724 / 3968
• Standard applicability note: The ISO 29xx / 37xx series are general test methods for hydraulic fluid power filter elements (burst resistance, structural integrity, material compatibility, axial load, flow fatigue, pressure drop vs. flow). Where a supplier can only provide hydraulic filter standards, request ISO 5011 data or the OEM specification sheet.

Standard Installation and Maintenance Procedure

Single-person operation; allow approximately 20–30 minutes.

1. Shut down, isolate power and depressurize. Press the emergency stop or shutdown button, disconnect the main power supply 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 at the intake end of the unit. Release the housing clamp or end-cover bolts and remove the cover. Criterion: cover is not deformed and the clamp is not seized; treat a seized clamp before proceeding.
3. Remove the old element and inspect its condition. Pull the element straight out and examine dust distribution and media condition. Criterion: replace immediately if the media is torn, punctured, the end cap is debonded or the sealing face is flattened — even if the interval has not elapsed. Black oily sludge on the outer surface indicates abnormal oil mist in the intake; check the upstream environment.
4. Thoroughly clean the housing interior. Wipe the inner walls and base with a lint-free cloth. Do not blow compressed air forcefully into the housing — this drives dust into the intake passage. Criterion: no loose dust on the inner walls; sealing face flat and free of debris.
5. Verify the new element. Compare old and new: 270 mm outside diameter, 120 mm height, intact end-face seal with no gaps, undamaged media. Criterion: all three dimensions and the visual check must match. If any item does not match, do not install — re-verify the part number.
6. Install the new element and refit the cover. Insert the element vertically into the housing, confirming it is fully seated at the base and the sealing face is properly aligned with no 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 noise (unusual noise usually indicates the seal is not compressed or the element is not seated); the air filter differential pressure indicator remains in the green zone.

The single most important rule: never start the compressor before the element is seated. Running with no element, or with an uncompressed seal, allows unfiltered air directly into the airend and can cause irreversible wear in a short time.

Frequently Asked Questions

Are 99273906 and 39588777 interchangeable?
No. 39588777 is for the ML37 / MU37 models with a 130 mm outside diameter and 250 mm height; 99273906 is for the M37 with a 270 mm outside diameter and 120 mm height. The dimensions differ by more than a factor of two and neither will physically fit the other's housing. Always verify by model plus part number.

How often should it be replaced?
Approximately 2000 hours under standard conditions, but this is not a hard limit. In high-dust environments (cement, foundry, woodworking, mining sites), shorten to under 1000 hours. Clean environments with short running hours may extend the interval. 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 dust accumulates, intake resistance rises; based on the compression ratio calculation, resistance increasing from 0 to 6 kPa raises compressor energy consumption by approximately 6.3%. If 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 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 completely covered in dust with no pleat pattern visible; or discharge capacity drops while current and energy consumption rise. Any one signal warrants replacement.

Can the element be cleaned and reused?
Not recommended. These pleated paper elements are designed as single-use components. Back-blowing with compressed air from inside out removes only surface dust; deeply embedded fine particles cannot be cleared, and back-blow pressure easily fractures media fibers or deforms pleat spacing, creating invisible channels that let unfiltered air pass. A cleaned element that looks clean but has lost filtration integrity carries more risk than benefit.

What else should be checked when replacing the air filter?
Check the differential pressure indicator for responsiveness (does it reset properly after being pressed), the intake hose for cracks or loosening, the housing seal ring for aging, and the inlet valve for correct operation. These components work together with the air filter; replacing only the element without checking the surrounding parts often leads to recurring intake problems.

Is this a genuine OEM part?
The 99273906 described on this page is an Ingersoll Rand OEM part number. When ordering, 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 all M-series models 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), ML37 uses 39588777. Sharing a series does not mean sharing an element — verify model by model.

What are the most common installation errors?
Two: trapping material at the sealing face or tightening the cover before the element is fully seated, causing leakage; and tightening cover bolts in a one-sided sequence, causing uneven loading 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. Filter paper absorbs moisture, swells and loses efficiency, and the metal cage corrodes when damp. Store on indoor shelving in a dry, ventilated area, away from walls and floors and away from water and oil. Use within 2–3 years while still sealed. Follow first-in-first-out rotation and avoid long-term stockpiling.

Compatible Models

• M37 — 6 m³/min @ 0.7 MPa — 99273906 — 270 mm × 120 mm (this product)
• M22 — 3 m³/min @ 0.7 MPa — 39588470 — 130 mm × 151 mm
• M55 — 10 m³/min @ 0.7 MPa — 39708466 — 278 mm × 125 mm
• ML37 / MU37 — 6 m³/min @ 0.7 MPa — 39588777 — 130 mm × 250 mm
• 30S — 3 m³/min @ 0.7 MPa — 42855429 — 130 mm × 123 mm
• 50S — 6 m³/min @ 0.7 MPa — 42855411 — 216 mm × 318 mm
• 75S — 10 m³/min @ 0.7 MPa — 42855403 — 278 mm × 251 mm

How to read this table:

• This page covers 99273906 for the M37 (first row). Other rows are provided as series reference to help avoid mis-purchase.
• ML37 / MU37 and M37 both have 6 m³/min discharge capacity, but the air filter part numbers and dimensions are completely different — matching discharge capacity does not mean a shared element. This is the most common point of confusion in this series.
• If your unit's nameplate model is not listed, provide a photo of the nameplate and the full model number, and we will confirm by reverse part-number lookup before ordering.

Note on model generations:

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

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 point. For specific part numbers, refer to the unit's parts manual.

• Oil filter element — main oil circuit, between cooler and airend. Removes wear debris and sludge from lubricant, protecting bearings and rotors. Replace together with the air filter; check the housing sealing face for oil seepage after replacement.
• Separator element — inside the oil separator tank. Separates oil mist from compressed air and returns oil to the system, controlling discharge oil carry-over. When replacing, check the oil return line for blockage — restricted return flow directly causes excessive oil carry-over.
• Air filter differential pressure indicator — on the air filter assembly. Indicates element clogging and signals replacement timing. Should reset properly after being pressed; a reading that never moves indicates failure and requires replacement.
• Coolant filter element — coolant circuit, between cooler and filter. Keeps coolant clean and prevents scale and wear debris accumulation. 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 triggers 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 the air filter assembly and the airend. Ensures the intake path is leak-free with no unfiltered air bypass. Check for cracks, aging and loose clamps — bypass leakage is as damaging as running without an element.

Recommended companion replacement: In high-dust sites, replace the air filter, oil filter and separator element together to avoid staggered maintenance intervals and repeated downtime. Schedule the coolant filter and thermostatic valve element according to their own service intervals.