Ingersoll Rand 99273906 Air Filter Element | M37 Compressor OEM Part

Product Overview

99273906 is the inlet air filter element for the Ingersoll Rand M37 rotary screw air compressor. It installs 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 ambient air is drawn in, dust, grit, fibers, water mist and oil mist are captured by the media before reaching the airend. Only clean air is allowed into the rotor meshing zone. Filter condition directly affects airend service life: hard particles accelerate rotor and bearing wear and contaminate the downstream separator element, oil filter and lubricant. A heavily clogged element reduces intake volume, lowering discharge capacity and raising energy consumption. Replacing the air filter on schedule is the lowest-cost protection available for the airend.

Key Specifications

• Part number: 99273906
• Product type: Air filter element / inlet filtration
• Compatible machine: Ingersoll Rand M37 rotary screw compressor
• Machine 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 micron
• Filtration efficiency: >=98% for particles >=5 micron
• Initial pressure drop: approx. 0.5-1.0 kPa
• Alarm differential pressure: 6.0-6.5 kPa
• Recommended replacement interval: approx. 2000 hours (adjust to operating conditions)

Technical Data

Filtration Performance

Air filter elements are characterized per ISO 5011 by filtration efficiency, intake resistance and dust holding capacity. The beta ratio used in hydraulic and lube filter specifications (ISO 16889 multi-pass) does not apply to this product. Dust holding capacity is estimated at approximately 380 g based on an effective area of 1.3 m2 and typical wood-pulp media capacity of 300 g/m2.

Flow and Resistance

• Rated air flow: matched to M37 discharge of 6 m3/min @ 0.7 MPa
• Filtration face velocity: approx. 0.077 m/s (within the typical 0.05-0.15 m/s range for air filters)
• Operating differential pressure range: approx. 1.0-6.0 kPa
• Energy impact: each 1 kPa rise in intake resistance increases machine energy consumption by approximately 1%

Because intake resistance raises the compression ratio, a filter running from new to the alarm point (0 to 6 kPa) can increase machine energy consumption by roughly 6% over its service life. On a 37 kW machine running 6000 hours per year, the electricity cost of an overdue filter far exceeds the price of the element itself. This is the engineering basis for the factory differential-pressure alarm setting.

Construction and Materials

• Configuration: pleated (folded) media, approx. 150 pleats, approx. 4.8 mm pleat spacing
• Media: imported wood-pulp filter paper, approx. 130 g/m2
• Support: galvanized steel perforated core and cage, approx. 0.6 mm thickness, open area >=45%
• End caps: galvanized steel with polyurethane adhesive bonding
• Seal: NBR rubber gasket, -30 to +100 C, oil and temperature resistant
• Sealing method: axial face seal (subject to actual unit)

Operating Conditions

• Working temperature: -10 to +100 C
• Relative humidity: <=80% RH, no condensation
• Burst strength (media): approx. 200-400 kPa per ISO 2758
• Collapse resistance: designed for differential pressure >=10 kPa (approx. 50% safety margin over the 6.5 kPa alarm value)
• No flame-retardant, anti-static or moisture-proof ratings are specified for this model

Service Life and Storage

• Service life: approx. 2000 hours under standard conditions
• Actual replacement interval: reduce to under 1000 hours in dusty, sandy or humid environments; follow the differential-pressure indicator
• Storage life: approx. 2-3 years unopened in dry, ventilated conditions; moisture or direct sunlight will shorten this significantly

Applicable Standards

The applicable product standard is ISO 5011 (inlet air cleaning equipment for internal combustion engines and compressors - performance testing), covering filtration efficiency, intake resistance and dust holding capacity. The ISO 2941 / 2942 / 2943 / 3723 / 3724 / 3968 series often cited in this category are hydraulic filter test methods (burst pressure, structural integrity, material compatibility, axial load, flow fatigue, pressure drop versus flow). If a supplier can only provide hydraulic filter standards, request ISO 5011 data or the original manufacturer specification sheet.

Installation and Maintenance

Single-person job, approximately 20-30 minutes.

1. Shut down, isolate and depressurize. Stop the machine, disconnect main power and apply lockout/tagout. Open the receiver drain valve and wait for the separator tank gauge to read zero.
2. Open the air filter housing. Locate the filter assembly at the intake end, release the clamp or end-cover bolts and remove the cover.
3. Remove and inspect the old element. Pull the element straight out and check dust distribution and media condition. Replace immediately if the media is torn, punctured, the end cap is debonded or the seal face is flattened. Black oily sludge on the outer surface indicates abnormal oil mist in the intake air.
4. Clean the housing interior. Wipe the inner walls and base with a lint-free cloth. Do not blow compressed air into the housing, as this drives dust into the intake passage.
5. Verify the new element. Confirm 270 mm outside diameter, 120 mm height, intact end-face seal and undamaged media. Do not install if any check fails.
6. Install and reassemble. Seat the element vertically and fully, confirm the seal face is clean and free of trapped material, then tighten the clamp or bolts evenly in a diagonal sequence.
7. Start-up check. Restore power and run for 5-10 minutes. There should be no abnormal whistling or intake noise, and the filter differential-pressure indicator should remain in the green zone.

Critical rule: never start the machine before the element is fully seated. Running without a properly sealed element allows unfiltered air into the airend and can cause irreversible wear within a short time.

Frequently Asked Questions

Are 99273906 and 39588777 interchangeable?
No. 39588777 fits ML37 / MU37 machines and measures 130 mm OD x 250 mm H. 99273906 fits M37 and measures 270 mm OD x 120 mm H. The two are physically incompatible. Always confirm by machine model plus part number.

How often should it be replaced?
Approximately 2000 hours under standard conditions. In dusty environments such as cement, foundry, woodworking or mining sites, shorten to under 1000 hours. The most reliable method is to replace when the differential-pressure indicator reaches the alarm point.

What happens if it is not replaced?
Failure cascades. As intake resistance rises from 0 to 6 kPa, estimated energy consumption increases by about 6.3%. If the media tears or the seal fails, unfiltered air enters the airend and contaminates the rotors, bearings, separator element, oil filter and lubricant, escalating repair cost from the price of one element to the level 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 fully covered in dust with no visible pleats; discharge capacity drops while current or energy consumption rises.

Can the element be cleaned and reused?
Not recommended. This is a disposable pleated paper element. Reverse blowing with compressed air only removes surface dust and can fracture media fibers or deform pleat spacing, creating invisible bypass paths. A cleaned element may look serviceable while actually being compromised.

What else should be checked at the same time?
Check the differential-pressure indicator response, intake hose for cracks or looseness, housing seal ring condition and inlet valve operation. Replacing the element without checking these parts can lead to recurring intake problems.

Is this a genuine part?
99273906 is the Ingersoll Rand original part number. When ordering, confirm against the part number itself rather than relying on model fitment or visual similarity alone.

Do all M-series machines use the same air filter?
No. M22 uses 39588470 (130 mm OD), M37 uses 99273906 (270 mm OD), M55 uses 39708466 (278 mm OD) and ML37 uses 39588777. Same series does not mean same element.

What are the most common installation errors?
Two: trapped material or incomplete seating before tightening the cover, causing leakage; and tightening cover bolts from one side only, causing uneven loading and skew. Always confirm seating, then tighten diagonally in stages.

Are there storage requirements?
Yes. Moisture causes media swelling and reduced efficiency, and corrodes the metal core. Store on shelves in a dry, ventilated room, away from walls, floors, water and oil. Use unopened stock within 2-3 years on a first-in, first-out basis.

Compatible Machine Models

No.	Model	Discharge Capacity	Air Filter Part No.	Element OD x H
1	M37	6 m3/min @ 0.7 MPa	99273906	270 mm x 120 mm
2	M22	3 m3/min @ 0.7 MPa	39588470	130 mm x 151 mm
3	M55	10 m3/min @ 0.7 MPa	39708466	278 mm x 125 mm
4	ML37 / MU37	6 m3/min @ 0.7 MPa	39588777	130 mm x 250 mm
5	30S	3 m3/min @ 0.7 MPa	42855429	130 mm x 123 mm
6	50S	6 m3/min @ 0.7 MPa	42855411	216 mm x 318 mm
7	75S	10 m3/min @ 0.7 MPa	42855403	278 mm x 251 mm

This page covers 99273906 for the M37 (row 1). Other rows are listed for comparison only, to help buyers avoid mis-purchase. Note that ML37 / MU37 and M37 share the same 6 m3/min discharge capacity but use completely different filter part numbers and dimensions. If your machine nameplate is not listed, provide a nameplate photo and full model number and we will confirm by part number before ordering.

Ingersoll Rand M37 compressors exist in different production generations. The 99273906 described here is the inlet filter for earlier M37 units. Newer M37-75 series machines use a different part number system in their parts manuals. For recent machines, confirm against the parts manual supplied with the unit, or contact us with the machine serial number. The most reliable confirmation is always to read the part number from the old element itself.

Related Components

Seven components in the M37 intake and lubrication system are maintained on a similar cycle. Confirm specific part numbers against the machine parts manual.

Component	Location	Function	Inspection Point
Oil filter element	Main oil circuit, between cooler and airend	Removes wear debris and sludge, protects bearings and rotors	Replace with the air filter; check housing seal for weeping after replacement
Separator element	Inside separator tank	Separates oil mist from compressed air and returns oil	Check the oil return line for blockage; poor return causes high oil carryover
Air filter differential-pressure indicator	On the air filter assembly	Indicates element clogging and replacement timing	Should reset normally when pressed; a static reading indicates failure
Coolant filter element	Coolant circuit, between cooler and filter	Keeps coolant clean, prevents scale and debris build-up	Replace together with the oil filter
Thermostatic control valve element	Between cooler and filter	Controls coolant flow through the cooler to maintain airend temperature	Check first if the machine runs cold or triggers high-temperature alarms
Breather filter	On separator tank	Balances tank pressure and prevents external dust entering the oil circuit	Inspect on the air filter cycle; shorten in dusty environments
Intake hose and housing seal ring	Between air filter assembly and airend	Ensures no leakage or unfiltered air bypass	Check for cracks, aging and loose clamps; bypass leakage is as harmful as no filter

Bundled replacement advice: In dusty sites, replace the air filter, oil filter and separator element together to avoid staggered maintenance cycles and repeated downtime. Schedule the coolant filter and thermostatic valve element on their own intervals.