7-27 Series
TMC (Tamrotor Marine Compressors) 7-27 Series — Starting / Working Air Compressor.
Inspector Detail
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Common issues
- Oil separator element fouling causing oil carryover into the air system
- Air/oil cooler fouling reducing cooling efficiency and tripping high-temperature protection
- Inlet air filter clogging reducing delivered capacity
- Minimum-pressure/check valve wear causing slow pressure build-up or oil carryover on start
- Solenoid/unloader valve failure
- Screw element bearing wear from oil contamination or low oil level
Inspection checklist
- Discharge air temperature trend
- Oil separator differential pressure
- Oil level and condition (contamination, viscosity)
- Safety/relief valve function test
- Inlet air filter condition
- Unloader/solenoid valve operation
- Vibration and noise level
- Automatic drain function on the compressor and downstream receiver
- Drive coupling/belt alignment and condition
Service intervals
| Oil change | typically 2000-4000 h, or per the specified oil type's own interval - confirm against the manual |
| Oil separator element replacement | typically 2000-4000 h |
| Air filter replacement | per differential-pressure indicator, typically 500-1000 h |
| Safety valve function test | at least annually or per class requirement |
| Screw element overhaul | typically 20,000-30,000 h - confirm against the manual |
Typical wear limits
| Oil carryover in discharge air | should stay within the manufacturer's specified limit for a well-maintained single-stage oil-lubricated screw compressor - confirm against the manufacturer's specification |
| Discharge temperature | sustained readings above the maker's high-temperature trip point indicate cooler fouling or low oil level - confirm against the manual |
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- oil separator element
- air filter element
- minimum pressure valve
- safety/relief valve
- unloader/solenoid valve
Safety
- Stored air pressure - isolate and vent before opening any part of the pressure system
- Hot discharge air and compressor casing surfaces
- Rotating drive coupling/belt guarding
- Oil mist/carryover fire risk if the separator fails and hot air lines ignite residual oil
Class survey
Starting/working air compressors are covered under machinery survey with function tests of safety valves, low-oil-pressure/high-temperature trips, and automatic duty-compressor cut-in for maintaining receiver pressure.
Components & Design
Component data being added…
Technical Data
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Common failures & inspection points
Verify safety valve opens at set pressure (typically 1.1-1.2 times max working pressure). Perform bench testing or in-situ pneumatic pressure test. Document set pressure annually. Check inter-stage valve set pressure does not exceed 1.2x stage working pressure; final stage not to exceed 1.1x rated discharge pressure.
Inspect oil level in crankcase sump before startup. Check oil color and clarity for water droplets or discoloration indicating contamination. Verify oil meets ISO VG specification for compressor type. Replace oil per maintenance schedule (typically 250-500 operating hours). Test oil for water content and acid number.
Verify air dryer and filters are functional and not blocked. Check intercooler and aftercooler operation. Inspect oil/water separator for debris or oil carryover. Sample discharged air for oil and water content per ISO 1217 and ISO 8573. Ensure moisture removal to prevent valve freezing and control system failures.
Visually inspect compressor body, air receiver tank, and all piping for rust, corrosion, stress cracks, or dents. Test for leaks at seams and connections using soap solution under pressure. Verify pressure vessel certification and hydrostatic test records. Check valve plate and cylinder head for erosion or damage from cavitation.
Confirm unloader valve and discharge line are clear and functional at startup. Verify automatic discharge valves open to prevent excessive pressure buildup at startup. Inspect for blockages in suction line and unloader passages. Test pressure relief under no-load and full-load conditions.
Type-general inspection and maintenance points for this equipment category — not model-specific.
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