Coltri MCH8 Compressor Oil and Consumables: Specifications and Service Intervals
Consumables decide whether a breathing-air compressor stays inside its air-quality limits between overhauls. This page sets out what a Coltri MCH8 typically consumes, how to judge the specification, and how to plan intervals so that filters and oil are changed on evidence rather than on habit.
1. Equipment overview
The Coltri MCH8 is a roughly 130-140 L/min class class breathing air compressor working to up to 330 bar, driven by single or three-phase electric motor, typically used for dive shops, fire stations, mobile refill vans. As a mid-size portable unit with mixed short and long fills, its consumable profile is dominated by the items below.
| Parameter | Typical specification |
|---|---|
| Free air delivery | roughly 130-140 L/min class |
| Maximum working pressure | up to 330 bar |
| Drive | single or three-phase electric motor |
| Filtration | cartridge filtration system |
| Typical applications | dive shops, fire stations, mobile refill vans |
These values are typical market configurations. Confirm every value against the data plate and the manual of the individual unit before ordering parts or planning service.
2. Lubricant: what actually matters
High-pressure breathing-air compressors run hot and are usually specified with a synthetic compressor oil. Several breathing-air-specific oils exist on the market - for example ST 755 type synthetic oil is marketed for breathing-air compressors, and food-grade synthetic ISO 100 oils are used where a food-grade classification is required. Before choosing, check three things:
- Viscosity grade: use the grade stated in the manual for your ambient temperature range;
- Compatibility: do not mix different oil technologies in the same crankcase; if you change type, follow a documented changeover procedure;
- Consequence: the oil is upstream of the filtration system. A degraded or wrong-grade oil shows up as oil carry-over and as a rising CO result in the air test.
Change interval: follow the manual. As a working reference, many high-pressure multi-stage units are inspected around every 100 operating hours, with the change interval set by oil type and duty; continuous-duty and high-humidity plants usually need shorter intervals and benefit from periodic oil analysis.
3. Consumables list
- Filter cartridge: cartridge - confirm by serial
- Lubricant: ST 755 type synthetic oil - change interval: per manual, commonly checked every 100 h
- Intake filter element, belts, valve plate kits, seals and O-rings, condensate drain valves, gauges
- Specific wear items for this model: cartridge, valve kit, belt, oil, intake element
4. Planning intervals on evidence
Record, at every service: operating hours, cartridge serial and change date, oil change date and grade, air test results, and any fault logged. Then set intervals by the worst of three signals - the manual's interval, the trend in air test results, and the environment (humidity, ambient temperature, duty cycle). Sites that plan this way almost never fail an air test unexpectedly, because the trend alerts them first.
5. Air quality and compliance
Breathing air is a life-safety product. In the EU the reference standard is EN 12021 (current edition), and in North America diving applications commonly reference CGA Grade E, while fire-service programmes often reference NFPA 1989 for breathing-air quality and filling operations. Limits differ between standards and editions, so always test against the edition in force at your site.
| Parameter | Indicative limit / requirement | What a failure usually points to |
|---|---|---|
| Carbon monoxide (CO) | Typical EN 12021 limit: max 5 ml/m3 (5 ppm) | Rising CO usually indicates intake contamination or overheated lubricant - check intake siting and stage temperatures |
| Carbon dioxide (CO2) | Typical EN 12021 limit: max 500 ml/m3 (500 ppm) | Elevated CO2 often traces to intake air drawn from a confined, occupied or engine-exhaust-affected area |
| Oil (lubricant mist) | Typical EN 12021 limit: max 0.5 mg/m3 | Oil carry-over points to separator, drain routine or a saturated cartridge |
| Water / humidity | Pressure dew point requirement to keep cylinders free of liquid water | Verify dryer performance, drain routine and cartridge condition |
| Odour and taste | No objectionable odour | Any detectable odour means stop using the gas and re-test before release |
A practical programme is: test every production batch or at the interval required by your authority, keep a written record of results, replace the filter cartridge by hours and by test result (whichever comes first), and re-test after any intervention on the filtration system. A Coltri MCH8 that passes its air test but shows a rising trend is telling you the cartridge or the intake environment needs attention before it fails a limit.
6. Service scope
BAOSI / DEJUE (Shanghai) supplies high-pressure breathing-air compressors and also supports third-party service and consumables for mixed fleets. For the Coltri MCH8 and comparable units we can supply compatible filter cartridges, valve plate kits, belts, lubricants and seals, and provide troubleshooting support, overhaul guidance and annual maintenance planning. Where a brand-specific part number is required, we match it from your serial number and filter housing type.
Need parts or a second opinion on a fault? Send the model, serial number, operating hours and the recorded stage pressures or temperatures - our technical team will respond with a parts list and a diagnostic plan. Contact the BAOSI technical team.
Disclaimer: This article is provided for general reference only. Specifications vary by serial number, build year and market configuration - always verify against the original equipment manufacturer's manual and your unit's data plate before service. Work on high-pressure equipment should be performed by qualified, trained technicians, and any safety-critical repair should follow local regulations and the OEM procedure.