Objective: verify the hydrocracked mineral air compressor oil CPI-9370-46 under air-compressor conditions in Vietnam (hot discharge, dusty and humid compressor rooms) and use oil analysis to set the change interval for each machine. Six machines at three plants were monitored; this article presents three representative machines. Result: the normal samples held a viscosity of 44–50 mm²/s, within ISO VG 46, and a TAN below 0.5 mg KOH/g up to almost 5,000 hours; the 75 kW machine went on to 7,612 hours on one fill when monitoring ended (last analyzed sample at 4,872 hours); one case of water entering the oil was detected early through routine sampling and dealt with.
Before adding CPI-9370-46 (a sulfur-free, hydrocracked mineral air compressor oil) to the range, Hop Tien and LUBRIZOL needed two answers in numbers from real machines in Vietnam: how long the oil keeps its viscosity and acid number at high discharge temperatures (75–98 °C recorded at sampling) in dusty, humid compressor rooms; and whether periodic oil analysis is sensitive enough to set the change interval for each machine. Six oil-flooded screw compressors of 22–75 kW at three plants (plastic pipe in Binh Duong, cement in North Central Vietnam, textiles in Dong Nai) were monitored for one year; this article presents three representative machines, and the data for the other machines are provided on request.
Before filling, a Hop Tien engineer identified the base oil in use on each machine from the oil label and the machine manual. The rule applied: with a different base oil (mineral/PAO versus PAG or ester), no topping up but a flush according to the TDS; with the same base oil, still drain the old oil at every low point, replace the oil filter, air filter and separator element, check seal materials against the TDS wording, and only then fill CPI-9370-46 and record the machine hours at the start.
Oil samples were then taken according to each plant's shutdown schedule, with discharge temperature and pressure recorded at sampling; the manufacturer's laboratory measured viscosity at 40 °C, total acid number (TAN), water content, particle count and wear metals. The laboratory's recommendations (filter change, oil change, resampling) were passed to the plant as soon as the results came in.
On the 22 kW machine at the plastics plant, four samples from 787 to 4,859 hours gave a viscosity of 44.6–49.9 mm²/s and a TAN held below 0.5 mg KOH/g: the oil was still within ISO VG 46 with no sign of significant oxidation after almost 5,000 hours. The 75 kW machine at the textile plant ran continuously; the last analyzed sample at 4,872 hours showed a viscosity of 49.5 mm²/s, a TAN below 0.5 mg KOH/g and a slight rise in water content, which was dealt with by changing the filter as recommended; the machine went on to 7,612 hours on the same fill when monitoring ended.
Oil analysis did its job at the cement plant: the 2,100-hour sample from a 55 kW machine showed 779 ppm water, rising calcium and a viscosity up outside the ISO VG 46 range, signs of water and dust from the environment entering the oil. The laboratory recommended draining the low points and changing the oil; the plant followed the recommendation, and the next sample, taken at 3,500 machine hours (oil after the change), was normal: 48.6 mm²/s, TAN below 0.5 mg KOH/g. The problem was dealt with before the machine showed any abnormality.
Hop Tien's conclusion: on screw air compressors running at high discharge temperatures, CPI-9370-46 can be used for the interval of up to 4,000 hours given in the TDS, and the interval can be extended with periodic oil analysis; Hop Tien does not recommend extending the interval without sampling.
| Plant · machine | Oil hours at sampling | Viscosity at 40 °C, mm²/s | TAN, mg KOH/g | Notes |
|---|---|---|---|---|
| Plastic pipe · 22 kW machine | 787 · 2,600 · 3,025 · 4,859 | 44.6 · 47.0 · 48.4 · 49.9 | Below 0.5 in every sample | Normal, within ISO VG 46 |
| Cement · 55 kW machine | 500 · 2,100 · 3,500* | 48.2 · 62.8 · 48.6 | Below 0.5 in every sample | 2,100 h: water 779 ppm, calcium high → low points drained, oil changed. *3,500 h is machine hours, oil after the change: normal |
| Textiles · 75 kW machine | 3,331 · 4,872 (machine went on to 7,612) | 48.9 · 49.5 | Below 0.5 in every sample | 4,872 h: water slightly up, filter changed as recommended; no sample after this point |
Three representative machines out of the six monitored (from the manufacturer's laboratory reports; TAN given against the threshold, detailed data provided on request)
Data from the oil-analysis reports of the manufacturer's laboratory and Hop Tien's sampling records. Detailed figures are left out of this article; Hop Tien provides the data and a detailed explanation on request. Plant names and machine makes are withheld in line with Hop Tien's practice.
Objective: fill the ammonia refrigeration compressor oil CPI-1009-68 into four NH₃ screw compressors with 11,400–49,100 running hours without letting old oil and sludge contaminate the new oil. Method: drain the compressor unit and the separator through the machine's oil drain valve, clean the filter, drain every low point until the oil runs clear, and only then pump in the new oil; done during a maintenance stop, without dismantling the machines.
Dong Thap · Oct 2016
Objective: in a station with several machines, choose the oil by each machine's conditions and the base oil in it, and change the oil without carrying old deposits into the new oil. The 132 kW machine runs hot (display reading about 96 °C at the survey) and was on another manufacturer's PAG-based oil; it was switched to CPI-1522-46, a PAG/ester oil of the same family. The 200 kW machine runs cooler and was given the PAO oil CPI-4601-46. Both were drained completely, the separator tanks cleaned and the separator elements and filters replaced before filling; Hop Tien recommends an analysis sample after 500 hours.
Dong Nai · Nov 2018 – Aug 2019
Objective: clean the varnish out of a 75 kW screw air compressor with many years of service and switch it to an NSF H1 registered air compressor oil without a long shutdown. Method: run the cleaning oil CPI COMP CLEAN II (not an H1 oil) in production for up to 500 hours per TDS so the varnish dissolves gradually; drain completely, clean the system and replace the filters as recommended; only then fill the H1 oil CPI-4265-46F and monitor by periodic oil analysis according to the plant's maintenance schedule.
Binh Duong (now Ho Chi Minh City) · Mar 2019
Objective: clean the carbon deposits from the chain and guide rails of an 8-chamber stenter before switching to LUBCON TURMOFLUID 40 B chain oil, with a procedure that can be repeated on the other machines: mechanical cleaning, spraying the cleaning oil LUBCON TURMOWOODOIL MKP Cleaner at the chain's working temperature in several rounds, blowing with compressed air, then changing the oil. Results assessed visually (before/after photos) and by the maintenance team's observations.
Dong Nai · 2017
Objective: get data from real machines before changing grease: how long LUBCON grease stays on the draw-frame rollers compared with the grease in use, and which grease suits the spindle bearings of the ring frames (spindle speed about 19,500 rpm) and the open gears. Result: on the draw-frame rollers the LUBCON grease was still in place after at least 18 days (when the trial was stopped), compared with about 9 days for the grease in use; the open gears and the ring-frame spindle bearings were stable after two weeks by observation.
Mekong Delta · Jun 2017