A working guide to fully automated, auto-diluting particle counters for commercial oil-analysis laboratories — the methodology, the ASTM D7647 method, and how to choose between the CINRG CS-APC instruments.
An automated particle counter is a laboratory instrument that measures the size distribution and concentration of solid particles in a lubricating fluid by passing a metered sample through a calibrated optical sensor. The "automated" qualifier refers to three things working together: robotic sample handling (a tray of cups is processed without operator intervention), in-line auto-dilution (every sample is diluted with a masking solvent before counting, per ASTM D7647), and software-driven workflow (batch files in, ISO 4406 / AS4059 / NAS 1638 results out, CSV format).
The instrument category exists because manual particle counting was the bottleneck in commercial oil-analysis production. A skilled technician working a manual optical counter could process 30–40 samples a shift if the fluids were well-behaved. Add water-contaminated samples, varnish-laden in-service oils, or sub-10 cSt diesel-engine oils to the queue and that throughput collapsed — each sample needed ultrasonic prep, manual dilution, microscope verification, or simply had to be sent out for a Millipore-patch count. Automated counters were designed to absorb those bottlenecks into a single instrument: 130–140 samples per 8-hour shift on the same hardware, regardless of fluid type.
Three properties distinguish a true automated particle counter from a portable or single-sample optical counter:
The ASTM D7647 dilution method was first published in 2010 to give optical particle counters a standardized way of handling commercial in-service oils. The conventional approach — counting the sample undiluted — gave inflated ISO codes whenever the fluid contained interfering soft species. Three categories of soft particles cause the problem:
Dilution with the correct solvent dissolves or disperses each of these species so they no longer scatter light. CINRG’s recommended diluent is 75% toluene / 25% isopropanol (IPA). The IPA component handles up to 2% water at a 1:1 dilution; the toluene re-solubilizes varnish precursors and large-molecule additives. The proposed ASTM D7647 revision (Procedure A, the new referee procedure) calls for 90/10 toluene/IPA, which CINRG’s CS-APC line is fully compatible with.
Procedurally, the instrument:
A complete tray runs without operator intervention. Solvent verification, sample volume measurement, dilution accuracy, process-control validation, and IVL enforcement all happen inside the instrument’s software loop. The technician’s job is to pour samples into cups, load the tray, and click Run.
Three configurations covering the full range of commercial-lab volumes.
| CS-APC-3 | CS-APC-2 | CS-APC-22M | |
|---|---|---|---|
| Format | Large-format production | Large-format (predecessor) | Benchtop in-house |
| Sample tray | 104 positions | 104 positions | 24 positions |
| Throughput | 130–140 samples / 8‑hr shift | 130–140 samples / 8‑hr shift | 130–140 samples / 8‑hr shift |
| Measuring range | 4–70 µm | 4–70 µm | 4–70 µm |
| Sensor | KLOTZ LDS 45/50 | KLOTZ LDS 45/50 | KLOTZ LDS 45/50 |
| ASTM D7647-10 | Yes | Yes | Yes |
| ISO 11171:2022 | Yes | Yes | Yes |
| On-site calibration | Yes (CS-CINSTAN-CFK) | Yes (CS-CINSTAN-CFK) | Yes (CS-CINSTAN-CFK) |
| Footprint | Production floor | Production floor | 16½″ W × 20½″ H × 24″ D benchtop |
| Target customer | High-volume commercial labs | Existing field installs (still supported) | In-house programs / satellite labs |
How to choose. If you process more than 100 samples a day on a regular basis, the CS-APC-3 is the right unit — the 104-position tray means fewer reload cycles and your tech is not babysitting the instrument. If you process under 50 samples per day, the CS-APC-22M’s benchtop footprint and lower acquisition cost win — same sensor, same methodology, smaller scale. The CS-APC-2 is the predecessor of the CS-APC-3 and remains fully supported in the field; it is no longer sold for new installations, but parts, calibration fluids, and service continue uninterrupted.
All three units share the same KLOTZ LDS 45/50 sensor, the same 4–70µm measuring range, and the same auto-dilution methodology. The instrument you choose does not change the result you get on a given sample — only the throughput and the footprint.
CINRG auto-diluting particle counters are deployed in over 80 commercial laboratories worldwide, including the largest oil-analysis service providers in Europe and North America.
“With the CINRG Particle Counter we have counted more than 80,000 samples (approx. 5,000 samples/month). We — and our customers — have found very reliable results. The dilution works perfect. The counts have excellent repeatability.”Peter WeismannOelCheck GmbH, one of Europe’s largest commercial oil-analysis laboratories
“With the CS-APC-2 we have been able to reduce the analysis and report times — in many cases to half — with this improved production capacity. This is why we have decided to accredit this test under ISO 17025.”Jose IgnacioTekniker, technology centre and ISO/IEC 17025-accredited testing laboratory
“CINRG has a state-of-the-art particle counter that far exceeds expectations. Approximately seven hours of preparation time is saved due to its automation. A definite asset to any oil-analysis laboratory.”Frank PerriWearCheck Canada, the laboratory where CINRG’s auto-dilution methodology was originally developed
An automated particle counter is a laboratory instrument that measures the size and concentration of particles in lubricating fluids by passing a metered volume past a laser beam. The "automated" part refers to robotic sample handling, in-line dilution, and software-driven workflow — replacing manual pipetting, ultrasonic prep, and operator judgment. CINRG’s CS-APC line is fully automated to ASTM D7647-10.
Portable counters (Beckman PODS, Hiac Royco, MP Filtri LPA) are designed for field use on undiluted samples — they're lightweight, battery-powered, and answer "is this fluid dirty?" on the equipment. Automated lab counters perform the full ASTM D7647 workflow including auto-dilution, soft-particle masking, and ISO 11171:2022-traceable calibration. The two solve different problems — portable for spot-checking, automated for the lab’s production queue.
In-service lubricating oils contain soft particles — water, varnish precursors, anti-foam additives, friction modifiers — that scatter laser light the same way hard contaminants do. Diluting the sample with a masking solvent (typically 75/25 toluene/IPA) before counting dissolves or disperses those species so only true abrasive particles are counted. Without dilution, ISO 4406 codes can be inflated by 3–7 codes on water-bearing or additive-loaded fluids. See our Ghost Particles paper for the underlying data.
Lab-grade automated counters typically process 3–4 minutes per sample with default parameters. CINRG’s CS-APC-3 and CS-APC-22M both run 3.5 min/sample, yielding 130–140 samples per 8-hour shift. The CS-APC-3 carries a 104-position tray for fewer reload cycles; the CS-APC-22M carries 24 positions in a benchtop footprint.
No. Once samples are poured into cups and a batch file is loaded, CINRG instruments run unattended — the system measures cup volume, dilutes, counts, validates against ASTM D7647 internal variance limits, runs process-control samples, and writes ISO 4406 / AS4059 / NAS 1638 results to CSV. Operator time is roughly 15 minutes per tray of 22–104 samples.
CINRG’s software emits ISO 4406:1999 three-tier codes (>4µm(c) / >6µm(c) / >14µm(c)), SAE AS4059 in both differential and cumulative forms, the legacy NAS 1638 contamination class, raw count data at 4, 6, 14, 21, 38 and 70µm channels, plus solvent background and dilution ratio for traceability. All output is CSV, suitable for direct LIMS import.
Under ISO 11171:2022 using a NIST-traceable Medium Test Dust primary calibration fluid — currently NIST SRM 2806d. CINRG instruments support on-site annual calibration by a trained customer technician using the CINSTAN Calibration Kit (CS-CINSTAN-CFK), a calibration-hardware kit, a step-by-step SOP, and an automated Excel template. Pre-calibration sensor-noise verification confirms signal-to-noise ratio ≥1.5 before the sizing-calibration begins.
Tell us about your sample volume, fluid types, and lab footprint. A CINRG engineer will help you scope the right configuration.
Tell us about your throughput, your test methods, and your facility. A CINRG engineer will help you scope the right configuration — and put you in touch with your nearest dealer.