ISO 11171 Standard: Guideline and Application

When the ISO 11171 Standard was officially released in December of 1999 it provided the hydraulic particle counting industry with definitive methodology by which a suitable liquid particle counter could be fully characterized and calibrated using a NIST traceable calibration suspensions and equipment. This guideline will provide clarity on what constitutes an ISO 11171 calibration and its relationship to a standard ISO-MTD calibration.

Standard Overview

ISO 11171 is an international standard and a common platform that specifies a formal process that ensures a liquid particle counter is calibrated accurately. Manufacturers performing this process must use the same yardstick as a basis for comparison. The resultant data package and certification(s) detail the functional attributes to the customer to ensure they are not using the instrument outside of its performance capabilities and can expect a consistent and useful test result.

The term “calibrated” for the purpose of this guideline will be defined as meeting a specification or pass/fail criteria. Additionally, the term “characterized” for the purpose of this guideline will be defined as determining the instrument performance.

Those elements are defined as follows:

  • Clause 6: Sizing calibration procedure (calibration)
  • Annex A: Preliminary instrument check (characterization)
  • Annex B: Coincidence error limits (characterization)
  • Annex C: Flow rate limits (calibration and characterization)
  • Annex D: Resolution (calibration)
  • Annex E: Accuracy (calibration)

What Calibration Do I Need for My Business?

There are three calibrations that can be conducted on a liquid particle counter that will allow the customer to report out to the latest reporting standards; ISO 4406, SAE AS4059, DEFSTAN 91-91, etc., which require the typical reporting sizes of 4, 6, 14, 21, 25, 30, 38, and 70 μm.

Fully Accredited ISO 11171 Calibration – Secondary:
This calibration option is only requested by customers who require a fully accredited calibration that includes all 6 elements (clauses and annexes) of the ISO 11171 standard. The calibration takes nearly a full day and ~35 bottles of differing fluids specifically detailed by the procedure. Although all of these elements must be completed upon the initial calibration, only the ISO-MTD calibration procedure is required on subsequent calibrations to maintain full accreditation as long as there is no change or compromise to the sensor or to the flow control system.

ISO-MTD Calibration – Secondary:
This is the most widely used calibration option due to its cost and relative simplicity in both labor and materials. It is NIST traceable and supports the latest reporting standards. It is one of the elements and therefore in accordance with ISO 11171. It is not to be confused with a fully accredited ISO 11171 calibration.

Fully Accredited ISO 11171 Calibration – Primary:
This is the identical calibration as the secondary calibration with the one only difference being that primary ISO-MTD calibration fluid SRM 2806 (available only from NIST) is used rather than a secondary calibration suspension (produced per Annex F of the ISO 11171 standard).

HIAC 8011+ and HIAC PODS+ Particle Counters

Beckman Coulter manufactures HIAC-branded particle counters for use in testing hydraulic fluids, oils, fuels, organics, glycols, and water. The systems described below were developed for specific aspects of the fluid power industry. Additionally, HIAC offers a complete line of sensors, samplers, and particle counters for all applications. Both the HIAC 8011+ and the HIAC PODS+ can be calibrated in full compliance to the ISO 11171 standard.

HIAC 8011+        HIAC 8011+   

The HIAC 8011+ was designed to analyze samples of hydraulic fluids, solvents, and aqueous solutions in a laboratory setting. This versatile system has many uses, including monitoring particle contamination levels in mobile and industrial hydraulic systems, measuring roll-off cleanliness of equipment, and testing cleanliness of parts washing systems.

Hiac Pods PlusHIAC PODS+

HIAC PODS+ has been redesigned to accommodate fuels, glycols, organics, and water based fluids. The PODS+ enables users to get particle count data onsite without sending samples to a lab. The instrument is fully battery powered and can sample fluids from 1 - 425cSt without dilution. The PODS+ provides user’s particle count data in less than 60 seconds, and the flow path of the instrument cleans in seconds, enabling users to quickly test multiple fluids without the concern of sample to sample carry over.