1. MacDermid Plc Offshore Div.
Particle Analysis
And Contamination Control
Simon McManus

2. INTRODUCTION WHY PARTICLE COUNTING IS CARRIED OUT WHAT ARE PARTICLES?
AUTOMATIC PARTICLE COUNTERS
CALIBRATING A MICROSCOPE
COUNTING
CONCLUSION

3. WHY PARTICLE COUNT? PREVENTATIVE MAINTENANCE EXAMINATION OF DEBRIS
CHANGES IN CONTAMINATION LEVEL PREDICT FILTER BLOCKAGE AND SYSTEM FAILURE (SEALS, PUMPS AND VALVES)

4. WHAT ARE PARTICLES? AN INDIVIDUAL UNIT OF PARTICULATE MATTER
SIZE AND SHAPE VARY GREATLY
WHAT THEY ARE MADE FROM
HOW THEY HAVE BEEN FORMED
INTRAMOLECULAR FORCES PRESENT

5. DAMAGE EFFECT FROM PARTICLES
SOFT PARTICLES (PASTE, FILTER MEDIA, SEALS ETC.) CAN BLOCK FILTERS.
HARD PARTICLES CAUSE ABRASION AND WEAR. THESE ALSO BLOCK FILTERS BUT TO A LESSER EXTENT.
HARD PARTICLES INCREASE CONTAMINATION LEVELS.

6. Polymers and Fibres

7. Black Metal

8. Bright Metal

9. Rust

10. Silica

11. AUTOMATIC PARTICLE COUNTERS (APC’s)
LIGHT SCATTERING OR OBSTRUCTION USE LIGHT REACTIVE ELECTRONICS TO SIZE THE SHADOW OF PARTICLES
OTHERS USE PRESSURE DIFFERENTIAL ACROSS MESH FILTERS OF A SET SIZE

12. PROBLEMS WITH APC’s IRREGULAR PARTICLES ARE ‘ROUNDED’ TO AVERAGE SIZE
LONG FIBRES ARE SEEN AS A STRING OF SMALL PARTICLES
GAS BUBBLES AND INSOLUBLE LIQUIDS ARE SEEN AS PARTICLES
APC’s HAVE PROBLEMS WITH OCEANIC HW 500 FLUIDS

13. CALIBRATING A MICROSCOPE
THE MICROSCOPE SHOULD HAVE A GRATICULE SCALE
THE GRATICULE MUST BE CALIBRATED
A CALIBRATED STAGE MICROMETER SHOULD BE USED
IN REALITY THIS IS NOT ALWAYS POSSIBLE

14. FIELD CALIBRATION OF GRATICULES
TOTAL FILTER MEMBRANE AREA SHOULD BE KNOWN. STANDARD MEMBRANES ARE 960mm squ
EACH INTERIOR SIDE OF ONE SQUARE IS 308µm.

15. PARTICLE ANALYSIS. ARP598B
100 ml OF FLUID IS USED
A MICROSCOPE SLIDE IS PREPARED (FILTER MEMBRANE)
AREAS OF THE SLIDE ARE EXAMINED AND CONTAMINATION LEVELS ARE MATHEMATICALLY CALCULATED FOR THE WHOLE SAMPLE
SIZES OF 5, 15, 25, 50 AND OVER 100 µm ARE EXAMINED

16. GENERAL RULES DURING COUNTING
TRY TO EXAMINE AREAS OVER THE WHOLE MEMBRANE, DO NOT CONCENTRATE ON THE MIDDLE FEW SQUARES
USE THE LARGEST DIMENSION OF THE PARTICLE
FIBRES ARE SIZED USING THEIR LENGTH. A FIBRE HAS A LENGTH MORE THAN 10 X ITS WIDTH.

17. TAKING A SAMPLE TURN ON THE SAMPLE VALVE TO OBTAIN A STEADY FLOW
LET HALF A LITRE OR SO FLUSH THE VALVE
FLUSH THE SAMPLE BOTTLE AND LID AT LEAST TWICE IN THE STREAM OF FLUID
DO NOT TOUCH THE VALVE UNTIL THE SAMPLE HAS BEEN TAKEN.

18. SAMPLE PREPARATION
SAMPLE HANDLING WILL ALWAYS INCREASE CONTAMINATION LEVELS
SAMPLING WILL ALWAYS INCREASE CONTAMINATION LEVELS
THE CONTAMINATION IN THE SYSTEM IS ALWAYS LESS THAN THE COUNT
THE ERROR SHOULD BE KEPT TO A MINIMUM

19. SAMPLE CARE
IF SAMPLES ARE TO BE PACKAGED CHOSE THE PACKING MATERIAL CAREFULLY
AVOID BOTTLE LIDS WITH PAPER INSERTS
CLING FILM OVER THE TOP OF THE BOTTLE CAN PREVENT DIRT INGRESS

20. CARE DURING PREPARATION
SLIDES SHOULD BE PRODUCED IN A CLEAN ROOM
DO NOT BREATH ON OR LEAN OVER THE SAMPLES
MAKE SURE ALL THE EQUIPMENT THAT THE FLUID MAKES CONTACT WITH HAS BEEN FLUSHED.

21. BLANK ANALYSIS
PREPARE A BLANK SLIDE USING FILTERED WATER, 100ml +or- 5ml
THIS COUNT WILL GIVE AN INDICATION OF BACKGROUND CONTAMINATION
THE TOTAL COUNT SHOULD NOT EXCEED 10% OF THE LEVELS BEING INVESTIGATED.

22. COUNTING PROCEDURE
IF DEBRIS DISTRIBUTION IS RANDOM, UNEVEN DISTRIBUTION WILL INVALIDATE THE COUNT.
COUNTING IS DONE TO ARP 598 TO GIVE A NAS OR AS CLEANLINESS LEVEL.
ERROR IN COUNTING SHOULD NOT BE GRATER THAN 10% BETWEEN OPERATORS OR LABORATORIES

23. NAS 1638

24. AS4059 Counts are reported as cumulative rather than interval
Optional Smaller size code
Numeric Cleanliness Class in a specified Letter coded size.

25. AS4059