Hydraulic Design & Consulting: Straight Talk

Understanding Spectrometric Report

Analysis can reveal wear from many sources such as:

Iron (Fe) - Pumps, valves, cylinders, or oxidation
Silicon (Si) - Airborne dirt, casting fillers, coolant inhibitors
Copper (Cu) - Bushings, cylinders or oxidation
Zinc (Zn) - Oil additives or bushings
Lead (Pb) – Bushings
Phosphorus (P) - Oil additive
Tin (Sn) - Bushings, plating
Calcium (Ca) - Oil additive
Chromium (Cr) - Valve spools, cylinders, or plating
Barium (Ba) - Oil additive
Aluminum (Al) - Gear pumps, valves, fillers
Magnesium (Mg) - Oil additives or salts
Nickel (Ni) - Wear from valves or tubing
Boron (B) - Oil Additive

Wear Metals and Contaminants metals Typical Values: 2-8 PPM

Al (Aluminum) Piston and bearings, push rods, air cooler, pump housing, oil pump, gearbox castings.
Ca (Calcium) Oil additives, water, grease, dirt.
Cd (Cadmium) Bearings, platings, additives.
Cl (Chlorine) Oil additives or process contaminants.
Fe (Iron) Engine block, cylinders, gears, valve guides, wrist pins, rings, camshaft, crankshaft, oil pump, bearings, and rust.
In (Indium) Flashing, synthetic oils solder.
K (Potassium) Coolants, additives, dirt.
Mn (Manganese) Shafts and valves.
P (Phosphorus) Additives, coolants.
Sb (Antimony) Crankshaft and camshaft bearings, grease, additive.
Si (Silicon) Dirt intrusion, seal material, additive, filter material.
Sn (Tin) Bearings, connecting rods, pistons, additives.
Zn (Zinc) Neoprene seals, galvanized piping, bearings, plating, additives.
Ba (Barium) Additives, water and grease.
Cr (Chromium) Rings, cooling system leakage, chromium parts in aircraft engines, cylinder liners, crankshafts.
Cu (Copper) Bushings, injector shields, coolant core tubes, thrust washers, valve guides, connecting rods, rings, bearings.
Mg (Magnesium) Cylinder liner, gearbox housing (aircraft engines), oil additive.
Ni (Nickel) Bearings, valves, gear plating, oil additive.
S (Sulfur) Oil additives, base oil
Ti (Titanium) Alloy components in aircraft engines, paint chips.
V (Vanadium) Gears, bearings, turbine blades, valves, fuel oil, catalysts.

TARGET CLEANLINESS (ISO 4406)
The fluid results target gives a quick overview of the condition of the sample submitted. The target measures the following five critical areas of fluid condition: 2µ, 5µ, & 15µ micron particles of contamination, water content, and viscosity of fluid. When the marker is in the inner circle of the target, this represents on-target fluid condition. The second ring on the target represents marginal performance. The third ring on the target indicates the need to resample the fluid because of the possible sampling error, and the last ring on the target indicates that immediate action is required (severely contaminated fluid). The Vickers target is a graphical way of understanding whether or not the fluid sample is meeting its target cleanliness level. The level of oil cleanliness required for a machine element depends primarily on its precision and in-service reliability. The size of the particles that cause the most damage in a machine element are those equal to, or slightly larger than, the clearance space between load bearing on sealing surfaces.

VISCOSITY OF A LUBRICANT (ASTM D 445)
Is defined as the fluid flow rate at a specified temperature of 100°F (40°C). Its units are reported in centistokes (cSt) or Universal Seconds (SUS). The obtained value is compared to new fluid viscosity.
Typical values:
32VG: 28-35 cSt (132-164 SUS)
46VG: 41-51 cSt (191-237 SUS)
68VG: 61-75 cSt (282-348 SUS)

WATER CONTENT (ASTM D 1744)
The water percentage by weight determines the amount of emulsified water in the oil. Samples are analyzed per ASTM D1744 and the total water amount is reported as percent by weight. Water in the hydraulic fluid can be high due to condensation, leaking coolers, gaskets, seals of a cracked cylinder head. Typical value <= 0.07%.

pH (ASTM E 70)
Represents the strength of the acidity of the hydraulic fluid. pH is usually measured for water containing hydraulic fluids (water/glycols, invert emulsions). Typical value 8.5 - 10.5.

TOTAL ACID NUMBER {TAN} (ASTM D 974)

AUTOMATIC PARTICLE COUNTS (ISO 11500)
This test detects solid contaminants with respect to their size distribution and quantity in the hydraulic fluid. The particle size distribution is defined by three range numbers separated by a slash (e.g. 19/17/14). The first of the three range figures corresponds to the number of particles greater then 2 microns (µ) in size, the second figure corresponds to the number of particles greater than 5µ in size, and the last figure corresponds to the number of particles greater than 15µ in size. The 5µ and the 15µ measurements indicate the level of contamination (e.g. 17/14) as defined by the ISO 4406 standard.