FTIR Analysis - Sulphation (USUL)

This page contains information about the Unsubtracted (JOAP) Sulphation analyte.

FTIR Analysis

USUL
Sulphation
FTIR

Sulphation
Method: Unsubtracted JOAP (Joint Oil Analysis Program)
Units: None

Sources of Sulphation

Engines

Sulphur products are caused by sulphur in diesel fuel and are by-products of combustion.

Sulphur products combine with the available water in the oil (such as condensation, water leaks) to form sulphuric acid.

Sulphur is determined by a deflection in the differential scan at a known wave number. The deflection is measured by an absorbance number and this is transposed to a % allowable figure developed for Caterpillar equipment.

Effects of Sulphur: -

Sulphur by itself may not cause problems. Sulphuric acid is the damaging agent and this is formed when condensation, water, etc. are present. In any engine, condensation does occur.

Sulphuric acid can: -
  • Lead to ring sticking.
  • Cause valve-guide/valve-stem corrosion, which in turn can lead to high top-end wear.
Benefits of Determining Sulphur: -
  • Monitor of fuel quality (sulphur content).
  • Management tool used with soot to monitor fuel consumption.
  • Diagnostic tool for cooling system efficiency (jacket water temperature).
Example of Use: -

For specific/constant applications, a distinct ratio of sulphur % to soot % can be expected. Also within one application, the normal % is known. If a deviation in either way occurs, the dealer Lab personnel will suggest a corrective plan of action.

Probable Causes of Sulphur Product Formation: -
(Applicable to Caterpillar engines)
  • Sulphur content of fuel.
  • High crankcase blowby.
  • Water in the crankcase.
  • Temperature.
Problem Diagnosis (High Sulphur): -

The analysis of sulphur-related problems is complex and can be time-consuming if the correct approach is not taken.

The Caterpillar dealer is in the best position to formulise a corrective workplan to match the products application.