Lubricants
What is it?
The HTHS is a multi-cell viscometer for viscosity testing of engine oils and base oils at high temperature and high shear. It meets all precision specifications of ASTM D5481 and SAE J300.
Why do we use it?
HTHS is one of the four basic viscosity measurements in SAE J300 which defines the rules around engine oil viscosity grades. It’s necessary to measure the HTHS of every formulated engine oil in order to check that it is within the viscosity grade. The HTHS test simulates the environment of the engine oil in the moving parts of an engine running at high speed. It has been shown that the HTHS of oil correlates well to fuel economy in some industry fuel economy tests, in particular the M111FE test which is part of the ACEA specifications.
How does it work?
Normally the test oil is heated to 150 ºC (the requirement for SAE J300). It is then forced through a capillary under pressure and from the time it takes to pass through this capillary and the pressure, the viscosity can be calculated. The capillary is typically of 0.15 mm in diameter and 15-18 mm in length. The test can also be run at other test temperatures if required.
Typical HTHS Dimensions & Specifications:
Parameter : Value
- Diameter of capillary : 0.15 mm
- Length of capillary : 15 to 18 mm
- Temperature control : 150 ± 0.1 ºC
- Pressure range : 350 to 3500 kPa (50 to 500psl)
- Pressure control : ± 1 %
- Sample volume : 7 ± 1 ml
The High Temperature High Shear machine: