Would someone explain HT/FS?
- Thread starter Shel_B
- Start date
do you mean HT/HS?
Post in thread 'Automated calculator for the A_Harman index, VII content, and base-oil viscosity'
https://bobistheoilguy.com/forums/t...nt-and-base-oil-viscosity.326624/post-5425917
https://bobistheoilguy.com/forums/t...nt-and-base-oil-viscosity.326624/post-5425917
Just go ahead an Google HT/HS Oil Bitog and you should find the info you need.
I am looking for HT/FS, and I've searched here and on Google.
It's a term made up by a BITOGer:
https://bobistheoilguy.com/forums/threads/htfsv-high-temperature-full-shear-viscosity.307409/
Thank you so much. I skimmed through the info and I'll read through it more thoroughly later this evening.
I picked a 10W30 oil for my Ford D.I. engine "educatedly intuitively" then weeks later I see on the chart (Gokhan's work?) that it is one of the best choices for low VM load and robust full shear viscosity in a 30 grade. In the car it has been performing fantastic. And it's affordable and ubiquitous. ( throws out shoulder patting oneself on back this one time -- ouch! )
Qsfs 10w30?
The term was created by a member. Not an industry-recognized term. No official test protocols are linked to that term.
One day, it will be industry acknowledged, as was the case with Noack Volatility.
Post in thread 'Would someone explain HT/FS?'
https://bobistheoilguy.com/forums/threads/would-someone-explain-ht-fs.360249/post-6247051
High-temperature, high-shear viscosity HTHS is measured at a shear rate of 1,000,000 s⁻¹. It applies primarily to journal bearings. At this shear rate, the contribution of the VII molecules to the viscosity is partial.
High-temperature, full-shear viscosity HTFS is measured at a shear rate of 10,000,000 s⁻¹ or higher. It applies primarily to valvetrain and parts of cylinders and rings. At these very high shear rates, contribution of the VII molecules to the viscosity is nonexistent, as the VII molecules fully align themselves with the flow—hence the full temporary shear of the VII molecules. Viscometers capable of measuring at a shear rate of 10,000,000 s⁻¹ have only recently become available.
Note that while HTFS was originally measured and studied in the recent paper by the famous veteran tribologist Hugh Spikes, who is the father of HTHS, the name HTFS is something I coined, and it is currently not a standard under the SAE J300 viscosity specification.
https://bobistheoilguy.com/forums/t...sv-friction-and-wear-state-of-the-art.310319/
High-temperature, full-shear viscosity HTFS is measured at a shear rate of 10,000,000 s⁻¹ or higher. It applies primarily to valvetrain and parts of cylinders and rings. At these very high shear rates, contribution of the VII molecules to the viscosity is nonexistent, as the VII molecules fully align themselves with the flow—hence the full temporary shear of the VII molecules. Viscometers capable of measuring at a shear rate of 10,000,000 s⁻¹ have only recently become available.
Note that while HTFS was originally measured and studied in the recent paper by the famous veteran tribologist Hugh Spikes, who is the father of HTHS, the name HTFS is something I coined, and it is currently not a standard under the SAE J300 viscosity specification.
https://bobistheoilguy.com/forums/t...sv-friction-and-wear-state-of-the-art.310319/
Not sure if the term was made up, but "full shear" isn't anything new or ground breaking. If you increase the shear rate high enough, the oil will shear to some minimum viscosity depending on it's VII level and temperature.
Source: https://link.springer.com/article/10.1007/s11249-018-1039-5
PDF download of above link: https://link.springer.com/content/pdf/10.1007/s11249-018-1039-5.pdf
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No, "full-shear viscosity" is not a made-up term. See my post above. It was described and measured in the paper by Hugh Spikes (the father of HTHS) et al. linked here.
My own contributions after their paper were:
1. I named the full-shear viscosity at 150 °C high-temperature, full-shear (HTFS) viscosity, in analogy with the high-temperature, high-shear (HTHS) viscosity measured at 150 °C and at a shear rate of 1,000,000 s⁻¹. In contrast, HTFS viscosity is measured at a shear rate of 10,000,000 s⁻¹ or higher.
2. I devised a calculator that extends @A_Harman's original calculations that calculate the "A_Harman index" to estimate the viscosity-index improver (VII) content and HTFS viscosity from only the density, KV40, KV100, and HTHS values. The calculator gives reasonably good estimates for most VII types, especially for OCP but except for the now-rarely-used PMA.
Note that the HTFS viscosity is also the dynamic viscosity of the base oil and additive package at 150 °C before the VII is blended in.
Gokhan's VII content and HTFS table
My own contributions after their paper were:
1. I named the full-shear viscosity at 150 °C high-temperature, full-shear (HTFS) viscosity, in analogy with the high-temperature, high-shear (HTHS) viscosity measured at 150 °C and at a shear rate of 1,000,000 s⁻¹. In contrast, HTFS viscosity is measured at a shear rate of 10,000,000 s⁻¹ or higher.
2. I devised a calculator that extends @A_Harman's original calculations that calculate the "A_Harman index" to estimate the viscosity-index improver (VII) content and HTFS viscosity from only the density, KV40, KV100, and HTHS values. The calculator gives reasonably good estimates for most VII types, especially for OCP but except for the now-rarely-used PMA.
Note that the HTFS viscosity is also the dynamic viscosity of the base oil and additive package at 150 °C before the VII is blended in.
Gokhan's VII content and HTFS table
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Full shear (or whatever anyone wants to call it) is nothing new, as shown by the article I linked above.
The term is not new, but the measurements in the Hugh Spikes et al. paper were new because no one had a viscometer capable of measuring into the second Newtonian phase, where full shear occurs, until recently. Therefore, the paper studied the transition from the high-shear viscosity to full-shear viscosity in detail for the first time. Previously viscometers only went up to a shear rate of 1,000,000 s⁻¹, but the viscometer used in the paper was able to go up to a shear rate of 10,000,000 s⁻¹.
