A nagging question about oil Flash Point?

[shortyb]

But flashpoint testing IRT fuel dilution is supposed to be strictly a screening test not a baseline determination. My biggest beef with those labs that use it as reportable values on a UOA.

Or folks put too much stock in that value.

Flash point for "quality", as in how an oil will perform, of a virgin sample is rather pointless IMHO other than to provide flammability numbers for SDS. Overall "quality", as in the batches are consistent, I believe is a good use of the FP numbers. I may be wrong in my belief though. Wouldn't be the first time, just ask my wife .

 

[shortyb]

Here is another question about flash point that I am not super clear on (or may be confused with. Or both) Is there any correlation between flash point (ASTM D92 or open cup) and Noack? I know they are 2 different tests with similar methodology, ie; heating an oil sample, but both flash off the lighter components (one for flammability, one for loss). So could one extrapolate any possible evaporative loss from a flash point test?

 

[2005jettatdi]

My credentials: I am a CPA, not an engineer or chemist.

I had understood a higher flash point means less chance of coking in your turbo after a hard drive without adequate cool down. Are some saying that does not matter? Since two of my four vehicles have turbos, it matters to me.

I understood another thing that matters is pour point. A lower pour point protects better at lower outside temps. That matters in all of my vehicles.

 

[kschachn]

I had understood a higher flash point means less chance of coking in your turbo after a hard drive without adequate cool down. Are some saying that does not matter? Since two of my four vehicles have turbos, it matters to me.

I understood another thing that matters is pour point. A lower pour point protects better at lower outside temps. That matters in all of my vehicles.

Does it mean that?

And in regards to pour point, that doesn’t always accurately represent the pumpability of the oil at low temperatures. We’ve seen several examples of oils on here which have low published pour points that don’t result in a superior winter rating.

 

[kschachn]

Here is another question about flash point that I am not super clear on (or may be confused with. Or both) Is there any correlation between flash point (ASTM D92 or open cup) and Noack? I know they are 2 different tests with similar methodology, ie; heating an oil sample, but both flash off the lighter components (one for flammability, one for loss). So could one extrapolate any possible evaporative loss from a flash point test?

I don't know exactly, but here is one answer from someone who knows more than I do:

Post in thread 'Flash Point and NOACK'

Feb 24, 2018

Flash point by ASTM D 92 is influenced by volatility and flammability. It is run under a hood to avoid air movement over the oil surface and the temperature is slowly increased at a prescribed rate until a flash appears on the oil surface when a flame is passed over.

Noack by ASTM D 5800 only measures volatility. The oil is heated rapidly, held at a constant temperature, and has air flowing over the oil surface. While both tests are influenced by volatility, the other significant variables negate any useful correlation.

Tom NJ

• Tom NJ

• 

 

[Tom NJ]

Here is another question about flash point that I am not super clear on (or may be confused with. Or both) Is there any correlation between flash point (ASTM D92 or open cup) and Noack? I know they are 2 different tests with similar methodology, ie; heating an oil sample, but both flash off the lighter components (one for flammability, one for loss). So could one extrapolate any possible evaporative loss from a flash point test?

Condensed from my old posts:

Noack and flash point are quite different. The flash point test gathers oil vapors in the space above the oil surface, mixes the vapors with air and attempts to ignite the vapor/air mixture with a flame, so it is affected by both volatility and flammability. Test conditions are also different. The flash point procedure slowly heats the oil from ambient and the flame is not applied until the oil is within 27°C of the expected flash point, so much of the light ends are already evaporated off.

Noack evaporates the light ends of an oil by blowing air across the surface at a constant 250°C and measures the weight loss of the sample. The Noack test sweeps the vapors away making it a more pure volatility test. Since both tests are substantially affected by volatility there is a correlation but it is rough since there is no flame involved in the Noack and the tests have substantially different temperature profiles.

If you added say 5% of a light solvent to an oil, the Noack loss would go up by 5% since all of the solvent would be evaporated off under the conditions of the test and measured as a loss. The flash point, however, would not be as affected since most of the solvent would be evaporated off before the flame is passed over the oil surface.

 

[Brian123]

I don't know exactly, but here is one answer from someone who knows more than I do:

Post in thread 'Flash Point and NOACK'

Feb 24, 2018

Flash point by ASTM D 92 is influenced by volatility and flammability. It is run under a hood to avoid air movement over the oil surface and the temperature is slowly increased at a prescribed rate until a flash appears on the oil surface when a flame is passed over.

Noack by ASTM D 5800 only measures volatility. The oil is heated rapidly, held at a constant temperature, and has air flowing over the oil surface. While both tests are influenced by volatility, the other significant variables negate any useful correlation.

Tom NJ

• Tom NJ

• 

Sounds like both tests Tom NJ referenced lead me to believe that I should be looking more at HTHS and what my oil temperatures actually are in either my car engine or lawnmower engine! Oil temperature for me dictates whether I need a 5W-30 or 5W-40 in my cars engine, and whether I need a 10W-30 or 10W-40 in my lawnmower engine!

 

[shortyb]

I don't know exactly, but here is one answer from someone who knows more than I do:

Post in thread 'Flash Point and NOACK'

Feb 24, 2018

Flash point by ASTM D 92 is influenced by volatility and flammability. It is run under a hood to avoid air movement over the oil surface and the temperature is slowly increased at a prescribed rate until a flash appears on the oil surface when a flame is passed over.

Noack by ASTM D 5800 only measures volatility. The oil is heated rapidly, held at a constant temperature, and has air flowing over the oil surface. While both tests are influenced by volatility, the other significant variables negate any useful correlation.

Tom NJ

• Tom NJ

• 

Wish more producers would include Noack in their PDS then, almost all will give you a FP. Seems this can cause some confusion between the evaporative loss (more applicable to use) vs. mere flammability of an oil.

 

[shortyb]

Condensed from my old posts:

Noack and flash point are quite different. The flash point test gathers oil vapors in the space above the oil surface, mixes the vapors with air and attempts to ignite the vapor/air mixture with a flame, so it is affected by both volatility and flammability. Test conditions are also different. The flash point procedure slowly heats the oil from ambient and the flame is not applied until the oil is within 27°C of the expected flash point, so much of the light ends are already evaporated off.

Noack evaporates the light ends of an oil by blowing air across the surface at a constant 250°C and measures the weight loss of the sample. The Noack test sweeps the vapors away making it a more pure volatility test. Since both tests are substantially affected by volatility there is a correlation but it is rough since there is no flame involved in the Noack and the tests have substantially different temperature profiles.

If you added say 5% of a light solvent to an oil, the Noack loss would go up by 5% since all of the solvent would be evaporated off under the conditions of the test and measured as a loss. The flash point, however, would not be as affected since most of the solvent would be evaporated off before the flame is passed over the oil surface.

Succinctly explained. Thank you!

 

[Tom NJ]

https://bobistheoilguy.com/forums/threads/flash-point-base-oil-quality-performance.292593/

Tom NJ, great, this is just what I have been looking for!

Sorry to persist but you mentioned "The problem with flash point is the test reproducibility by ASTM D 92 is +- 9°C (+- 16°F). " In the case of the three generations of Mobil 1 5w-30 ESP above, the difference reported in flash point between 2005 and 2018 is 15°C and 2005-2026 is 33°C respectively: i.e. well outside that sampling error. Care to comment about what might be going on?

Changes that large are most likely the result of a formulation change, but some of the difference could also come from other factors. In addition to batch variations, who reports the flash points also plays a role and that person may change from time to time.

From my old post:

The flash point reported on Technical Data Sheets may not be representative of the actual product. Some companies correctly report the average of actual plant batches, some report their higher/est results, some report their lower/est results - depends on who is preparing the data sheet and their intent. Some TDS preparers are non-technical and report whatever they are told by whomever they ask, some are HS&E folks who prefer conservative results, and some are marketing folks who prefer a more shall-we-say liberal interpretation for comparison to competitors. I have seen substantial differences in flash points on TDSs among manufacturers of the very same pure ester. We just don't know who came up with the number, or how, or why.

I would like to think that a company as large and reputable as ExxonMobil would have a policy on organizing and reporting data in a consistent manner, but who knows.

 

[shortyb]

@Tom NJ-So why don't/won't companies include a Noack instead of flash point for their PCMO products? I think it would be much more useful and applicable for deciding what to use than just a flash point number. IF one were to use test numbers for comparison that is.

 

[Tom NJ]

Wish more producers would include Noack in their PDS then, almost all will give you a FP. Seems this can cause some confusion between the evaporative loss (more applicable to use) vs. mere flammability of an oil.

Flash point is a useful test for internal quality control, and is a standard reported property on SDSs for safety reasons. It is not of much use for end users for the reasons noted in posts above (except for BITOGers who use it to try to predict base oil composition ) .

 

[kschachn]

Changes that large are most likely the result of a formulation change, but some of the difference could also come from other factors. In addition to batch variations, who reports the flash points also plays a role and that person may change from time to time.

From my old post:

The flash point reported on Technical Data Sheets may not be representative of the actual product. Some companies correctly report the average of actual plant batches, some report their higher/est results, some report their lower/est results - depends on who is preparing the data sheet and their intent. Some TDS preparers are non-technical and report whatever they are told by whomever they ask, some are HS&E folks who prefer conservative results, and some are marketing folks who prefer a more shall-we-say liberal interpretation for comparison to competitors. I have seen substantial differences in flash points on TDSs among manufacturers of the very same pure ester. We just don't know who came up with the number, or how, or why.

I would like to think that a company as large and reputable as ExxonMobil would have a policy on organizing and reporting data in a consistent manner, but who knows.

This is so crucial.

 

[kschachn]

Sounds like both tests Tom NJ referenced lead me to believe that I should be looking more at HTHS and what my oil temperatures actually are in either my car engine or lawnmower engine! Oil temperature for me dictates whether I need a 5W-30 or 5W-40 in my cars engine, and whether I need a 10W-30 or 10W-40 in my lawnmower engine!

Really only if you’re attempting to fine tune it to some mythical sweet spot. Pick something with more than adequate HT/HS and keep an eye on fuel dilution.

 

[Tom NJ]

@Tom NJ-So why don't/won't companies include a Noack instead of flash point for their PCMO products? I think it would be much more useful and applicable for deciding what to use than just a flash point number. IF one were to use test numbers for comparison that is.

I suspect the marketers would rather have you rely on their claims and approvals than try to dissect the oil properties for comparison to competitors, so the less said the better. I agree I would like to see Noack instead of flash point, but splitting hairs in Noack comparison is also not very useful due to its reproducibility and again who decides what number to report.