Dirty Diesel

The standard method of test flash point is simple. Fill a brass cup with oil and set into a raised ring. Insert a thermometer.

Put a burner under the ring. As the oil heats, wave a small gas flame over it. At some point, you'll see a quick flash. That's the flash point. Read the thermometer.

At a higher temperature, you'll get a sustained flame. That's the flame point.

Viscosity is usually checked with a calibrated glass tube, measuring time to flow through a capillary. The tube is generally partially immersed in a silicone or other heat transfer oil. The hardware is not real cheap, but the test is.

You could use a cup viscosimeters if you can find the right size. It won't give a specific value, but will be fine for comparisons.

I never compliment Guests, but in this case I have to!!

If you would just join and identify yourself fully in some (difficult) manner, I would even give you a GA!!

I never give GAs to guests EVER as it is such a waste of time!!!

Sorry, I forgot to log in. My first job was in a QC lab, and those were two of the tests I ran.

Thanks for the compliment.

The GA is for your previous post as guest, well done!

I work with a biodiesel program at a technical college, and face some of the same questions. Viscosity changes as temperature changes. The same fuel will be thicker when cold in winter and thinner when warmer in summer, so have your fuel at the same temperature when tested. A cup viscometer is easiest and cheapest. It's not the ASTM test, but it can give you some guidance if you control temperature and do a set of calibration standards with good material in the acceptable zone and material known to be bad in the reject zone. Get a metal container (pint, half-pint?) and drill a small hole in the bottom. Try a couple different size holes to get a good flow of 3 minutes or so. Have a large dish with a small rubber pad in the bottom. Set the cup on the pad so the pad acts like a seal over the hole. Fill up the container and lift it up and allow it to drain. Time it with a stopwatch from when you lift the cup until the first break in the flow. For flash point, you need a sealed container, like with a sliding cover to keep vapors inside while heating. It needs to have a thermometer in it to monitor temp. When you reach the specification temp, open the cover and hold a small flame source in the opening. If it flashes, it fails. No flash, it passes. Commercial units have a small propane tank like for a plumbers torch and a thin tubing going to a small nozzle which is lit. Check for water! Water should be suspected if the fuel is hazy. It will settle out on the bottom of a quart sample in a glass jar. The black is carbon black. It may settle a bit if standing for a long time. Keep filtering! That is always important! Try a batch with Kero. See how it runs. I believe they are similar, but kero may boil a little higher. You may end up with a thinner winter formulation and a thicker summer formulation. It may help to run the fuel line over the manifold a couple times to pre-heat the fuel on the way to the injectors.Warming it will thin it and help it spray better. I run my diesel on used cooking oil (filtered to 1 micron), warming up & shutting down on diesel. You may also consider adding used cooking oil if filtered properly. Use liquid oil like soy or corn. Avoid oil that is solid at room temp.

Waiting for vapors to start coming out of a hot cup container and then sticking a lighter flame to it sounds scary! I'd definitely wear a face shield trying that. A cup of fuel is a lot of material! You'd lose some volatiles before you see vapors. The standard method uses a closed cup to retain vapors until tested at temperature. The idea is there is a flash point specification. Heat to that point and test. Open the container and quickly insert the flame. No flash, it passes. Poof, it fails.

I did say "the crudest method", and the saucepan is wide open, the lighter will flash weakly, safely. I've used this with motoroil, furnace fuel, as well as furnace fuel (HFO) and kero blend. Try it, come and re-read the post, then comment.

PS. Please also re-read the first post, seems like a gas flame "waved over" the vapour worked for him as well.

We had a tube, about 12" long with a connection to the gas at the pivot end. This way we could wave the flame over the sample safely. BTW, this my previous post was not a totally complete description, but it was a simplified version of the ASTM spec we followed. No closed cup, since this was not a go/no go test. As I recall, it was an open dish about 2" dia and 1/2" deep.

LOL, I sent you to re-read your own post where you "waved" a gas lighter over the mixture. Nevermind I understand your knowlegability better now. You do deserve a GA.

thanks to everyone for their comments.. I think that I have enough information to keep from blowing myself up.... Keep em com'in... It makes for great reading..

Just wondering how much oil you put in your mix.

We have been using a 25% diesel to 75% oil... Sometimes the mix smokes excessively and then I just swing by the station and put it $10.00 worth of additional diesel and it usually clears it up.. Good Luck..

Canola?

careful the feds are none to pleased, feeling like they should be getting paid, or at least granting you waivers on excise tax