Water washing 50 / 50 test - clarity with hot or cold oil & water.

[neisel]

I think either I've been 50 /50 testing the wrong way or you guys who do water wash are using soapy fuel.

I've long had the problem of needing to water wash far too many times for my liking & in comparison to what I read other water washers had experienced. The last batch I did seemed to be pretty light on soaps, judging from fallout in the 7% pre-wash & first proper water wash but I couldn't get a clear pass. I decided to re-check all the steps of my process & discovered I have been doing it wrong.

Somewhere along the line I started doing water washes with cold water & increasingly cold oil. I did the 50/50 test the same way - cold / cold. My rechecking the steps reading indicated for the 50 / 50 both should be warm to hot.

Below is a picture of my latest batch. The cloudy jar is after AT LEAST 10 water washes with cold BD / cold water in the 50 /50 test. The clear is the 50 /50 with the same BD with warm oil & hot water.

Now I'm perfectly happy to hear the warm / hot test is the correct one as it'll save me a lot of ww'ing, but I'm concerned about cloudiness of the cold test.

Why does the same BD go crystal clear with hot water when it looks like watery skimmed milk with cold?

[dgs]

I would say the cloudy water layer in the cold test is due to monoglycerides. It may clear with time.

Just because you get a clear pass with a 10/90 doesn't mean all the mono's are converted into bio (FAME) far from it unfortunatley.

Your photo looks as though the bio in the cold test is clearer than the warm test. If you leave the samples for long enough the bio layer will keep shedding water until it ends up at about the 950ppm level. You should then find at temps above about 23degs it is clear and below that it goes cloudy.

[neisel]

dgs,

monoglycerides = unconverted WVO?

The jar on the left is the warm oil / hot water one. The water in that jar went crystal clear after a few seconds.

[nigelb]

10 water washes..ffs. I can get my fuel clear and clean in 4 x 10lt. A 50/50 test is very basic shed science. What you need to do is test the ppms of soap in your fuel with a soap test kit. Cheap enough to prove of your process.

If you tested for soap ppm after each wash you might be in for a bit of a surprise. It'll probably show that you arn't washing for long enough.

Back to the drawing board. I'd deffo be looking at ways to reduce the amount of washes.

It's well documented on here about my process and water washing. Some people get it...some dont.

[neisel]

That ^^^^ is really no help at all & doesn't address or answer the question I'm asking.

But thanks anyway.

[dgs]

Hi neisel,

monoglyceride = 1x fatty acid chain still attatched to the glycerine molecule (soluble in methanol) They can be a real pain for water washers. I prefer to emulsify and remove them. Keeping them to a minimum is a good idea which I do by doing an extra reaction even after passing a 10/90. If a 10/90 test was just on the 'cusp' of a pass there will be lots of mono's left in the bio, so doing the extra reaction with a minimum of catalyst at high temperature seems to convert most of them.

I must admit what you are finding is really strange. As nigel says a proper titrated soap test would really tell you where you were at. Having said that when your warm sample is clear I doubt there is any soap in there, making mono's a possibility.

Do you pump wash?

[neisel]

dgs,

I usually do the first 2 water washes by very slowly sucking in 15-18 litres (into 145 of BD), after that I just dump 20 litres of water into the machine & pump wash for at least 30 mins. I've found the speed with which the water is introduced on the first 2 washes to be the determining factor as to whether there's an emulsion or not. After the first 2 washes I couldn't make an emulsion if I tried.

[nigelb]

That ^^^^ is really no help at all & doesn't address or answer the question I'm asking.

But thanks anyway.

I think being advised to re-examin what you do regarding wter washing is probably the best advice you'll get.

Have a look at historical posts regarding washing and soap testing and I think you may be able to improve what you do.

Personaly.... I think the 50/50 test is an indicator and should be treated as such. Proper soap testing with kits available on the bay is the way forward to proving off your process. The two samples you pictured above are an indication of a false positive in at least one of the jars. Test your bio for soap and get a ppm value.