Julian / HMPE Test

[K.H]

Ok all done and now outside just as the weather is warming up!
One thing ive noticed is that the water washed sample is lighter than the demethed,i wonder if its down to oxidization?
Is there a test for that?,might ask on the VOD,have you noticed a difference in colour?

[Julian]

Sorry, I rather messed up the test I was going to do.

I'd made an adjustable "GL never overflowing thing-a-me-bob" and was eager to try it, so forgot to take the sample before washing started ... doh!

Took a sample after a couple of minutes of washing and heated it to remove the water, then left the bloody thing in the shed ... what a tosser!  Must remember to concentrate!  Going to do another batch tomorrow, so I'll get it right this time.

I had done something vaguely similar on the previous batch.  I did everything which I thought would promote HMPEs ... demethed at a high temperature, didn't do a 7% water wash etc.  Sure enough, the day after I stopped bubbling to remove residual Meths, copious amounts of HMPEs appeared.  I took a DSS and that showed fine cloud like HMPEs after a day or two outside. So I water washed everything ... bio, HMPEs and Glycerine, took ages but finally got reasonably clear wash water.

That batch went into the car last Friday and the DSS while looking hazy and slightly vicious (possibly starting to gel) isn't showing noticeable signs of HMPEs.

It will be interesting to see if you get HMPEs in the un-washed sample ... keep us posted.

Yes, with every comparison I've made between washed and un-washed, the washed sample is always lighter.

Another thing I've noticed most times when water washing is that for the first few hours, a white scum looking substance is washed out along with the water which appears not to be water soluble.  This seems to appear while the bio still looks like bio, but once the orange stage is reached it appears not to form.  I'll try and collect some on the next batch and see what it's soluble in.

I've been struggling to understand why water washing appears to reduce HMPEs, when they are not water soluble.  Perhaps this scum stuff is HMPEs or some thing that promotes them.

PS, you must use a lot of vinegar in your house!

[Julian]

Moved topic to "Chatter board" as not wiki related (you'd think an administrator would post in the right place)

[K.H]

Moved topic to "Chatter board" as not wiki related (you'd think an administrator would post in the right place)

I did actually look,just saw the bio and veg related bit,must try harder!,its not this picky on the VOD 

[K.H]

So how did you get on with the non overflowing wash tank?,best thing GL ever did AFAIC 
Glad to see that you get a difference in colour,if i had read this first i wouldnt of bothered posting on the VOD.
The scum that you see been washed out does that initially float on the top? i get a white scum that soon gets washed out,normally in the first hour or so

[Julian]

Yes, but I also see something similar when, later in the wash, I changed the mist to a jet for more vigorous washing, but that didn't seem to separate out of the water draining from the tank.

I was wondering if the scum is the same stuff that forms the intermediate layer when doing a 50/50 test.

GL's NOWT seems to work OK, but mine's constructed a little differently.  It's fitted to the drain from the tank, so no pipe work is inside the tank and the overflow height can be adjusted up and down, a bit like a trombone.   I did had an issue with the scum blocking the tundish into which it discharges, but then it only has an 8mm hole at the bottom, so to be expected I suppose and not really an issue with GL's design.

[Tony]

Maybe water washing removes sub micron particles that otherwise form the nucleation sites for HMPE crystal formation?

Could scatter some dust into an otherwise good batch and see what happens

[K.H]

Well a marked difference after a night of -3,the washed sample is not as bad as it looks as it is only the inner glass surface that is covered

[Julian]

Assuming the bottles are swapped from their above position, certainly a marked difference.  The un-washed sample looks more gel like than HMPEs to my inexperienced eye.  That said I guess HMPEs could be lurking unnoticed in the gel.  Were both samples treated with Wintron?

Be interesting to see what happens if you warm the un-washed sample just slightly and slowly so the gel liquefies but any HMPEs are not melted.  Got anywhere with an ambient of around 3-4°C? ... (think before you type Julian) ... the fridge should do it, they usually run at circa 2°C.

Still haven't got round to running my next batch, will try to do so tomorrow.

[K.H]

Err yes the positions are swapped,i took them in the garage to take the pic!,
No winterisers in them,straight bio
HMPE,s aside a big difference in the condition of the two bio,s surely this must have been noticed before?

[Julian]

As you can see them "in the flesh" what do you think the contaminates are in each sample?

The washed sample looks to be too course for HMPEs as I know them, could they be water crystals?

[Tony]

Keith, you wash with running mains water don't you?  If this water is colder than ambient then maybe HMPEs are taken out because they form around the water droplets as it cools the bio?

[Julian]

Usually mains water seems to be between 8-12°C depending on the time of year and how deep the service pipe is.  Mine's a little different as it's delivered to the shed by hose pipe but is still usually above ambient this time of year.

Very good theory though.  I wonder if we could set up some tests washing with cold water ... tank outside or beer chiller running vs. mains water direct.

[K.H]

Yes to mains,outside via a hosepipe,when i turned it off the hosepipe froze,the samples are in the garage now which will be quite cold so i will take pics tomorrow morning
Without stirring up a hornets nest this seems to suggest that water washing winterises the bio to some extent

[Julian]

As you may have guessed, I'm not a strong advocate of water washing, but that was the intension of the tests.  From things I've read on the VOD I had an inkling that there may well be something in the water washing and HMPE connection.  The issue as I saw it was that no one seemed to have proved it conclusively, hence the small scale tests I did a little while back.

I think we need some corroborative experiments (I really will try and get to my next batch tomorrow ... and not cock it up this time!).  Tony, are you in a position to try water washing?  My first whole batch washes were done simply with a drain on a settling tank, the spray nozzle shown here ... http://www.biopowered.co.uk/wiki/File:Plant_sprayer_nozzle.JPG and a careful eye on the level in the tank.

Perhaps we could persuade NigelB to give it a go, it's a lot easer for a water washer to do the test than a non water washer ... I'll send him a message.