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theratt
2nd July 2006, 01:02 PM
i have made myself a 20LT drum with a paint stirrer for agitation
whats the ideal mixing times some say 1 hour others less??

tillyfromparadise
2nd July 2006, 01:43 PM
Hello theratt

It depends on temperature.
At 50deg C the reaction takes about 1 hour.
for every 10deg lower in temp double the reaction time.
Do not start timing until all methoxide has been mixed into the Oil and the oil undergoes an increase and sudden decrease in viscosity.

I assume with your small set up you will just put all the methoxide into the reactor on top of the oil and then stir with the drill.
I would suggest that an initial 1- 2 minutes stir with the drill will put you at the beginning of timing.
Then just re-mix for a minute every 10- 15 minutes for the time necessary for the temperature you are running the reaction at.
If in doubt mix longer, you can not overmix.

Tilly

theratt
2nd July 2006, 05:55 PM
cheers tilly, ill give that method a go ,i thought i had to run my drill constantly, if i can batch it like you say,thats much better

David
3rd July 2006, 02:00 PM
A couple of thoughts on using a drill......

Firstly, most drill motors throw a lot of sparks which may not be a good thing around methanol fumes particularly if you are using an open drum. You would certainly want to have the drum full so the drill was in the clean air rather than say making a 5L batch where the drill was lowered into an enclosed space full of flamable fumes. Obviously good ventilation while mixing would be a nescessity for a number of reasons.

Secondly, I wouldn't be using a good drill to do the mixing as drills are not designed to run for an hour at a time and running them this long does put a lot of wear and stress on them. I would go to bunnings and pick up a cheapie drill for $16 or $20 so if it burned out it wouldn't really matter. Certainly trashing a $20 drill would be a lot prefrable to having the motor in your good Bosch or DeWalt drill repaired.

Perhaps instead of using a mixer on a drill you may be better off using one of those drill pumps. You could plumb some hoses into the drum and have the drill a lot further away from the fumes. I saw some of these pumps in a cheapie shop the other day for $5 ea.

I made up a mixer when I was mucking round making soap ( Real soap that is, rather than BD by-product :p) out of an old blower motor from a car. I atached the mixer just with a length of stiff plastic hose. I made up a bracket to mount the mixer on so I could go do other things while it was mixing rather than having to stand there and hold it which was tireing and very boring as well. It worked really well as was a lot quieter and less grinding on the nerves than a drill screaming away.

theratt
4th July 2006, 11:20 AM
cheers david
yeh it can be bit noisey but its only a cheepy and has variable speed so i dont have it flat out also have my drum fully enclosed and vented outside my shed , have long shaft so the drill is 2 feet away from the top of the drum just to be sure