Biopac, purity doesnt matter too much. If you add a measure full of crushed carbide to 100gm fuel sample that is 4 times more than is necessary to react with all the water in a 1000ppm sample.
(My measure is the metal screw cap from a bottle of wine, level full)
If the carbide is in small pieces it is more convenient to crush but it is more easily spoiled in storage. Medium size rocks are harder to crush but store better.
Biotom, sounds like you are sitting on a goldmine, or a bomb, maybe both.
Another source of carbide is the local producer of acetylene gas for welders.
Here is another source of calcium carbide. In Lithuania and other eastern European countries it is used to kill moles. A few stones are placed in the mole tunnel and the damp earth reacts with it to flood the tunnels with acetylene. The moles die of suffocation.
Im sure similar products are sold in Poland, Latvia etc. Its not expensive and comes very well packed in a tin.
So I set up my manometer today and began to calibrate it. Immediately issues arose. Once the vessel was sealed my indicator began to recede and then very slowly increased as pressure began to build. Any thoughts on why this might have occurred?
"It is easier to ship recipes than cakes and biscuits." -Keynes
If the level is dropping before rising it can be caused by the temperature of the liquid being tested cooling on the initial mixing so it shrinks slightly causing a slight vacuum. Ether have everything ie jar, bio, room, etc at the same temperature or measure from the lowest point of the indicator. I have a 2cm piece of the same clear tube split length ways and placed as a slide on my mamoneter tube to mark the lowest point to aid in reading.
Justin what you describe is normal. The level will drop by as much as 10 or even 20mm before beginning to rise due to gas production. Womble idea of a marker attached to the tube is a good one. Another approach is to make your calibrated scale moveable so that you can slide the zero point of the scale down to match the lowest level.
How are you going to calibrate? There are 3 popular methods.
1. heat 2.5 litres of biodiesel up to 120°C for at least an hour to remove all traces of water.
Add 0.5ml of water to 1 litre of this anhydrous bio, test and mark the result as 500ppm.
add 2ml of water to 1 litre of this anhydrous bio, test and mark as 2000ppm.
2. The Rickdatech method. Buy a litre of new veg oil from the supermarket and test it. Plot the result on a graph, add 0.5ml of water to 0.5 ltre of the oil and test that and plot that also on the graph. Draw a line through the two points and then draw another line parallel to the first through the zero point of the graph. This second line is your calibrated scale. See the full explanation of this method on www.make-biodiesel.org .
3. If you live in Ireland I can post you a sample of biodiesel that tests at 1000ppm.
I like the idea of the slider. We will try that out.
As for calibrating I plan on suing the first method. Seems like the simplest. Thank you all!
"It is easier to ship recipes than cakes and biscuits." -Keynes
Hi all, new member here. What a great thread! So informative. I'm making the manometer today.
Just wondering if anyone had further success with Baking Soda aka Sodium bicarbonate. I can get calcium carbide from a research supplier ($50 for 500g), but I would prefer to store something benign. It also seems that calcium hydride would be safer as it produces hydrogen gas rather than acetylane.
You can't use hydride in a manometer, it reacts too quickly.
That's a shame, since hydride is a lot safer to store. Any other options that Calcium carbide?
I've tried sodium bicarbonate and it doesn't seem to work. I have a sandy brae and a karl fischer but I have found a really convenient way as a quick check.
By using a cheap r/h sensor with a lcd readout (in england they are about £4) I measure the humidity in the headspace above the drying biodiesel. When the humidity gets to 28% or lower the biodiesel is at a maximum of 150ppm water (as checked with my s/b) It's really easy, cheap and works well.
That's a smart idea for a straightforward field test or at least indicator. I will definitely be trying this!
At what temperature?
Hello john, hope you are OK.
The biodiesel is at 65degsC. I'm using one of IMB's turbodryers.
The temperature of the air exiting the extraction fan is @ 33degsC. When the bio is up to temperature (and probably @ 800ppm water) the R/H starts off at around the 50% mark. As the drying continues it reduces until it gets down to 26%.
I've followed the R/H using the sandy brae and the correlation is quite accurate.
Thats a really good idea, and cheap and easy to retrofit. I hope you dont mind if I recommend it to all of my existing customers and install it into all of my future turbo dryers.
Of course I don't mind, it's a small mod to a very good idea.
Since making the above post and the posts on the effective drying thread I've realised that on a sunny day the geometry of my bio room has the sun shining on the sensor and confusing the result.
I ran a test recently on a dull and cool day so the sun wouldn't be an issue. Here are the results;
time biodiesel temp R/H (sensor) temp(sensor) water by s/b
start 65degs 50% 26.3 860ppm
+1 hour 66degs 42% 27.4 400ppm
+2 hours 66degs 36% 27.5 180ppm
+3 hours 67degs 30% 28.5 130ppm
+4 hours 67degs 28% 29.0 120ppm
The turbo dryer was started 20 mins before the first sample was taken (so the sample was representative) this is probably why the first s/b water result at 860ppm is slightly lower than
Sorry folks when it posted all the results were condensed together but I'm sure you can still understand it.
Biotom, I know I said i would produce a graph but i think the results speak for themselves, Thanks Dave.
Do you know whether " temp(sensor)" is an accurate reading for the air temperature or is it reading the temperature of something else such as whatever the sensor is mounted to.
Allow me to post your chart in a more readable way
time......biodiesel temp.... R/H (sensor]...temp(sensor)...water by s/b
It is the temperature of the air exiting the fan. I have never tried to compare it to another thermometer, but have two sensors and they agree within 0.1 degs C.
It is set in a plastic shroud around the fan so not affected by ambient air. The sensor is about 4cms long and the shroud thickness about 1mm, so it is set into the airstream.
Thanks for the better chart Tilly.
I hope somebody can help me. When I test the dryness of my bio I dont get pressure increase in the manometer with calcium carbide, and there it remains for a couple of days even. I have done the tests at various temperatures to no avail, the rerults are the same. I dry my bio for one hour at 70 degr C and then pump it over a cone shape outlet for another hour, with a fan blowing cool air over it. If someone can explain this I will be most gratefull.
Try holding your warm hand over the sample jar, if you get a displacement of liquid it will prove you have no leaks.
Are you sure your carbide is OK. Are you crushing it fresh for every test.
If it has turned to powder it is an indication it won't work.
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