Here in the Inland Empire one cannot purchase hypodermic needles without a prescrition. Except at many public parks. You need? I get!
Great. Name the film HIV+ :o
Originally Posted by wildbillbugman
"I cannot buy syringes with needles in the USA without a prescription from a Doctor."
Wow, I got a whole bunch just sitting here, I find them useful for separating solutions or taking up small amounts of chemical rather than trying to pour into a 10ml graduate cylinder.
Might I suggest looking on eBay for printer ink refill bottles that usually come with syringes + needles I think mine came from HK (you may want to adapt the tubing to a needle and araldite it in rather than use the syringe+plunger).
I can mail you some if you want.
Perhaps we could start some sort of fund raiser?
Anyway, PE, it might be cheaper in the long run from not having to use so much raw material if you get someone to make this stuff (hardware) for you? Someone that builds complex stuff out of their house.. my uncle was building prototype magnetic mineral separating machines for the mining industry out of his home workshop (though there were a few indicents of magnets exploding and putting holes through tin walls, or exploding and collapsing back in on themsleves :P)
What kind of pump are you using? Might I suggest a cavity pump?
Last edited by Athiril; 05-23-2010 at 11:49 PM. Click to view previous post history.
Had a program here in LA were you could get the needles for free with one catch,you had to be a drug addict.Go figure.
Originally Posted by Kirk Keyes
I agree. The Masterflex, which I have, is probably the most popular in many circles and is the pump we used for a lot of things at EK, so I felt confident in it.
The problem is that this formula is probably wrong for this scale and that formulas made at this scale must be very carefully chosen for all characteristics including flow rate or pumpability, if that is to be done. A three hour run is not possible without pumps.
Therefore, I think I will move on to an emulsion with a higher flow rate or a shorter run time or both.
As for getting someone to build things for me, that is what I did with the coating blades and it just did not work out in the long run! Plastic joints leak or fall apart in these hot solutions, or they absorb chemicals. Stainless Steel is expensive and hard to work with... etc....
And, if I get too specialized, then who can do this in a home darkroom? After all, that is one goal of my work.
Thanks for all of the suggestions though.
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I've been seriously thinking the motor-controlled syringe concept and how I could improve the concept to an acceptable point and then make a cheap prototype. I have the experience and ability to make all the required control electronics and software (to have a feedback from the measured vAg, for example), and the mechanics is not impossible either if I can keep it simple. However, this all will take time as I have many other projects going on. But, if I ever get a working prototype under construction, I'll be in contact with you, PE!
Basically I would need three solutions - AgNo3 solution, Br solution and I solution, correct? Allocating three syringes for every solution would make total of 9 syringes. They would be controlled by linear stepper motors that cost about 15 USD each. IIRC the ones I've been planning to buy can be controlled by 0.024 mm steps. With small syringes (down to 1 ml or even smaller, if needed) you could get very slow and steady stream. OTOH, 50 ml is the biggest easily-available cheap syringe. I have 25 of them and they cost about 1-2 USD each. With three syringes per solution, for example, 5 ml, 20 ml, 50 ml, you could get total 75 ml of each solution with very flexible flow rate range. Syringes would be connected to very thin tubing, e.g. 0.6 mm, 1.0 mm, 1.5 mm respectively. You would lose only a ml or so of the solutions in this short tubing. If there is problem with solutions dripping out instead of spraying, very small nozzles could be made at the end of the tubes.
This won't scale up much, but I bet it could be made to work with small volumes (0,5 liter or less of emulsion?) quite well, but it would take time. And I don't have the necessary know-how in the modern emulsion making, which is a problem. I would be very thankful if you, PE, could post some examples of the exact pumping ramps/curves, so I could get a better idea what's needed.
Rather than a pump, how about using a gas pressure system with a pressure regulator via the needle? It should be pretty consistent, air or inert gas would do it I'd imagne?
I imagine you could use a decent air-compressor also.
IE: Something along the lines of my awesome CAD schematic here
Kodak used syringe systems for some flows due to the limitations of pumps. The ratio of high to low flow rates required many pumps. This ratio is called the "turndown ratio". There was a very long series of threads on various methods for doing this and Bob Mazzullo contributed a lot of good ideas and drawings.
The air or gas driven system is good but does require a flow meter to get enough precision, as well as a regulator to add vAg control. Feedback is difficult.
As with most emulsions, you will need a minimum of about 5 delivery systems. AgA, AgB, XA, XB and XC. These represent 2 concentrations of silver and two of 2 different salts. To make my 1 L emulsion, I delivered 300 ml of silver and 300 ml of salts (approx) to a 300 ml starting kettle. So, consider that your delivery systems will need to contain up to 300 ml.
Hmmm, PE, wouldn't a pressure regulator at the end of your setup allow you to increase pump output and restrict it with the regulator, and hence give you a regulated consistent output?
Yes, however precision flow meters in this range are very expensive, and many of them use brass or copper fittings which corrode in the presence of AgNO3. They usually run in the range of Liters / minute or CC/min, in ranges far above what I use.
Originally Posted by Athiril
At EK, I had the complete catalog of one of the large companies and had their precision flow meter kit with dozens of them in the kit. I used them for many projects, but finally dissolved a set with the wrong chemistry. I had to reorder several very expensive meters and learned that you need stainless points and balls. Some of mine were Dwyer IIRC.
This need for stainless increases the cost.