I saw a thread asking about how to effectively dispense liquids, and I thought I could offer some suggestions for people who are trying to pick up some lab-grade equipment and go all out, with the added bonus of accuracy.
I'm currently a Senior in college with a double major in Biology and Environmental Studies. I have worked in my school's Biology department, as well as for the Department of Environmental Services in my County. Part of my job with the County was obtaining accurate measurements of suspended solids within water samples, so I thought some of you may find my knowledge of lab-grade equipment useful. I am very familiar with lab equipment, so this sort of thing is second-nature to me, but I'll warn you that some of it may take some practice if it's your first time using it. I'll give instructions and explanations below where it's relevant. I'll use Amazon just to give you an idea of what you're looking for, but many suppliers may be cheaper and sell in bulk (if that's what you're looking for).
.
I'm hoping you won't be scared off by how technical it sounds, so here are some images of how simple this rig really is:
Here's what your setup will look like (with another clamp towards the top).
Here's another image, but please don't take the labels seriously unless you want to die. It's hard to find clear "blueprints" that aren't talking about chemistry of some sort.
And here is how your bulb will fit onto the top of your burette/pipette.
.
Here's a list of equipment you may find useful:
1. A Burette (or volumetric serological pipette).*
2. A stopcock (if not included with your burette).
3. Parafilm (or, alternately, seran wrap).
4. A bulb filler or plastic pump for your burette.
5. A ring stand.
6. Two ring stand clamps.
Total cost: ~$50-70, shipping included**
*Use of serological pipettes, instead of a burette, can cut down your costs by 10-20 bucks and eliminates the need for a stopcock (but requires more accurate measurements!). Please see this photo for accurate pipette readings, which are taken from the bottom of the meniscus.
**Assuming that a stopcock is included with your burette purchase.
.
Some descriptions:
- A "Burette"
First, you'll want to find yourself what's called a "Burette". This may also be referred to as a "column". It's essentially a glass or plastic tube (doesn't matter which material, really; plastic will be cheaper, though) with measurements of fluid volume in mL. These come in many sizes, depending on how much liquid you're trying to dispense in one sitting. If you want to leave PG/VG in the column, you're going to have to keep the liquid from evaporating; I'll explain that below. The following link will show you what a burette looks like and the variety of options you have to choose from. Which one you get shouldn't really affect you too much.
http://www.amazon.com/gp/bestsellers/industrial/318052011/ref=sr_bs_1
Note that this burette comes with a "Stopcock"-- the valve that lets you control flow. You can use this to bring it down to a drip, or keep a heavy flow.
- No stopcock? No problem.
You can buy a 2-way stopcock on Amazon as well. PTFE is the material it's made out of, but you should make sure your stopcock bore is the same as your column burette.
Here's a link to a search for stopcocks. Unless you're trying to fill more than one bottle at once, a 2-way should do.
- Parafilm:
This is basically lab-grade seran wrap/wax paper. Except it's better than that. The purpose of this is so, if you're leaving a liquid in your column, you'll keep it sanitary, isolated, and unevaporated.
Here's a link to some parafilm.
- A filler or pump for your burette/pipette.
You need to get the liquid into your burette/pipette! In this case, you have two options:
These are kinda finicky and difficult to get used to. You squeeze the bulb and slowly release it so that you fill your burette/pipette to the desired quantity. Remember that gravity is going to pull the liquid back down when you remove the bulb by eliminating the vacuum! The way you counter this is by pressing the burette/pipette down into the bottom of the container to prevent the release of the liquid. Takes some getting used to, but this is pretty common in a lab.
A pipette pump:
This is the easier option of the two. Just pop it on your pipette and turn the wheel to fill it. Make sure to get the right size!
- A stand to hold up your burette/pipette, and clamps to hold it in place.
You're going to want a ring stand to attach your burette/pipette to, as well as a couple clamps to hold it in place. The ring stand is a pretty simple purchase, but clamps come in many different forms. What you're looking for is something that can attach to a ring stand of any size (to make sure it works with yours) and can hold any width of burette/pipette upright. For this reason, screw clamps are the best option, as opposed to circular clamps that are meant for other (normally distillation and chromatography equipment). I've put a couple examples below:
If it were me, I would go with example 3. The way examples 1 &2 work is that one screw is secured to the ring stand, and the other is secured to your burette/pipette. I would suggest buying two clamps.
.
I hope I've helped any of you who may want to upgrade your setup with some better equipment!
.
PLEASE NOTE THAT THIS EQUIPMENT SHOULD BE CLEANED REGULARLY TO MAINTAIN STERILITY. DISH SOAP SHOULD DO, BUT MAKE SURE TO GET ALL OF IT OUT! Labs typically use a glassware cleaner called Alcojet because it's non-ionic (won't typically cause chemical reactions) and is low foaming. Dish soap and the like are unnecessarily foamy because people think that foam = clean, but in reality, this is the reason why you get streaks on your wine glasses. Alcojet is basically dish soap without the foamants, and is unnecessarily expensive if you make sure to do a thorough job cleaning.
If you really need to go precise, you can't do better than buying a 0.1 g precision scale (or better, especially if you want to mix small amounts).
I used my mg scale to measure some mixes and it highlighted an interesting point for me: VG is about 25% higher density than PG, so doing volumetric ratios doesn't make a whole lot of sense. I mean you'll still come out with fixed ratios but 50/50 PG/VG by volume is quite a bit different from 50/50 by mass.
I thought of this. The only problems is price, vg is a little to thick to use in accurate setups, and you can fill and measure into another container just as effectively but quicker.
I guess it would be better suited for people doing a lot of bottles, one after another. But I feel like when you're shelling out as much as some people do on vapemail or at the B&M, this could be a good investment if they want to do 5x10mL bottles rapid-fire with a quick refill time once they get used to it. I did consider that other methods of measuring work pretty well, but for me, this is way faster with much less of a chance for stuff to topple over.
I've considered adjustable pipettes. You dial in the amount you want, drop the tip in the solution, press a button, and it sucks up exactly as mucha s you wanted. I used them in my chem 2 class in College, and instantly fell in love thinking about the possibilities with mixing. Then I found out they are like $300-$400 a pop.
How fast are you dispensing vg with these? In chemistry labs in college for titration labs it was very slow and tedious I can imagine it with thick vg
I can get it to a pretty solid pour out of the nozzle. PG isn't so viscous that it wont slow. All you have to do is open the nozzle all the way. Your titrations took a long time because there was probably some sort of distillate in there, or something to otherwise block the flow. You may also be thinking of column chromatography. That shit takes forever. In my first semester of my sophomore year, I had to come up with a way to synthesize curcumin because an analogue of it is a really good prostate cancer drug, and it's really hard to make for cheap. I was staring at columns for probably 2 hours every time I went into the lab. And vacuum filtration was even worse.
Wow and I am just sitting here trying to work out how many mls are in a drop that comes out of my flavour bottles!
It's actually much simpler than it sounds at first! Here's a picture of what it looks like when you've got it all together, except that this guy only uses one clamp.
Actually, I think I'll add a similar photo to my post so people understand that the equipment might sound complicated, but it's really very easily done.
I've been watching eBay for peristaltic pumps. I was hoping to find one with enough ass to push 100% VG, but they're all closing in the several hundred dollar range. Just gotta catch the right one...
I'm also a senior biology major. All of this information is both accurate and possibly useful, but the viscosity of the liquids here will cause problems with both general flow and the valve. The openings would have to be large on the burette to do much good. It may work, but slowly.
Disposable glass pipettes may work well with a wheel type pipette pump however. There are powered handheld versions of the wheel pump that are the next level up but get that pump clogged with VG or flavorings instead of air and you're gonna have a bad time.
The use of parafilm for storage is great in the cases where you're storing flavorings in glass containers, but some aluminum foil between the threads and the cap will do just as good to prevent evaporation.
Ah, that's two people that have told me a burette won't work well. Volumetric pipette it is, then. I don't know why viscous fluids flow so well for me out of burettes; very strange.
It's mostly thin liquids that do well in the burettes because of the relative gauge of the opening and the hole in the rotating valve. If there's pressure enough it'll work but it depends on the burette if you're just relying on gravity. You want that pressure behind the fluid or a plunger. I use oral syringes from the pharmacy that are super cheap. They have a short plastic tip but are a huge gauge, and hold 12 ml.
PG does fine with a blunt tip luer lock syringe.
If you want accuracy that this ~$70 setup may provide in a more practical sense, measure by weight with a scale using graduated cylinders.