|Use only clean and dry hoses for the gas supply. If you want to work with exclusion of water, do not use hoses that have already been used as cooling water hoses. After passing through such hoses, the inert gas would be saturated with water vapor! Attach a cannula to the end of your gas supply as shown. The tube must have the appropriate diameter so that the cannula fits tightly.|
It is even more convenient if you also cut a 1 ml syringe to size:
- Obtain a 1 ml disposable syringe.
- Remove the plunger.
- Cut off the top of the syringe.
- Insert the syringe fragment into the tubing.
- Attach the cannula to the syringe.
The syringe fragment is best left on the tube permanently. If necessary, only change the cannula.
|Small defect, but devastating: the left cannula tip is bent. With this you tear large holes in a septum, which no longer closes completely after pulling out the cannula. Only use cannulas with a sharp point as shown in the picture on the right with (very) high magnification!|
|Grease the cannula with a very small amount of ground joint grease. This makes it easier for it to slide through a pierced septum and damage it less.|
|If the septum already has holes, push the cannula through the same holes over and over again. Do not make a sieve out of the septum!|
|Clamp the supply bottle so that it cannot tip over. Then insert the cannula connected to the gas supply into the septum of the bottle. You can bend the cannula as you like, but not kink it, as the cannula will then break. The bottle is now under a slight overpressure.|
|Take a disposable syringe of the appropriate size and a cannula long enough to reach the liquid in the storage vessel. Put the cannula very firmly on the syringe! Lightly grease the cannula with ground joint grease and push the syringe deep into the vessel. Watch out! The overpressure in the storage vessel can - and should - slowly push the plunger of the syringe out. If it does not come out by itself, check the gas supply. If necessary, you can easily help with your hand. However, if you are sucking in with the syringe, you can get air in the syringe and / or in the storage jar. |
However, some gas in the syringe is perfectly normal and comes from the dead volume of the empty syringe. (See illustration) The small gas bubble must not enlarge when you pull it!
|Now comes what you have to "dare" the first time. The syringe that has been inserted into the supply bottle can also be bent down without the cannula breaking. Make sure that the nozzle for the cannula is not attached centrally in the middle but to the side for a good reason. Bend the syringe down so that the nozzle is now on the top edge of the syringe - just above the air bubble, as shown in the illustration. Push the gas bubble back into the storage vessel! Whoops! The gas bubble is gone!|
|The syringe will now remain free of air bubbles if you now allow the syringe to fill due to the excess pressure that is still present in the bottle. Wait until the required amount is in the syringe and then pull it out of the septum, taking hold of the cannula so that it does not tear off the syringe. Afterwards - not earlier - you can also pull the cannula for the gas supply out of the storage bottle. The bottle thus maintains its overpressure and is protected against the ingress of air.|
When things have to be done quickly and when it doesn't really matter.
Fill a syringe with inert gas by withdrawing and deflating a few times in a stream of inert gas. Insert the syringe filled with inert gas into the storage vessel and press the inert gas into the bottle. This puts the vessel under overpressure. Now draw as much liquid into the syringe as you need. Remove the gas bubble as described above. Pull the syringe out of the supply vessel. Of course, this method only works if the amount of gas pushed in is in an appropriate ratio to the gas volume in the bottle. To do this, check the level in the bottle!
|Septa are essential for working with syringes. There are different types of septa. On the left of the picture you can see the screw connection familiar from the basic equipment ("Quickfitt"). Instead of a seal for a tube or a thermometer, you can also insert a septum. The septum shown here even has an inert Teflon coating on the elastic carrier material. On the right you can see a so-called everting plug. It is available for the common joint sizes and also for different pipe diameters. Dealing with it is much easier than pronouncing the name: The conical part is inserted into the joint or pipe and the jacket is slipped over the joint or pipe.|