You could not leave the flea-market without a metal mesh soda siphon, or acquired the “ol’ reliable” from a family member. Your desire is to make soda water in it. What next?
Well, I have good news for you. Provided the glass bottle is not damaged and the siphon head is intact, a thorough cleaning and replacement of some parts can make the “Kovočas Merkuria” siphon, also known as the Czechoslovakian or Czech mesh siphon, fully functional. If you take care of it, it can be a functional ornament of your home for many years to come. The only difficulty may be the possible lack of spare parts in the future.
IMPORTANT! There is an older and a newer version of the Merkuria mesh siphons. This article describes the repair of the newer version. If the top end screw edge is smooth and the lever pin does NOT have a screw slot, you have the newer type, on which this write-up is based on. If the end cap screw has a coin edge and the pin has a flat head screw slot, you cannot use the information described here.
The method described on this page is based on my own experience and does not constitute as professional advice. I cannot accept any responsibility for any damage or injury that may occur during the repair or use of the siphon. You perform the steps described on this page entirely at your own risk.
You now own a household appliance that could easily have came off the production line 40-50 years ago. Needless to say, it’s worth attempting to assemble it with due respect and care. Some parts need attention because it is no longer possible to find spares. Seals on the other hand can be easily replaced, giving your old siphon a new life.
Necessary tools
Czech soda siphon repair kit (sold by Szász Kft.)
You’ll most probably need this set, because it’s the only one that contains the so-called Czech siphon pipe rubber. The package contains 6 or 7 parts in total, and has the barcode 5997969307101. Be careful not to buy the Hungarian soda siphon, cream whipper or plastic soda siphon repair kit, as the packaging is very similar!
Since relatively few people undertake this kind of repair, it is possible to pick up a kit that has been gathering dust on the shelf for a long time. If you see any blue rubber parts in the package, it is the most modern version of the kit and you can safely buy it. If there is no blue rubber part inside, then it may be an older item, but you will have to buy the proper neck rubber separately.
The kit can be purchased in larger supermarkets in Hungary (e.g. Auchan) and specialised household stores (e.g. Vasedény), and can also be ordered online. The parts can be ordered online.
Siphon pipe
For the pipe rubber you will also need a new siphon pipe. This can be more problematic to obtain, so it is best to buy it online with the kit if possible. Although the siphon only has a 1 litre capacity, I recommend buying the 2 litre tube as it can be cut to size.
| Szász part | LISS part |
| 2l siphon pipe (A31) | 9031 Siphon pipe 2 l |
Spanner tool
The kit sometimes comes with a spanner tool, but this is not suitable for complete disassembly of the siphon head. You will need to DIY or find another tool to remove the gas inlet valve. Replacing the valve seal is critical to the proper functioning of the siphon, so here are your options.
The best case is if you have an original Merkuria spanner tool for the siphon. The picture is of a factory key for a Merkuria Automa cream whipper.
By cutting or grinding off the narrow end of the tool from the Szász set, you can make an excellent spanner that you can get by with. The picture below shows the original state and the finished tool.
If you are not able to modify the spanner, a 12 mm chisel is also an excellent choice. I did the first reconditioning with one myself, and it worked perfectly. If you can find a chisel set that might also include a 4 mm dowel pin punch (e.g. NEO Tools 33-060), look no further. The dowel pin punch will be of great service later on when removing the lever pin. If you don’t have a spanner tool at all, you will also need a buttering knife to remove the clamping screw.
Not recommended alternative: New siphon head
It goes against my principles, but for the sake of completeness I have to mention that Szász Kft. also sells a complete siphon head (Hungarian soda siphon head, barcode: 5997969307118), which you can immediately put on the Merkuria soda siphons instead of the old one. However, you probably didn’t arrive to this page because you’re searching for the royal road. If you were, you would have already ordered one of the modern soda siphons. There is little point in keeping an old mesh glass bottle that has been around for half a century alive with a new head when the “soul” of the old unit can be perfectly refurbished with some love. If your goal is to keep using grandma’s soda siphon, keep reading!
To remove the neck rubber: tweezers
Many times you are only able to remove the neck rubber broken into pieces, but even with an intact rubber, a pair of tweezers can help.
To remove the old valve rubber: a thick crochet hook
The valve rubber is almost always hardened and brittle in well-used siphons. This component gets easily stuck inside the head when the gas inlet valve is removed and is very hard to access. The best tool for pulling it out is a crochet hook of suitable thickness. The proper thickness is about 4-5 mm, if thicker than this, it will not fit inside the valve rubber.
To unscrew the clamping screw: pipe wrench
The clamping screw at the top of the siphon head can be a hit or miss. Sometimes it can be easily unscrewed by hand, but sometimes it takes a lot of force to get it to move. This is where a pipe wrench comes in handy.
For pushing out the lever pin: Metal pen refill or 4 mm dowel pin punch
The lever pin is usually firmly stuck in the plastic siphon head and does not come out easily. It’s not hard to knock out with a hammer and a punch, but it’s even easier to disfigure the head with a wrong move. I therefore recommend an expendable metal pen refill for the purpose. If you don’t bend it, a good quality (steel-tipped) refill will continue to work afterwards, weaker refills will be ruined by this. A metal refill is necessary because a plastic one will break and is not capable of exerting the necessary force.
For lubricating rubber parts: household silicone grease
It’s not essential that you use it, but moving parts, especially if they are made of rubber, should be lubricated. It prolongs the life of the seal and is good for the sealing ability. Remember, the material is in contact with your drink. It is worth using a product that is food safe, such as T-Silox OXETT A2.
For descaling the bottle: 20% vinegar and a bottle washing brush
If you have a peek inside an old siphon, you can often see interesting stalactite formations. Vinegar is perfect for removing scale. It also helps you to wash your siphon thoroughly, as you’ll want to do this many times after a vinegar treatment to ensure there’s no aftertaste. As the bottle is transparent, aesthetic treatment may be necessary on the inside. Some people add an abrasive to the washing water to remove deposits by scrubbing action.
May be necessary: Neck rubber
If you have bought a repair kit that does not include a blue neck rubber, you will definitely need one. The alternative is to buy a newer, shorter version of the puncture pin, which can be used with the old neck rubber.
If you’ve made it this far and you’ve got everything on the list, that’s half the battle! The operation is not difficult, if I was able to do it, you can do it too.
Disassembly
During the disassembly process, parts must be turned counterclockwise to loosen.
1. Unscrew the siphon head from the flask. Pull out the siphon pipe.
2. If the bottle has a plastic level pipe, pull it out. You can remove the old type pipe with a level pipe extraction tool. If you have the new type, you can remove it by inserting the end of the cartridge holder in the tube, turning it clockwise and pulling it out.
3. Fill the flask up to the neck with 20% vinegar and set it aside for a day to let the vinegar descale it. Make sure that the vinegar does not spill on the metal mesh or the chrome neck piece!
4. Unscrew the cartridge holder from the siphon head.
5. Use the wider end of the spanner tool – or the blunt end of a buttering knife if you don’t have a tool – to unscrew the siphon head screw.
6. Use tweezers to pull out the neck rubber (or, in the case of old, worn-out neck rubber, dig out the remnants), or gently pry it out with the tip of a knife.
7. Use the narrow end of the spanner tool to tilt the pin to one side or the other. You do this just to loosen it so it falls out by itself when you turn the thread downwards.
8. Using the ground down end of the spanner or the 12 mm chisel, unscrew the threaded metal ring located under the puncture pin. Be careful not to damage the threads on the inside!
9. Poke out the valve and the valve rubber with tweezers or a crochet hook. Be very careful with the plastic valve pin as it is a difficult part to replace!
10. Unscrew the clamping screw at the top of the siphon head. If necessary, use anti-slip material or grip it with a pipe wrench, but be careful: the locking screw is a visible part of the siphon head and can easily be disfigured. Remove the spring under the screw from the siphon head.
11. Push the lever pin out with the tip of a metal pen refill or 4 mm dowel pin punch. The less maintenance the siphon head has received, the more difficult the operation is.
12. After removing the lever pin, the lever falls out of the siphon head.
13. To remove the valve stem the pen refill, dowel pin punch or any other thin, blunt object comes in handy again. Reaching up through the bottom of the siphon head, you can push the valve stem out.
14. All removable parts are out of the siphon head at this point. The exterior should be cleaned gently, without scrubbing, using some dishwashing liquid. Unfortunately, the shiny polyamide material is easy to scratch, so care should be taken. The inside of the siphon head can be cleaned by rinsing it thoroughly with detergent several times. The push lever should also be cleaned, as dirt often accumulates on non visible parts. A distinctive feature of Czechoslovakian soda siphons is the thin, chromed lever.
Replacing parts
Rubber parts are meant to be replaced with every maintenance. The colour of the new part is irrelevant, I have seen red, black, white and blue rubber and silicone based seals. They perform equally well, with a possible difference in their durability. This is something worth discussing after a few decades 🙂
For rubber parts, if a part is included in the repair kit, consider replacing it even if the old one is in good condition. Safety first – it’s not worth taking any risk to save a few hundred forints. However, always save the old part if it is in good condition. Everything is easy now, as there are still replacement parts available to be bought, but that may not always be the case.
Check which of the rubber parts are due for replacement:
The plastic valve stem and valve needle found in Merkuria siphons are not easily available as replacement parts. These two components must be reinstalled after replacing the gaskets, and care must be taken to prevent damage to them during the reconditioning process.
Decide which of the plastic and metal wearing parts you wish to replace:
The puncture pin is a very important wearing part, so it is advisable to replace it during every maintenance. The siphon head screw is not included in the recommended repair kit, but it can be purchased separately. Replacing it is generally not necessary unless it has been previously removed improperly, which may have caused it to become deformed.
Prepare replacement parts, discard worn parts.
Assembly
1. Replace the O-ring and the valve seal on the valve stem but take care not to damage or deform the stem. This step requires a bit of effort due to the stiffer material of the new O-ring. Apply a thin coat of silicone grease to the rubber parts, then push the valve stem back into the valve bore with the lever slot in the correct orientation until the opening and the opening in the head are completely aligned.
2. Push the lever back in place, fiddle with it until it snaps into the slot of the valve stem and moves into its normal position.
3. Push the lever pin back into place using a hard, non-fragile surface (such as a tabletop). If necessary, nudge the lever slightly to keep it out of the way. You can push the pin back almost fully with the table top, and without damaging the siphon head. It is not essential that the pin sits exactly in the centre of the hole, but if it does bother you, you can adjust it with the tool you used for pushing it out. Be careful though.
4. Check that the pin and lever work as expected: if you can operate the lever, everything is placed correctly.
6. Check the lever again, the spring should now work as usual. Be amazed at how easily and smoothly you will be able to dispense soda water thanks to the new parts and silicone grease! Some backlash of the lever is acceptable.
7. Remove the old valve rubber from the valve needle, then apply a thin coat of silicone grease on the surface of the needle where the valve rubber will fit. Slide the new valve rubber onto the needle until the wide collar sits correctly on the valve. Also apply a thin coat of silicone grease to the outside of the new rubber, especially on the collar.
8. Push the valve needle in its place, then using the ground down end of the spanner or the 12 mm chisel, screw back the threaded metal ring. Be careful not to overtighten or damage the threads on the inside!
9. Pick up the new puncture pin and put it in its place. It is important that the base of the needle sits in its place straight and centered. Use the end of the spanner tool or a screwdriver to adjust the round base of the pin until it sits into its place.
10. Apply a thin coat of silicone grease to the rimless end of the new neck rubber. Then press the rubber firmly into place with the rimless side facing inwards.
11. Use the spanner tool or the blunt side of a knife to turn the siphon head screw into place. Make sure that the rubber is still straight at the end of this operation and that it is not wrinkled.
12. Assemble the new pipe rubber and the new siphon pipe. Unfortunately the original pipe is not usable with the new pipe rubber. Cut the pipe to be long enough to reach the bottom of the siphon. You can test the exact length by cutting it slightly longer than necessary, then putting it in place and threading the head onto the siphon. The “excess” will extend over the top of the pipe rubber. Cut the bottom of the pipe in a V shape on both sides, as it is standard practice.
13. After soaking for a day, wash the siphon flask thoroughly with drinking water using a bottle washing brush until you are satisfied with its cleanliness. Store the siphon pipe with the pipe rubber and the restored siphon head removed until everything dries fully.
I would like to thank Robert, the owner of Acqua Spumante, for his help regarding the repair process.