Jokari Fizz-Keeper Pump Caps, 3 Pack-Count

I was just a little apprehensive about this device prior to purchasing it but I went ahead and took that chance. I am very happy with how it keeps my soda from going flat. The key is to pump it up many times until you feel the container pretty darn hard. The harder you get it the longer your carbonation will last. Mind you, it does take a little more time as the container empties but it’s well worth the extra minute or two. I will follow up to the durability in about a month. Stay tuned!!Update: 5/02/2024.Well, that was sure a long month!! Regardless, I’ve used these countless times over the past 3 years and it still works like when I first pursued it. It hasn’t lost the ability to keep your drinks fresh and fizzy. There are no signs of wear after heavy usage. Additionally, I’ve been using these on regular sized plastic drinks that hold a little more volume than I normally drink so I just pop this on and the beverage stays carbonated for several weeks. Enjoy!

These fizz keepers work when new but quickly lose their ability to pump air into the soda bottle. They last maybe two months with regular use. I bought a three pack and now after two months of use I’m down to one that still works. They just stop pumping with the piston moving freely in and out but with no pressure being built up in the bottle. Feels like a seal or a gasket is wearing out over a short amount of time. If just a month or two of use is acceptable for the price then go for it but I won’t be buying them again.

Don't listen to that mumbo-jumbo about Raoult's and Henry's Laws of PHYSICS applied and interpreted by mere CHEMISTS! They're all wet-- pun intended. In fact, these things work FINE by substantially increasing the net pressure over the surface of the soda pop, thereby completely destroying any "ideal-gas" characteristic of the water-dissolved CO2; i.e., the mole-fraction to be equalized above the surface of the bottled Coke/Pepsi is artificially reduced by the gross overpressure of the container's internal atmosphere. Some CO2 comes out of solution-- less if you keep it refrigerated-- but nowhere near as much as for a simply recapped bottle.I've had a 3-liter version of this li'l pumper capping a big 7Up bottle for well over 2 months now; it's been 2/3-consumed for most of that time. I had a small glass last night and the FIZZ is still there... still stings the back of the throat! Got nearly a decade of experience with these things....However, there ARE a few tricks to making 'em work successfully:1. CUT that nasty remnant-band off the bottle on those that come with 2-piece caps. That "ring" left on the shoulder of the bottle-top will prevent the Pumper from screwing-down fully and achieving a GOOD SEAL. I've destroyed 2 of these gizmos over the years by failing to recognize this trick and ended up overtightening 'em to the point of cracking the screw-cap. Talk about a bad seal then!!So, cut off that offending "washer" and screw-down firmly with the Pumper and it should last forever.2. LUBRICATE the valve-seal every so often by rinsing it in clean running water WHILE operating the pump; run the water over the top shaft and listen for the "flatulence."Turn off the water and pump it dry a half-dozen times and you're ready for the next Coke. It's also a good idea to gradually ROTATE the piston inside the cap as you're pumping in this way-- good for the seal... equalizes wear.3. Once screwed-onto the bottle, DON'T OVERINFLATE it past the stiffness or rigidity of the way you got it out of the icebox-- a good target point to keep from overdoing things. And yes, it's best to refrigerate the bottle of pop at least overnight before opening it and resealing with the li'l pumper-cap. Remember how that freshly chilled bottle FELT before opening the original cap... squeeze its sides a few times like a melon... remember the sensation. Then, never exceed that level of stiffness once you seal and start cranking on the pump-cap.Anything else...?

I had one of these jewels over 40 years ago, and to my amazement, I found this on Amazon, so I could not wait to see if it works the same. It does! I have had it for some months now, and it has worked like a charm. It takes me about two weeks to drink a 2-liter, so this is a necessity. I pour me one small glass, about 8-9 ounces worth, and this fizz keeper will requirer approximately 20-25 quick pumps. You are able to pump super fast, so it really takes no time at all. As I pour more and more out of the bottle, it takes more pumps, but they go super fast as well. The fizz seems just as good on day one, as it does on day 24!

When you take about one 8oz glass out of a 2 liter bottle, it takes only 20 to 30 pumps to get a nice pressure in the bottle. As the bottle gets low, it takes over 100 pumps. As the bottle gets low, I generally don't pump that much. Maybe around 70. I've counted them.There are a couple of problems. It doesn't take long, maybe going through about 15 two liter bottles, and this thing gets a bit harder to pump. I have lubricated mine with a light coating of food grade grease, and that helps. Also, there is a rubber O-ring inside, that seals the cap. After you pump pressure into the bottle, and go to unscrew the cap the next time, somehow, sometimes, that O-ring doesn't let loose and let the pressure out of the bottle. Suddenly you run out of threads, and this thing pops off worse than a champagne cork. It inevitably hits something, every time, and breaks. It never survives the experience. You always have to listen for the pressure being released each time you unscrew this thing. If you don't hear it, rock the cap back and forth to get some pressure to release. Unscrew just a little more and rock again for a little more pressure release. When the pressure isn't being released properly, try to always keep the palm of your hand touching the top of the cap. If it pops off, it will go into your palm, and not fly off and get broke. It has popped off this way into my palm one time, and it didn't hurt at all. I do wonder about the next time.Overall, if you want to do the pumping, this thing is fairly good. Just be careful when unscrewing it.