I have an old "Ultraflate" "trigger grip" CO2 inflator. I've never used it. Given that it has a trigger, I assume I can control the flow of CO2. In order to locate a puncture in a tube, sometimes I have to inflate it slightly after its been removed from the wheel. Can I do that with this inflator? In other words, will a quick blast of CO2 with this inflator be enough to inflate the tube a little, but not so much that it will burst it when it's not in the tire?

You won't burst the tube but you may not have enough gas left to inflate your tube afterwards. Have extra cartridges or replace the tube, doing the best you can to locate the offending object. Practice with the gadget at home.

Yes you should be able to regulate it. A 16g cartridge should be able to get 2 700x23C tires to a rideable psi (~70-80) or 1 mtb tire to ~40 psi

If you have presta valves, you can blow enough air into them with your mouth to find the leak.

Yep.

But a 16g cartridge should have enough to check the tube and still fill it up. I still like to carry two, just in case.

^^^THIS^^^

Two for sure. The last flat that I had was on a run with the trailer. I picked up a chunk of roofing deck passing a construction zone. The damage was just a small hole on the tire side. Patched in minutes (tool kit had tube for wrong bike). Flat three miles later. Using the frame pump four times got me home. The metal poked a little hole on the tire side and created a shotgun blast of tiny pokes on the rim side. One cartridge would have left me pushing.

Thanks for the replies everyone.

This past week I got my first flat on my 20-inch 95psi tires (folding bike). That was the first time this question occurred to me. Since I didn't know the answer, I called a co-worker to pick me up, and immediately went out and bought a portable hand pump for future use. I see now that it was unnecessary - I could have located the puncture, fixed it and reinflated with the CO2 I was carrying.

After work today I decided to practice using the CO2. It worked like a charm. In fact, the one 16g filled the 20-inch tire almost exactly to 95psi. (I deflated the tire before re-inflating it.) In the meantime, I discovered that I could only manage to get around 65 psi with the Lezyne Pressure Drive hand pump I purchased, even though its rated for up to 120 psi (honestly don't know how that's possible, unless larger tires are easier to pump). I've now got to decide whether to keep it and carry it as emergency backup or return it. Think I may just return it and carry two cartridges. Can't beat the time and effort savings.

Perhaps your problem is going with the "high end", elite Lezyne pump. I guess that it has it's merits, although your experience doesn't seem to reach those limits. Perhaps you might try the Topeak Road Morph that we mortals use, with success every time we need to inflate a tire. I realize that it doesn't cost as much, but the value is in the performance.

Funny you should mention this. Yesterday afternoon I took a trip to the one bicycle store listed as a Topeak retailer in my area specifically to check out the Morph pump because of what I read about it after my disappointment with the Lezyne, only to find they don't carry Topeak pumps any more. Yes - if I decide to also carry a hand pump I intend to check it out instead of the Lezyne.

CO2 = no pumping = no brainer.
Still, I carry a mini-pump for checking tubes and pre-inflating the repaired tube/tire. I think my cartridges are smaller than yours. If I flat halfway into a longer ride I want to re-inflate to my previous pressure, not limp home on 70 - 80 psi. JM2C

I wonder how they determine the rated pressure for bicycle hand pumps.

The laws of physics can't be violated no matter who makes the pump. The diameter of the pump barrel and the power of the person pushing the pump handle combine to determine how much pressure is possible. The length of the pump adds a volume factor that determines how many strokes it will take to get your tire up to pressure.

If you're the kind of person who is willing to realize that you don't have a flat too often and is willing to put up with a little aggravation when you do, you might be a candidate for a mini pump. Mini pumps are designed to be easy to carry when you're not using it which is most of the time.

If, like me, you find flat tires frustrating and don't want to add any more frustration to your day, you need a pump that has some different design elements. 1. Size matters. Longer means fewer pumps to reach operating pressure. A skinnier barrel means less force is required to reach operating pressure. Fatter barrels do have their place but it's only for mountain or cruiser bikes that have high volume lower pressure tires. 2. A pump that has a foot brace and a hose lets you use your torso rather than just arm strength to push the handle. That's a big deal if you're trying to get to 100 psi. 3. Another big plus for the hose is that you don't stress your valve stem sideways while you pump. Stress it too much and you'll ruin your new inner tube. A pump with those features won't look as cool strapped to your bike. It's designed for (hopefully) rare times when you are actually using it.

One other thing. Several posters have used the term "enough air pressure to get you home". I think that's a bad concept. Whenever I've had two flats on the same ride, the second one has generally been my own fault. The last time that happened it was because I didn't take the time to find the tiny little sharp stone that punctured my first inner tube. Other times I've wimped out on getting my tire up to full operating pressure and was rewarded with a pinch flat a few miles down the road. When I take whatever time it takes to fix my puncture properly, I only have to do it once. That brings up my objection to using CO2. It's convenient to both carry and to use and it's super fast - maybe too fast. With CO2 you can inflate a 700 X 23 tire in about 2 seconds PROVIDED you have both tire beads properly seated and no little fold of inner tube is caught under one of them. Otherwise KABOOM! You have just not only ruined your brand new inner tube but now you don't have any CO2 left to inflate another one.

I dust all my spare inner tubes with talc or baby powder before storing them in the seat bags of my family's bikes (many different tire sizes). The last time I failed to do this, the new tube was pinched and ruined during inflation. I don't carry a patch kit (foolish, I suppose), so I want the tube to work the first time.

When I inflate a new or patched tire using a hand pump I always first blow it up just a little after getting it and the tire back on the wheel. Then I check the seating all around before inflating it all the way. Can't I do the same with the CO2 and trigger chuck I have?

Yup. That's what I do.

I carried CO2 only on my road bike for years and it never let me down. I inflate my inner tube by mouth and place it into the tire then install the tire and tube as a sub assembly onto the rim. I still check all around on both sides before injecting the CO2. It's by far the fastest and most convenient way to inflate your bike tires provided you are careful.

Can't inflate my inner tube by mouth - I have Schraeder valves - but still, sounds like preliminary, slight inflate with CO2 after install followed by seating check before full inflate will help avoid problems.

Yes. All the modern inflators will do this, but the trigger models make it more convenient. Practice a couple of times in the house, before needing it in bad weather, or dark.
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I do a lot of long rides, coming home late at night. I carry three cartridges and a decent pump. I can ride home with 40 psi in 23mm tires if required. But, it's so little work with the gear I have, I fill the tires right up. Below freezing the inflator will freeze up and not inflate the tire. I put the inflator under my coat to warm up, and then fill the tire quickly before it gets too cold, this works ,but the cold also keeps the pressure low when filled from an inflator. The pump is better around 20F.

If you want higher pressure than the cartridge will give, put some air in the tube first, then add the co2 afterwards.
This way means the pumping is easier that it is at high pressure.

Read this chart.....

CO2 Chart | Genuine Innovations

Is it possible to use a threadless cartridge on a threaded inflator ?

Probably not. You need to have a way to puncture the cartridge and to hold it onto the inflator. You won't want to hold the cartridge with your bare hands because it gets real cold as it inflates.

If you could break the seal of the cartridge, there's nothing holding the cartridge to the inflator head so it would take off like a missile.

Depends on the inflator, if it is just a chuck-head inflator you're correct...inflators like the OP's Ultraflate (I have one) have a thread on cage around the entire cart so it will keep some seal but not a very good one but at least it won't go flying

I thought the chances were slim it would work, and I don't have a ultraflate....thanks guys

I'm surprised to read this (that it will not seal well with a non-threaded cartridge). My recollection is that the Ultraflate was designed to use both threaded and non-threaded cartridges (hence the threaded sleeve), and it may have even come with a non-threaded one. Is this from experience, Marcus?

Photo for anyone not familiar with this model:

Yes, if you have one of the inflators that has a body to surround the unthreaded cartridges. They do both kinds of cartridges

If you have the old yellow body innovations, it has threads, but, it also has the yellow body to use with non threaded.
That inflator will use all the cardtriges except the 16 gram unthreaed. It also does presta and schrader.I use 12 gram unthreaded CO2 paint gun cartridges from Wallmart. They are the cheapest.

The very newest inflator that is black body and green trigger, the 'Ultraflate" will take all the different kinds of cartridges including unthreaded 16 gram.

It will work with the 12 gram unthreaded. It did not look like it would work with the 12 gram unthreaded, so I tried it. The body just screws on more to bring the shorter cartridge to the puncture needle. One needs to turn the body as fast as possible to get a good seal with the 12 gram unthreaded. The extra travel of the body using the 12 gram cartridges, has a lot of threads between the point where the needle punctures to where it is a tight seal. So get a good grip and go fast when you reach the puncture point. I had to do it twice to get it right.

This infaltor will do presta and schrader as they all will.

I've done it 20 times by now. It seals fine,when you feel the puncture tip just touching the needle, get a good grip on the cage and spin it fast to get it to the seal.

This! I left the house at 5:15am for my first commute to work with my new bike. I got a few miles from the house, and hit some metal junk on the bike trail, and punctured the tire. It was dark! I walked my bike back a half mile or so to the corner bank. I tried to use the C02, and didn't do well with it. I had not practiced or even watched a youtube vid to familiarize myself with the use. Fail on my part. I've studied up on it since then.