Mechanical series tube

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Rossum

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Thankfully most hybrid and faux hybrid mech allow positive end down which is the way I run,my vcm(vent holes are through the button
The hazard with positive end down is that any flaw in the battery's wrap will produce a dead short the moment you press the button.
 

Punk In Drublic

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Vent hole location is also very important on a tube mod. Cells are designed to vent from the positive end. Yet many tube mods have the vent holes at the bottom of the mod. What happens if the cell swells a bit before it vents? There will be no path for the gasses to make it from the top of the mod down to the vent holes.

I agree – assuming proper cell orientation is used and the device can withstand the pressures. But although the cell may begin to expel through the positive side, pressure build up inside the cell could very well rupture the metal can to which it could prevent the device from relieving the pressure
 
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bombastinator

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Thankfully most hybrid and faux hybrid mech allow positive end down which is the way I run,my vcm(vent holes are through the button
To expand on @Rossum ’s statement it makes the case the positive lead rather than the negative.
 

Punk In Drublic

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Baditude

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Baditude

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Vent hole location is also very important on a tube mod. Cells are designed to vent from the positive end. Yet many tube mods have the vent holes at the bottom of the mod. What happens if the cell swells a bit before it vents? There will be no path for the gasses to make it from the top of the mod down to the vent holes.

To expand on @Rossum ’s statement it makes the case the positive lead rather than the negative.
I've written on this topic in the past. Mech Mods with top venting holes?

It's an important topic that seems to get ignored by the mech mod community, including the mechanical mod manufacturers.
 

bombastinator

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Baditude

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I am not convinced this level of engineering goes into these devices and that vent holes, (although adequate for a venting battery - which to my knowledge is of low pressure release) are enough to prevent a device from breaking apart under pressure.
Mooch has discussed this briefly. Probably no mod manufacturers actually test their product for adequate ventilation in beta testing. Some manufacturers drill a couple of holes in the bottom of the tube or in the bottom-firing switch. Many have no ventilation holes at all. Although no safety standards exist, the total absence of vent holes (in theory) constitutes manufacturer negligence in my opinon.

Ideal location for vent holes in a mech mod:

68706802_2576686059264208_4178669039142305792_n.jpg
 
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vicsch

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When I first started vaping (late 2010) The FDA was involved in a lawsuit, shipments were being seized by customs, and vaping was coming to an end.

But I loved this stuff, so what to do ... what to do!?!
It was obvious that I needed to (at least) learn how to be "self reliant", so I set out to learn how to make my own mods & atomizers, and DIY my own liquids.
As a result, I have several mods that I made myself, and even an atomizer made from a coax cable connector. And, I still DIY my own juice.

Not quite as bad as tappin into the AC, but almost! ;)
To me its no mistake buying product after product or in this case device after device ... 'cause I'm hooooked on buyin' the cute 1's especially (Even if I never use 'em at all, So i'll put 'em in my will) ... lol !
 

homeuser6

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The tensile strength of any device needs to be able to withstand the maximum pressure that is capable from any cell that fits said device. This will allow vent holes to relieve that pressure. If the tensile strength is not able to withstand the pressure, then vent holes will not be able to perform their duty and the device will break.

Or vent holes have to be of size to be able to relieve pressure quicker than it is able to build up so that the tensile strength of the device is not breached.

so how can we test for these characteristics ?
 

Punk In Drublic

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Mooch has discussed this briefly. Probably no mod manufacturers actually test their product for adequate ventilation in beta testing. Some manufacturers drill a couple of holes in the bottom of the tube or in the bottom-firing switch. Many have no ventilation holes at all. Although no safety standards exist, the total absence of vent holes (in theory) constitutes manufacturer negligence in my opinon.

Ideal location for vent holes in a mech mod:

68706802_2576686059264208_4178669039142305792_n.jpg

There are many consumer products that pose a high risk if misused. A quick Google shows more than 400k people suffer from power tool injuries each year – with over 200 of those resulting in death. Are tool manufactures on the hook for negligence? But the key word here is misuse!

You had a video on one of your blogs which is no longer there. I also cannot find it on YT – might have been removed, but it shows a user in a vape shop who device blew up in his face. If you pause the video at the right moment, you can see gas/smoke ejecting from the sides prior to the fire ball explosion. I am going to play the speculation card here and speculate the device had vent holes. And if so, those holes did not prevent the device from exploding into pieces.

I have read that these cells, once thermal runaway has been reached, can expel 2 to 3 liters of gas – possible even more with larger capacities, all within milliseconds. Can we say without a once of doubt those 3 tiny holes in your picture (6 if they are shadowed on the other side) are large enough to relieve that kind of pressure while taking into account the weaker points of the device such as the 510 or threaded caps? And how are those an ideal location should the battery can rupture? A battery will vent through it’s positive cap. This is a very low pressure event. Thermal Runaway is chaotic, meaning unpredictable once reached. Once in this state it can eject out the positive cap, split the cell, or just explode.

I get what you are saying, and understand your objective. I just do not feel such holes are engineered in any kind of way to relieve enough pressure that will prevent a device from bursting. The tensile strength of the device has to compliment the holes. Proper attention to your build and battery care is a more effective way at mitigating risk. In other words, do not allow the cell to reach a state of thermal runaway. Unfortunately we cannot teach everyone proper battery practices – just as we can’t teach everyone that a circular saw or nail gun is not a toy!
 

Punk In Drublic

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so how can we test for these characteristics ?

I have no idea – that is not my area of expertise. But if you look at it from a logical perspective, compare any vape device (can any of them can enter a state of thermal runaway) to an item that was designed to handle pressure. Gas lines and fittings as an example. Word of difference between the puny threads of a 510 vs a gas fitting.
 
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Baditude

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@Punk In Drublic , I get what you are saying. In my A Beginner's Guide to Your First Mechanical Mod, I write:

"In a mechanical mod with a metal piston switch and no wiring, your weak link is the battery. This is not a link you want to break while it is in close proximity to your hand or face. Over taxing a battery in a mech can create a little pipe bomb.

There are risks with lithium-ion batteries if misused or short-circuited, and there have been several incidents and some injuries. But this is a common challenge across many types of battery-powered devices. We've all seen the media reports of cell phone batteries or even flashlights exploding or catching on fire.

Too many people are jumping into mechanical mods without understanding what they are getting into and not realizing it is not a care-free device like an eGo or Provari. It requires more attention to details and a better understanding of all the variables. Too often people on forums say, " Mech mods are easy, just drop a battery in and go. I don't understand why others say it is not for beginners." Because if you don't understand all the things you need to watch for there is a serious chance of something possibly going terribly wrong down the road.

Mech mods are not toys or learning devices. They need to be understood before you begin to experiment with them. So far most novices have been lucky. However, some people don't check the batteries they use, don't know what resistance their coils are, don't know how to work an Ohm's Law calculation, etc, and nothing has happened, giving a false sense of security to others to try the same things, but all it will take is one bad coil or one bad battery to change someone's face forever.

When it comes to advanced mass marketed systems like cell phones and laptops and hybrid electric cars, the system designers of those products have taken appropriate steps to make them "safer" for uninformed end-user use. Purely mechanical unregulated ecig battery mods and uninformed end-users is a dicey proposition.

Most consumer battery operated devices are no where near the limit of the battery's operating limits. The high-end flashlights and ecigs and RCtoys come to mind as applications that really push the limits. With the RCtoys the device is physically far removed from the person so a mishap is inconsequential. With ecigs a mishap is literally in the persons face.

These batteries were not originally intended for what we are using them for. In fact, I have read that Panasonic, Sanyo, Sony, and Samsung, don't even like the fact that we're using these batteries because they were not intended for single cell, unprotected use in any consumer device. The fact that they're available can be attributed to modders of flashlights, pen lasers, and bicycle electronics. A demand formed around those markets and it was filled by various folks, and then e-cigs came along and the demand skyrocketed."


__________________________

It would be ideal if all vapers could read something like this, but that is unrealistic. You can put all kinds of warnings in the package or on the product page on a vendors website, but most customers are not going to read it.

As to the video you brought up, I'm not sure which one it was. It's my educated guess that occurance is an extreme rarity. My guess is that person's mod got extremely hot before it vented or exploded, and they ignored it.

According to Mooch, one can not estimate how long it takes for a battery to vent, or go into thermal runaway, but its my guess that there are generally signs that a battery is about to blow before it happens. The primary sign is HEAT.

"Venting can be a rather gentle event or it can be a pretty energetic spurting and spraying of gas and liquid. Be careful, that liquid is toxic and flammable! The battery does not burst and there are no sparks or flames. The amount of gas produced is relatively small and can usually be handled quite easily by the venting holes we see in mods."

"It is quite difficult, but not impossible, to bring the temperature of a battery up quickly enough to go into thermal runaway without it venting first. About the only way to do it is with a short circuit.

Both venting and thermal runaway can take hours to occur or they can happen very quickly. You will typically be able to feel a battery getting hot before it vents but do not assume the same for preventing thermal runaway. That depends on a very, very fast rise in temperature, happening before the battery can vent. You might not feel the battery get hot first." Li-Ion Battery Chemistries - What are the differences in their safety?

@TrollDragon said that when he walks into a vape shop, he frequently sees vapers who have to put their mod down to rest because its too hot to hold. Where is people's common sense? If your mod is getting too hot to hold in your hand, then you're doing something terribly wrong.

don't know how many guys in vape shops I've been in that had to set their mech down as it was getting to warm to hold.

I just step away from them.

There's not a lot of safety features in a mech mod, but I believe the absolute minimum safety feature should be adequately placed vent holes of a decent size.
 
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Punk In Drublic

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There's not a lot of safety features in a mech mod, but I believe the absolute minimum safety feature should be adequately placed vent holes of a decent size.

I’m not saying devices should be void of venting holes – I am just questioning their functionality. I understand that some may look for venting holes in a device as means of safety. And that is perfectly fine. BUT!!! They should not fall for a false sense of security because of them. A box mod with magnetic doors can be just as fatal given the right circumstances.
 

Eskie

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I’m not saying devices should be void of venting holes – I am just questioning their functionality. I understand that some may look for venting holes in a device as means of safety. And that is perfectly fine. BUT!!! They should not fall for a false sense of security because of them. A box mod with magnetic doors can be just as fatal given the right circumstances.

Thing is, it depends on the volume of gas produced and how quickly it can be released. I recall Mooch posting either in a thread or his blog about a venting battery producing several liters of gas. That's a lot of gas to get rid of to prevent a rapid increase in pressure within a device. Several 2-3 mm vent holes may well not be enough to allow sufficient outgassing before the object's structural integrity fails. In the case of tube mech, that's either the bottom cap, or the top where the 510 connector is. If it's a hybrid, then it's the few threads in a hole the size to accommodate the 510 pin of the atty. That's seems like a particularly weak spot compared to the bottom cap (not all, depends on build)or the casing itself (splitting a SS or brass or even copper tube isn't the most likely weak spot). So the atty blows of the top, maybe propelled into your face (the 2 deaths occurred that way, one in the neck the other in the skull) along with a bunch of hot gas. And that's without the ignition of the Li in the cell itself (which venting is supposed to prevent).

Turning to your box mod with magnetic doors, the difference is those doors will blow off but immediately provide a very large area for the gas to dissipate through. There will be no rapid rise without relief of internal pressures within the box itself. That's not to say hot gas flying around makes for a pleasant day, but it won't result in the kind of pressure increases that occur in a metal pipe that cannot vent fast enough. I guess the flying door could cut you, and the gas result in burns, but there won't be the type of explosive rupturing seen in a tube mech venting through the hybrid threaded hole as the weakest point for failure. If there is a true 510 connector on the top of the tube, then I guess it becomes a toss up on what's fastened the least to determine the likely point of failure.

Is having a few 2 mm holes drilled around wherever the positive end of the battery will be located sufficient to depressurize several liters of hot gas in the time required to prevent excessive pressure buildup within the tube? Probably not, but it's better than nothing and may prevent the catastrophic launching of a metal atty directly at your head. Maybe. But anything that can pop off leaving a large space for rapid degassing will limit the risks of excessive pressure, and serve to keep the battery cooler by evacuating the hot gas away from the can to reduce the risk of full on thermal runaway (higher pressures around that can will help increase temps that much faster, sorta like a pressure cooker). Maybe positive down designs with pop off bottom caps may be the best way to assure rapid reduction in pressure should outgassing occur. That, or lots more and bigger holes.
 

Punk In Drublic

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Thing is, it depends on the volume of gas produced and how quickly it can be released. I recall Mooch posting either in a thread or his blog about a venting battery producing several liters of gas. That's a lot of gas to get rid of to prevent a rapid increase in pressure within a device. Several 2-3 mm vent holes may well not be enough to allow sufficient outgassing before the object's structural integrity fails. In the case of tube mech, that's either the bottom cap, or the top where the 510 connector is. If it's a hybrid, then it's the few threads in a hole the size to accommodate the 510 pin of the atty. That's seems like a particularly weak spot compared to the bottom cap (not all, depends on build)or the casing itself (splitting a SS or brass or even copper tube isn't the most likely weak spot). So the atty blows of the top, maybe propelled into your face (the 2 deaths occurred that way, one in the neck the other in the skull) along with a bunch of hot gas. And that's without the ignition of the Li in the cell itself (which venting is supposed to prevent).

Turning to your box mod with magnetic doors, the difference is those doors will blow off but immediately provide a very large area for the gas to dissipate through. There will be no rapid rise without relief of internal pressures within the box itself. That's not to say hot gas flying around makes for a pleasant day, but it won't result in the kind of pressure increases that occur in a metal pipe that cannot vent fast enough. I guess the flying door could cut you, and the gas result in burns, but there won't be the type of explosive rupturing seen in a tube mech venting through the hybrid threaded hole as the weakest point for failure. If there is a true 510 connector on the top of the tube, then I guess it becomes a toss up on what's fastened the least to determine the likely point of failure.

Is having a few 2 mm holes drilled around wherever the positive end of the battery will be located sufficient to depressurize several liters of hot gas in the time required to prevent excessive pressure buildup within the tube? Probably not, but it's better than nothing and may prevent the catastrophic launching of a metal atty directly at your head. Maybe. But anything that can pop off leaving a large space for rapid degassing will limit the risks of excessive pressure, and serve to keep the battery cooler by evacuating the hot gas away from the can to reduce the risk of full on thermal runaway (higher pressures around that can will help increase temps that much faster, sorta like a pressure cooker). Maybe positive down designs with pop off bottom caps may be the best way to assure rapid reduction in pressure should outgassing occur. That, or lots more and bigger holes.

Well put and I shadow much of what you have said. But to comment on the magnetic battery doors – once the doors are blown off, what happens during the remaining thermal runaway event? Do the cells just fizzle out? Do they take flight in an unpredictable path, with enough energy to cause harm? Or do they blow up, sending shrapnel of their metal can, and molten hot goop flying everywhere? All examples could cause serious harm - the later 2, under the right circumstances could be fatal. In referencing the 2 known fatalities – one produced enough energy to breach a person’s skull. The second severed carotid artery….that does not take a lot of energy.

When assessing risk, one can not make assumptions for doing so you assume risk, not mitigate it.
 

Tabac man

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I have never used a mech and won't be anytime soon. I am enjoying reading these type of threads though just for enlightenment and I applaud those who contribute with their opinions and experiences. What better source of information for those interested in mechs? These discussions need to be had I feel, even if there is divided opinions. Airing them is a good thing.

One question if I may. What are the disadvantages of a positive down design? From the outside looking in, so to speak, it seems like a no brainer. A bit like pointing a weapon down range and having a safety near the thumb.
 
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