Mityvac explodes!

[atikovi]

Actually, implodes to be accurate. Was sucking out the milkshake from the top of the coolant reservoir due to a transmission cooler leak, when I heard a big boom. Don't these things have a relief valve or something to prevent this?

 

[LXCam]

Wellll that *****..



No really

 

[RKA]

They don't generate enough vacuum to crack the case like that. I pump mine up and it gets to the point where the pumping is ineffective because it's max'd out. My guess is the plastic had a defect or it was damaged in some way that went unnoticed, but under vacuum it went boom.

 

[rlitman]

They don't generate enough vacuum to...

There's a hard limit on how much vacuum they can generate, and that's your absolute air pressure.

 

[Danglerb]

There's a hard limit on how much vacuum they can generate, and that's your absolute air pressure.

This, inside no pressure, outside 14 psi or so.

 

[DHCrocks]

how old was it? was it exposed to sunlight during storage? probably just aged plastic as they tend to get brittle over time. it does look a little discolored due to age.

 

[Junkdrawer Dog]

how old was it? was it exposed to sunlight during storage? probably just aged plastic as they tend to get brittle over time. it does look a little discolored due to age.

I'm guessing this. I've been surprised more than once by how quickly UV exposure can degrade plastics that aren't sufficiently UV stabilized for outdoor exposure. A couple summers on the patio could do that.

 

[atikovi]

Maybe 10 years old and stored inside.

 

[dogdog]

that plastic looks hardened and brittle .. maybe call them see if they would send you a replacement ?

Or...

salvage the valves and build your self one from metal...


I think other places sells a metal ones as well...

 

[Danglerb]

MityVac stuff does not seem to like sunlight. My brake bleeder melted sitting in the back hatch of my car.

Casual look doesn't appear that they sell a replacement tube, just all the other parts at crazy prices.

 

[tym]

Maybe 10 years old and stored inside.

Fluorescent lighting?

 

[atikovi]

Maybe an hour a day.

 

[Git]

This mighty vac is well over 15 years old. Stored inside, used for brake fluid, radiator fluid, heck any kind of fluid. The plastic is still translucent on this vs that broken opaque looking one.

 

[Fedwrench]

I've seen more than a couple shatter like that but, it was from the tech sucking hot coolant into the mityvac.

 

[kb1982]

Photodegradation caused by uv exposure that breaks down the polymer chains. Ive head a few motorcycle front brake resivors do the same thing. The plastic changes colors, gets chalky and britle. There are additives that can be mixed in to help fight off this effect, but if a product last for its intended life cycle from the manufacturer, thats all good enough for them. I guess i did manage to learn something from my time operating 1000 ton plastic injection molding machines.

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[dadsEH]

A coat of paint would have protected it....just sayin.

 

[mark#3]

I could never get mine to work?

 

[kb1982]

I could never get mine to work?

Only reason it shouldnt work would be you have a vacuum leak or the venturi vac generator is messed up. Sometimes they will **** up debris and clog themselves.

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[mark#3]

Thanks for the feedback,I don't know what the venturi vac generator is, maybe I am missing stuff, never got replies from the MFG

 

[kb1982]

It works on the same principle that a carburetor does to draw in fuel. Heres a video of how it works.

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I should have watched more of the video. Wasnt aware that it went so far in depth on the engineering aspect. Way above my knowledge. The picture below explains it alot better. Port D is where the vacuum created, which causes the fluid to be sucked up. Any debris blocking this will cause it not to work.

 

[joe_padavano]

I don't know what the venturi vac generator is,

It's how a carburetor works.

 

[Git]

I could never get mine to work?

I have had it happen to mine. As I recall if you take it apart, the actual 'plunger' has a piece of leather or something on the end (bottom) that acts as a seal. Over time it can get dried out and needs to be rejuvenated

 

[Danglerb]

Thanks for the feedback,I don't know what the venturi vac generator is, maybe I am missing stuff, never got replies from the MFG

Two types of these devices, one with a manual pump, one with a venturi that make vacuum with shop air (HF sells one for $12 or so).

 

[Milton Shaw]

That is visual proof on why not to use pvc pipe for pressure. If just a max of 14.7 lbs per square inch did that what would 175 or so air pressure do to you. I agree with some of the others that that plastic was sun damaged to cause that. Can you source a replacement tube at a plastic supply house.

 

[RKA]

There's a hard limit on how much vacuum they can generate, and that's your absolute air pressure.

Practically speaking, the internal pumps in these oil extractors only get to 25 in/Hg or so. Beyond that the seals leak and you're not getting a deeper vacuum no matter what you do. The cases can sustain that without issue (unless there is some other weakness contributing to the failure). Now, hook up an HVAC vacuum pump to this thing and let it try to build to 28.99 in/Hg and you'll find you won't get close to a theoretical limit because the case has imploded long before you hit the HVAC pump's limit.

 

[rlitman]

Practically speaking, the internal pumps in these oil extractors only get to 25 in/Hg or so. Beyond that the seals leak and you're not getting a deeper vacuum no matter what you do. The cases can sustain that without issue (unless there is some other weakness contributing to the failure). Now, hook up an HVAC vacuum pump to this thing and let it try to build to 28.99 in/Hg and you'll find you won't get close to a theoretical limit because the case has imploded long before you hit the HVAC pump's limit.

You really think that the 1.96 PSI difference between the hand pump and a deep vacuum is the difference between implosion and not? That seems like a bit too little of a safety margin.

For my own oil extractor I use a HF pneumatic vacuum "pump" venturi. I watch the gauge rapidly go to 25, then take a minute or so to go to 26. When I walk away and return, it always passes 28. I'm sure that the internal pump can do at least as well, but the thing about pumping a vacuum is that as there's less air to remove, less molecules find their way into your pump, and the process slows down dramatically.

 

[RKA]

There is one way to find out...send me your extractor.

 

[rlitman]

There is one way to find out...send me your extractor.

I'm not worried about my extractor, because mine isn't plastic. I use a forklift propane tank for storage.

 

[yhprum]

Wellll that *****..


not any more

 

[atomicpunk]

Counterfeit Mityvac, effin China.

 

[dogdog]

Counterfeit Mityvac, effin China.

you are a genius....

Can you share your Intel-ma-gence with us on how did you come up with this conclusion? Normal people like me would not be able to decode that statement from the "very" STABLE genius likes of you.

 

[PoorOwner]

 

[tym]

I can hear Phil Swift screaming in my ears now...

 

[Danglerb]

Can you replace the plastic with a piece of PVC or ABS?

 

[Stuart in MN]

That is visual proof on why not to use pvc pipe for pressure. If just a max of 14.7 lbs per square inch did that what would 175 or so air pressure do to you. I agree with some of the others that that plastic was sun damaged to cause that. Can you source a replacement tube at a plastic supply house.

Is the Mityvac container actually made of PVC, or is it some other type of plastic? And, as the original poster said, it hasn't had any particular exposure to the sun.

 

[rlitman]

Is the Mityvac container actually made of PVC, or is it some other type of plastic? And, as the original poster said, it hasn't had any particular exposure to the sun.

It looks like PP or maybe PE.

 

[scubadoober]

I think every on is under estimating that amount of force that is being applied to the outside of that vessel. Even at a 10 psi differential there is almost 7,000lbs of force trying to collapse it.

 

[Danglerb]

The "force" was less than 14.5 psi, and its a level of force the tube should be designed to easily accommodate. 10" ABS schedule 40 pipe is rated at 100 psi, burst many times that.

More I think about it the failure shown looks more like it fell over and hit something, not saying it did, just vacuum force alone doesn't seem to explain the damage well.

 

[atomicpunk]

you are a genius....

Can you share your Intel-ma-gence with us on how did you come up with this conclusion? Normal people like me would not be able to decode that statement from the "very" STABLE genius likes of you.

Calm down snowflake, it was a joke.