Thread: Look what can still happen if a cyclone bin is not emptied early enough

I wonder if this is metal fatigue. Looks like the crack has propagated from the weld at the unsupported end which would be subject to residual stress and make it susceptible to vibration. Just a thought.

So really you don't know anything about what caused it or whether the cyclone bin was full? You're just surmising what the cause was? I would have expected the shed shaking to have been preceded by a loud bang and there to have been some evidence of what had hit the impeller.

Originally Posted by aldav

So really you don't know anything about what caused it or whether the cyclone bin was full? You're just surmising what the cause was? I would have expected the shed shaking to have been preceded by a loud bang and there to have been some evidence of what had hit the impeller.

Sorry I forgot to mention that there have been loud bangs in the past consistent with something getting into the impeller.
These combined events may have started the cracks.

Here's another photo of the impeller.
IMG_3151.jpg

Clear Vue cyclone?

Pete

To me it looks like the impeller was spinning in the wrong direction.

It would still suck but with a reduced flow and a lot of high frequency vibration leading to fatigue failure.

Originally Posted by Bohdan

To me it looks like the impeller was spinning in the wrong direction.

It would still suck but with a reduced flow and a lot of high frequency vibration leading to fatigue failure.

It does look like that. various sparkies have been rearranging the wiring for that DC in the last couple of years so it does not surprise me that this happened.

The other thing could be is that this thing is on a VFD and it also would not surprise me if someone has run it backwards.
There was a perspex cover over the VFD controls but one time I was there a few months go I noticed it was taken off..

"If it is even remotely possible that something can occur .... it will occur in a community shed." That is one thing that is as sure a bet as one will ever get.

Originally Posted by Bohdan

To me it looks like the impeller was spinning in the wrong direction.

Yes, like Bohdan, it looks like that to me too. The fins are bent the wrong way for an impact if it was spinning in the right direction. Also, an impact might bend one fin or at most two, but not three. I'd also expect the fan housing to be badly dented with an impact given that amount of fin damage.

I'm also inclined to agree with DerekC, that there has been metal fatigue happening at those tack welds. They are only there to hold the fins in place ready for the full weld to be done on the working face and never designed to take the forces with the impeller running in the reverse direction.

A shed member may have been having a fiddle, but I also have my doubts about the 'average' sparky knowing which way is up on a VFD.

Originally Posted by NeilS

but I also have my doubts about the 'average' sparky knowing which way is up on a VFD.

I can certainly back that up. When first cleaning the filters on the air handling units we had in a motel I found double ended motors installed upside down and fans installed the wrong way round. Some of them didn't move any air at all. VFD's would definitely be a step too far for the sparky's that installed those relatively simple motors.

Originally Posted by NeilS

.... I also have my doubts about the 'average' sparky knowing which way is up on a VFD.

Its not that difficult to check rotation direction.

Originally Posted by Mobyturns

Its not that difficult to check rotation direction.

You're assuming that they would know which way was the right way.

This happened to the same impeller back in March this year.
I recommended they look to see if the impeller was OK.

IMG_4795.jpg

Originally Posted by Mobyturns

Its not that difficult to check rotation direction.

It would have sucked... a bit.

Job done!

Originally Posted by BobL

This happened to the same impeller back in March this year.
I recommended they look to see if the impeller was OK.

If one or two of the impeller fins were already bent over back then I expect the housing would have got a fair old buffeting from the irregular air pressures generated in that zone.

I'd have pulled the impeller out after that happened and check it to see if it was still in balance even if the fins looked OK.