|
|
Post by shovelhead13746 on Mar 23, 2024 2:13:27 GMT
In the FAQ section Cablehack noted that Float valve faults can be eliminated with a capillary tube conversion, or sometimes with a partial crimp of the high side tube.
Can someone elaborate on the partial crimp? I would like to try a few things before sending this out for capillary tube conversion.
Thanks All
|
|
|
|
Post by turbokinetic on Mar 23, 2024 3:42:52 GMT
In the FAQ section Cablehack noted that Float valve faults can be eliminated with a capillary tube conversion, or sometimes with a partial crimp of the high side tube. Can someone elaborate on the partial crimp? I would like to try a few things before sending this out for capillary tube conversion. Thanks All It is possible to re-cut the seat in the float valve, if you would rather not modify your system. You would have to work on the system charged, or build a recovery setup to remove the charge first. I would recommend repairing the float seat, or using a capillary tube but would not recommend attempting to crimp any lines since this will produce an orifice-like restriction which is not ideal for this use. Sincerely, David |
|
|
|
Post by elec573 on Mar 30, 2024 6:10:25 GMT
I would agree with turbo he has done excellent work on ca ‘s and would follow his advice.
check out his post and it will give you an insight on what must be done.
|
|
|
|
Post by cablehack on Mar 31, 2024 6:25:26 GMT
That mention of the partial crimp goes back a long time, possibly even back to the Flickr group. Back then, there was a rash of CA's with worn float valves. One of the members tried it to confirm the float valve was worn. I wouldn't recommend it as a permanent fix, however, but merely as an interesting diagnostic. I will edit the FAQ since it's too 'experimental' to be practical. I just can't see ideal operating conditions being obtained that way, and to get the crimp just right for proper cycling times would be incredibly difficult. To answer the question, it was done with a special tool used for crimping refrigeration lines. I'm fairly sure there was a pic posted of it. But yes, it did allow the evaporator to frost when it didn't previously.
|
|
|
|
Post by ChrisJ on Apr 4, 2024 15:45:04 GMT
I attempted to crimp the line on one of my CA machines.
I failed.
It went from not even close enough, to too restricted.
The machine has been sitting like that for probably 10 years now. At one point it'll get a cap tube or I might attempt to fix the float.
After trying so hard to be careful, and go slow and still failing I'd never try to crimp another one. It's just way too fine of an adjustment you're trying to do by crushing copper tubing.
I believe cablehack is right, that's from the Flickr days.
|
|
|
|
Post by turbokinetic on Apr 5, 2024 14:10:49 GMT
I attempted to crimp the line on one of my CA machines. I failed. It went from not even close enough, to too restricted. The machine has been sitting like that for probably 10 years now. At one point it'll get a cap tube or I might attempt to fix the float. After trying so hard to be careful, and go slow and still failing I'd never try to crimp another one. It's just way too fine of an adjustment you're trying to do by crushing copper tubing. I believe cablehack is right, that's from the Flickr days. Chris, the reason this is so difficult is because you're creating an orifice-like restriction as opposed to a capillary tube effect. There is a difference in the way fluids behave in each of these two scenarios. The cap tube works by the fluid sticking to the walls and creating drag as the molecules slide past each other. The speed of the flow increases the drag, so there is a curve formed which softens the changes in flow versus pressure changes. This doesn't happen with an orifice. In that situation, any small change in pressure will make a linear change in flow; making it impossible to get a stable system. |
|
|
|
Post by ChrisJ on Apr 30, 2024 12:10:53 GMT
I attempted to crimp the line on one of my CA machines. I failed. It went from not even close enough, to too restricted. The machine has been sitting like that for probably 10 years now. At one point it'll get a cap tube or I might attempt to fix the float. After trying so hard to be careful, and go slow and still failing I'd never try to crimp another one. It's just way too fine of an adjustment you're trying to do by crushing copper tubing. I believe cablehack is right, that's from the Flickr days. Chris, the reason this is so difficult is because you're creating an orifice-like restriction as opposed to a capillary tube effect. There is a difference in the way fluids behave in each of these two scenarios. The cap tube works by the fluid sticking to the walls and creating drag as the molecules slide past each other. The speed of the flow increases the drag, so there is a curve formed which softens the changes in flow versus pressure changes. This doesn't happen with an orifice. In that situation, any small change in pressure will make a linear change in flow; making it impossible to get a stable system. There's also something about the refrigerant starting to boil in the cap tube, causing even more restriction, isn't there? It's been many years since I read about one but I recall it being a very complicated device as far as actual operation. But I do remember them saying they actually adapt to load within reason. |
|
|
|
Post by turbokinetic on Apr 30, 2024 14:22:14 GMT
Chris, the reason this is so difficult is because you're creating an orifice-like restriction as opposed to a capillary tube effect. There is a difference in the way fluids behave in each of these two scenarios. The cap tube works by the fluid sticking to the walls and creating drag as the molecules slide past each other. The speed of the flow increases the drag, so there is a curve formed which softens the changes in flow versus pressure changes. This doesn't happen with an orifice. In that situation, any small change in pressure will make a linear change in flow; making it impossible to get a stable system. There's also something about the refrigerant starting to boil in the cap tube, causing even more restriction, isn't there? It's been many years since I read about one but I recall it being a very complicated device as far as actual operation. But I do remember them saying they actually adapt to load within reason. Yep, the theory of operation is pretty deep and involves a lot of factors. Due to surface tension between the liquid and the inside of the tube, the layer in contact with the tube wall isn't moving fast since the wall is wetted by and sticking to the liquid. The resistance to flow gets greater with grater fluid velocity in the tube, so it is somewhat self-regulating if there is a solid stream of liquid. |
|
