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Post by turbokinetic on Apr 5, 2020 3:22:09 GMT
Here is one way to restore a CA to functionality if the float seat is eroded and the valve is bypassing.
https://youtu.be/8WrkWh8U-Mc
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Post by cablehack on Apr 5, 2020 13:25:00 GMT
Great video - thanks for posting! Interesting to see the whole float chamber on its own. As far as I know, the NCG bypass tube was only used in the form B machines.
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Post by turbokinetic on Apr 5, 2020 14:16:21 GMT
Great video - thanks for posting! Interesting to see the whole float chamber on its own. As far as I know, the NCG bypass tube was only used in the form B machines. Glad you enjoyed it! I had guests over when doing the first one (the one running now) and as such didn't want to make videos at that time. Had a few minutes yesterday; and stumbled across that float chamber while doing some spring cleanup. I had always wondered if those NCG bypass tubes ever got caught in the float mechanism or caused other issues. It sure is a fiddly thing to re-assemble! |
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Post by cablehack on Apr 6, 2020 3:11:35 GMT
I had always wondered if those NCG bypass tubes ever got caught in the float mechanism or caused other issues. It sure is a fiddly thing to re-assemble! I've often wondered the same thing. It looks like the tube has to bend around above the float, for it to go up inside the upper chamber. |
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Post by ckfan on Apr 6, 2020 22:55:59 GMT
I loved your video on this. Great stuff as always. Makes me wonder if you could use this method to gain access to a DR float to unplug it?
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Post by turbokinetic on Apr 7, 2020 3:43:15 GMT
I loved your video on this. Great stuff as always. Makes me wonder if you could use this method to gain access to a DR float to unplug it? Hi Ray. Glad you enjoyed the video! The DR float is totally different. Remember it has the spring-loaded pin-lifter system operated by the service port screw. Those are a cast steel base plate with the mechanism attached. I have turned the weld away on one and opened it up, but not sure if I did a video. However, on the DR float, it would be entirely possible to drill out the tubing and ream the seat without cutting the chamber open. |
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Post by ckfan on Apr 7, 2020 12:04:59 GMT
That’s very interesting. I’m trying to imagine how you would actually go about doing that.
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Post by turbokinetic on Apr 7, 2020 14:29:13 GMT
That’s very interesting. I’m trying to imagine how you would actually go about doing that. When Paul was here, we did one. Tried every way to get the orifice cleared, but no avail. When drilling the old line out, the blockage was actually below the seat and at the top of the line its self. Some hard greed crud. |
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Post by ckfan on Apr 8, 2020 1:37:29 GMT
That’s what I call ‘flavor country’ right there.
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Post by elec573 on Apr 10, 2020 1:08:16 GMT
Very nice video ! Thanks for posting it.
My understanding is it was the seat was worn out ? What are the seats made out of ?
And why was it worn out ? Just wondering why or maybe it has been answered all ready .
Looking for future failure problems.
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Post by turbokinetic on Apr 10, 2020 19:07:15 GMT
Very nice video ! Thanks for posting it. My understanding is it was the seat was worn out ? What are the seats made out of ? And why was it worn out ? Just wondering why or maybe it has been answered all ready . Looking for future failure problems. Thanks! Glad you liked the video. You're correct, the seat was worn out, eroded and oval shaped. The tool I had in the drill was used to re-grind the seat to a new, round orifice where the needle can fit and fully close off the metering orifice. Because the tool made the seat deeper, it required adjustment of the length of the housing to get the mechanism working again. After re-grinding the sea, the set was now further away from the needle, so that the seat needle would not reach even when the float was fully down. The shortening of the housing eliminated this problem. The seat looks to be brass, I would say. |
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Post by elec573 on Apr 12, 2020 2:04:46 GMT
Just for conversation sake what do you think wore out the seat ?
The menthol format, maybe like water erosion over time .
I know these fridges are old , and well past what they were supposed to work , hopefully they can live on !
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Post by Travis on Apr 12, 2020 23:48:44 GMT
I believe the NCGs pushing down on the float over time causes the seat to wear. That’s what I’ve learned from earlier posts about CA failures.
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Post by ChrisJ on Apr 21, 2020 11:15:28 GMT
I believe what Travis said.
The NCG holding the float down results in wire drawing or cavitation.
No one really knows though. For now I'd say make sure any CA is running properly and NCG free with a proper heater.
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Post by turbokinetic on Apr 21, 2020 12:48:54 GMT
I believe what Travis said. The NCG holding the float down results in wire drawing or cavitation. No one really knows though. For now I'd say make sure any CA is running properly and NCG free with a proper heater. Most of the time when you see this type of erosion in a metering device, it's related to chemical / mechanical processes working together; such as cavitation you mention. In the case of the CA, there never seems to be any oil outside of the compressor in the ones I have opened. The float needle seems to operate very "dry" compared to other designs. When the methyl formate breaks down, it results in formic acid as well as NCG's. There could be a passive layer built on all the brass parts, blocking the erosive effects of this acid. This passive layer could be very soft or fragile; so that the high velocity flow through the needle and seat area constantly removes the passive layer exposing reactive metal to the formic acid. So with the CA, it has a much higher operating pressure due to the NCG buildup; causing much higher fluid velocity at the set area. This is possibly breaking down the passive layer on the metals, leading to erosion at a higher rate than expected. So as said, it goes back to maintenance and not bleeding NCG's out of the system. |
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