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Post by birkie on Oct 10, 2018 1:11:45 GMT
This one was next on the list for my little SO2 purge party. As it turns out, it was missing a pound of refrigerant. I only got out about 3.8 lbs; it should have 5.
The frost line did seem a little low when it was running, this probably explains why. It makes me wonder how much oil never made it back to the sump. When the last bit of SO2 was boiling out, it had the distinctive sound of bubbling through a pool of oil...
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Post by ckfan on Oct 10, 2018 22:32:27 GMT
That’s neat but it makes me wonder why it was a pound low. Where did the stinky gas go?
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Post by elec573 on Oct 11, 2018 2:19:26 GMT
That’s neat but it makes me wonder why it was a pound low. Where did the stinky gas go? Makes me wonder about my drs if they have a very minute leak ? Sometimes I smell like a old smell or just old when I open my dr . I have not experienced so2 directley so hopefully that’s not it .
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Post by birkie on Oct 11, 2018 2:54:42 GMT
That’s neat but it makes me wonder why it was a pound low. Where did the stinky gas go? I'm not sure - there was no obvious smell when transporting it, or in the garage. A slow, steady leak during its whole life (releasing 1 lb over ~88 years) would be about 14 mg per day. If that much was released into a somewhat large airtight bedroom over the course of a day, the SO2 odor would just barely reach the threshold of being detected by the nose. So it kind of makes sense that it wouldn't stink up our "nowhere near airtight" ~1950s era garage. The thing about that is if the leak were around the evaporator or lines, and 14 mg leaked into the small 4 cubic foot cabinet over the course of the day, a whiff of that would definitely exceed the threshold of pain. So if there is a leak, it's not down below. The purge screw was particularly difficult to open (thank goodness for turbokinetic's tip of using a tap wrench) - it took some force to get it open. Once open, it wouldn't close 100%. With some oil covering the purge screw, you'd see a bubble form every few seconds. So it's possible the purge screw never sat well. Makes me wonder about my drs if they have a very minute leak ? Sometimes I smell like a old smell or just old when I open my dr . I have not experienced so2 directley so hopefully that’s not it . Well, so far the rusty DR3 (with the corrosion on the lines) and DRB3 both were right on the mark. I still have more machines to go, but so far the DRA2 is the only one low by any measurable amount. This is one reason I'm taking my time and weighing how much washing soda is needed -- to see how many machines are filled to spec, and how many lost some SO2. So far, this means the DRA2 gets a little extra attention to see if the location of any leaks can be verified and eliminated.
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Post by elec573 on Oct 11, 2018 3:50:59 GMT
I like your thinking , a small leak would be hard to find . Especially one that took years to leak out . Was wondering about what so2 left behind like a tracer back to its leak ? I think we need a chemist or someone else to follow the clues .
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Post by birkie on Oct 11, 2018 23:22:03 GMT
I like your thinking , a small leak would be hard to find . Especially one that took years to leak out . Was wondering about what so2 left behind like a tracer back to its leak ? I think we need a chemist or someone else to follow the clues . You know, I was just thinking a bit more about this. The leak rate would be about 5g/year, or almost 0.2 oz. I believe that is in the range of electronic leak detectors. So when I fill it with R124, maybe a standard leak detector will find something.
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Post by turbokinetic on Oct 12, 2018 18:56:39 GMT
That’s neat but it makes me wonder why it was a pound low. Where did the stinky gas go? I'm not sure - there was no obvious smell when transporting it, or in the garage. A slow, steady leak during its whole life (releasing 1 lb over ~88 years) would be about 14 mg per day. If that much was released into a somewhat large airtight bedroom over the course of a day, the SO2 odor would just barely reach the threshold of being detected by the nose. So it kind of makes sense that it wouldn't stink up our "nowhere near airtight" ~1950s era garage. The thing about that is if the leak were around the evaporator or lines, and 14 mg leaked into the small 4 cubic foot cabinet over the course of the day, a whiff of that would definitely exceed the threshold of pain. So if there is a leak, it's not down below. The purge screw was particularly difficult to open (thank goodness for turbokinetic 's tip of using a tap wrench) - it took some force to get it open. Once open, it wouldn't close 100%. With some oil covering the purge screw, you'd see a bubble form every few seconds. So it's possible the purge screw never sat well. Makes me wonder about my drs if they have a very minute leak ? Sometimes I smell like a old smell or just old when I open my dr . I have not experienced so2 directley so hopefully that’s not it . Well, so far the rusty DR3 (with the corrosion on the lines) and DRB3 both were right on the mark. I still have more machines to go, but so far the DRA2 is the only one low by any measurable amount. This is one reason I'm taking my time and weighing how much washing soda is needed -- to see how many machines are filled to spec, and how many lost some SO2. So far, this means the DRA2 gets a little extra attention to see if the location of any leaks can be verified and eliminated.
It's interesting you mention this. I smell what seems to be a slight SO2 whiff every time I open the door of my DR. It's of course worse now that there is a door gasket installed. In talking with Travis, he has noticed some of this odor around other DR's as well. He was thinking it could be coming from the foam rubber insulation. Possibly the foam was "blown" with SO2? But in the case of my fridge, the foam rubber has been replaced with modern materials.
The fridge still operates well; although folks tell me that it seems a little louder than most based on my videos.
I bought this one under somewhat suspicious circumstances. I have a concern that it was rough handled before I bought it, possibly leading to some damage.
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Post by ckfan on Oct 15, 2018 13:21:04 GMT
Hopefully it doesn’t decide to start hissing at you!
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Post by turbokinetic on Oct 15, 2018 13:55:14 GMT
Hopefully it doesn’t decide to start hissing at you! LOL me too! If; on the off-chance it does start hissing; It's on a dolly so it can be rolled outside very easily.
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Post by birkie on Apr 2, 2019 3:10:41 GMT
I had a whole afternoon to work on projects this past weekend. As I started disassembling a 1950 GE chest freezer, I finished triple evacuating the DRA2, and filled it with R124. Boy, the machine sure has personality.
The final vacuum bounced up to 900 microns after 10 minutes (still creeping up very slowly), probably due to off-gassing of SO2 from the pores of the metal. Thinking this was realistically the best I could hope for, I filled it with 5.25 lbs of R124. The nameplate and Nickerson & Collins say 5 lbs of SO2, the 1942 manual says 6. So we'll see what the frost line looks like after it has run a while.
After starting it up, it was very quiet. Watts seemed a bit on the low side, dropping quickly to 140, then down to the low 120s by the end of pulldown. It took a little over three hours to get to that point, whereas on SO2 it was about an hour. The machine didn't rattle at all the whole time.
On a hunch, I decided to give it a heat treatment with hot water. By the sound of it, it dumped a lot of oil (and refrigerant) into the sump. It sounded "splattery" at first, which changed to a constant hiss accompanied by a trickle. After the heat treatment, I left it alone for about a day, until the heater stopped bubbling.
I started it up again, and the experience was quite different. About ten minutes into pulldown, it started rattling (it didn't do that during the first pulldown after freshly being filled with R124). When it was on SO2, I had to jack up the left side in order to reduce the rattle to acceptable levels. I did the same thing this time as well, which helped. After about a half hour, the it was tilted as far as I was comfortable, but the rattling caught up with it. It was a fairly angry rattle, but I let it go on. Ambient temperatures were on the cool side - about 60F in the garage. After about 40 minutes, it cycled off. Watts were higher than the first run - starting around 180 and dropping to about 130 at the end.
When it kicked on again, it rattled towards the end of its 'on' cycle, but not nearly as bad.
The third cycle was interesting. It started off at about 140 watts. After about 10 minutes, I heard two large thud sounds which I swear shook the cabinet (it was up on wheels). The watts then jumped to 170, and the cycle ended at about 140. That is what I would have expected for this machine, at the cooler temperatures it was running under. There was no real rattle this cycle, it just got a little chatter towards the end.
The next cycle started off at 170 watts, and ended around 140. No rattle. It was followed by an interesting cycle that started of at 110 watts. After about 10-20 seconds or so, I heard another thud, and watts shot up to 170 as usual.
I was watching the pressure gauge on the service port. The thuds did not affect the high-side pressure in any significant way.
I froze a probe to the evaporator. Temperatures ranged from about 24F at the beginning of the cycle, to 6F at the end. Control was on the warmest setting. Cabinet was about 36F. Ambinent temperatures averaged in the upper 50s. Cycle times were about 15 minutes on, 1hr 10 minutes off.
Here's a little video about two thirds into a cycle. The rattle is totally gone, and the evaporator has a nice coating of frost. The frost line higher than it was on SO2 (it was missing over a pound of SO2). Will keep it going for a while. It's going to be cool tomorrow (high in the mid to upper 40s), then should get nice in the 70s by the weekend, so we'll see how it does with these varying conditions.
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Post by ckfan on Apr 2, 2019 12:11:50 GMT
Sounds like every other float that I’ve come across that doesn’t want to fully open. I’m glad it started behaving for you!
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Post by birkie on Apr 2, 2019 12:45:23 GMT
Sounds like every other float that I’ve come across that doesn’t want to fully open. I’m glad it started behaving for you! In this case, I'm suspicious it might be something else. The reasons are: * For the first pulldown (when watts were low), there was flow through the float, no evidence of refrigerant backing up into the coils * The sound seemed to come from below, in the evaporator * There was an instant change in wattage after the thud, but no discernible change in high-side pressure I think it might be like what might be happening in David's Frigidare, where the refrigerant in the evaporator is superheated then all of a sudden starts boiling. So the compressor rapidly draws the suction line to a vacuum, watts go low, refrigerant is calm, then the surface tension in the evaporator bursts and a bunch of gas is liberated in one loud thud. Pressure in the suction line shoots up to normal, watts instantly spike up to normal, and normal boiling ensues. Plausible?
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Post by turbokinetic on Apr 2, 2019 12:50:11 GMT
I had a whole afternoon to work on projects this past weekend. As I started disassembling a 1950 GE chest freezer, I finished triple evacuating the DRA2, and filled it with R124. Boy, the machine sure has personality. Isn't that the truth! It seems the DR's had special engineering features to ensure they were just unpredictable enough to keep us enthusiasts.... enthusiastic about them! Do you think it could be trapped SO2 in the cotton winding insulation? Also, there are void spaces in the compressor which take (possibly) years to fill with refrigerant. For instance, when I repaired the Meter-Miser compressor a couple months ago, a "PSST!" of liquid refrigerant fizzed out when I removed the bolts holding the mechanism together inside the unit. Apparently the blind holes had seeped full of refrigerant over the decades, but even though the unit had been disassembled (but those bolts still tightened) for months - it still had the trapped material in there. I believe there is talk about finding puffs of SO2 in bolt holes when rebuilding DR's as well. It sounds very good in the cycle in the video! I have a feeling that the float mechanism was probably just sticky from the SO2 "gum" that we all know and love (not). Hopefully the new, clean R124 will help to clear that from the float mechanism and allow it to work properly from now on out.
I also wonder if there's a possibility of mechanical wear on the float linkage? This could give the float a pop-on / pop-off action. Once the wear is severe enough, this action could become pretty extreme.
Thanks again for sharing your projects with us!
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Post by birkie on Apr 2, 2019 13:33:33 GMT
It seems the DR's had special engineering features to ensure they were just unpredictable enough to keep us enthusiasts.... enthusiastic about them! They were also constantly making changes to the design on the fly. Any two machines might differ from one another in unpredictable ways, leading the enthusiast to seek out more! Yes, exactly. That's what made me think that for a non-rebuilt machine, getting it to stay around 900 microns was about the best one could expect. I just replied to Ray about that - so far the evidence seems to lead me away from he float, but it's inconclusive yet. The evaporator probably has at least 4.75 lbs of refrigerant in it at all times. I just don't see how the the float suddenly opening could induce such an instant change in compressor watts without any observable effect on the high-side pressure. That being said, I don't have a low-side port on this machine to tell with certainty, so am open to a surprising answer Oh, checked on it quickly this morning. It was 35 in the garage, the machine cycled happily. No rattle. Interestingly watts were pretty much identical to the cycles at 60F ambient. Started at 170, and shut off around 140. Pressures were real low - about 16 PSI at rest, rising to about 26 or so during the cycle.
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Post by birkie on Apr 22, 2019 23:43:01 GMT
This little DRA2 has been running happily for the past three weeks on R124. Today, however, I checked on it and noticed that the the machine was still running despite this: Yes, the evaporator measured at -17.5 F! The cabinet was about 14 inside. That means the evaporator must have been pulled down to at least a 15" vacuum. It looked the contact arm was still in the "on" position, while the bridle was in the "off" position. Physically pressing down the "off" button made the contacts snap open. Who knows how long it was running with the controls stuck 'on'. After an almost 4-hour "off" period, it snapped back on and cycled normally. Interestingly, the dome was just pleasantly warm when I shut it off manually, and the machine sounded happy. Ambient temps were in the mid '70s at the time. All I have to say after all this is ... wow.
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