[Gray Wolf]

Originally Posted by C'Ya

I did a test with tr21 with sight glass at inlet connected to 3/8" 20' 20 ft coil immersed in low tox(pet safe) anti freeze bath than connecting to take apart filter/drier all in freezer except tr-21 end, hose from collection tank to drier. Sight glass showed vapor with liquid than going to vapor near end. I cant say it will make pump last longer, but pump before test was acting like it was hesitating before it would start with no load(sticking), now days later starts like it was brand new. Extra tubing didn't seem to effect recovery time but did increase vac down slightly, and the tr21 ran cooler than ever I could hold my hand on "HOT" printing on head no problem, ir temp gun showed about 90F after two tube run five passes each tube with after cooler after pump, r/c tank hit 36f at valve and on tank it was about 32f.
The bucket the coils are in was plastic which insulated the lowtox, so of to find a better bucket and/or add recirculating pump and coil in freezer to help chill the lowtox.
Thanks
C'Ya

Good experiment! Were you able to measure vacuum pressure at both ends of the 20' coil?

[C'Ya]

Thanks GW, I did not I just received extra new gauges(2 low 1 high) the other day and will be checking at various locations and will report back.
I am also considering adding a dual pressure control as a safety measure against possible air being pulled in system, but that's another topic and want to do more testing first.
C'Ya

[C'Ya]

GW I performed 1st test with added gauges, the gauge at collection pot, gauge at exit of 20' coil and high gauge before coil going to recovery tank.
What I observed:
When gauge at c/p read 10"HG the one after coil read 12-13"HG the closer I got to 22"HG they started to even out to about 22-23"HG at end of coil closing off tank the gauge at coil pulled to about 28"HG with in a minute give or take few seconds.
The high pressure gauge read about 20# at start and maxed out at 40# after second tube 30# after first but ran 30# most of run, I assume the jump on second tube was air in tube after switch, I need to add a tee and valve at fill valve to vac tube down after tube change pulling 30" on collection pot for second run makes extra work at clean out so I don't pull second down to 30" instead I go about 22".
I do vac down return line to recovery tank to start since it doesn't vac down during stating vac stage than open vapor valve to pressurize line but used same port for my pressure gauge so some air from hose at gauge did get in, even though I cracked line and and purged with vapor at gauge, that's not like a vac down but makes me feel safer than not doing so.
Pump ran cool except when I kicked on and forgot to open valve at c/p so heated up to about 120F than but dropped back to 80's real fast, stayed about 65 before that opps.
Tank at valve was about 26F on IRstat and 14F at steel next to valve, but I forgot to flip fast freeze switch on freezer until 2nd run so that had an effect since compressor runs constant in fast freeze mode for rapid cooling.
Next test should go better if I can eliminate human error, not that that was bad run.

Side note I did not calibrate the high gauge, need to pick up can of isobutane and was at 5lb line to start test will try to get that calibrated soon for more accurate high side numbers once grab can of zippo or bernzo butane being its isobutane.
Hope this helps.
C'Ya

[C'Ya]

also no liquid slugging(hammering) was observed so throttling was not needed

[icdog]

Does anyone have a pic of the CPS MT69 setup?

[C'Ya]

Here's link to cps page
https://www.cpsproducts.com/product/r...formator-MT69/

[C'Ya]

I normally just use refrigeration grade copper(potable water rated), 304 stainless, or 3003 aluminum.
can make coils any size like and works good in freezer. Not sure I'd recommend copper for extreme cold temps though.

[Gray Wolf]

Originally Posted by C'Ya

GW I performed 1st test with added gauges, the gauge at collection pot, gauge at exit of 20' coil and high gauge before coil going to recovery tank.
What I observed:
When gauge at c/p read 10"HG the one after coil read 12-13"HG the closer I got to 22"HG they started to even out to about 22-23"HG at end of coil closing off tank the gauge at coil pulled to about 28"HG with in a minute give or take few seconds.
The high pressure gauge read about 20# at start and maxed out at 40# after second tube 30# after first but ran 30# most of run, I assume the jump on second tube was air in tube after switch, I need to add a tee and valve at fill valve to vac tube down after tube change pulling 30" on collection pot for second run makes extra work at clean out so I don't pull second down to 30" instead I go about 22".
I do vac down return line to recovery tank to start since it doesn't vac down during stating vac stage than open vapor valve to pressurize line but used same port for my pressure gauge so some air from hose at gauge did get in, even though I cracked line and and purged with vapor at gauge, that's not like a vac down but makes me feel safer than not doing so.
Pump ran cool except when I kicked on and forgot to open valve at c/p so heated up to about 120F than but dropped back to 80's real fast, stayed about 65 before that opps.
Tank at valve was about 26F on IRstat and 14F at steel next to valve, but I forgot to flip fast freeze switch on freezer until 2nd run so that had an effect since compressor runs constant in fast freeze mode for rapid cooling.
Next test should go better if I can eliminate human error, not that that was bad run.

Side note I did not calibrate the high gauge, need to pick up can of isobutane and was at 5lb line to start test will try to get that calibrated soon for more accurate high side numbers once grab can of zippo or bernzo butane being its isobutane.
Hope this helps.
C'Ya

Sounds like static pressure losses were about two to three inches at maximum flow and maybe an inch at about -22" Hg.

You can increase the effieciency of a coil in a freezer, by putting a bulkhead fitting near the bottom of a tank in the freezer, for a vertical condenser coil to exit and self drain, and filling the tank with antifreeze.

You get a large heat sink and more surface area to dissipate heat from, to a medium that transfers heat faster than air. A 1/2" X 20' length of stainless tubing is still easily rolled around a mandrel by hand until the end gets short, or you can pickup stainless wort cooler coils already wound.

[C'Ya]

Thanks GW, I was thinking along same lines, so far stock pots are looking like best(affordable) option for coil cooling tank(s), I already have bulkheads so once initial testing is complete and I get around to testing 1/2" tubing, than I'll build vertical condenser, shame is I have 50' of 3/8" 304 I ordered earlier, but can always use for return coil to r/c tank. Still debating on stock pot I'd prefer stainless steel but considering an aluminum one since it would make a better heat sink, but galvanic corrosion is always a concern when mixing metals, either sure beats a plastic bucket otherwise.
Just wanted to do tests with what I had on hand to see if it worked well before spending more on the 1/2" 304. Knowing liquid slugging doesn't appear to be an issue with 3/8", 1/2" upgrade is planned, my main concern was larger diameter may be to efficient at condensing and cause liquid slugging, than needing throttling, which my more experienced than I HVAC friends think could be an issue possibly choking the pump at times. But if that's an issue the 1/2" should work fine on r/c tank side and move 3/8" back to inlet side of pump.
Thanks again I appreciate other peoples input, especially a designer of the wonderful terpenator projects.
C'Ya

[Gray Wolf]

Originally Posted by C'Ya

Thanks GW, I was thinking along same lines, so far stock pots are looking like best(affordable) option for coil cooling tank(s), I already have bulkheads so once initial testing is complete and I get around to testing 1/2" tubing, than I'll build vertical condenser, shame is I have 50' of 3/8" 304 I ordered earlier, but can always use for return coil to r/c tank. Still debating on stock pot I'd prefer stainless steel but considering an aluminum one since it would make a better heat sink, but galvanic corrosion is always a concern when mixing metals, either sure beats a plastic bucket otherwise.
Just wanted to do tests with what I had on hand to see if it worked well before spending more on the 1/2" 304. Knowing liquid slugging doesn't appear to be an issue with 3/8", 1/2" upgrade is planned, my main concern was larger diameter may be to efficient at condensing and cause liquid slugging, than needing throttling, which my more experienced than I HVAC friends think could be an issue possibly choking the pump at times. But if that's an issue the 1/2" should work fine on r/c tank side and move 3/8" back to inlet side of pump.
Thanks again I appreciate other peoples input, especially a designer of the wonderful terpenator projects.
C'Ya

If I already had 3/8" 304 tubing, that is what I would use too. 1/2" will be faster, but not dramatically so.

I wouldn't worry about galvanic corrosion with an aluminum pot, as it would be minor to non existent in that application.

As you've noted, liquid to a pump without non slugging heads can break the pump. Perhaps a surge chamber might be required.