Latest / The Refrigeration Mentor Podcast / Episode 400. Top 8 Critical CO2 Sensors Every Tech Should Know with Andre Patenaude

Transcript

Episode 400. Top 8 Critical CO2 Sensors Every Tech Should Know with Andre Patenaude · The Refrigeration Mentor Podcast

• 0:00
  Trevor: Welcome to this session. I'm so excited that you're here coming to hang out with us to learn a little bit, grow a little bit. I'm hanging out with my good friend Andre Patenaude from Copeland. We're gonna be diving into CO2, and this is what we talk about all the time. We travel around the world, we talk about CO2, we train CO2.
• 0:03
  Same thing with the critical sensors, and that's really how we classify critical sensors. You can see the definition that a critical sensor occurs, when it fails, you get immediate loss of refrigeration, either one or more suction groups. So that's the definition. There, there are critical sensors, there are non-critical sensors, and there are informational sensors.
• 0:06
  but we need to know the main ones, and it can- Right ... there, there's a lot to it. I, now, I've been to a ton of startups. I do tons of trainings, and I see tons of systems, and a lot of the, the things that I see out there, there's a lot that it's done incorrectly for CO2. You know what I mean? When I was thinking, I was doing training four or five years ago, when there wasn't as many systems and even maybe even a little longer, there was a little bit more cautious on the CO2 systems 'cause it was new, high pressures and stuff like that.
• 0:09
  Andre: Yeah, absolutely. Absolutely. So the system I'm gonna be talking about, and I'll be showing over and over, is this particular one here. Now, it's a basic booster architecture, and let me just walk through it because you're gonna see this 35 times in the next, in the next hour, right? So here's where I'm laying out my medium temp compressor suction group is here.
• 0:12
  'Cause in Europe, the, the average is 60 bar, which is 800 and some PSI, I think 60 bar is. 60
• 0:15
  Trevor: And one of the things to remember is, like, this is no different than HFC. Just remember- ... when you're checking your subcooling, you check your pressure, your SCT, SDT.
• 0:18
  Andre: That's right, outside. It's okay for the pressure transducer to be in the building 'cause pressure losses are insignificant for the, the few feet that it... But temperature is very different.
• 0:21
  The recommendation is gas cooler out close to it at least 12 inches or shorter to the outlet, five or seven degrees. The same kind of good, good practice that you do on, when you're securing bulbs to, to, to pipes. Metal clamps, thermal mastic paste, waterproof insulation, and preferably white insulation because it does have an impact on sun- Yeah
• 0:24
  Trevor: Yeah.
• 0:27
  Andre: But there's some other mitigation. We can move the high pressure valve to a fixed opening position. Def- it defaults to 50% in the... It's native to the E3 setup. But just 'cause it defaults to 50% doesn't mean you have to leave it at 50%, because if you know that when you're operating that valve is kind of operating at 25% normally, 'cause it might have been oversized to begin with, if it defaults to 50%, it'll be way too much.
• 0:30
  Trevor: I seen, when I was out in Quebec, I was at a few Arnig sites, that's what they had on ref plus gas coolers- Yeah
• 0:33
  they're like, "Trevor, I'm on the roof. It's minus 30 out, and it's blowing 40 miles an hour, the wind, it's-
• 0:36
  Trevor: Oh, great. Because that was a question, too. It's like all of a sudden, okay, we got an alarm, but that alarm- Yeah ... has to trigger some sort of flex combiner at this point to say, "Okay, well, we got this alarm. Go to board poi- board 2.1- Yep ... and start sensing from that one versus...
• 0:39
  The high pressure valve is moving, and that pressure transducer is measuring that. Even in heat reclaim mode, it's used to modify that. So even in the winter, we might be pushing it in transcritical mode, and again, it's, it's, it's measuring and adapting and providing the information for the high pressure valve positioning.
• 0:42
  with the gas gas by- pass valve, because one thing happens, it can throw the whole system out of control. You know what I mean? And then people start playing around with P&IDs. I recommend do not touch that. You know what I mean? Like, that's the last- Yeah ... resort usually. It's usually just some setup, a procedure.
• 0:45
  Andre: Okay, well- And then the other one from a mitigation perspective is you can transition the gas cooler outlet temperature to T1. But you still don't have your pressure, but you can try to control off T1. So it, it, it becomes a little more complicated, but the other two provides you some, some reasonable flexibility.
• 0:48
  So if the pressure is less than the set point if it's lower than the set point, the high pressure valve opens, the bypass valve closes, and the reverse, right? If it's above the set point, well, this high pressure valve closes and the bypass valve opens to try to maintain. And so really that flash tank is, is this, it's really a, a simple static set point, like I said.
• 0:51
  You compare the saturated flash tank pressure to my liquid temperature. Should be pretty close, right? It is a saturated condition inside of a flash tank. So if you have more than 10 degrees, something's off. It's either the transducer or the temperature sensor. Get someone in to check it out before you get, Yeah.
• 0:54
  Most commonly fails open, doesn't detect oil. So, again, you might have some contamination or, or something else that's caused the low level control to fail, and the impact would be oil starvation leading to compressor shutdown.
• 0:57
  Adiabatic gas cooler. Pre-cool sensor. So we debated a lot on what we're gonna call this sensor, but we, we, we, we decided on pre-cool sensor 7A location. That sensor is installed between the adiabatic pad, the gray here is the adiabatic pad, and the angled is your aluminum- To your actual coil, okay?
• 1:00
  'Cause th- you're only four degrees out. You could... The humidity wasn't super high. We would've been able to probably keep that system in subcritical that whole time, for an example.
• 1:03
  So it's only measuring ambient there. And as I mentioned at 80 degrees above, all fan speeds are 100%. When you open up this little cabinet here, there's a a sub- a basin down here that when it reaches a right temperature, that basin fills up with water, and the circulating pump is really what sends the water up onto the pads.
• 1:06
  Andre: Yep. So that's RefPlus, a little bit different. Güntner, they sent me photos of theirs, and that's below their electrical panel. They have a dry bulb sensor as well.
• 1:09
  Andre: You're right. It's just to make anyone listening here to kind of think about exactly what you said. What, what else is there that I could point to in order to prevent my s- I may not have the perfect, redundant centers everywhere, which you won't. So you have to be a little bit more inventive, a little bit more MacGyver.
• 1:12
  So if someone cuts the wire, you lose communication. Think of it like that way. And then some people don't do it that way either. I've seen lots of sites, no, 10 volts is 100%. But- Right ... if you think about what's the backup, the worst-case scenario is in the summertime. If the fans come on in the wintertime, it's bad too, 'cause you're gonna crash the rack because it's gonna drop off.
• 1:15
  You know what I mean? Depending who's running that store, they're just like, "No, you let it just run like this until you have to really do something." And so we wanna be proactive, and sometimes your hands are tied as a technician. All you can do is document this stuff. That last thing is really, really important.
• 1:18
  I'm guessing this is adiabatic gas cooler. What would the correct action to keep operating the system? So it depends on the manufacturer there, but a lot of them will have a hose fitting. So you can just go and put a hose up there and just tie it in and it'll just run in the water all the, all the time.
• 1:21
  So controls are not gonna go away. They're gonna g- they're gonna get more complicated. Or with AI, maybe less complicated. That's not a bad thing. But you as an individual with all these, these screens that you need to understand and set points you need to set, just be aware of the cause and effect of, of what's going on.