Threads on Atlas ORP Industrial sensor

[TopJimmy]

For Atlas Industrial ORP sensor they sent me recently: despite their website claiming 3/4 NPT, it is not. The thread is something different. Can’t be certain but I think it is 3/4 BSPT. I bought an adaptor on Amazon $14 and a #14 o-ring from Ace (BSPT uses o-ring for sealing and the gasket supplied with the adaptor is not suitable). Now everything fits perfectly! Don’t know what Atlas’ deal is, I emailed them with no response.

Amazon.com

 

[TopJimmy]

When I initially tried to screw it into my flow cell with teflon tape it leaked, then found my flow cell threads were buggered. Got a 3/4 NPT tap to clean up the damaged threads. Compared the tap to the sensor caps and perfect fit. Compared tap to sensor threads and it was way off. I don’t know if the brits count threads differently than US but I counted 16 tpi on the sensor and NPT is 14. In any case, what I did with the adaptor works with no gimmicks.

 

[MyAZPool]

Nice work! Looking good.

 

[mgtfp]

Which board are you connecting your sensors to?

 

[TopJimmy]

Raspi 4b with Whiteboxlabs T3.

 

[Sabot]

What advantage is there to go with the Atlas industrial vs. the lab probe?

 

[TopJimmy]

I did lab grades probe for pH and ORP trying to limit cost. The lab grade pH is doing fine but I couldn’t get the lab grade ORP to give reliable, repeatable results—it was all over the place. Maybe a bad probe, idk. I am testing industrial grade ORP now in the hope that it is going to act right.

 

[jonpcar]

What advantage is there to go with the Atlas industrial vs. the lab probe?

I’m a bit undecided with this as well. The lab probes are listed as being ‘about’ the same accuracy/durability for about 1/3 the price and avoid all the threading issues. I probably will only install a pH probe, so it sounds like that might be OK.

I did lab grades probe for pH and ORP trying to limit cost. The lab grade pH is doing fine but I couldn’t get the lab grade ORP to give reliable, repeatable results—it was all over the place. Maybe a bad probe, idk. I am testing industrial grade ORP now in the hope that it is going to act right.

Please let us know if you see a difference in the ORP probe readings. It seems that most people have variability with ORP readings and usually have to interpret the results in one fashion or another.

BTW @TopJimmy, what size are the PVC fittings in your picture? Thx.

 

[TopJimmy]

3/4” pvc. So far I’m not happy. About the same ORP readings. My FC on the pool and spa is 10: orp has ranged from 680 to 550. Orp on spa orp has been 300 to 350. Seems like something else is going on possibly with the computer hardware itself. I’ve grounded the metal bits to the pool grid and house ground. I’ve switched the probes from pool to spa—no change. CYA is less than 25. At this juncture IDK if ORP will be useful to me. Acid dosing is good, tho…
I might do some more data collection and see if there is ANY correlation between FC and whatever ORP I get, but so far it seems totally unrelated.

 

[Sabot]

What software are you using?

 

[TopJimmy]

Njs-pc with REM. Sensor readings direct from Atlas’ python code is the same.

 

[Sabot]

I wonder if the probe might perform better if installed in a Sampling Chamber rather than in line with the water flow, even in a reduced pipe size. I noticed that Pentair's ChemCheck and various Chlorine Analyzers probes seem to use sampling chambers. If the answer is yes, how do you source a sample chamber on a pool owner's budget?

Would having valves at both ends slow the flow enough to create a sampling chamber on the bypass loop?

I had a bit of overthinking; I was thinking about ensuring that the probe was in contact with the water flow. I found out that you can purchase Schedule 40, which is clear. If deployed, I would be protected from direct sun, for I am unsure if it would discolor. In particular, a clear tee with the needed fittings to mount the probe.

 

[TopJimmy]

Not sure. Looking at these commercial flow cells, it shouldn't matter as long as no air pockets are present.

FlowCell / FlowCell XL | Process Analytics | Hamilton Company

FlowCells for measuring one or two parameters at a time with multiple piping connection options.

www.hamiltoncompany.com

This is my flow cell setup. I have top valves for air bleed, bottom valves for drainage/sampling, and isolation valves to cut off pressure/suction for probe servicing. The pressure is supplied just aft of the filter and suction (with check valve) is at pump basket.

 

[Sabot]

How did you tap into the PVC? Did you use something similar to the drawing that I attached? If yes, where did you purchase them?

 

[TopJimmy]

I used threaded tees (SxSxFPT) for pH and ORP. For the PRS & RTD I used a smooth tee with appropriately sized threaded bushing—couldn’t find a threaded tee with 1/2 or 1/4 FPT at the time. Eventually found pvcfittingsonline.com which is my go to now, so they might have.

 

[TopJimmy]

Here is my current dashpanel. Chemistry of pool and spa is largely the same:
250 CH, CYA <25, TA 80, FC 10

 

[TopJimmy]

Oh also I forgot: I probably got the original threaded tee's from Atlas when I ordered the lab grade probes. If you order their tee, they come with the fitting that screws into the tee to secure the lab grade probe (3/4 NPT)

 

[mgtfp]

Last year, I had bought the Atlas pH/T/ORP combo industrial probe with the Wifi pool kit.

It turned out that the Wifi pool kit was entirely useless, because the board created a huge error on the pH measurement (with huge I mean pH plummeting below 4 when the sun hit the electronics box and moving back up when shading the box - I later quantified that by exposing the box to defined temperatures while keeping the water sample with the probe in it at constant temperature). I'm not sure if that was because the Aussie Atlas distributor had sent me an older version of the Wifi Pool kit ("legacy"), I just returned it and got my money back, felt deflated and didn't want to waste more time and money on ordering the current version directly from Atlas in the US. If anyone made a positive experience with the current WiFi pool kit then please share.

Anyway, the pH part of the probe itself seems to have been good, my issues were purely caused by the Wifi pool kit. Maybe a bit unresponsive towards temperature changes, it took ages for the temperature probe to react to temperature changes (like when turning on the pump and getting colder water again replacing warmer water in the pipes), and for the pH signal to slowly drift to a constant value again.

I didn't expect the ORP part to be working with my CYA around 80, I just ordered the combo industrial probe because I liked the robust design, and having to put only one probe into the plumbing. But my observations were that the ORP measurement seemed quite erratic.

 

[TopJimmy]

Yeah I don't know what the problem is. I tried grounding all the metal bits to the pool grid & house ground, but that had no effect whatsoever. At this point I'm ready to give up on ORP. Might be something in the whiteboxlabs design, possibly some anomaly in my installation (doubt it). But whatever it is, pH probes are good, ORP is not (at least in terms of what ORP measurement should be). I think I could try switching my ezo chips around, try Atlas' new replacement for the T3, etc, but I fear I'd be chasing waterfalls. And we all know how that goes...

 

[jonpcar]

I wonder if the probe might perform better if installed in a Sampling Chamber rather than in line with the water flow, even in a reduced pipe size. I noticed that Pentair's ChemCheck and various Chlorine Analyzers probes seem to use sampling chambers. If the answer is yes, how do you source a sample chamber on a pool owner's budget?

Would having valves at both ends slow the flow enough to create a sampling chamber on the bypass loop?

I had a bit of overthinking; I was thinking about ensuring that the probe was in contact with the water flow. I found out that you can purchase Schedule 40, which is clear. If deployed, I would be protected from direct sun, for I am unsure if it would discolor. In particular, a clear tee with the needed fittings to mount the probe.

I’ve been in the pre-planning stages to add additional probes for a few years (haha) after seeing all the excellent work by members with the Atlas probes (thanks @MyAZPool and the host of others working on nodeJS, REM, nixie…and those users who have actually implemented them). This is exactly what I have been thinking if I ever get around to it. I like the idea of those clear pvc fixtures and I do think they would have to be protected from the sun, but I don’t think they will serve any other purpose other than being cool .