Using aftermarket sensors with RolaChem controllers

[Guest]

I have a 70,000 litre pool with a fairly ancient RolaChem RC25-7 controller injecting acid and chlorine from 20 l containers.

I have finally accepted that the ORP and PH sensors are dead. pH is not such an issue as I have an instrument quality meter and the pH is pretty stable. I do need to replace the ORP sensor however.

A call to the local agent went like this:

"Gidday, I'm after a replacement ORP sensor for a RolaChem controller"

"one moment please... -is that the RC-9?"

"No, it's an older one, but I'm sure it will be compatible if it has a BNC connector"

"OK. That'll be $640"

"Ahh, no sorry, I just need the sensor, not the whole setup"

"That's the price of the sensor. The units are $3500...."

Now I see Ebay has aftermarket ORP sensors for $30. At that price I could afford to replace them every year. I'm assuming that being based on a cell potential, all ORP sensors are basically the same.

Does anyone have a comment or experiences?

Thanks

 

[JasonLion]

The really inexpensive sensors tend to be quite bad and are almost never rated for continuous use. There are a couple of sensors in the $200 range which are much better. I have used sensors from CAT Controllers without problems, and I have heard mostly good things about a couple of their competitors in the same price range.

In addition to the BNC connection, you need to make sure that the threading/seal on the body where the sensor attaches to the flow chamber or piping is compatible with your existing setup or you can locate an appropriate adapter.

 

[Guest]

Thanks for that. I'm hopeful I can locate or make any adapter required. I had a quick look at CAT Controllers but couldn't find mention of ORP sensors offered as spare parts.

Some links to your sources of mid-range priced sensors will be useful.

 

[JasonLion]

Here is a random source for the CAT Controllers ORP sensors. Many other places have similar prices, but they had a nice chart of the different models, which most places do not have.

 

[Guest]

I had a good response from these guys: http://atlas-scientific.com/product_pages/sensors/orp-sensor.html. Cheap, and they reckon it is fine for the application.

 

[gazing_south]

hi rossmcm
Are you from Australia? I have the same unit and spoke to the only guy in Sydney who services them - quoted me AU$500 to service the unit including replacing both probes, upgrading the electronics to the mark II version and overhauling the feeder tubes and pumps. Before I went ahead and pulled the trigger on this I wanted to see if I could replace the sensors myself with cheaper ones (the cheapest brand ones I can find in Australia is around $225 each, so $450 for the pair.

The atlas-scientific ones look interesting however I am concerned that they are too long for the opening in th eplumbing and I am not sure how I would retro-fit them using the screw cap.... did you go down that route?

Cheers
GS

 

[Guest]

Hi GS,

From New Zealand actually (not the same place, I respectfully point out to our northern hemisphere readers.... .

I did source an ORP sensor from Atlas, around US$90 IIRC. No problems, and I would deal with them again (and may do for the pH sensor).

The bad news is that I haven't had the time to fit it and have been using a chlorine "floaty" dispenser as an interim measure since, which has been pretty good actually.

Yes, the sensors are longer than the RolaChem originals (which I don't see as too much of a problem except they will stick out a bit and there is the risk of hitting them as I move around in the confined space of the "pool cavern"). The bigger hurdle is fashioning the adapter. You have renewed by interest - I will post photos of both sensors soon.

The $500 deal from the pool guy in Sydney sounds pretty good actually.

My brother was visiting recently from Melbourne and he uses salt water chlorination and swears by it.

Best regards,
R

 

[jblizzle]

From New Zealand actually (not the same place, I respectfully point out to our northern hemisphere readers.... .

:lol: Oh, so you are the Canada of Australia

{Any Redditors around here?}

 

[Guest]

No, Australia is the U.S. of New Zealand. :lol:

 

[gazing_south]

I'm a kiwi myself - so totally understand why you don't want to be called an Aussie

Let me know how you go - I thinking get some calibration solution for ph and orp and do a proper clean and calibration of the probes before I pull the trigger on the overhaul.

Geoff