Acid check valve plugging periodically on IntelliPH

[Vegas Mike]

Suggestions to eliminate acid check-valve plugging? Have a Pentair IntelliPH acid dispenser with a tank-mounted Stenner pump. The Pentair 522513Z check valve plugs once a year with what looks like fine black plastic shavings. I see a very small amount of black debris in the acid tank, but seems too difficult to attempt cleaning the tank. The 522513Z check valve has an internal ball. Anyone have experience using a duckbill check valve on 32% muratic acid? Considering a Stenner UCDBINJ duckbill, which looks like it may be more resistant to plugging. Pressure ratings on the check valves are 26psi to 100psi, but I don't know how much pressure is required on the acid pump side to push acid thru. Seems high when I test the valve. Doesn't seem such high pressure is necessary since the check valve is installed downstream of the filter, just ahead of the SWG.

 

[ajw22]

Let's see if @Dirk has ideas when he passes by.

 

[Dirk]

but seems too difficult to attempt cleaning the tank

Sorry, but your approach makes no sense to me. You're willing to change the affected part with another, not knowing if it'll solve the problem, or even work at all, when you've already identified what's wrong, but just don't want to fix it? It wouldn't be my approach.

When the tank is almost empty, disassemble the tank (it's eight bolts, I believe), and dump what's left. Rinse it out thoroughly, and be sure to clean and inspect the filter at the end of the intake tube. If that filter is missing, or damaged, replace it. Then thoroughly clean the top half of the IpH. Inspect both halves for anything that might be contributing to the debris. Then reassemble. There are no moving parts in the tank, so the debris might have been there since its manufacture.

The pump's tubes need periodic replacing. Do that if it's been more than two years. The injector also wears, so replace that, too, if it's old.

The IpH requires regular maintenance, including periodic replacing of the parts worn down by the acid. That's how I'd handle this issue. If you want to try re-engineering it to avoid that, I don't have any experience with that, so can't be of any help.

 

[Vegas Mike]

Thanks for your insight Dirk, and taking the time to help. Actually, discovered that the acid tank continually develops new debris. Maybe stuff falls in when I take off the lid, or plastic scrapes from the container edge each removal. So my initial statement that you could clean the tank once and for all seems incorrect.

Since I have to replace the injector anyway, was checking whether anyone else had experience with the duckbill-type injector for acid, which seemed to me less likely to plug. Indication the injector plugged is a sudden increase in pH. I remove the injector and confirm it is plugged using a spare Stenner pump (my winter chlorine pump), and also test the injector's replacement. After the new injector is installed, the pH returns to setpoint within a day. This proves to me that the plugged injector was at least the immediate cause of the problem. I find the fine, plastic-like shavings plugging the injector on the acid side.

But, you are right that I should clean the tank and especially verify the filter is clean and in place. How else could junk appear downstream if the filter is working? And maybe there are residual shavings from manufacture still lurking that get washed in with each acid addition. But I'll wait for winter when the acid fumes are attenuated -- 114F today.

Have been replacing the peristaltic pump tubes yearly. Good to hear I could do that every two years instead. Buying the replacement tube was initially problematic because of inaccurate Pentair documentation. The correct tube for my Pentair IntellipH "Blue" pump is a Stenner EC30C-x series, but I just bought the "Repair Kit for Intelliph OEM Pumps" Poolweb #522386.

 

[Dirk]

Good to hear I could do that every two years instead.

Uh, you might not be able to count on that. Pentair advises annually. I went four years, and that was way too long, as mine was severely compromised by then. I came up with two years based on my usage, YMMV. Check it annually and replace as needed (is what I should have written). They'll get brittle and/or brown.

I don't know the particulate size that little filter is supposed to keep out, but it seems like it is not doing its job. But, of course, that's not the source of the problem.

FWIW, mine doesn't have those shavings, and yours shouldn't. I would consider your situation a manufacturing defect. Is your unit still under warranty? If so, get it replaced. If not, you'll have to go exploring to see if you can identify where the shavings are coming from.

I don't have any experience with duck bills, but I have completely disassembled a Pentair injector. I could see how it could get clogged up. It basically works like those old pool snorkel sets, where the ping-pong ball plugs up the snorkel when you would submerge. Except the Pentair injector's ball is moved by pressure, not gravity or displacement. If shavings collected in the wrong spot, they could keep the ball from moving. So you're on the right track in that regard.