Low Lead Flow Switches, Chlorine Resistant Seals?

Teemok

I've checked with a couple manufactures and they say they have no low lead flow switches. Is this just such a small exposure situation that not even the inspectors care? I was told by a tech support person that there's no demand. That seems hard to believe. A commercial customer of mine gets 2-3 years before it leaks. Using the factory AWN Lochinvar part (TACO but not made by TACO). It was wired with liquidtight conduit. When the switch seal leaks the water travels up the conduit and spills into the boiler case near the board running down the inside back, making it look like it could be a flue seal leak. Still not sure how nothing shorted out. Drain hole gets preemptively drilled now.

Teemok

Wow, complete silence.  

hot_rod

It is a tough environment for a flow switch. Hot water, high velocity, high TDS, a witches brew of chemicals.

High chloride level potable water must be tough on those paper thin stainless bellows.

As you discovered it is a high warranty switch. Paddle erosion is a big fail point also.

You would think you could sense flow external to the pipe? Like ultrasonic flowmeters work. They have incredible accuracies across a wide flow range.

Have you tried Grundfos vortex sensors? They are composite and have a lot less material sticking into the flow stream.

Screenshot 2025-01-20 at 1.16.50 PM.png

Screenshot 2025-01-20 at 1.16.34 PM.png

Teemok

Thanks for the feed back @hot_rod . I get that it's a hard engineers problem. SS bellows are on some but Epdm seems to be the material of choice. 135F isn't all that extreme. This is domestic water production, hence the low lead question. SF water is good. Chlorine yes but I don't think it qualifies as a witches brew. Am I missing something about DHW low lead requirements? Are flow switches exempt? On one hand we made it to the moon in the 60'S and on the other our DHW flow switches are leaded and last 3 years. It's hard to tell what's planned obsolescence and what the real limits of modern materials and engineering are. It's more service work I guess but not having good solutions raises questions from clients. Shrugging and sending another bill is not who I want to be.

hot_rod

We are constantly monitoring water quality around all the markets we serve. Chlorine, chloramine, peroxide, iodine, phosphates. There are all sorts of blends and maybe over dosages to engineer o-rings around.

Do your inspectors actually carry around low lead test kits? Rumors around of some manufacturers just adding stickers on the box indicating lead free or low lead.

The LL rating has to do with the amount of brass actually exposed to the water. So depending on the part and application for the listing.

We had this question with backflow preventers, for boilers. The water passes through and ideally never goes back into the home or city supply. Same with a fill valve. So do they need to be LL? The target seems to be moving and nobody has the answer to some of these questions.

You might look at Harwil. Oxnard California, they have some Noryl plastic switches rated to 180F. You screw them into a tee that you supply.

They have brass versions also, not sure if they have any NSF listed.

Screenshot 2025-01-21 at 11.20.36 AM.png

Teemok

I think you are right, it's just too small of a leaded brass area to be concerned with. Gray area, mystery moving target reg. explains the silence. I've never seen an inspector with a LL test kit. 😁 I'm just trying to do the right thing. The area is very small but it is in the flow path of potable water unlike a fill double check. It seems like a coating or a bonded stainless cap would reduce exposure and then you charge more and market as compliant. Making it with a serviceable seal would make it set it in a class of it's own. I just paid extra for a LL- T and P with only a sticker on the box to differentiate it from the leaded unit with the exact same part number. I guess I'll join the shrug and install another one majority. Thanks for the Harwil tip. It looks like it's a reed switch (low current) and not adjustable. I see what you meant by a brew when you have to be good with all and any of it.

hot_rod

this is Californias take on it.

https://dtsc.ca.gov/lead-in-plumbing-fact-sheet/

Emerson explains it from a manufacturers perspective

https://www.emerson.com/documents/automation/white-paper-lead-free-asco-en-3674086.pdf

Teemok

The way I read it is, either the components is or is not compliant. There are many thousands of violations being installed regularly. It's not a gray area, it's just flat out non compliance with little to no enforcement. It's all in the regulation game I guess. I've just ruined any ignorance defense I might have had. I'd have to go with the flow of traffic speeding ticket defense.

hot_rod

The trick or challenge is defining the “wetted area” as a % of the valve brass. Who double checks the manufacturer’s numbers? Why are BFDs over 2” not required to be LL?

Actually it takes a pretty specific set of water conditions to leach lead out of brass. Most pluming and hydronic components develop a “patenia” from minerals in the water that seals the bare brass from the fluid anyways. So the whole LF or LL is a bit of an over reach. A solution looking for a problem. Especially if your town still had lead piping in the street😳

We are doing more and more with composites. It eliminates the LL issue and speeds manufacturing. You see more and more circulators being made with composites. That may eliminate separate volutes for potable water and hydronics?

When a composite piece drops off the line, it is ready for assembly. No drilling, machining, threading, flashing removal, polishing, etc.