Chemical Injection Valve for Static Inline Mix Chamber

I have well water. The water is acidic and needs Sodium Hydroxide (NaOH) solution added to adjust the pH. The system has a Pulsa Feeder static inline mixing chamber, part no STM100-PVC. The NaOH is injected using a Chemical Injection Valve screwed into a port in the mixing chamber. The injection valve body includes a check valve. I don’t have a part number for the chemical injection valve.

Sediment has clogged the mixing chamber and injection valve. The NaOH solution is no longer flowing (or not flowing well) into the mixing chamber. I need to replace them; or at least the injection valve.

The problem I am having is, I cannot find the Chemical Injection Valve. There is no part number stamped on the existing valve. Pulsa Feeder does not know the part number. It is not listed on their website, and parts folks wrote back that they did not know the part number (derp).

I believe the specs for the injection valve are 1/2-inch MNPT to screw into the mix chamber port. But I don’t know (1) the quill length, (2) the check valve type (ball, duck, etc), (3) the material, (4) the max psi rating, and (5) the coupling size.

Regarding (5), the feed from the diaphragm pump is 3/8-inch O.D. clear pipe. The current injector valve uses a compression fitting. So I think I need 1/4-inch I.D. or 3/8-inch O.D. coupling.

My question is, what do I need for the Chemical Injection Valve?

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Here are some products I’ve come across, but they lack specs so I’m not sure if they meet the needs of the application.

• Stenner Injection Valve, 1/4-inch, part no UCDBINJ
• Stenner Injection Valve, 3/8-inch, part no UCINJ38
• Stenner Injection Fitting, 3/8-inch, part no UCAK300

For the Stenner valves, I believe the 1/4-inch and 3/8-inch size are the smaller threads nearest the quill body. I believe the next set of threads closer to the check valve are 1/2 NPT threads. But that is just speculation on my part.

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Here are the images of the inline mixing chamber with the injection valve. I took them to a few plumbing supply houses this morning. I was not successful in finding the valve. The plumbing supply houses lacked experience with well water systems.