Alfa laval water tranducer question

Hello everyone, I would like to know what is the purpose of the valve (marked red on the photo) on the water tranducer on Alfa Laval purifiers.
Alfa Laval

Looks like the flow adjustment valve. Should have an adjustment screw with a locknut on it.

Thank you for the feedback. It has adjustment screw with locking nut. From the drawing I can see that it is spring loaded valve but what is confusing me is that there is air line connected to the valve body. Only thing that I can think off is that air pressure is not applied (valve closed) when PLC is doing the leak test to monitor the PT4 value (backpressure) that would explain the air line? Back pressure and flow we adjust with the valve after this one (don’t know if that is the correct way but it doest the job).
P.S Manual checked for the answer but there is no explanation only drawing.

The air line is used for controlling the position. It’s been a while since I’ve had to mess with one but I’m pretty sure it opens with air pressure, closes without but double check that. In your operating manual’s section on parameters there should be a section labeled “sequence diagram” that will show you when the valve is supposed to be open and shut based off of which timer is currently counting down. The valve is V4.

Like you, I typically controlled flow with a different valve and used V4 to regulate backpressure.

Valve V4 will close (air on?) during timer 66 for the “bowl leak test” where it measures the pressure drop in PT4. The valve stays open/throttled for backpressure for the rest of the runtime.

Thank you for the feedback.

sorry i read this, tells me how much i’ve forgotten!! damn!