Adding ball valve before flow sensor

I need to add a ball valve to shut off my sprinkler system, as needed. The most convenient and economical solution would be to add it upstream to the wireless flow sensor, as it is on a PVC riser. Has anybody added a ball valve like that and not had subsequent problems with the flow sensor?

You just need ~10 inches of straight unobstructed run upstream of the sensor in the meter. You can get by with somewhat less at lower flow rates. Your picture looks like it may be about 10" to the 90 degree. If you could put the ball valve vertical and then raise the horizontal part with the meter to accommodate the valve, you would be fine. (you would end up with the same situation you have now)

That makes a lot of sense. Just to be double sure, we put the valve on the vertical part of the OUTLET side. Thanks for the advice.

That would be even better since downstream side of meter is less sensitive to flow changes and gives you the highest probability of success. But, you could put it on either side since meter has the straight run from the 90 already.

My preference would be to use threaded connections and a union. But I used galvanized on my risers, expecting PVC to break eventually. The insulation is going to help minimize UV damage, for sure. And you aren’t getting hit with a weed eater there.
I’m also surprised you don’t have a valve at the beginning of where ever you irrigation split off from main line at meter box, or maybe where line enters your house. I guess you live where it never snows so you don’t have to drain the system, or require a back flow preventer.

I am in San Antonio. Until last year, it almost never snowed, then we got the great winter storm. We also do have a backflow preventer, but it is in-ground and the valve handles are almost impossible to access and starting to rot. We installed a brass valve in the outflow riser. So far, so good.


With a horizontally (or worse, downhill) mounted solid state flow sensor, there must be enough back-pressure on OUTLET end of the meter to prevent cavitation or bubble-inducing flow around the sensor. If you can’t re-orient the meter, it’s sometimes suggested that you install an adjustable valve DOWNSTREAM from the meter. Just installing the valve downstream, fully open, may create sufficient back-pressure to make the meter work properly. If not, gradually, in small increments, close the valve until it does. On a meter with a flow display, you can see the problem as intermittent display of zero values while the meter is in active use.