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North Central Iowa | I'm going to have to slightly disagree with the other responders. There isn't anything wrong with using a smaller flow meter in a larger line, with some things to keep in mind.
1. 4WD is correct on the straight runs before and after the meter. Flow wants to be as uniform across the pipe as it enters the meter. But a reducer/increaser near the meter, as long as not too drastic a change at once, doesn't impact the meter performance.
2. The meter size is all about being in the sweet spot of the meter range. As I have a 60 ft sprayer and usually end up running around 10 gpm, a 3/4" raven meter is the best selection (good for up to 15 gpm). Their 1" meter I would be running near the lower end of its recommended range when I'm running slow and/or only 1 boom section on (I think rated for up to 60 gpm). You can have a meter that is "too big", then there isn't enough velocity to have it spin fast enough to accurately meter. The Raven meters have a low end flow rate that they are rated for as well.
3. Yes, a smaller meter has more headloss, but as long as your pump puts out plenty of pressure, this isn't an issue as all the flow is going through the meter on its way to the nozzles and hasn't reached the section control valves yet. At this point in the flow schematic, one isn't concerned about even pressure distribution to all the nozzles yet. Once the flow goes through your section control valves, that is when it is most important to keep your line pressure losses to a minimum (and similar to each other) so that all the nozzles see the same supply pressure (and hence spray a nearly equal gpm). Once the flow has gone through the section control valves, the flow in each line is much less (1/3rd if you have 3 section), the flow and velocity in each hose to the spray boom is pretty low so keeping with 3/4" hoses or larger keeps the pressure drop real low. | |
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Flow meter
