# Thread: Flow Meter Purchase?

1. ## Flow Meter Purchase?

Studying up on a variety of topics for this summer, going to try and tackle adding solar heat panels, hard plumbing and a DIY sprinkler fountain all in one project.
I'm reading up on various pump dynamics (pressure, volume, head loss, etc) and I'm wondering if there's any opinions on whether a flow meter is worth throwing into the mix?
I'm looking at the Blue-White flow meters and for +- 50 bucks they seem rather easy to install, and I believe such a unit would replace a lot of calculating should I need to determine proper pressure and other such numbers.

Or am I taking all this a bit to far?

PS, I've got a 1 hp pump, I'm planning on 160 square feet of solar heater, the length of 1.5" pipe from filter to first point of contact going TO the solar would be an estimated 35' - that's to the "front" of the panels, to the back end would be about 50' or so. The panels will be on the garage so water will travel vertically for about 10'.
Last summer was the first with a pool and my pump was running 10 or 11 psi (going by memory) with about 20' of 1.5" pipe between filter and outlet directly.

2. ## Re: Flow Meter Purchase?

Flow rates are interesting and can be useful under some situations but they are not totally necessary either. Plus flow meter accuracy is usually limited to 10% of the maximum scale and you need to be very careful on how you install the flow meter making sure you have the required straight piece of pipe on both ends so in some installations, they are not possible without reworking the plumbing.

At 10% accuracy, there are other methods including a simple guess which can get you close enough. At the coarsest estimates, you can use plumbing curve estimates overlay on top of the pump's head curve, and you will probably not be too far off.

For example, I am guessing that your current plumbing is 1.5" with single suction and return pipes from the equipment to the pool? This type of pool will usually have a plumbing curve close to:

Head (ft) = 0.0167 * GPM^2

Which will cross the pump's head curve at 48 GPM with 39' of head. I bet that is within 10% of actual values.

3. ## Re: Flow Meter Purchase?

Keep an eye on eBay. They sometimes come up pretty cheap. That's how I got mine.
flow-meter-blue-white-flowmeter-model-no-f-30150p-t39712.html?hilit=flow

My pump is putting out 50-52 gpm. Woo hoo.

4. ## Re: Flow Meter Purchase?

Originally Posted by bobodaclown
Keep an eye on eBay. They sometimes come up pretty cheap. That's how I got mine.
flow-meter-blue-white-flowmeter-model-no-f-30150p-t39712.html?hilit=flow

My pump is putting out 50-52 gpm. Woo hoo.
As mas985 states and I confirmed in the manual for this meter, the accuracy is +/- 10% of the full rate flow ... i.e. 10% of 100 = 10 GPM. So I think that means that your flow is really somewhere between 40 and 60 GPM ... seems like an estimate based on your plumbing would also get you in that range.

Although it should give some indication of something going wrong if you saw a big change for some reason.

5. ## Re: Flow Meter Purchase?

Thanks for the comments, really gives me something to think about.
I think perhaps I'll devote more energy in working out the math manually (thanks mas985), I never contemplated the error factor with the flow meter as I just assumed they would be right on.

Thanks again!!

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