Jess Stryker's
Landscape Sprinkler Design Tutorial
Step #2
Water Meters
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Jess Stryker's |
The water meter isn't usually something you get to select. You either have one, or you don't! If you buy your water from a water company or municiple water district you probably have a meter, if not you probably don't.
The water meter measures how much water you use, so the water company can charge you for it (of course!). You may not have a water meter, I didn't have one at a couple of the homes I've owned (water was just a flat monthly fee regardless of how much was used). If you do have a meter it will most likely be located near where your water supply taps into the water company's pipes. This is usually right next to the curb, or on the side of the alley. In some cold weather areas the meter is inside the house basement. If the meter is buried in a box, be careful when you open the box. Over the years I've encountered just about every creepy thing one can imagine in those boxes! It's not a bad idea to have a can of bug killer in one hand when opening it. The meter should have a size stamped on it, if not, call your water company and ask them for the meter size, it should be in their water billing information.
The pressure loss in water meters is based on the meter size and the flow rate. The chart below gives typical pressure losses for various meter sizes and flow rates. If your meter is a combination of two sizes (like 5/8 x 3/4) using the smaller size from the chart below is the safe way to go. These meters are made by taking one size meter and putting a different size inlet and outlet on it. The problem here is that I have no way of knowing which size it really is! But you may be able to figure it out. If you can figure out what size the inlet/outlet is, then you will know what you have. If the inlet is the smaller of the two sizes, then you know the meter is the larger size and you can use the larger size in the table below. If you're not sure just use the smaller size!
Find your meter size below, then use your "Initial Design Flow" (from your Design Data Form) to find the PSI loss. Enter the PSI loss from the table below on the water meter line of the Pressure Loss Table. If you don't have a water meter just enter 0 on the table.
5/8" meter:
5 GPM = 1 PSI loss
7 GPM = 2 PSI loss
9 GPM = 3 PSI loss
11 GPM = 4.5 PSI loss
13 GPM = 6 PSI loss
15 GPM = 8.3 PSI loss
Don't exceed 15 GPM
3/4" meter:
4 GPM = 0.5 PSI loss
8 GPM = 1 PSI loss
11 GPM = 2 PSI loss
14 GPM = 3 PSI loss
17 GPM = 5 PSI loss
20 GPM = 6.5 PSI loss
Don't exceed 20 GPM
1" meter:
8 GPM = 0.5 PSI loss
13 GPM = 1 PSI loss
19 GPM = 2 PSI loss
23 GPM = 3 PSI loss
26 GPM = 4 PSI loss
29 GPM = 5 PSI loss
32 GPM = 6 PSI loss
34 GPM = 7 PSI loss
Don't exceed 34 GPM
1 1/4" not a standard water meter size
If you have one it is probably a 1 1/2" with a 1 1/4" inlet and outlet. But, then again, it might be
a 1". What do you mean, that's not very helpful?
1 1/2" meter:
17 GPM = 0.5 PSI loss
22 GPM = 1 PSI loss
31 GPM = 2 PSI loss
38 GPM = 3 PSI loss
45 GPM = 4 PSI loss
50 GPM = 5 PSI loss
55 GPM = 6 PSI loss
60 GPM = 7 PSI loss
Don't exceed 60 GPM
2" meter:
36 GPM = 1 PSI loss
51 GPM = 2 PSI loss
63 GPM = 3 PSI loss
72 GPM = 4 PSI loss
82 GPM = 5 PSI loss
88 GPM = 6 PSI loss
100 GPM = 8 PSI loss
Contact manufacturer for larger size meters.
That wasn't hard, was it? We're gonna fly through this!
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