Meter Capacity Rules
Calculate maximum flow rates and pressure loss through water meters. Essential for sizing irrigation systems within meter capacity limits.
Water Meter 75% Flow Rate Rule
Calculates the maximum recommended design flow rate for your irrigation system based on your water meter size.
Max Design Flow Rate (75%)
37.5
GPM
Why This Matters
The 75% Rule is a safety standard to protect your water meter from premature wear and ensure its accuracy. Running a meter at 100% capacity for long periods (like during irrigation) can cause damage. Your system's total GPM for any single zone should not exceed this calculated design flow rate.
How to Use These Rules Together
When sizing a system, you must satisfy all capacity rules. The most restrictive one "wins":
- The 10% Rule: Meter pressure loss must be less than 10% of static PSI.
- The 75% Rule: Your peak zone GPM should be less than 75% of the meter's max rating.
- The Velocity Rule: Water speed in your pipes should be less than 5 feet per second (FPS) for PVC to prevent water hammer.
Water Meter 10% Pressure Loss Rule
Checks if the pressure loss from your water meter is within the acceptable 10% limit of your static pressure.
Find this value in the manufacturer's chart for your meter size and flow rate.
Passes 10% Rule
Calculated Pressure Loss
8.3%
Why This Matters
To ensure your system has enough pressure to operate correctly, the pressure lost through the water meter should not exceed 10% of your total static pressure. If it fails, you must either reduce the flow rate (GPM) going through the meter or use a larger meter.