CSLB C-36 Plumbing ContractorFixture and Appliance InstallationHard
A plumber is installing a water softener for a residential client. The client's main water line is 1 inch in diameter, and the peak flow rate requirement for the household is estimated at 12 gallons per minute (GPM). The water softener manufacturer specifies that the system should be sized to handle 75% of the peak flow rate to avoid excessive pressure drop and ensure adequate treatment time. What is the minimum service flow rate the water softener should be capable of handling?
- A12 GPM
- B9 GPM
- C16 GPM
- D7.5 GPM
Show answer & explanationAnswer & explanation
Correct answer: B. 9 GPM
To calculate the minimum service flow rate, multiply the peak flow rate by the specified percentage: 12 GPM * 0.75 = 9 GPM. This ensures the softener can effectively treat the water during typical peak usage without significant pressure loss.
Why the other options are wrong
- A. 12 GPM is the peak flow rate, but the manufacturer specifies sizing for 75% of peak, not the full peak.
- C. 16 GPM is higher than the peak flow rate and not derived from the 75% rule.
- D. 7.5 GPM is 62.5% of the peak flow (12 * 0.625), which is less than the required 75%.
Water Softener Flow Rate Sizing
The process of determining the appropriate service flow rate capacity for a water softener based on household peak demand and manufacturer guidelines to ensure efficient operation.
- Based on peak household water usage (GPM).
- Often sized to handle a percentage of peak flow to balance treatment and pressure.
- Incorrect sizing can lead to pressure drop or inadequate treatment.
Memory trick: Peak flow then percentage, for a softener with good advantage.