Percent Time
Calculate the percent-time pump feed setting for solid chemistry programs on cooling tower controllers that use fixed-interval feed events. Enter system makeup, cycles, dosage, solution strength, pump parameters, and feed event interval to get the controller feed setting and daily solution demand.
Understanding Percent-Time Feed
- What is percent-time pump feed?
- Percent-time feed runs a chemical metering pump for a set fraction of each fixed-interval feed event. The controller turns the pump on for that percentage of the cycle, delivering the daily solution demand in evenly spaced doses.
- When should I use percent-time versus proportional feed?
- Percent-time control suits systems with relatively steady load and predictable makeup. For variable-load systems whose makeup swings, proportional (per-water-meter-pulse) feed tracks demand more accurately.
- What pump settings affect the percent-time result?
- The pump’s rated capacity plus its speed and stroke settings determine actual output; together with the feed-event interval and the program’s solution demand, they set the percent of time the pump must run.