Pressure tank

A pressure tank provides the 5-7bar / 75-100psi pressure to the misting nozzles.

Table of contents

Tank assembly

The pressure tank has three 3/4" threaded tee fittings (one all-male and two male-female-male) attached to its 3/4" male threaded connector, creating four connection points:

Pump input: Connecting the Discharge side of the pump
Bypass output: Connecting the Bypass intake of the Spray+Bypass assembly
Spray output: Connecting the Spray intake of the Spray+Bypass assembly
Drain tap output: Connecting to a ball valve tap for manually draining the pressure tank

Pump attached above the pressure tank on the Aeroponics table:

Air chamber pressure

The pressure tank's air chamber should be pressurized slightly below the low-pressure limit when there is no water in the tank. The red line in the below graph shows how fast the nutrient pressure drops with different air chamber pressures. Each spike represents a tank refill, notice how much more often the tank needs to be recharged when the air chamber is incorrectly pressurized. With the correct pressure, 12 misting heads and a 1-second spray duration around 0.1 bar / 1.5 psi is lost at each misting cycle, meaning the tank needs to be recharged every ~2 hours (Low limit: 5 bar / 72.5 psi, High limit: 7 bar / 101.5 psi )

Drain tap

A ball valve tap provides a way to drain the pressure tank and reservoir during maintenance. The tap has a 3/4" connector just like the washing machine hose connecting it to the Drain tap outlet of the pressure tank.