Pressure Tank - 18 Litre

Pressure Tank - 18 Litre
$139.00 each

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These quality pressure tanks are used to store water while the pump is running. The stored water is released until the pressure has reached the cut-in pressure of the pump controller (pressure switch or digital controller). The larger the tank size, and/or the larger the pressure difference between cut-off and cut-in, the more water is stored in the tank.

These tanks are ideally suited for a wide range of applications, including booster systems, thermal expansion, irrigation systems and hydraulic hammer arresting.


  • 5 year warranty
  • Patented stainless steel connection, 25 mm / 1" BSP thread size
  • Long life butyl food grade & bacteria resistant membrane
  • This "Pressure Wave" tank is designed to screw onto the pump or fitting (mounted upright), using the 25 mm BSP connection
  • Maximum pressure: 1,000 kPa

 Please note that the diaphragm can not be changed. When the diaphragm ruptures, the tank becomes inoperable. This is common for many pressure tank manufacturers today.


Size Considerations:

  • More water is stored in a given size tank by increasing the pressure difference between the cut-in and cut-out pressures of the pump
  • Larger tanks require less pump starts per hour, so save electricity compared to smaller tanks. Pumps draw high power at start-up, so the fewer times a pump needs to start the less electricity is wasted.
  • As a guide, electric motors should not be started more than 30 times per hour, or much less in the case of submersible bore hole pump motors (this is given by the manufacturer). For Franklin electric submersible bore hole motors, the maximum number of starts per hour is 4 (for motors 0.75 to 4 kW) or 2 for motors 5.5 to 22 kW.
  • As a rule of thumb for jet and centrifugal pumps, as a worst case scenario a pump may start and run for 1 minute, then rely on the pressure tank to run for 1 minute. To use this approximation, use a tank with the draw off volume being equal to the flow rate of the pump at the cut-out pressure.


  • HJ200 pump operating on a pressure switch setting of cut-in of 29 psi (200 kPa), and cut-out of 51 psi (350 kPa).
  • The flow rate at 51 psi is about 15 Litres/minute.
  • Looking at the draw off table in the 20-40 psi (or 150-300 kPa) range, a suitable tank would be either a 35 Litre or 60 Litre tank.
    Please note that often smaller tanks are used, and these will work (long runs of poly pipe will also act as pressure tanks as the poly expands and shrinks with pressure). However while smaller tanks are cheaper to buy up front, more frequent pump starts will cost more over time (in terms of wasted electricity).

 Note: if you are designing a pressure tank for a submersible bore hole pump, do NOT use a pressure tank that is too small. Exceeding the maximum number of starts per hour as stated by the motor manufacturer (eg Franklin) can cause the motor to overheat and burnout!