Water Pressure tanks

Water pressure tanks for sale

What is a Pressure Tank ?

It is a tank that consists of a diaphragm or bladder that separates the tank into parts, the compressed air section (upper section for vertical tanks) and the water section (lower section for vertical tanks).

How does it work?

As the pump pushes water into the tank it compresses the air inside the tank's diaphragm. Once water valves are opened inside the house the compressed air pushes the water out of the tank towards the house.
The pressure tank works in conjunction with a pressure switch which will switch on/off the pump when the pressure drops below the set value. With Pressure Tanks, the term 'Drawdown' is commonly used and it refers to the amount of water available in the tank between the pump turning on and off.

Advantages of Pressure Tank

• It acts as a water reservoir allowing water to be pushed out from the tank without the pump cycling. This protects and increases the lifespan of the pump.
• They control the water pressure which eliminates air from water pipes and thereby reducing water hammering .

How do I size a Pressure Tank ?

In terms of pressure tanks, size matters, usually, the bigger the better. A tank of the right size prolongs the pumps life by eliminating cycling (turning on and off rapidly which causes the motor to heat up). Big tanks mean a large draw down and therefore less cycles. A minimum runtime of 1 minute is
recommended by most manufacturers for 0.75kW motors or less to ensure sufficient cooling operation.
For motors larger than 0.75kW the runtime is longer(2 minutes or more).

To size a tank you need the following:

  1. Pump flow rate in litres per minute (L/min)
  2. Minimum runtime for the pump
  3. Cut-on and cut-off pressure

Tank Drawdown = runtime X flow rate Nb: Drawdown is not the same as the tank capacity, it is usually less than the tank capacity.
To calculate the tank capacity Boyle’s Law may be used

P1 = pre-charge absolute pressure
P2 = The cut-in absolute pressure
P3 = The cut-off absolute pressure

Can a Water Pressure Tank Explode ?

A pressure tank can explode if the working pressure inside the tank exceed the pressure it was designed for. If the water temperature falls below freezing point a tank may explode. There has been few incidents reported about pressure tanks exploding.

When to Replace/Repair a Water Pressure Tank ?

A ruptured bladder, leakage and water-logging in the tank are some of most common problems experienced with water pressure tanks. The signs below alerts the user that there might be a problem with the tank.
• The pump cycles on and off
• water pressure has been reduced.
• The runtime has reduced to about 30 seconds.
• Corrosion being seen on the tank’s exterior.
• The pressure gauge shows lower pressure than usual.
• Pump remains running.
• Presence of air in the pipes.

If you notice the above signs you might need to contact a professional to perform further inspections or it means it is time to replace the tank.

Highest Quality Pressure Tanks

We offer a full spectrum of pressure vessels for heating, thermal, pressure booster, water hammer, reverse osmosis and water well applications.

Please contact us for more information