A pressure stabilizing tank is a prerequisite for a water pump to enter sleep mode. It utilizes the property that water has very low compressibility, using external force to store water in the tank. The gas is compressed and the pressure increases. When the external force is removed, the compressed gas expands and can expel the water.
The pressure tank mainly consists of a valve cover, inflation port, air bladder, carbon steel tank body, and flange. When connected to a water system, it primarily functions as an accumulator. When the system water pressure exceeds the nitrogen pressure between the carbon steel tank body and the air bladder, the system water is forced into the air bladder under the system pressure. This process compresses the nitrogen between the tank body and the air bladder, reducing its volume and increasing its pressure. The nitrogen between the tank body and the air bladder is pre-filled at the factory. The tank body has a painted coating, and the inlet and outlet are directly connected to the system via tees or metal hoses. The vent valve can promptly release any air overflowing from the system and the air bladder, or it can be directly closed with a gate valve to prevent water from overflowing from the top. Below the dust cap are the inflation and deflation ports, which can be used to replenish nitrogen or release some gas. Secondly, this process increases the overall water capacity of the system, reducing the system pressure until a new equilibrium is reached between the system water pressure and the nitrogen pressure between the tank body and the air bladder, at which point water intake stops.
When the system water pressure is lower than the gas pressure inside the expansion tank, the water in the air bladder will be squeezed out by the pressure of the nitrogen gas between the tank and the air bladder and return to the system. The system water volume decreases and the pressure increases, while the nitrogen gas volume between the tank and the air bladder increases and the pressure decreases, until the two reach a new equilibrium. At this point, the water stops being squeezed back into the system from the air bladder. The pressure tank plays a role in regulating the system pressure fluctuations.
Selection formula for pressure stabilizing tank in variable frequency water supply equipment:
To avoid frequent pump starts, the regulating volume of the pressure tank should meet the pump flow rate (L/min) for a certain period of time. The calculation formula is as follows: V=K×Amax
K = Pump operating coefficient, which varies with pump power, as shown in the table below:
P(HP) 1-22-45-89-12＞12
K0 . 250. 3750. 6250. 8751
Amax = Maximum flow rate of the water pump (L/min)
Pmax = Maximum operating pressure of the water pump (pressure of the system when the water pump stops)
Pmin = Minimum operating pressure of the water pump (pressure of the system when the water pump starts).
Ppre = Pre-charge pressure of the pressure stabilizing tank
V = Volume of the pressure vessel
1 HP (horsepower) = 0.735 KW
