How does a water storage tank work?
A water storage tank holds clean water from your reverse osmosis system until a demand for water is initiated in the house or business. Water is pumped into the tank from the water source, like a well or a reverse osmosis system. The tank accumulates water until it is full. When you need access to water, be it to fill your glass up with crystal clear water, run a bath, or irrigate a field, the storage tank provides you with instantaneous access to water.
Water storage tanks are generally either pressure tanks or atmospheric tanks. Point-of-use applications, like reverse osmosis storage tanks, usually implement pressure tanks. Outdoor applications or large scale municipal water storage operations usually use atmospheric tanks.
How do pressure tanks work?
Pressure tanks use compressed air to create water pressure within the tank. A pressure tank is constructed with an air chamber or bladder and comes with a pressure pre-charge. As the tank fills up with water, the weight of the water will begin to compress the air. As the air continues to compress, the pressure within the tank builds. When the tank reaches a certain internal pressure, it signals to the feed source to cease delivery. When you open a faucet in your kitchen, the air pressure bears down on the water as it is released from the tank, propelling pressurized water through your pipes and out of your kitchen sink. When water exits the tank, the air will start to expand again, reducing the tank pressure, and signaling to the water source to recommence delivery. If the pressure tank is being used to store well water, this means the tank will signal the well pump to turn back on. If the storage tank is collecting RO water, lowering pressure will signal the reverse osmosis system to restart production. These tanks are known as hydropneumatic tanks because they use the combined power of water and air to generate pressure within a tank.
Pressure tanks allow for pressurization without the aid of pumps. Since air will compress and water will not, the air within the tank will organically increase the pressure of the water as the tank fills up. There are also pressure tanks that do not rely on hydropneumatic pressure. These are known as constant pressure tanks. Constant pressure tanks provide city-like water pressure at all times, regardless of how many appliances are demanding water. A hydropneumatic tank can become overwhelmed if too much water is being drawn from it and sent to multiple sources concurrently (for example, if the shower is running at the same time as the dishwasher.) This results in a loss of pressure throughout the home. Constant pressure tanks use a sensor to monitor water pressure and keep the water in the tank at a stable, consistent pressure.
The optimal shape and dimensions for mixing tanks can be summarized in two words: It depends.
While the various components of a mixing system are often manufactured separately, determining the optimal specifications for any one of them requires an understanding of the entire system. The tank’s ideal shape and dimensions and the agitator’s ideal size and location are interdependent – and they all depend on the system’s specific purpose.
To find the optimal shape and dimensions for a mixing system, it is important to keep that purpose in mind, while considering the advantages and disadvantages covered in this article.
Determining the optimal height
To find the optimal height to diameter ratio for a mixing tank, it is important to keep in mind the tank’s specific purpose. Generally, both narrow and wide tanks have their advantages and disadvantages.
The narrower a tank is, the better its heat transfer will be – a factor that can be critical for certain mixing scenarios. Additionally, wider tanks require wider agitators – and because wider agitators need more torque, they require larger shafts and gears, which are more expensive.
On the other hand, a narrower tank will require a higher-speed agitator with a longer shaft, giving the tank a lower critical speed – a factor that can be a major problem for certain mixing purposes.
Considering cylinders
Cylindrical tanks are a common choice, not least of all because they are relatively inexpensive to manufacture.
In a cylindrical tank with a centrally positioned agitator, low-viscosity liquids can begin to swirl – a phenomenon that can prevent a solution from becoming homogeneous. In order to prevent swirling, it is common to install a baffle within this type of tank. But while baffles are an effective solution to the problem of swirling, they also complicate the clean-in-place (CIP) process, making it take more time.
