I tried to search on the internet for the answer to this question and was immediately overwhelmed with big long technical terms and definitions that really did not seem to answer the simple question of “what is a balance tank?”, and also how does it work. I was also constantly clicking on what seemed to be possible answers to these 2 simple questions, but were actually advertisements for companies toting about how amazingly balanced their balance tanks are.
After sorting out ads and the overly complicated explanations about how balance tanks work in specific applications, I was able to create a definition and understanding that I, as well as anyone without an engineering degree would understand. A balance tank takes and holds a fluid that is coming out at different and variable speeds so that it can release it at a specific uniform level of output. To give you an example of this, imagine a pipeline at the sewer treatment plant is carrying waste from the sewers, pipes and toilets of a town. All of that sewage and waste is coming in at variable levels and amounts. Unfortunately, the treatment center needs to have an even flow of waste to ensure that it can run efficiently and avoid air getting into the treatment process. In comes the balance tank! The Balance tank will take the non-uniform inflow of waste and make sure it enters the treatment center equipment at a uniform speed and level of pressure without any added air.
So, the next question that I had after finding the answers to what a balance tank is and how it works was “Where do balance tanks get used and how are they used?”. I have already used the sewer treatment plant as an example of one place that balance tanks can be used but balance tanks are very versatile and a necessary part of the manufacturing of a wide variety of goods such as dairy products, water products, oil and many more.
Sanitary HTST balance tanks are used in the dairy industry and any other industry that produces products for human consumption. The reason that they are called “Sanitary”, is because they are made of 304 or 316 grade stainless steel. This grading of steel is necessary to keep the products sanitary and to avoid contamination and HTST stands for High Temperature/Short Time. The balance tanks also need to be PMO compliant, which stands for Pasteurized Milk Ordinance. This Ordinance was put in place by the US Public Heath Service in 1924 when they developed the standard Milk ordinance to facilitate states that had voluntary pasteurization programs. The Pasteurized Milk Ordinance (PMO) was put in place for Grade A Milk and is now sometimes referred to as the regulatory gold standard in the US Dairy Industry. A Sanitary HTST PMO Compliant Balance tank allows there to be a constant supply of milk. There is a part inside the balance tank known as the Float assembly valve and this piece of equipment is able to control the liquid level and ensure that the level is constant. This ensures that the head pressure on the milk or product leaving the tank is even and uniform at the level needed. The balance tank is also able to prevent air from entering the pasteurizer by creating a downward slope inside the tank. This is done by simply placing the top of the outlet pipe lower than the lowest point of the tank. (see diagram)
SOURCES
What is a Balance Tank and Why is Maintaining Consistent Pump Head Important?
hollandaptblog.com/2014/03/25/what-is-a-balance-tank-and-why-is-maintaining-consistent-pump-head-important/
Balancing tanks
https://www.nottingham.ac.uk/etc/sol_b_tanks.php
UV Solution for PMO Compliant Pasteurized Equivalent Water
smithengineeringinc.com/uv-solution-for-pmo-compliant-pasteurized-equivalent-water/