Tanks are commonly used in many industries. No matter the type of tank whether it is for storage, cooking or processing, there are questions that need to be asked before purchasing a tank.
What size tank do you need?
Tanks are measured by the amount of product they can contain; in the US most tanks are measured by the number of gallons it holds (other countries may use liters, imperial gallons, and cubic feet). To determine the capacity of a tank, first measure the inside diameter of the vessel and the straight side (length of the cylinder).
When purchasing a tank, make sure you buy something a little bit larger than the actual number of gallons you intend to use. Keep in mind, if you are going to use a mixer you may have to account for vortexes and splash. Hopefully your business will grow and buying a larger tank will give you some time before you need to upgrade.
(When looking at purchasing a tank you will have to ship double check the circumference. Anything at 102 inches or below can be shipped standard. If it is above that you may need special permits or routing. )
What kind of composition should the tank have?
Stainless steel is most often used for holding product that has to be kept in sanitary environments. It has a smooth finish, so as not to allow product to accumulate in its walls. Stainless steel is resistant to corrosion and is quite durable. Most often used in the food, pharmaceutical & chemical industries stainless steel is extremely versatile. Stainless steel will most often be from the 300 series. 304 or 316 are the most common. Because of the chemical makeup of 316, it can be used in more corrosive environments. To learn more about the different types of steel Click Here
Steel is considered Carbon Steel if it contains less than 2.1% carbon and has low alloy. Over time carbon steel will corrode. Carbon steel can be pitted so product can become trapped in the tank. Carbon steel tanks are usually not considered sanitary and will primarily be used for chemicals or waste water.
Note: Tanks made of either stainless steel or carbon steel are measured by their gauge. The smaller the gauge the thicker it is. This chart refers to the thickness in inches and weight of the gauge. If your product will require a higher pressure or even the ability to handle internal reactions, the wall thickness will require a heavier gauge.
Plastic and Fiberglass tanks are used for corrosive material such as gasoline or vinegar.
What are your process requirements?
If your product needs to be heated or cooled you may need to consider a jacketed tank. Jacketed tanks possess an outer shell from the inside of the tank that allows steam, hot water, or hot oil to circulate in order to heat the product inside of the tank. Cooling tanks are also jacketed and use mediums such as glycol or other forms of coolant to ensure the contained product remains at a cooler temperature.
If you need to prevent the temperature from rising or dropping too fast, an insulated tank is often used. If a tank contains a product that is hot in temperature, the insulation will prevent a person from burning themselves. Insulated tanks are usually cheaper and if you don’t need to heat or cool your product but need to minimize temperature changes this may be a good alternative.
For reactions, using a glass lined tank is often times the best choice. A glass lined tank will have the entire interior lined with glass. Glass lined tanks are exceptionally strong and are often used as reactors in chemical and pharmaceutical processes.
There are times when a product may need to be mixed inside of a tank and an agitated tank will provide this ability. Mixers come in all shapes and sizes from a simple propeller type mixer to a large, heavy duty, sweep agitated mixer with single, double or even triple motion agitation.
- Propeller Type Mixers are usually driven by an electric or air powered motor that is connected to a stainless steel shaft with a three blade rounded propeller clamped to the other end.
- A Turbine agitator is similar in that it has a motor at the top and a shaft but there are usually four rectangular blades connected to the other end.
- Single Motion Agitators always spin in one direction and usually run along the bottom of the tank and often have arm extensions up the side walls sometimes with scraper blades attached.
- Double Motion Agitators are similar to the single motion but they have two shafts that counter rotate causing a much more volatile mixing of the product. More agitation can be added to make a triple motion agitation by simply adding a third blade running at a different RPM.
Covers on tanks are typically either a dome top or a flat top. The cover can be welded on or remain open top with hinges or flip up. If they are welded they might have a manway on the top. A manway is a hole between 18-20 inches so that a person can get inside the tank to clean. A cover may also have a site glass, a port(for things like mixers, or an infeed for product to enter.
After you have finished storing or mixing your product, you will need to drain the tank. Tank bottoms can be cone, dish, flat, convex or a slant and usually have an outlet either in the bottom or in the side near the bottom. A tank with a cone bottom will have much more positive flow while a tank with a flat bottom may not drain completely.
At the bottom of the tank there will be an outlet for drainage. Outlets require a fitting in order to attach a valve. If you need to keep things sanitary, make sure to ask about the valve because not all valves are considered sanitary. If your product requires a sanitary valve, you will need either a Tri-Clamp Fitting or Sani-Thread Fitting to connect the valve to the outlet. If you do not require the outlet to be sanitary then you can also use a non-sanitary threaded fitting. Valves are what allow the product to either stay in the tank or flow from the outlet at the bottom. Ball Valves, Butterfly Valves and Gate Valves are three styles that can be used to allow product to flow after it is ready to move on to the next part of your manufacturing process.