Expansion tanks are necessary for use in thermal fluid systems. The expansion tank collects the overflow of thermal fluid created as its volume expands due to heating. The size or capacity of the expansion tank is based mainly on the amount of thermal fluid in the system and the temperatures to which it is heated. One expansion tank is normally used for each heater. However, a backup heater may not require a separate expansion tank.
Larger tanks are usually mounted on separate skids whereas smaller ones are usually mounted on the heater. Mounting the tank on a separate skid provides more flexibility in layout and arrangement of the system components, especially if the tank is unusually large. Moreover, related pumps can also be mounted on the skid.
Expansion tanks are not normally insulated, unless there is concern that workers may accidently touch a hot tank and receive burn injuries.
A nitrogen system is available to provide a nitrogen blanket inside the tank to minimize oxidation of the thermal fluid and prolong its life.
Pump skids we build are usually adjuncts to our heaters and may also include the expansion tank. They usually stand alone, separate from the heater. They may include multiple pumps, including a back-up pump needed if the system cannot be shut down for maintenance.
Use of separate skids provides flexibility in plant layout and eliminates the need to incorporate them in the heater skid.