The core criteria for selecting the expansion tank and low-position tank of a thermal oil furnace are to match the total volume of the system's thermal oil, thermal expansion characteristics, and operational requirements, while also meeting installation, safety, and medium compatibility standards. The specific selection method is as follows:
I. Selection of Expansion Tanks
The core function of the expansion tank is to absorb the thermal expansion volume of the heat transfer oil, vent and remove moisture, and maintain system static pressure. The key to selection lies in volume calculation and structural matching.
1. Core parameters: Effective volume calculation
The effective volume of the expansion tank must be capable of accommodating the volumetric expansion of the heat transfer oil within the system from room temperature to the maximum operating temperature
2. Structural and Material Requirements
Material: Preferentially select Q235 carbon steel (low cost and suitable for conventional operating conditions); if the heat transfer oil contains corrosive components or the operating temperature exceeds 320°C, 304 stainless steel can be selected.
Structural attachments: Must include vent port (exhaust dehydration), overflow port (to prevent overpressure), level gauge interface, and oil inlet; a breather valve is recommended at the top (to balance internal pressure and prevent thermal oil oxidation), and sealing is strictly prohibited (to avoid thermal expansion causing overpressure in the tank).
Insulation: If installed outdoors or in low-temperature environments, an insulation layer must be added (to prevent the heat transfer oil temperature inside the tank from dropping too low, which could affect reflux).
3. Installation and Associated Selection
The installation height of the expansion tank directly affects the system's static pressure. During selection, it is essential to clarify: the bottom of the expansion tank must be at least 500mm above the highest point of the system. Therefore, the external height of the tank must match the available installation space on-site to avoid system air resistance due to insufficient height.
III. General Selection Considerations
Match system operating conditions:
If the system operates under negative pressure conditions, the expansion tank must be designed with negative pressure sealing and equipped with a vacuum vent valve;
If the system operating pressure is high, the wall thickness of the expansion tank and low-level tank must be checked according to pressure vessel standards (typically for atmospheric tanks, except under special operating conditions).
Safety and Compliance:
The tank must be electrically grounded;
When installed in explosion-proof areas, accessories (such as level gauges and heaters) must be explosion-proof.
If you want to know more about our product, please contact us!
Post time: Jan-15-2026
