Negative pressure control of tubular heating furnaces.
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Regarding the negative pressure in tubular heating furnaces, some say it is 20–50 kPa, others say 20–40 kPa, and still others say it should not exceed 3 mm of mercury. Which one is correct? What is the basis for this?
In fact, it still depends on the manufacturer’s specifications – different heating furnaces have different requirements!
It should be 20–50 kPa.
Heating furnaces manufactured by different manufacturers have different structures and sealing conditions, resulting in varying negative pressures within the furnace chamber. We generally keep it between 35-45 PA.
The main goal is to ensure that the air required for combustion can be drawn into the furnace. A high negative pressure results in more air being drawn in, while a low negative pressure leads to less air being drawn in; either situation has an adverse effect on proper combustion. Positive pressure also causes flames to be ejected outward; therefore, the negative pressure in the furnace varies within a certain range depending on the type of furnace, the fuel used, and the method of air supply. In short, the furnace operates under slight negative pressure.
Generally, the negative pressure in the furnace below the convection chamber is controlled at -2 mmH2O gauge