Effect of fluorine-containing explosion suppressants on methane explosions

To investigate the suppression effect of fluorine-containing explosion suppressants (FESs) on methane (CH₄) explosions and the corresponding suppression mechanism, a 20-L spherical explosion testing device was used to analyze and compare the effects of perfluorohexanone (C₆F₁₂O) and heptafluoropropane (C₃F₇H) on CH₄ explosion parameters. The explosion limit and pressure were obtained before and after adding these FESs. CH₄ explosion triangles under the action of the FESs were drawn, and the explosion hazard degree (F) was determined. The results reveal that the addition of C₆F₁₂O and C₃F₇H reduces the upper explosion limit (UEL) and lower explosion limit (LEL) of CH₄, with increased concentrations of C₆F₁₂O and C₃F₇H causing faster decreases in the UEL than in the LEL. The explosion limit range of CH₄ with C₆F₁₂O is smaller than that with C₃F₇H. When the concentration of CH₄ is low, increases in the C₆F₁₂O and C₃F₇H concentrations first cause an increase and then a decrease in the explosion pressure, and the rise rate of explosion pressure increases. After adding the aforementioned FESs, F first increases and then decreases. When the concentration of CH₄ is high, the two FESs only inhibit the explosion pressure. Compared with C₃F₇H, C₆F₁₂O has a stronger inhibitory effect; C₆F₁₂O has a smaller CH₄ explosion triangle area, higher critical oxygen concentration (18.27% vs. 17.70%), and lower F value. Both FESs have promotion and inhibition effects on CH₄ explosion because of the comprehensive physical and chemical effects on CH₄ explosions; however, the performance of C₆F₁₂O is superior to C₃F₇H.