We operate four types of leak testing, including water tank testing, and burst testing. Every coil and connecter that we make gets tested for leaks . Bubble Leak Test. Every coil is subjected to an underwater bubble leak test at a minimum 380 psi. For higher pressure applications, we apply 600 psi up to 1,000 psi, according to our customer specifications. Tests are normally conducted for 10 minutes to identify leaks in brazing, which are then identified, marked and repaired.