Double butterfly valve is one type of long pattern butterfly valve. It's one type of high performance butterfly valve, which is with eccentric action reduces torque and seat contact during operation extending valve service life. Its seat can be repaired on site, no need dis-assembly. The double flanged eccentric butterfly valve is suitable for 90° on-off operation and regulation service. The double eccentric butterfly valve long time face to face is according to EN558-1 series 14.