The use of two rupture discs in combination allows the process to continue safely after one disc has been destroyed as the process is still secured by a second (closed) disc. For this reason, production processes that use toxic or corrosive media or have variable or high back pressures are often protected by two rupture discs installed in series. These can either be installed individually or more elegantly in a double disc assembly rupture disc holder. This also makes it possible to use different types of rupture disc in combination, e.g. a three-section rupture disc and a reverse acting rupture disc. Likewise, the two rupture discs can be designed to respond at different pressures. The space between the two discs is monitored to ensure that no back pressure builds up and any leakages due to corrosion of the primary rupture disc are identified immediately.
The response pressures of the two discs depend on the operating conditions. Double disc assemblies are installed as insert units between welding neck flanges to DIN or ANSI standards. The flow direction must be observed during installation.