Pressure vessels, piping systems, and many other types of equipment widely in use today are designed with a specific design pressure in mind, and when this is exceeded, problems can often occur. For this purpose, back pressure relief valve manufacturers produce the industrial axial flow fan equipment necessary to prevent overpressure from occurring.  This article will seek to explain the sizing and selection of these units in order to help you chose the most appropriate back pressure relief valve for your desired application. First of all, back pressure relief valve manufacturers recommend that you only select the valves to use in your system if you are 100 percent certain of what your system requires in order to remain protected.
It is not simply enough to try and match the size of an available vessel nozzle, or pipeline size, to the one that you will be replacing. Instead, it is crucial that you use the following three step process.1. Every piece of equipment must be examined to be certain that it meets the minimum overpressure requirements. 2. Each vessel must possess an appropriate design basis. Choosing the optimal basis for your design will often entail assessing several worst case scenarios to find the one that is most possible.3. Once you have found your design basis, this will be used to figure out which valve size will be necessary. Another piece of equipment that is essential in many systems in order to prevent overpressure from occurring is the back pressure regulator valves.  
These are typically used as bypass valves that can help maintain a constant pump discharge pressure. It can be used on systems that hold chemicals or corrosive liquids, but only when the proper materials are used. It is important when selecting this type of unit that you take care not to oversize it, even when the surrounding components are themselves oversized. If the liquids in the system may contain pollutants that can cause obstructions, be sure to use a filter or strainer before the inlet of the valve. Probably the most difficult problem that back pressure relief valve manufacturers face is determining the right required relieving capacity. However, there are many tried and true processes at their disposal which can make things go easier. It is important that these valves are designed to protect against the worst case scenarios in order to protect against them on a daily basis.