Hydraulic surges can be generated within a matter of seconds anywhere that the fluid velocity changes and can travel through a pipeline at very high speed, damaging equipment or causing piping failures from over-pressurizing.
Surge control products have been used in many industries to protect the maximum working pressure of hydraulic system for decades.
A rupture disc is a sacrificial part because it has a one-time-use membrane that fails at a predetermined differential pressure, either positive or vacuum.
Advantages: Disadvantages: Surge relief valves are known for their quick speed of response, excellent flow characteristics, and durability in high pressure applications.
Surge relief valves are designed to have an adjustable set point that is directly related to the max pressure of the pipeline/system.
Pilot operated surge relief valves are typically used to protect pipelines that move low viscosity products like gasoline or diesel.
Advantages: Disadvantages: Piston-style gas-loaded surge relief valves operate on the balanced piston design and can be used in a variety of applications because it can handle high and low viscosity products while maintaining a fast speed of response.
An inert gas, most commonly nitrogen, is loaded on the back side of the piston forcing the valve closed.
When used in the closed end plenum system of a surge relief valve, it must also perform an on/off function to correct for thermal expansion and contraction.
Being a pressure control device designed for use under flowing conditions, it is not well suited to perform the on/off function needed in a closed-end system such as a surge relief valve plenum.
Another common issue is that regulators are required to operate outside of their design limits when making the corrections needed for thermal expansion and contraction.
As a result, inconsistent corrections are made to the system pressure which impact the gas-loaded relief valve's set point.