An OPSO or SAV is a safety device for LPG pressure regulators. It prevents impermissible high overpresssure.
The OverPressure Shut Off (OPSO), former name: safety shut-off valve (SAV), is usually integrated in the fitting. It protects connected consumer equipment from inadmissible high pressure. If the outlet pressure exceeds the maximum, the OPSO responds and blocks the gas supply.
A diaphragm in combination with a spring monitor the outlet pressure of the fitting. If the maximum permissible value is exceeded, a bolt releases the spindle (see video). The gas flow is blocked.
Overview thanks to visual indicator
You can see whether the safety device has responded by the visual indicator. In normal mode, it is set to green. If the OPSO responds, it switches to red.
You can find more information on the GOK website.