Silo overpressure

[DrejzaVu]

I have aluminum silos for holding plastic pellets built to DIN 4119 (which I currently don't own). Per the drawing, they were built with a 0.5 psig overpressure. There is a pressure-vacuum vent valve on the top. The setting at 0.5 psig will provide insufficient relief capacity based on a calculated purge flow into the silo. Once the pressure gets up to 0.6 psig, the capacity is sufficient (per its curve). The question: Is this overpressure acceptable? Thinking of pressure vessels, they get hydrostatically tested at 150% of MAWP and PSVs can have 10% overpressure relief tolerance. Does anyone know the DIN 4119 standard who can tell me if there is necessary information to answer this question?