Foam density is quoted in kilograms per cubic metre. For refrigeration panels and cabinets, polyurethane foam is commonly specified at roughly 38 to 42 kg/m³. In that range the foam has small, uniform closed cells that trap gas well, enough strength to stiffen the walls, and good adhesion to the metal skins.
Higher density is not automatically better. Above a certain point the foam gets stronger and heavier but conducts slightly more heat through the solid plastic. Lower density saves material but can leave the foam weaker, more prone to shrinkage and with larger cells that insulate less well over time.
For a buyer, density is mostly relevant when comparing cold-room panels or specifying custom insulated enclosures, where a supplier should state the foam density and core thickness. For plug-in cabinets, the practical signs of good foam are straight, rigid walls that do not flex when pressed, and no sweating on the outside in humid weather.