Vacuum devices for pressure molding, low-pressure molding, ingot molding, sand molding (metal casting); vacuum devices for injection molding (plastics); controls, valves, pneumatic installations and spare parts for these devices; devices for transporting molten metal and thermoplastic materials (for injection molding), particularly for automatic feeding of casting machines and of injection machines (plastics); installations for assembly and casting and injection molding, in particular under pressure, controls, valves, pneumatic devices and parts for these machines and installations