The O-ring K 27276 is designed as the sealing element where metal tube K 27264 interfaces with fittings or housings in the ZV40/48 fuel pressure line. Its job is to create a fluid-tight joint against a smooth tube surface under high pressure and vibration. Typically specified from a chemically resistant elastomer compatible with diesel, the ring must be fitted to the correct groove and protected from scoring during assembly. Regular checks and prompt replacement of this O-ring prevent seepage at tube joints and help maintain stable injection pressure and engine performance.