The sinuses are air-filled cavities. 1  They are located: 2  Within the bony structure of the cheeks. 3  Behind the forehead and eyebrows. 4  On either side of the bridge of the nose. 5  Behind the nose directly in front of the brain.
An O-ring is a round ring that is used as a gasket for sealing a connection. O-rings are typically constructed out of polyurethane, silicone, neoprene, nitrile rubber or fluorocarbon. These rings are commonly used in mechanical applications, such as pipe connections, and help to ensure a tight seal between two objects. O-rings are designed to be seated in a groove or housing that keeps the ring in place. Once in its track, the ring is compressed between the two pieces and, in turn, creates a strong seal where they meet.
Rubber O-ring Seals-O'rings. PPE manufactures and supplies fully moulded and CNC machined elastomer O-rings from 1.5mm (0.06) to 2.5 metres (8ft) outer diameter and 0.8mm (0.03) to 12mm (0.47) cross section.All of the rubber O-rings we manufacture are available in both small quantities and large volumes.Standard and non-standard O-ring sizes.We hold a comprehensive range of standard O-ring moulds to BS1806, BS4518, AS568 and ISO3601.ubber O-ring Seals-O'rings. PPE manufactures and supplies fully moulded and CNC machined elastomer O-rings from 1.5mm (0.06) to 2.5 metres (8ft) outer diameter and 0.8mm (0.03) to 12mm (0.47) cross section.