b'Sealing Unless otherwise stated all machines are designed for operation in unsealed vessels at atmospheric pressure.Where sealing is required machines can be supplied with the appropriate shaft sealing and mounting flange as an optional extra.V-Ring Shaft SealThis is the simplest form of shaft sealing and is designed to prevent the possible ingress of material from outside the vessel. It is also used to minimise vapour loss from the vessel and prevent liquid escaping if a spray ball is used.Single Mechanical Shaft Sealing If the vessel needs to be fully sealed, mechanical shaft sealing is necessary. The mixer shaft is sealed where it passes through the mounting flange by a single mechanical shaft seal. This seal is surrounded by a quench cup which must be filled at all times during operation with a compatible non-flammable fluid to cool and lubricate the seal. This type of arrangement is suitable for operation at atmospheric pressure or vacuum only.Double Mechanical Shaft Sealing Where there is positive pressure in the vessel, double mechanical shaft seals will be required. The seals are mounted in a chamber that must be flushed with a compatible non-flammable fluid at a pressure not less than 1 atmosphere (15 psi) in excess of the pressure in the vessel. This type of arrangement is suitable for operation under positive pressure, atmospheric pressure and vacuum. Sealant flushing systems can be supplied as an optional extra. Gas lubricated non-contacting double mechanical shaft seals are also available.Silverson.com 22'