More Safety and Reliability Thanks to the New AGSZ Gas-Lubricated Agitator Seal from Burgmann
14 November 2007
The new AGSZ agitator seal from Burgmann Industries Wolfratshausen/Germany is a logical enhancement to the manufacturer's gas seal portfolio for low RPM machines in the chemical, pharmaceutical and food industries.
The Burgmann AGSZ functions properly regardless of the direction of rotation, and it is designed for use on top drives in tanks with standardized connections. Only two parts need to be replaced to convert the AGSZ481 for steel tanks with connecting flange (DIN 28141) and shaft end (DIN 28154) to the steel-free AGSZ461 version for enameled tanks with flange (DIN 28137 T2) and shaft (DIN28159). The seal does not need to be removed in sterile applications which comply with CIP/SIP cleaning/sterilization requirements.
The central rotating seal made of solid silicon carbide (SiC) has wider sliding faces which produce a gas film of much greater stability. The result is safe, non-contact operation even in rugged agitator applications. Buffer gas consumption has been reduced by 75% compared to the previous model (AGS), and leakage measurement variations remain within a much smaller range. The stationary spring-backing of the seal faces makes the AGSZ less sensitive to radial movement such as shaft wobble or shaft skew. Stationary design, which has a proven track record on pump seals, is now being used on agitator seals.
A specially designed clamping ring for torque transmission allows up to 2 mm axial movement of the shaft. The floating bearing on the shaft is integrated into the seal. Acting as the fixed bearing between the rotating shaft bushing and the stationary housing, it provides effective protection against the negative effects of movement at the sealing gap.
Very good emergency running characteristics in the start-up and slow-down phases or during failure of the buffer gas supply are guaranteed by the high-strength coating on the seal faces. Being double-balanced, the seal remains closed even when there is no buffer gas. A reduction in the number of wearing parts helps to reduce maintenance costs and simplifies installation.
