Telstar has developed a new chamber/condenser main isolation valve for application in GMP industrial freeze dryers. The cartridge mushroom valve (CMV) is less complex and easier to maintain than other valve types, thereby providing enhanced process safety.
The valve uses rotational movement which enables elimination of the protective bellows system that characterises the conventional mushroom valve. This decreases the risk of leakage and therefore provides a greater level of process safety, the company says.
The valve can either be installed in new freeze dryers or retrofitted to existing units currently equipped with butterfly valves. Companies using GMP industrial freeze-dryers with butterfly isolation valves incorporated between the drying chamber and condenser now have the opportunity to take advantage of the benefits of a mushroom valve. The CMV fits in the space normally occupied by a butterfly valve.
Unlike conventional mushroom valves, the CMV mechanism is driven by a rotary actuator that moves a link system comprising three articulated arms. The third of these arms is directly attached to the main shaft of the valve. The valve main disc is connected to the shaft by two independent links. The first link (double) connects the shaft to a bracket attached to the disc, while the second connects the shaft to the valve body. The precise combination of geometrical location and length of the two links converts the rotation of the main shaft onto a linear movement of the disc against the valve seat. In addition, the link system between the shaft and the actuator is arranged as a toggle joint that is self-locking when the valve is in the closed position; this provides a reliable and stable leak tightness of the valve.
While designing a mushroom valve into new equipment is a relatively straightforward task, retrofitting a mushroom valve to existing equipment has until now not been an affordable proposition, the company says.
The valve is provided with lifting lugs to ease its installation in the freeze dryer. The linear actuator typically used to operate mushroom valves has been replaced by an innovative mechanical system that results in a mushroom valve with a compact design. The very small size of the new valve enables users to install it in a space as narrow as that required for a butterfly valve.
In addition, gaskets have been minimised to reduce elastomer surfaces in contact with the process and engineered for easy cleaning and sterilisation. The valve design uses standard O-rings rather than the custom elastomeric moulded seals of a butterfly valve and achieves the same leak-tightness as a conventional mushroom valve without the use of a sealing bellows.
Hall 3.1 Stand C49
