Telstar, part of the azbil group, has developed a new chamber/condenser main isolation valve for application in GMP industrial freeze dryers.  The ‘Cartridge Mushroom Valve’ (CMV) is an innovative solution with less complexity and easier maintenance; providing enhanced process safety. The new valve has been designed to operate using rotational movement in a manner which enables elimination of the protective bellows system which characterizes the conventional mushroom valve. This decreases the risk of leakage and therefore provides a greater level of process safety.

The new valve has been designed to be either 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 readily attain the benefits of a mushroom valve. The new Cartridge Mushroom Valve has been carefully designed to fit in the space normally occupied by a butterfly valve. Furthermore the new CMV requires less maintenance than a traditional mushroom valve.

Unlike conventional mushroom valves, the Cartridge Mushroom Valve mechanism is driven by a rotary actuator that moves a link system comprised of three articulated arms. The third of those 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 link 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 it 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 valve is provided with lifting lugs in order to ease its installation in the freeze dryer. The linear actuator typically utilized to operate mushroom valves has been replaced by an innovative mechanical system that results in a mushroom valve with an extremely compact design. The very small volume of the new valve enables end-users to install it in a space as narrow as that required for a butterfly valve.

Gaskets have been minimized to reduce elastomer surfaces in contact with the process and have been engineered for easy cleaning and sterilization. The valve design utilizes standard O-rings rather than the custom elastomeric molded seals of a butterfly valve and achieves the same leak-tightness as a conventional mushroom valve without the use of a sealing bellows.