Central Research Laboratories (CRL) researches, designs and manufactures machines and systems that allow human operators to safely perform dexterous maneuvers in hazardous, "unfriendly" or sterile environments through tele-operations. Some CRL products are used by pharmaceutical manufacturers utilizing isolator technology.

One of CRL's core product lines is the sterilization of pharmaceutical transfer equipment. A beta flange gasket for their 190 mm Rapid Transfer Port is sterilized by dry heat before transferring items from a beta bag or container into a sterile isolator. A heater control system is required to ensure the dry heat sterilizing temperature is maintained for the selected soak time.

Lethality rate (Fh) is a measure of a system's sterilization process. Typically, a programmable logic controller (PLC) system had been used to control the sterilization process to ensure a repeatable lethality rate. For CRL, the control elements that made up the system included a process controller, limit controller, solid state relay (SSR), mechanical contactor, control thermocouples, limit thermocouples, temperature transmitters and a heater assembly.

Problem:

PLC process controllers, while being very flexible, require extensive software validation in the pharmaceutical market. The FDA validation process requires significant resources from both CRL and its customers. By purchasing a standard controller with embedded code, this troublesome process can be greatly reduced, if not eliminated altogether.

Solution:

Watlow's new EZ-ZONE ST integrated control loop combines the functions of a PID process controller, overtemperature limit protection, SSR power switching, heat sinking, mechanical contactor power disconnect, profile ramp and soak in one easy-to-use package.

Results:

EZ-ZONE ST offers CRL many benefits, including multiple program ramp and soak capabilities for differing time and temperature profile sterilization needs; a reduction in installation time, particularly wiring and termination time; and a hardware controller that reduces the size of the control enclosure and reduces assembly cost. EZ-ZONE ST's multiple machine control inputs help ensure correct processing such as event input detecting the proximity sensor, event input to reset limit, event output indicating successful completion of the sterilization profile and diagnostics to detect input errors. Another benefit for CRL is the addition of a remote user interface, a lower-cost method than using a PLC.