Asco Scientific has developed a miniature inert solenoid valve using a “resilient” Kalrez1 seal. In the design of any analytical instrument one of the most critical components to consider are the solenoid valves used to control fluid flow. These must be free of the problems of leakage that can cause instruments to produce inaccurate analysis results. However, most of the inert solenoid valves on the market today use a solid PTFE diaphragm for sealing, which has inherent leakage problems. At the heart of any type of automated analytical instrument is the fluidic circuit. This is designed to reduce the amount of repetitive manual steps required to analyse a substance. It achieves this by automating the flow of various fluids, such as solvents, buffers, reagents, samples and cleaning solutions, through the analytical instrument. Key to this automated operation is solenoid valves, which are used to select between different fluids, divert flow, and dispense fluid. Solenoid valves are used because they are a relatively inexpensive way to electronically control fluid flow.
Asco’s new solenoid valve is an inert isolation valve (series 462) that uses a “resilient seal” against the valve seat. The series 462 uses a soft Kalrez1 disc inserted into a PTFE diaphragm. The PTFE diaphragm provides the rigid structure that isolates the fluid from the solenoid components and the Kalrez1 disc provides a very tight seal on the valve seat. As Kalrez1 is an elastomer, it has excellent sealing characteristics. It is also a very inert material; therefore it is compatible with the majority of solvents and reagents used in analytical instruments. In addition, the resilient nature of the Kalrez1 disc means that it is not easily scratched by particulate matter, as is the case with a complete PTFE diaphragm. Finally, if there is any particulate on the valve seat or deformation of the valve seat, the Kalrez1 disc will tend to conform around the particulate or deformation to provide a better seal than PTFE.
