#1 Prevention of shear in sensitive materials
Pinch Valves are typically used in “on-off” applications; applications that don’t require flow control or modulation – you just want to start and stop the flow.
Conventional on-off valves often require the fluid to be regulated to move through a convoluted / complex flow path, even when fully open. This can be an issue for biological materials (proteins, DNA, etc) which can be easily “sheared” when forced through complicated paths.
Pinch Valves offer “line-of-sight” flow paths where the open tube, even if slightly pinched does not significantly block the flow path. Because of the slight venturi effect produced by the pinch, flow through the tubing can actually be enhanced rather than restricted.
#2 Handling of non-liquid effluents
Pinch Valves are often used on the waste side of instrumentation, “dumping” solutions to a collection device or simply out of the instrument. The waste stream can have many components; liquid, particulates, precipitates and coagulations inadvertently formed from mixtures of chemicals. These accumulated non-liquids can lead to coating on the inner surface of a conventional valve. The coating process is uneven and can eventually lead to the valve becoming clogged.
Pinch Valves offer a three-fold solution to this problem:
1. The tubing can be pre-treated to prevent the build-up of films. Bio-Chem Valve™ silicone tubing (link opens pdf data sheet) is Platinum cured which significantly reduces the possibility of film build-up.
2. The tubing is subjected to a very hard squeeze when the valve is closed. This squeeze is particularly effective in removing any film build-up
3. If the tubing does become blocked – it can quickly and easily be replaced without having to remove the valve from service.
Read more about Bio-Chem Fluidics Pinch Valves here…
Posted by John Tully