Pardon the pun, but check valves are fairly straight forward -- they ensure flow in only one direction. In most designs, the upstream fluid force pushes a spring-loaded poppet open, allowing flow. An increase in downstream or back-pressure force drives the poppet back into the seat, stopping reverse flow. But their simplicity shouldn’t be taken for granted. Chemical Processing spoke with Brian Strait, Business Development and Marketing Manager at Check-All Valve Mfg. Co., and learned that not all check valves are created equally.