Check valves are ubiquitous in all sorts of piping systems. Although they may be familiar to plumbing and mechanical contractors, the more than half dozen different types of check valves are designed for different functions and types of service. Contractors need to take care to select the correct check valves for the piping systems they are designing and installing.
The question was in the Manchester Evening News, a British newspaper, and it caught my eye when I was going through my daily Google Alerts on things that have to do with heating.