![Spirax Sarco Spira-trol modular control valves](https://img.wattagnet.com/files/base/wattglobalmedia/all/image/2018/08/an.Spirax-Sarco-Spira-trol-modular-control-valves.jpg?auto=format%2Ccompress&q=70&w=400)
The Spirax Sarco Spira-trol are modular control valves. Their modular design, with a quick-change "clamp-in-place" seat, means their duty can be altered to match changing plant conditions, rather than replacing all of the valves.
The self-aligning "clamp-in-place" seat also simplifies maintenance, so no special tools are required and there's no need to take the valve out of the pipeline. There are different versions available: electrically and pneumatically actuated Spira-trol valves from 0.5" to 4".