Which Schedule thickness is required for a Category 3 vacuum system using plastic piping?

In a Category 3 vacuum system using plastic piping, Schedule 40 is required due to its balance of strength and weight, making it suitable for the pressures and applications associated with this type of system. Schedule 40 piping has a thicker wall compared to schedules with lower thickness ratings, allowing it to withstand the vacuum pressures and potential external loads without failing.

Using Schedule 40 ensures that the piping maintains structural integrity under the conditions it will encounter, including both the internal vacuum pressure and any external stresses such as weight and temperature changes. This is particularly important in vacuum systems, where even small failures can lead to significant operational issues or safety hazards.

The other schedules, like Schedule 20 or Schedule 30, do not provide the same level of strength necessary for the demands of a Category 3 vacuum system, while Schedule 80, although thicker and stronger, may be an over-specification, potentially making it unnecessarily heavy and less cost-effective for applications needing the characteristics of Schedule 40. Thus, Schedule 40 strikes the right balance for typical applications in a Category 3 vacuum system.