The selection of heads requires consideration of multiple factors. The primary factor is user requirements, followed by chemical process requirements.For solid-phase media in vertical vessels, conical heads are often preferred to facilitate material flow and discharge.For liquid-phase media, elliptical or spherical heads are typically selected.

Pressure conditions also play a critical role:Low- to medium-pressure vessels commonly use elliptical heads.High- and ultra-high-pressure vessels generally employ spherical heads due to their superior stress distribution.Additionally, mechanical stress analysis must be conducted:If a large opening is required in the stress transition zone of an elliptical head, localized stress concentrations may necessitate the use of a spherical head instead.In rare cases, installation space constraints may dictate the choice of head type.

This selection process ensures optimal performance, safety, and compliance with engineering requirements.