---
title: Temperature Limits
description: "#### **Type px or type py pressurisation** The temperature class shall be based on the higher of the hottest external surface of the enclosure or the hottest internal component surface. Internal components may exceed the enclosure T-class if the enclosure…"
url: "https://www.eicstech.com/kb/pressurisation-ex-p/basics-on-pressurisation-tempurature-limits/"
updated: "2022-06-01"
category: Explosion Proof Basics / Pressurisation (Ex p)
---

# Temperature Limits

#### **Type px or type py pressurisation**

The temperature class shall be based on the higher of the hottest external surface of the enclosure or the hottest internal component surface.

Internal components may exceed the enclosure T-class if the enclosure is marked with the time for them to cool to the T-class.

#### **Type pz pressurisation**

The temperature class shall be based on the hottest external surface of the enclosure, taking into account internal Ex equipment remaining energised in the absence of over-pressure.