What is a 90 min steel fire rated door?

The 90 minute Fire Rating is a valid label and are commonly referred to as "Smoke and Draft control door assemblies". Depending on the local fire code and the openings's application, these doors can be specified as either with or without a hose stream test. 90 minute with hose stream: These are openings that have successfully passed a 90 minute fire test, the standard hose stream test and bare a label that specifically states "Ninety-Minute-steel Rating Fire Door".