Inspecting pressure relief valves

Heating · Controls · printed page 144 (PDF page 145)

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Book index entries

Inspecting Inspecting Pressure Relief Valves on Boilers Pressure Relief Valve – on Boilers – Inspecting

Text in the illustration

no piped extension
valve between boiler and pressure relief
extension pipe too small
extension capped, threaded or corroded at bottom
exhaust flue
valve set too high (e.g. 50 PSI)
extension pipe dripping
BTU rating of valve doesn't match boiler
boiler

Generated explanation

The illustration compares seven improper boiler pressure-relief valve conditions with a correct installation marked by a green check. Red prohibition symbols identify a missing discharge extension, a valve between the boiler and relief valve, an undersized extension, and an extension capped, threaded, or corroded at its lower end. Additional examples identify an excessively high pressure setting, a dripping discharge pipe, and a relief-valve BTU rating that does not match the boiler. The correct example shows a relief valve connected at the top of a boiler with a discharge pipe turning downward and terminating with an open end alongside the boiler; an exhaust flue rises above the unit.

Components

boiler pressure relief valve relief valve discharge extension pipe intervening shutoff valve discharge pipe cap exhaust flue

Defects shown

Missing relief valve discharge extension Shutoff valve between boiler and pressure relief valve Undersized discharge extension pipe Discharge extension capped, threaded, or corroded at bottom Relief valve pressure setting too high Dripping relief valve discharge pipe Relief valve BTU rating does not match boiler