Boiler safety valves must be lifted by a hand easing gear how many psi below operating pressure?

In boiler systems, safety valves are crucial for ensuring the safe operation of the boiler by relieving excess pressure. The specific requirement that a safety valve must be lifted by a hand easing gear at a certain pressure below the operating pressure helps ensure that the valve is functioning properly and is capable of responding to overpressure conditions.

The correct response identifies the range of 200-300 psi as the designated pressure range for the hand easing gear to lift the valve. This requirement is significant because it ensures that there is a sufficient margin below the normal operating pressure, allowing for safe and effective valve operation. If a safety valve can only be tested or operated at a pressure that is too close to the normal operating pressure, it risks being ineffective in a real overpressure situation, potentially leading to dangerous conditions.

The chosen range balances the need for ensuring the valve can be tested adequately without approaching the danger zone of the boiler's normal operating parameters. Understanding these ranges helps machinists maintain equipment safely and comply with safety regulations.