🔍 Key Concepts

• Steam pressure reducing valve function and how it controls downstream pressure and flow • Role of a fixed orifice in stabilizing flow and preventing hunting or oscillation in control systems • Difference between a range spring setting in a control valve and a separate flow-restricting orifice

💭 Think About

• Think about what the fixed orifice in the steam supply line is doing to the flow and pressure before the steam enters the evaporator. If that orifice is removed, what changes for the control valve? • Consider whether the pressure reducing valve alone can control both pressure and flow over all load conditions without any additional flow restriction. • Ask yourself if changing the range spring in the regulator would fully replace the function of the fixed orifice, or if those two components serve different purposes.

✅ Before You Answer

• Verify which component primarily controls downstream pressure and which one primarily affects flow stability and rate. • Check whether the control orifice inside the valve can always provide enough impedance to replace a separate fixed orifice in the line. • Confirm whether all three statements (A, B, and C) can logically be true at the same time, or if one of them must be incorrect given how these systems are designed.