A pressure regulator is designed so that a rise in downstream steam pressure reduces off the inlet flow of supply steam. This action primarily reduces which flow?

A pressure regulator is designed so that a rise in downstream steam pressure reduces off the inlet flow of supply steam. This action primarily reduces which flow?

• A. Inlet
• B. Barometric
• C. Downstream
• D. Upstream

Answer: (A)

The regulator’s job is to keep the pressure on the downstream side at a set value by adjusting how much supply steam can enter the system. When the downstream pressure rises, the regulator tightens the inlet valve, cutting back the amount of steam that can enter. That throttling on the inlet side is what primarily reduces the flow entering the regulator from the supply, i.e., the inlet flow. Barometric pressure is unrelated to this regulation, and while the downstream flow toward the load is what the system aims to stabilize, the immediate action to achieve that stability is to reduce the inlet (supply) flow. Upstream refers to the supply side as well, but the task described specifically shows reducing the inlet flow.

The regulator’s job is to keep the pressure on the downstream side at a set value by adjusting how much supply steam can enter the system. When the downstream pressure rises, the regulator tightens the inlet valve, cutting back the amount of steam that can enter. That throttling on the inlet side is what primarily reduces the flow entering the regulator from the supply, i.e., the inlet flow. Barometric pressure is unrelated to this regulation, and while the downstream flow toward the load is what the system aims to stabilize, the immediate action to achieve that stability is to reduce the inlet (supply) flow. Upstream refers to the supply side as well, but the task described specifically shows reducing the inlet flow.