🔍 Key Concepts

• Blowdown on a safety valve is the difference between the pressure at which the valve pops and the lower pressure at which it reseats • On a huddling-chamber safety valve, blowdown is set by controlling how much steam is directed into or out of the huddling chamber around the disc/nozzle area • Different parts of the valve adjust different things: one for set pressure (spring compression), another for manual lifting, and another for blowdown / reseating behavior

💭 Think About

• Look at which labeled part is located right at the nozzle/huddling-chamber area and would control steam flow into that chamber—would a part up at the top of the spring be able to do that? • Ask yourself: which component is normally used to change only the opening and reseating characteristics, without changing the cold spring compression and set pressure? • Compare what each choice says the part does (release nut, compression screw, adjusting ring, seat bushing) to what those parts are typically responsible for in any spring-loaded safety valve.

✅ Before You Answer

• Identify which part in the illustration is clearly the spring compression adjustment for set pressure and eliminate that answer • Identify which part is related to manual testing / lifting of the valve and eliminate that answer • Focus on the part located around the nozzle / seat and huddling chamber; that is the one that would realistically affect blowdown by changing steam flow and lifting force.