Important Equipments of Chilled water systems

A: Principle: Dissolved oxygen plus carbon steel at low temperature produces magnetite. Applied here: Intermittent operation pulls in fresh oxygen, generating black sludge that settles in low points. Common trap: Option C sounds plausible, but galvanic effects are localized, not system-wide fouling.

A: Principle: Hydraulic separation allows stable chiller flow with variable distribution demand. Applied here: Expansion plans and diversity point to a decoupled primary–secondary layout. Common trap: Option D works at small scale, but it limits turndown and future staging.

A: Principle: Dashed items on P&IDs often mark scope or installation status. Applied here: A dashed bypass with no tags flags a required minimum flow path that wasn't installed. Common trap: Option B confuses internal pump features with external piping notation.

A: Principle: Water is effectively incompressible; trapped thermal expansion drives pressure. Applied here: With the relief isolated, pressure climbs rapidly to a mechanical failure point. Common trap: Option B mixes suction conditions with a closed, static overpressure scenario.

A: Principle: Heat transfer depends on both temperature difference and flow rate. Applied here: High flow collapses ΔT even when coils are active, a classic low-ΔT condition. Common trap: Option C causes capacity loss, but you'd see uneven coil temperatures.

A: Principle: Glycol compatibility and corrosion resistance govern material choice. Applied here: SS316 with EPDM handles glycol chemistry and avoids rapid degradation. Common trap: Option D appeals on heat transfer, but copper suffers in glycol systems.

A: Principle: Entrained air and particulates need continuous removal. Applied here: A combined separator addresses both oxygen ingress and debris from makeup. Common trap: Option C protects equipment but doesn't clean the loop.

A: Principle: Pumps follow their curve regardless of drawings. Applied here: Higher system head shifts the operating point left, cutting flow. Common trap: Option D overestimates what a VFD can correct when head is fixed.

A: Principle: Minimum flow bypasses manage thermal and hydraulic limits, not transients. Applied here: They keep flow moving but don't absorb valve slam pressure waves. Common trap: Option C tempts those who link flow directly to motor amps.