Refrigeration safety and controls When discharge (head) pressure in a refrigeration system rises excessively, a high-pressure control should stop the compressor. State whether this is correct.

Introduction / Context:
High-pressure (HP) controls are critical protective devices in vapour-compression systems, preventing dangerous operating conditions and equipment damage when condensing pressure becomes excessive.

Given Data / Assumptions:

• Compressor with appropriate HP cut-out switch.
• Potential causes: condenser fouling, cooling water failure, fan failure, overcharge, non-condensables.

Concept / Approach:
Compressor power and discharge temperature rise with head pressure. HP controls monitor discharge pressure and open the control circuit when pressure exceeds a safe limit, shutting the compressor to avert damage.

Step-by-Step Solution:
Detect abnormal rise in condensing pressure.HP switch trips at setpoint (e.g., corresponding to safe saturation temperature).Compressor stops, allowing investigation and correction (restore cooling water/airflow, clean condenser, purge non-condensables).

Verification / Alternative check:
Manufacturers specify HP cut-out settings in service manuals; safety codes require these protections for most systems.

Why Other Options Are Wrong:

• Limiting correctness to a specific condenser type or expansion device is incorrect; HP protection is universal best practice.

Common Pitfalls:
Bypassing a tripping HP control without diagnosing the root cause; mis-setting the differential leading to short-cycling.

Final Answer:
Correct