Pump Protection

Chapter from the Pumps & Hydraulics Design Guide.

PUMP PROTECTION POLICIES

Protection Requirements by Hazard

Hazard	Protection Method	Detection	Action	Typical Setpoint	API 610 Requirement	Notes
Low flow	Min flow spillback	Flow transmitter	Open spillback valve	Manufacturer min flow	Required	Thermal + hydraulic limits
Deadhead	Spillback or PSV	Discharge pressure	Open spillback / PSV lifts	Shutoff head + margin	Required for blocked discharge	Check relief valve sizing
Dry running	Level switch on suction	Level transmitter (LSL/LSLL)	Trip pump on LSLL	Vessel LSLL	Required for can pumps	Consider time delay to avoid nuisance trips
Reverse rotation	Check valve + NRV	Reverse rotation relay optional	Non-return valve prevents	N/A	Check valve required	Hydraulic transient on fast closure
High temperature	Temperature element on casing	TI/TAH on pump casing	Alarm, potential trip	50°F above normal	Recommended for hot service	Indicates low flow condition
High vibration	Vibration probe	Accelerometer / proximity probe	Alarm at 2×, trip at 4×	Per API 610 Table	Required for special purpose	Baseline at commissioning
Seal failure	Seal leak detection	Level in seal drain / pressure	Alarm, plan switch to backup	Per seal plan	Required	Dual seals: primary failure detection

Motor Protection Coordination

• Motor HP selection: rated pump BHP at end-of-curve or max impeller diameter × service factor
• Non-overloading motor: select motor HP ≥ max BHP on curve at rated impeller
• Typical service factors: 1.0 for API 610, 1.15 for general purpose NEMA
• Locked rotor protection: motor protection relay with thermal overload
• Phase loss protection: negative sequence relay or dedicated monitor

Source: Pumps_Hydraulics_Design_Guide_v1.xlsx · sheet “Pump Protection”

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