Pump Selection

Chapter from the Pumps & Hydraulics Design Guide.

CENTRIFUGAL PUMP SELECTION — API 610

API 610 Pump Type Classification

Type	Configuration	Typical Flow (GPM)	Max Head (ft)	Typical Service	Advantages	Limitations	Common Applications
OH1	Overhung, foot-mounted	10–2,000	600	Light duty	Low cost, simple	Foot alignment sensitive	Chemical feed, utility water
OH2	Overhung, centerline-mounted	10–5,000	800	Hot service (>250°F)	Thermal growth handled	Higher cost than OH1	Hot oil, reflux, charge pumps
OH3	Overhung, close-coupled	5–500	300	Low flow	No coupling, compact	Motor bearing loads	Seal flush, small chemical
BB1	Between bearings, axial split	100–20,000	600	High flow, low head	Easy maintenance	Not for high pressure H2	Cooling water, crude charge
BB2	Between bearings, radial split	50–10,000	3,000	High pressure	Handles high P	More complex maintenance	BFW, high-P hydrocarbon
BB3	Between bearings, multistage axial	100–15,000	2,000	Multistage	High head capability	Axial thrust management	Pipeline, multistage BFW
BB5	Between bearings, multistage radial	50–8,000	6,000+	Very high pressure	Highest heads available	Complex, expensive	High-P injection, boiler feed
VS1	Vertical, single stage	10–5,000	200	Sump service	Below-grade suction	Bearing access difficult	Sump pumps, drainage
VS6	Vertical, multistage (can)	50–3,000	5,000	Low NPSHA	Very low NPSH required	Expensive, long lead	Condensate, LPG, cryogenic

Pump Type Selection Decision Criteria

Parameter	OH1/OH2	BB1	BB2/BB5	VS6	Key Decision Factor
Temperature	<250°F: OH1 >250°F: OH2	Ambient–300°F	Any	Cryogenic OK	Hot service → OH2 minimum
Suction Pressure	Low–moderate	Low–moderate	High	Low (submerged)	High P → radial split (BB2)
NPSH Available	Normal	Normal	Normal	Very low	Low NPSHA → VS6 or OH2 w/ inducer
Flow Range	Low–moderate	High	Moderate	Low–moderate	High flow → BB1
Head Required	Low–moderate	Low	High–very high	High	High head → BB2/BB5 multistage
H2 Service	OK if low P	Avoid (axial split)	BB2 preferred	OK	H2 service → radial split mandatory

Key API 610 Requirements

• Minimum design life: 20 years, 3 years uninterrupted operation
• Preferred operating region: 80–110% of BEP flow
• Minimum continuous stable flow: per manufacturer curve, typically 50–60% BEP
• Rated point: must be within preferred operating region
• Maximum allowable working pressure: defined by casing pressure class
• Hydrotest pressure: 1.5× MAWP at ambient temperature

Source: Pumps_Hydraulics_Design_Guide_v1.xlsx · sheet “Pump Selection”

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