Route your duty point to the right pump — centrifugal vs PD, ASME B73 vs API 610, and the API 610 type
Understand pump type classifications, the API 610 OH/BB/VS families, and when to specify each
Three routing stages:
A chemical-duty ASME B73 pump is generally limited to:
Cross any line, or run flammable hydrocarbon service, and the duty belongs to an API 610 heavy-duty pump.
Use API 610 for flammable hydrocarbon service or whenever the duty exceeds the ASME B73 application envelope — discharge above 275 psig, temperature above 300°F, speed above 3600 rpm, driver above 150 HP, total head above 450 ft, or suction above 75 psig. ASME B73 chemical-duty pumps suit general, non-flammable water and chemical service within those limits.
OH = OverHung (impeller cantilevered outside the bearings), BB = Between Bearings (impeller carried between two bearings), and VS = Vertically Suspended. API 610 §4.2.2 / Table 1 defines specific configurations: OH2/OH3/OH6, BB1–BB5, and VS1–VS7, each suited to a different flow, head, and NPSH range.
Choose positive displacement when viscosity exceeds roughly 300 cP, when precise metered/dosing flow is required (controlled-volume, API 675), or when very low flow must be delivered at very high differential pressure. Centrifugal pumps handle the broad mid-range of higher flow at moderate head.