Integration Planning
positive displacement pump types
Before specifying positive displacement pump types, decide which geometry can move the actual fluid without treating a catalog family as interchangeable. Gear, rotary lobe, progressive cavity and other displacement machines share a working principle and differ in shear, solids handling, slip and seal layout. A published rotary-lobe hygienic example that lists flow, differential pressure and temperature in separate columns still does not select a type for abrasive wastewater or for a blocked discharge.
Decision dossier
Input checklist
-
Input checklist: Upstream
Collect fluid identity, viscosity at temperature, solids, shear sensitivity, suction condition, required flow with test temperature, differential pressure in bar, quantity and destination. If several types are still open, say so. Do not pick rotary lobe only because a public SRU-style page exists. That page is a configuration example for one hygienic family, not a type decision for this plant.
-
Control boundary
Ask each factory how the quoted type is protected against a blocked discharge and whether the selected rotary lobe geometry and seal arrangement—if lobe is even the type—suit the actual wastewater or process fluid. Gear pumps and progressive-cavity pumps need the same blocked-discharge question. Relief, bypass and PLC interface signals are design items. They are not implied by a casing photograph.
-
Downstream
Decide whether the quote is a bare pump or a skid with motor, base, instruments and piping stubs. Record FAT and SAT measurement points. Spare parts for rotors and seals should be listed if they will affect ranking. Connected load, three-phase supply, footprint and any cooling water or seal flush stay on the same checklist so types are compared on one utility set.
Trade-off reminder: specifying a single machine keeps the RFQ short; specifying an integrated skid moves interface risk to the supplier but raises the quoted total. Either route still needs test conditions. This page does not claim engineering or compliance outcomes. Continue with the project brief or the skid scope article.