Centrifugal refrigerant pumps are specialized pumps designed to circulate liquid refrigerants (e.g., ammonia (R717), Freon (R134a), or water/glycol mixtures) in HVAC, industrial cooling, and refrigeration systems. They must handle low-viscosity fluids while preventing cavitation, flashing, and seal leaks.
HVAC Systems (Chilled water circulation)
Industrial Refrigeration (Ammonia systems in food processing, cold storage)
Heat Pumps & District Cooling
Supermarket Refrigeration Racks
| Feature | Purpose |
|---|---|
| Closed Impeller | High efficiency for low-viscosity refrigerants. |
| Double Mechanical Seals | Prevents refrigerant leaks (critical for ammonia). |
| Stainless Steel or Cast Iron Construction | Resists corrosion from refrigerants like NH₃. |
| Low NPSHr (Net Positive Suction Head required) | Prevents cavitation in low-pressure systems. |
| Vertical or Horizontal Mounting | Space-saving (VS1) vs. easy maintenance (OH1). |
| Refrigerant | Pump Material | Sealing Requirement |
|---|---|---|
| Ammonia (R717) | Stainless steel (AISI 316) | Double mechanical seals (API 682 Plan 53B) |
| Freon (R134a, R404A) | Cast iron / Bronze | Single or double seals |
| Water/Glycol (Chilled Water) | Cast iron / Stainless steel | Standard mechanical seals |
ASHRAE 15 – Safety standards for refrigerant systems.
API 610 (For heavy-duty industrial ammonia pumps)
HI (Hydraulic Institute) Standards – For performance testing.
ATEX Certification – Required for flammable refrigerants.
| Challenge | Solution |
|---|---|
| Cavitation (due to low suction pressure) | Ensure NPSHa > NPSHr + 0.5m margin. |
| Refrigerant Leakage (Ammonia is toxic) | Double gas-barrier seals (API Plan 74). |
| Flashing (liquid → gas at low pressure) | Maintain sufficient subcooling. |
| Corrosion (Ammonia attacks copper/brass) | Use stainless steel or composite materials. |
Grundfos (CR, NBG series)
Armstrong (4300 Series for HVAC)
Sundyne (High-pressure ammonia pumps)
Flowserve (API-compliant refrigerant pumps)
Centrifugal refrigerant pumps must be:
✔ Leak-proof (double seals for hazardous refrigerants like NH₃).
✔ Cavitation-resistant (low NPSHr design).
✔ Corrosion-resistant (stainless steel for ammonia).
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