Factors to consider when choosing the right pump for your application

Think pump selection is an complex exercise?

As the pump experts, we are here to make the process as pain-free as possible.
Having following information at hand will make things easier.

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  • Fluid name and concentration
  • Specific Gravity
  • Viscosity
  • Flammability
  • Temperature
  • Flow rate
  • Head (suction, system and discharge)
  • NPSH Available (NPSHA)
  • Description of application
  • Experience (if any) with suitable materials of construction

Pump Selection Factors

chemical

FLUID CONCENTRATION

  • Critical to deciding materials of construction for the pump
  • If fluid is a trade name refer to MSDS (Material Safety Data Sheet)
  • Chemical resistance can vary with concentration and temperature
  • Refer to our chemical compatibility guide for more information
gravity

SPECIFIC GRAVITY

  • Specific Gravity is the weight of a given liquid compared to the weight of the equivalent volume of water.
  • By definition, water has a specific gravity of 1.0, but many chemicals have specific gravities greater than 1.0.
  • Many solvents and petroleum distillates have a specific gravity less than 1.0.
fluid-viscosity

VISCOSITY

  • Viscosity is a measure of the resistance of a liquid to flowing.
  • It is needed to:
    • Calculate friction loss in piping system
    • Correct the pump curve
  • Common units are cP (centiPoise) & cSt (centiStoke).
flammability

FLAMMABILITY

  • Extreme care must be taken when pumping flammable fluids
  • Pumps with stainless steel construction are highly recommended
flow-rate

FLOW RATE

  • Flow rate is the volume of liquid that needs to be pumped.
  • It can be expressed as metric units like m3/hr(cubic meters per hour) or lpm (liters per minute) or GPM (gallons per minute).
  • Flow rate is required to calculate friction loss in the users piping system.
temperature

TEMPERATURE

  • Maximum ambient temperature is based on motor maximum temperature
  • Minimum ambient temperature is based on pump materials of construction
piping-head

HEAD

  • Also known as Total Dynamic Head (TDH), there are different types of head.
    • Suction head: when the liquid supply to the pump is above the pump
    • System head: pressure required to make the fluid flow through the piping system
    • Discharge head: the maximum height reached by the pipe from the discharge port of the pump
    • Use our Friction Loss Calculator to calculate your total head loss.
suction-lift

SUCTION LIFT

  • Suction lift happens when the liquid supply to the pump is below the pump.
  • Equal to the static height in feet or meters that the liquid supply is below the pump centerline, less suction line losses.
static-discharge-head

NET POSITIVE SUCTION HEAD

  • Net Positive Suction Head (NPSH) has two definitions:
    • NPSH Available (NPSHA): the absolute pressure at the suction port of the pump.
    • NPSH Required (NPSHR): The minimum pressure required at the suction port of the pump to prevent it from cavitating.
    • Use our Friction Loss Calculator to calculate your total head loss.
impeller-damage

CAVITATION

  • Caused when the NPSHA is lower than the NPSHR required by the pump
  • Cavitation bubbles are formed in the low pressure region and rapidly collapse when entering higher pressure regions in the pump, causing erosion damage
  • More likely with hot fluids, fluids with high vapor pressures, suction sources that are under reduced pressure (vacuum) or larger impellers operating near full flow
altitude

ALTITUDE

  • Higher altitudes
    • reduce lift capability
    • reduce NPSHa
    • affect motor by reducing cooling from the motor’s fan
gas-atmosphere

ATMOSPHERE

  • Hazardous atmospheres: need to follow strict guidelines for flammable fluids
  • Corrosive vapour filled atmospheres: consider chemical duty motor
  • Washdown areas: consider wash down duty motor
  • High humidity: consider tropical duty motor

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