Pump terminology can be confusing especially when you are trying to find the
right pump for your application. Wastecorp uses the following industry
standard terms in our pump engineering specification documents
Discharge Head: This is the vertical distance that you are able to pump
liquid. For example, if your pump is rated for a maximum head of 18
feet, this does not mean that you are restricted to 18 feet of pipe. You
can use 300 feet, so long as the final discharge point is not higher than
18 feet above the liquid being pumped.
Suction Lift: This is the vertical distance that the pump can be above the liquid source. Typically, atmospheric pressure limits vertical suction lift of pumps to 25 feet at sea level. This does not mean that you are limited to 25 feet of pipe. You could use upwards of 300 feet of suction pipe, so long as the liquid source is not lower than 25 feet below the pump center line.
Total Head: Sum of discharge head, suction lift, and friction loss.
Total Dynamic Head: Used when calculating dynamic discharge head
plus dynamic suction lift or minus dynamic suction head into one
Friction Head: Pressure expressed in Lbs., required to overcome the
resistance to the flow in the pipe system.
Suction Lift: Used when the liquid source is located below the center line of the pump
Suction Head: Used when the liquid source is located above the center line of the pump. This may also be referred to as "flooded suction."
Static Suction Lift: Used to describe the distance from the pump
center line down to the free level of the liquid source below the pump.
Static Suction Head: Used to describe the distance from the center
line of the pump up to the free level of the liquid source above the pump.
Static Discharge Head: Used to describe the maximum vertical distance
from the pump center line to the point of free discharge.
Dynamic Suction Lift: Used when calculating the static suction lift,
friction head loss and velocity head into one computation.
Dynamic Suction Head: Used when calculating the static suction head
minus friction head and velocity head.
Dynamic Discharge Head: Used when calculating static discharge head,
friction head plus velocity head into one computation.
Flooded Suction: Liquid flows to pump inlet from an elevated source by
means of gravity.
Suction Lift at Various Elevations
|Altitude (ft)||Suction Lift (ft)|
The Altitude Factor (Facilities at higher elevations)
Since air is thinner and heat is not dissipated easily at higher
altitudes, standard motors are designed to operate below 3,300 ft.
Most motors must be derated at higher altitudes. The chart below
provides typical horsepower derating factor. A 3 HP motor operating at
6000 feet for example would be derated to 2.82 HP, assuming a 40
degree ambient temperature rating.
Example : 3HP x 0.94 = 2.82
|Altitude (ft)||Derating Factor|
6601 - 8300
8301 - 9900
9901 - 11,500