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LIFT & HEAD

Lift, Head & Flow

Pump manufacturers document the performance of their pumps in several ways. LIFT & HEAD are used to rate the ability to move water vertically while FLOW reflects the quantity of liquid that can be moved in a given amount of time.

Liquid Pump Terminology

Discharge Head

This is the vertical distance that you are able to pump the liquid. Say your pump is rated for a maximum head of 100 feet, this does not mean that you are restricted to100 feet of pipe, you could use 300 feet, so long as the final discharge point is not higher than 100 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 (see chart below). This does not mean that you are limited to 25 feet of pipe, you could use upwards of 200 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.

Friction Head

Pressure expressed in Lbs. that is required to overcome the resistance to the flow in the pipe system. (see section below)

In a general conversation about the performance abilities of a pump, the term head usually refers to the maximum vertical distance from water source to discharge point that water can be pumped. Please note that at this limit, the pump can push the water no higher. This is a rating assigned by the manufacturers based on design technologies and benchmark testing. An individual pump may perform slightly above or below that mark. This rating should be used to compare pumps and help evaluate the pump's suitability for the application.

Various Units for HEAD

Different pump manufacturers express their head ratings in different units. One might state that the maximum head for a specific pump is 200 feet while a competetive pump is rated at 90 PSI. A third pump may give the head at 6 bar. Although sounding quite different, they are actually comparable. The chart below shows the relationship of the various units.

A Bit About Suction Lift

The vertical distance that a pump may be placed above the water level (and be able to draw water) is determined by pump design and limits dictated by altitude. The chart below shows the absolute limits. The closer the pump is to the water level, the easier and quicker it will be to prime.

Friction Head (Loss)

As water is pumped through hose or pipe, pressure is consumed (or lost) due to the friction of the water against the inner surface of the waterway. The amount of loss depends on many factors including nature of waterway surface, rate of water flow, diameter of hose, pressure, temperature as well as the straightness of the water path. Sounds complicated ??? Well it is.

The 1½" hoses available on our website experience a pressure loss of about 0.07 psi/ft. based on a flow rate of 60 gpm. Very few products can boast a lower loss rate. Competitive hoses are rated at 0.09, 0.14 & 0.16 psi/ft. Older hoses, hose in disrepair or trash /junk hose may have ratings in the 0.20 - 0.30 psi/ft. range or higher -- based upon the same flow rate.

For general planning purposes, consider pressure loss to be 7 psi per 100 ft. length of hose @ 60 gpm. In theory, with a pump producing 100 psi, 1000 ft. of hose will leave you with 30 psi -- excluding elevation and other sources of head loss. If you restrict flow to 30 gallons per minute by using a different nozzle, then pressure loss becomes 2 psi per 100'. In this case, 1000 ft. of hose would leave you with 80 psi -- quite adequate for fire protection. In reality, the only way to get a true feeling of the effects of the various head loss factors is to actually perform tests in your setting.