Sizing & Selecting Metering Pumps0 pages

BULLETIN AB-08

Sizing and Selecting Metering Pumps
Planning a Metering Pump Installation
This guide is intended
to help the user define
variables to be evaluated
for proper selection and
installation of a chemical
metering pump or a
complete chemical
feed system.

MOTOR DRIVEN
HYDRAULICALLY
BALANCED
DIAPHRAGM
PUMP

Sizing and Selecting
Metering Pumps
Identify the required capacity in terms of flow rate and
discharge pressure. Do not oversize a metering pump.
A metering pump should be sized so the maximum
expected flow rate is 85% to 90% of the pump
capacity. This leaves additional capacity if
needed. The minimum capacity should
never be less than 10% of the pump
capacity to maintain accuracy.
Consider materials of construction.
Metering pumps are available in
a variety of materials. Selection
must take into consideration
corrosion, erosion or solvent
action. Solvent-based chemicals may
dissolve plastic headed pumps. Acids and caustics
may require stainless steel or alloy liquid ends. Consider the
effect of erosion when handling abrasive slurries.
Is the chemical viscous or is the chemical a slurry? Does the chemical release
gas? Special liquid ends are available for these specific applications. Standard metering
pumps handle clear liquids with viscosities ranging from water-like to 1500 cps. Special
liquid ends can handle viscosities to 5,000 cps and light suspensions. For true slurries
or higher viscosity, tubular diaphragm heads allow pumping chemicals to 20,000 cps
or slurries containing up to 10% solids. Liquid ends are available which automatically
vent accumulating gases.