You are here
Flow monitors watch for plugged outlets
Flow monitors are like an extra
set of eyes. You can’t watch every herbicide nozzle on a sprayer or every
fertilizer outlet on a corn planter or sidedressing machine. But with a glance
at a bank of clear plastic columns, you can instantly tell whether all outlets,
including the hidden ones, are applying approximately the same rate. (Some
farmers use a cab camera so they can check the monitors without turning
around.) Flow monitors are inexpensive, simple, and reliable. And they work.
Year after year, they prevent weed strips in beans and nitrogen skips in corn.
They don’t regulate the flow
of liquid, and they don’t tell you how many gallons per acre of liquid are
being applied. They simply tell you whether all outlets are applying roughly
the same amount, which means within about 10% of each other. There are styles
for both squeeze pumps and pressure pumps.
When all of the balls in all
of the columns are lined up, the flow of liquid to the various outlets is
uniform. When one ball is lower than the others (as shown in the photo), it
means the flow through that column, hose, and outlet is too low due to a
restriction or blockage. When one ball is higher than the others, it means the
flow is too high. That’s typically due to a leak in a hose or fitting.
Three Companies Make Flow
Three companies make flow
monitors: Willmar Fabrication, CDS-John Blue, and Wilger. Their products are
fairly similar. They even have some interchangeable parts. But the ways in
which two of these companies entered the market couldn’t be more different. In
1984, Minnesota farmer Steve Claussen designed the first flow monitor. His
initial office was a basement room in downtown Benson, Minnesota, furnished
with a card table and a phone. Today, his company, Willmar Fabrication, builds
a wide range of equipment including sprayers, seed tenders, and, of course,
Redball Spray Monitors (aptly named for the red balls that warn if a system is
In contrast, CDS-John Blue,
a 125-year-old pump manufacturer from Alabama, introduced the CDS-John Blue VisaGage
II in the fall of 2009.
The third company, Wilger
Industries, Ltd., was founded in Saskatoon, Canada, in 1976 by Wilf Wilger to
build field sprayers. This company started making Wilger Flow View flow
monitors about a dozen years ago. The U.S. arm of the company is located in
Lexington, Tennessee. Wilger, Inc., is headed by Mark Bartel and has
distributors throughout the U.S.
The original Redball flow
monitor was sold in banks of four. According to Bartel, Wilger had a customer
who was making hooded sprayers that only had three spray tips under each hood.
Consequently, Wilger developed a modular concept to accommodate any number of
outlets and, thus, entered the market.
Each company makes two or
more models. Some are used with squeeze pumps.
Others are used with PTO,
hydraulic, electric, or ground-driven pressure pumps.
The Wilger Isolated Feed
Flow Indicator shown is used primarily with squeeze pumps to monitor individual
lines. Each column of the flow monitor is fed separately at the bottom of that
column. The individual columns lock together at two locations. Both Willmar
Fabrication and CDS-John Blue also make flow monitors to monitor individual
lines (see table below).
Orifices (round discs with a
hole in the center) can be used with the individual flow monitors to control
The flow monitors for
individual lines are sometimes used with pressure pumps, also. In that case,
there’s a flow divider positioned between the pressure pump and the flow
monitor. A large hose delivers liquid to the flow divider. Then smaller
individual hoses distribute the liquid from the flow divider to individual
column flow monitors.
The second major type of
flow monitor uses a manifold. With this approach, one hose from a pump can
supply multiple outlet hoses that run to individual nozzles or openers. Big
application equipment typically uses several manifolds.
Wilger creates a manifold by
hooking several columns together.
Willmar Fabrication offers
two types of manifold flow monitors. One is a flow monitor with a manifold at
the bottom and four columns. That unit cannot be taken apart. The other type of
manifold is created by hooking individual columns together. That approach is
more flexible. For example, you might only want 11 outlets on a 12-row nitrogen
sidedressing machine. You could make three manifolds with three columns each
and one manifold with only two columns.
CDS-John Blue offers
manifold-type flow monitors in banks of four. Or, you can hook individual
Choosing the correct
components for a flow monitor system is like choosing spray tips. Obviously,
you need to decide what kind of pump you will use and whether you will use
metering orifices or flow dividers. Plus, you need to know your application
rate, application speed, and the nozzle or opener spacing. You also need to
decide if you are going to run more than one nozzle or opener per flow monitor
column. And you need to know what liquids you will be using so that you can
order the appropriate seals.
The company websites have
helpful information such as conversion charts for various types of liquid
fertilizers, which have different flow rates than water.
The manufacturers have
several plastic, glass, and stainless steel balls so you can find the right
match for your system.
You can build your own
system, of course, or there are retail dealers who specialize in putting kits