Diaphragm Type Metering Pumps

Madden Pump’s chemical metering pumps have been around since the 1950’s and the design continues to withstand the test of time. “If it ain’t broke, don’t fix it”. We have found Farmers seem to appreciate this phrase in particular, as we continue to service their 60+ year old metering pumps with replacement valve parts to this day.

Though our metering pumps can certainly be integrated into modern control systems, the pumps in and of themselves are simple and durable. Two particularly important features when the top interest you may be seeking is reliability/trust. Madden metering pumps are relatively easy to understand and work on for most any end user, nowadays something that is less and less common with industrial equipment. In a world obsessed with technological advancement, the Madden design still keeps an emphasis and appreciation on dependability and simplicity. Our pumps are designed to minimize downtime and the stress that comes with an application being taken off line.Madden Pump nitrogen injection metering pump

The process of injecting liquid chemicals into another process is used frequently in agricultural applications. Madden has metering pumps being used in manure processes, water treatment, and irrigation. The most common being nitrogen injection into a center pivot irrigation system.

Let’s talk a little bit more about this application as well as what makes the Madden chemical metering pump so simple and reliable.

Center Pivot Irrigation, and Nitrogen Injection

Odds are most readers of this article have more knowledge of center pivot irrigation systems than we do; assuming you’re here based on a related search. For those readers, we’ll expand and focus on Nitrogen Injection here shortly. But for those who may not know the inner workings of center pivot irrigation, the basic idea is to evenly disperse water throughout the fields to help with consistent and even growth of crops. Water is usually pulled from a local creek, river, pond, or well and then piped throughout the fields.

From the water source, a large transfer type pump is installed to pull the water and send it to the systems “pivot” point(s). As the name suggests, these systems move in a circular pattern based on this central pivot point. Many sprinkler type heads are installed throughout the length of water piping to help with even dispersion of the water. Motors connected to the wheels throughout the length of the system allow it to slowly move over the fields.

The complete system also includes electronic controls that allow farmers to monitor moisture levels in the fields and to then start and stop irrigation in certain locations accordingly. Center pivot irrigation systemThus helping to maintain even and healthy growth in all locations.

For complete details on center pivot irrigation, how it works and why it’s so beneficial for crop yields, we suggest checking out Valley Irrigation’s website.

Nitrogen Injection specifically…

As for the process of using a chemical metering pump to add Nitrogen into the center pivot irrigation system, let’s discuss how this works and why a diaphragm metering pump is an ideal choice.

Based upon past experience, most systems call for one of our MF series metering pumps, specifically the 3.6-36 GPH design or the 6-60 GPH design, these flow rates seem to offer the appropriate Nitrogen addition based upon the percentage you are recommended to maintain in the water. Farmers will either have a portable Nitrogen dosing system they can take from pivot point to pivot point, or they will set up small Nitrogen injection stations at each center pivot system. These injection stations would usually consist of at least a 55 gallon Nitrogen holding tank/drum, chemical metering pump, relief valve, and injection quill to dose the Nitrogen directly into the center pivot system’s water line.

For the same reasons center pivot systems are a great choice for even dispersion of water throughout the fields, chemical metering pumps are a great choice for Nitrogen injection because they are consistent and accurate in their flow rate. Diaphragm metering pumps like Madden Pump’s, are positive displacement type pumps with an accuracy of +/-1%. It is important to maintain a consistent flow of Nitrogen into the center pivot’s water line for the best results; too little Nitrogen will not help the crops, and too much will saturate the area and bleed back into the ground water.

You can learn much more on specifically Nitrogen “chemigation” on the University of Minnesota’s Extension site here.

We will finish this article expanding on exactly why positive displacement pumps are the ideal choice for this process and how positive displacement works.

Positive Displacement Pumps for Nitrogen Injection

Now that we’ve touched on the basic ideas of Center Pivot Irrigation and how it is ideal for even water dispersion to crops, and how Nitrogen Injection when evenly injected into the water line can greatly boost yields and crop health, let’s get into the specifics of the Madden metering pump. Specifically, how it works to provide even chemical injection while being so simple, effective, and durable.

Breaking down “positive displacement”:

With the Madden diaphragm type metering pump, the +/-1% accuracy is achieved through precisely controlled positive displacement of a liquid chemical. With our pump, the inlet and outlet valves are a check ball valve type, which is what ensures each and every stroke of the diaphragm will inject the exact same amount of chemical as the previous stroke and will again with the stroke to follow.

As the piston inside of our pump draws the diaphragm backwards, the bottom inlet check valve’s ball will unseat, allowing a precise amount of Nitrogen (or any chemical for that matter) to enter the pump’s solution head. At the same time, the top outlet check valve’s ball will be pulled down and seated firmly, ensuring no liquid back tracks into the solution head or exits prematurely. Then, as the piston pushes the diaphragm forward, the opposite actions occur. The top check valve’s ball unseats, allowing this precise amount of nitrogen to exit the pump’s solution head; and at the same time, the bottom valve’s ball seats firmly, ensuring no liquid backtracks into the suction line.

And with this repeatable action, you get consistent and accurate injection of your Nitrogen into the center pivot irrigation’s water line. Over and over and over.

As mentioned earlier, unlike most other injection type pumps, the Madden design strikes a great balance between tech savvy and simple and rugged. Many designs have so much technology preinstalled into them that they become an overkill expense for what you really need, and others try to combat this by making the pump as inexpensively as possible, usually with a plastic body and these simply don’t offer a significant service life.

Our design is made from an all-aluminum body and all metal internal parts. Additional technology can be added, but it is not integral to the pump. The base design is rugged and dependable. For Nitrogen injection applications, it is common for our metering pumps to last well over 20 years with only minor wetted end part replacements needed. You can learn more about Madden pumps by browsing the rest of our website.


We’ve yet to meet a farmer disappointed in the Madden pump design when it comes to dosing Nitrogen into their Center Pivot Irrigation system. Arguments can certainly be made for other pumps and their designs but it seems clear that when it comes to trusting a pump you can “set and forget” to dependably do its job, the Madden metering pump more than holds its own.

We take pride in being an American made product and backing it with responsive customer service. All of our parts are readily stocked at our facility so that we can service customers at a moment’s notice.

If you work with Center Pivot Irrigation systems or directly with chemical injection in agricultural processes, we’d love to have the chance to work with you on your next application. We can be reached at our toll free line 800-369-6233.

One Reply to “Chemical Metering Pumps Well Suited for Agricultural Applications Like Nitrogen Injection into Center Pivot Irrigation Systems”

  1. […] Chemical Metering Pumps Well Suited for Agricultural Applications Like Nitrogen Injection into Cente… 08/02/2019… Sometimes less is more. Read about how the Madden chemical injection pump design is one of the most reliable and dependable brands in the market. Farmers love our pumps! […]

Comments are closed.