Diaphragm Type Metering Pumps

Down time in an application is costly. When process equipment is offline, time is being spent figuring out the problem, as well as being spent again to procure parts to repair the Chemical dosing systemissue. In the meantime, your application is down, and often times in production facilities it costs money directly due to production loss. In the case of a chemical metering pump, being offline could mean allowing untreated liquids to continue along in your process, ruining an entire batch.

Dosing pumps malfunctioning or needing repairs is always a nuisance, but depending on the application, it can be more than a nuisance, it can be a critical hit to your business with every minute it is offline.

The keys to ensuring smooth, 24/7/365 operation with your chemical dosing pump is to buy a durable dosing pump designed for your process liquid, and practice proactive maintenance. Let’s take a look at some steps you can take to ensure your chemical dosing pump is a dependable workhorse in your chemical metering application.

Designing the best wetted end for your chemical metering pump

When planning dosing applications where dangerous and corrosive chemicals are involved, it is important to consult with an experienced engineer for advice on material compatibility, or look up your chemical in a material resistance chart at a minimum. Chemicals commonly used to treat water for example, like sulfuric acid, caustic soda, and sodium hypochlorite are very corrosive and dangerous to the touch and material compatibility is very important.

Making sure your wetted end, primary diaphragm, and valve materials won’t corrode or disintegrate via the process liquid will keep pump operators, other employees, and surrounding materials safe from constant leaking of harsh chemicals.

Madden Pump’s certified sales reps are particularly helpful here. Their job doesn’t stop at showing the right size pump for your application, it also includes finding a design that includes materials that will last as long as possible. When you combine their experience and resources, with the materials Madden has available with their diaphragm metering pumps, you can be confident your pump will be a dependable work horse. Madden Pump has materials available to pump 99.9% of liquids. Once you have material compatibility in line, take a moment to consider further safety and durability precautions.

With particularly dangerous chemicals, Madden offers a double diaphragm set up, as well as a leak detecting pressure switch. The Type DDB double diaphragm adds a secondary piston, secondary diaphragm, and a spacer which includes a 1/4” NPT hole to be used as a weep hole or connecting point for the pressure switch. This set up ensures that should a fatigued primary diaphragm ever go unnoticed, the process liquid will never reach the interior of your pump. With a double diaphragm, you are essentially helping to ensure you will only ever need to make minor wetted end repairs with your Madden pump.

As for the leak detecting pressure switch, this also serves the same purpose of adding another security feature.JN series, Madden chemical metering pump with automatic leak detection

Inside the spacer there should be no pressure building up, it should be the same pressure as the ambient air surrounding the pump. If the primary diaphragm were to fatigue, this would allow pressure to build up in the spacer between the secondary and primary diaphragm. Madden Pump suggests setting the chemical dosing pump’s leak detecting pressure switch to its lowest setting; this way a small increase in pressure caused by a ruptured diaphragm will flip the switch. The switch is normally wired to sound a high level alarm and/or directly shut off the pump.

A Type DDB double diaphragm and pressure switch is one of the best ways to ensure safe working conditions and optimal dependability from your chemical pump. It also protects the pump by never letting process liquid reach the pump’s interior.

These accessory components help ensure longevity and safety without the need to constantly check on your chemical dosing pump. But if you want to make sure your process is always running smoothly with no down times, nothing beats proactive maintenance. So, let’s go through what to look for when maintaining your chemical dosing pump.

Proactively maintaining your chemical metering pump

The frequency in which you should check your chemical injection pump for fatigue parts depends on many variables, such as how corrosive the process liquid is and how often the pump runs.chemical dosing system, robust diaphragm pumps

It can be a bit of a catch 22 as the applications that utilize very dangerous and corrosive chemicals are a hassle to remove the pump’s solution head for maintenance, yet these are the applications that should probably be checked most often. And then fairly non corrosive chemicals which don’t need special gloves or other precautions followed before removing the pump’s solution head are easy to check, but likely don’t need to be very often.

No matter what your chemical metering pump is dosing, Madden Pump recommends that at a minimum you check on your pump’s primary diaphragm status at least twice a year. This can usually be conveniently done during a winter and summer shut down for most companies.

And here are some things to look for to be proactive to increase the service life of the pump and to catch fatigued parts before they rupture:

  1. Remove the solution head and check for a fatigued/ruptured diaphragm, look for signs of wear and tear.
  2. Listen for vibrations, if heard, check that the motor and coupling are aligned properly
  3. Check the oil level in your Madden pump. It should sit just above the midway point on the drive shafts

But other than that, there really isn’t much to maintain on a Madden metering pump. That is by far the most commented benefit of our pumps by distributors and end users, “they just seem to last forever”.


Make sure your diaphragm metering pump is chemically compatible with your process liquid and proactively maintain it to get the most out of your investment; and if your application can’t afford to have a pump offline, then make sure it’s a Madden diaphragm metering pump.

Not only do we design some of the most robust diaphragm chemical metering pumps on the market, but we also work hard to be as responsive to distributors and end users as possible.

Madden has employees willing to go the extra mile to help get pumps out the door in a day for emergency situations.

With Madden Pump, you get peace of mind that downtime will not be an issue.

If you have an inquiry for a chemical dosing pump, check out our sales rep page or call us at (800) 369-6233.

One Reply to “Preventative measures you can take to ensure a long service life for your chemical metering pump as well as a safe pumping enviornment”

  1. […] Preventative measures you can take to ensure a long service life for your chemical metering pump as … 06/08/2017… With 65 years of experience, Madden Pump walks you though steps to take to keep your chemical dosing application running smoothly 24/7/365, as well as how to properly design wetted ends for dangerous chemicals. […]

Comments are closed.