What Makes a Good Sanitary Metering Pump?

At Triplex Sales, we specialize in tailoring our product offerings to support our customer’s high purity fluid handling needs. While many of the applications we work on are “one off”, increasingly, we find ourselves supporting “another one of those”. While history doesn’t repeat, if often rhymes, and over the forty plus years that we have been specifying and applying pumps, valves, and heat exchange equipment, one type of application we see again and again are metering and batching applications. In this post, we will take a closer look at what makes a great sanitary metering pump and which products from our portfolio we recommend.

To begin, let’s define what a metering or batching application is. By definition, a metering application or metering pump is a pump that moves a precise volume of liquid in a specified period of time. A batching application is an application where we are going to combine the repeatability of a good metering pump with the output of a flowmeter to control a valve downstream to dispense a preset amount of product.

So what makes a good pump for these metering or batching applications? Let’s break it down:

  • Repeatability- we want a pump that is going to give us the same output every time, generally regardless of downstream pressure. And we need to know what volume we are going to displace per revolution. This means that centrifugal pumps are out- they operate based on the affinity laws (a topic of a future post) and displacement is directly dependent on downstream head pressure. Ideally, we’d use a piston type pump, but because they typically use check valves, they’re difficult to clean and often pulse. The most repeatable sanitary pumps that we see in the sanitary space are rotary lobe pumps and progressive cavity pumps. The Waukesha line of Universal Pumps, as well as the Netzsch line of progressive cavity pumps, because of they’re tight tolerances and constant fluid displacement per revolution, are ideal for sanitary metering applications.
  • Versatility- In many of the sanitary applications that we are dosing or metering in, we’re dealing with a range of products and viscosities. For consistent metering and batching, we need to be able to handle all of these products. While peristaltic or hose pumps are great for thinner fluids, they struggle with higher viscosities. And while twin screw pumps work well for handling whole solids, the loser clearances mean they have more slip than a rotary lobe pump with thinner fluids. Starting to see a theme? There is not a more versatile sanitary pump on the market than Waukesha’s “Can Do” Universal line of PD pumps.
  • Wide Flow Range/Turn Down- When we look at metering and batching applications, we see flows from a few milliliters per minute all the way up to hundreds of liters per minute. Accordingly, batching and metering pumps need to have wide flow ranges (scalability) and high turn down. Here again we find that the Waukesha Universal Pump and Netzsch Progressive Cavity Pumps are ideal solutions. The Waukesha Universal Pumps range from 1 GPM all the way up to almost 400 GPM and the Netzsch progressive cavity pumps will a nice hole for where we need flows below 1 GPM. Rotary lobe and progressive cavity pumps also pair great with Variable Frequency Drives and even servo motors to give us excellent turndown in a single model of pump.
  • Dependability- Metering and batching applications are often the key process in a manufacturing facility. If you can’t batch into your blend tank or meter fragrance into your Glade line, you can’t make product. If you can’t make product, you’re out of business. This is another spot where the Waukesha Universal Series of pumps shine. Whether it’s the easy to tear down Universal 1, the CIP-able Universal 2, or the front loading seal benefit of the Universal 3, all Waukesha pumps are assembled in Delevan, WI and supported nationally by the best sanitary distributors in the country (OK…. As the Midwest’s leading Waukesha dealer, we might be a little biased), you’ll never have to worry about your Waukesha pump slowing down your metering or batching application.

That’s a wrap on our first post on sanitary metering and batching systems. Future posts will go deeper on batch controller and valve recommendations, but we wanted to start with the core of the system- the pump. So for your next sanitary metering or batching system, consider a Waukesha Universal Pump or a Netzsch progressive cavity pump and be sure to contact a Triplex Sales Engineer today!

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