At Triplex, we help service and support hundreds of Waukesha Universal 1 Series pumps every year. And do you know why the Universal 1 pump was originally called “Universal”? While the history of the Waukesha pump product line is something for a future post, the Universal pump was first called “universal” because it was one of the very first sanitary pumps to be configurable with both an o-ring and mechanical seal. Even today, the most common seal configuration we see with a Universal 1 pump is a single o ring seal. An integral to every single o-ring seal is a seal sleeve. So how does the single o-ring seal work and what sleeve options are available? Let’s take a closer look.
The single o ring seal is so popular because it’s simple and perfect for pumps that are taken apart to be cleaned like the Universal 1 pump. It’s a simple seal featuring a shaft o-ring, body o-ring, and seal sleeve. The shaft o-ring goes in the front groove of the pump shaft and the sleeve goes over the shaft (the rear groove is for a mechanical seal and please don’t be tempted to put an o ring in both grooves), engaging with the shaft drive pin. The body o-ring is installed into the o-ring groove on the pump body and “rides” on the shaft sleeve. The sleeve turns with the shaft, acting as a rotating seal surface while the o-ring acts as the stationary seal face.
Whether you’re looking at your U1 you’ve had in service for 30 years or specifying a brand new one, you’ll have three seal sleeve materials to choose from- stainless steel, zirconia or ceramic, and chrome oxide. We’ll spend the rest of this post talking about the pros and cons of each.
Let’s start with the least expensive- stainless steel. We consider stainless the “standard” sleeve material. While legacy versions of the sleeve featured pins, current versions are slotted and reversible. And while inexpensive, they stand up well to frequent handling associated with a pump designed to be taken apart. Unfortunately, stainless isn’t a high lubricity surface and the body o-rings will tend to wear on the sleeve, requiring change out.
Next, we have zirconia or ceramic. You can easily spot zirconia sleeves with it’s brilliant white sheen even in the dirtiest of applications. Zirconia is the standard material in an “ePump”, Waukesha’s baseline pre-configured U1 pump offering. While they’re not reversible, the ceramic material has higher lubricity, is much gentler on the body o-rings and lasts longer than stainless sleeves. Accordingly, we prefer zirconia for sticky or abrasive products vs. stainless. Drawbacks to zirconia are primarily fragility. Zirconia is a hard material and will break or shatter if dropped or subject to excessive shaft deflection because your bearings are shot.
Finally, we have chrome oxide or “ChromeOx” sleeves. Chrome oxide sleeves are basically stainless steel sleeves that have been chrome oxide coated. They look like the stainless sleeve but with a black stripe. Chrome oxide coatings are highly effective as seal surfaces, effectively improving abrasion and wear resistance. While they’re expensive (approximately equivalent to a mechanical seal), they’re great for the stickiest, most abrasive products. Chrome oxide seals, because of their stainless base, are durable as well as reversible. We recommend this material when customers just don’t want to replace sleeves (you will still have to replace the o-rings).
So the next time you’re servicing or specifying a Universal 1 pump with single or double o-ring seal, consider the sleeve material. For simple, general purpose applications, stainless steel will work just fine. For abrasive applications, consider zirconia seals. And when we need to pull out all the stops but stay with an o-ring seal, consider chromium oxide sleeves. And as always, if you have any questions about your Waukesha Universal 1 Pump, contact a Triplex Sales Engineer today!