What is the Best Seal for My Waukesha Universal 2 Sanitary PD Pump?

Waukesha Universal 2 Pump

Following up on our one of our last posts, in this post we’ll do a deep dive on the seal options available for the Waukesha Universal 2 and considerations when selecting and specifying a seal for your next Universal 2 PD Pump Applications.

Single Mechanical Seal

The standard seal configuration for a Waukesha Universal 2 Positive Displacement Pump is a carbon vs. ceramic single mechanical seal. This seal works great for most lighter duty applications where we’re handling relatively clean fluids.

The single mechanical seal in a Waukesha Universal 2 Positive Displacement Pump is made up of two primary parts- a stationary inner seal (that is engage by 3 pins) and a rotating seal seat. Other than carbon, the inner seal is available in ceramic, silicon carbide, and tungsten carbide. The rotary seal seat is available in ceramic, silicon carbide, and tungsten carbide. We’ll typically specify ceramic or silicon carbide for more abrasive products and save tungsten carbide for abrasive products with low lubricity when we want to avoid using a seal flush.

The Waukesha Universal 2 Positive Displacement Pump single mechanical seal is also available with narrow face seals. The narrow face seal uses a narrow width on the sealing face that creates a higher unit loading to break through thick product and film residue. We’ll do a deeper dive on that in a future post.

Single Mechanical Seal w/ Flush

The single mechanical seal with flush uses identical parts to our standard single mechanical seal, but the pump body is drilled to accommodate a fluid flush. This is great for abrasive applications that can create large amounts of friction in the sealing zone. By “flushing” this area, we remove product from the sealing zone and extend seal life.

Occasionally in flushing applications, we’ll recommend using a high pressure barrier seal (HPB). We use this seal when we need to use high pressure flush fluid to exclude product from the seal area. Again, we’ll do a deeper dive on this in a future post.

Double Mechanical Seal w/ Flush

Much like the Waukesha Universal 1 Series Pump, The Waukesha Universal 2 Series Pump is available with a double mechanical seal option. Great for highly abrasive and vacuum applications, the double mechanical seal is the one we use when nothing else works.

Material selection is critical with a double mechanical seal as well and the seal parts are the same materials as offered with a single mechanical seal. The additional piece, the stationary outer seal, is only available in carbon.

Again, because we’ll have two seals riding on the seal seat, that’s going to generate a lot of heat and we’ll need a flush fluid to dissipate it. While setting up the flush can seem like a burden, double mechanical seals significantly extend seal life performance with hard to handle products, so the net benefit of increased uptime far outweighs flush piping cost.


To close, while seal selection in the Universal 2 Pump may seem more straight forward than with a Universal 1 Sanitary PD pump, it is important to remember that the reason we’re using Universal 2 pumps is so we do not have to constantly tear them apart and service them. We want to let them run and make us money. That being said, it is even more critical in these applications to make sure we’ve selected the correct seal and perhaps more importantly, the correct seal materials. Future posts will do a deeper dive on seal material specifications.

As always, if you have any questions about which mechanical seal to use in your Waukesha Universal 2 Pump, contact a Triplex Sales Engineer today!

Related Posts

One thought on “What is the Best Seal for My Waukesha Universal 2 Sanitary PD Pump?

Leave a Reply