The C Series Pumps has been a Workhorse in the Sanitary Process Industry for Years

The C-series pump is possibly the longest running sanitary pump that has ever come to market. While new centrifugal pump technologies have emerged, the C-series has endured. For over 50 years, this pump has provided customers with simplicity, ease of maintenance and ability to handle low viscosity fluids. This post will focus on some of the seal variations of the C-series pump.

Seals

Type D Seal – the type D seal is the original and most common seal supplied with the C-series pump. It is what we call an “external balanced seal”. It has a rotary seal (carbon as standard), rotating against a stationary seat. In this case, the stationary seat is the stainless steel backplate of the pump. While this seal configuration will struggle with slurries or exceptionally hot fluids, it is ideal for many beverage, dairy, and juice applications. Service kits are inexpensive and easy to replace.

Type DG Seal/Seat – While the D seal is great, customers have needed a solution for applications where they may be handling abrasive, non-lubricating products. For these applications, we recommend the Type DG seal configuration. This seal assembly uses a modified back plate to enable us to affix a silicon carbide, ceramic, or tungsten carbide stationary seal to the back plate. The type D seal rotating portion is then assembled so that it rides on the stationary seal we’ve just installed. The rotating seal can then also be upgraded with a harder material as well, such as silicon carbide. With combinations such as silicon carbide vs silicon carbide, maximum corrosion and wear resistance for hard to handle products can be achieved. The stationary seat is reversible to save money and existing Type D pumps can be retrofitted into a DG seal.

Type E Water Cooled Double Seal – the type E seal is the C-series version of a double mechanical seal with flush. The seal is located within a stuffing box affixed to the pump back plate. The stuffing box is then filled with a flush fluid. This seal configuration should be considered for slurries or sticky/abrasive products where a double mechanical seal would typically be used. This may also be an ideal choice for vacuum applications.

Internal Seal – One of the newest seal configurations used introduced for the C-series sanitary pump is an internal seal design. Using a recessed back plate, this internal seal is located inside the product zone. The internal seal (also sometimes known as a John Crane Type 21 industrial seal), has two silicon carbide seals. The stationary seat is pressed into the back plate. The pump impeller then pushes on a spring that is engaged with the rotating seal face to allow seal face contact between the two parts. This seal is great for hot fluid applications where a flush is not practical. It’s also performs well in applications where the pump is going to be Cleaned In Place. We recommend this seal for many different applications and have found it to be an especially useful in brewery applications transferring hot wort out of the brew kettle.
The above was a quick pass at the standard seal configurations available for the C-series pump. If you have any questions about your C-series pump or sanitary pump application, contact a Holland Sales Engineer today.