Pumps are essential throughout the world. They are used to move all types of liquids in a wide variety of applications. Examples of industries where pumps are used are: Chemical & Pharmaceutical, Oil & Gas, Pulp & Paper, Power Generation, Water & Wastewater, Food & Beverage, Cosmetics, General Industrial, and much more.
Seals are an integral part of any rotating equipment handling fluids. There are a wide a variety of seals as well depending on what the end-user of the equipment is looking to achieve based on a specific application. For the purposes of this article, we will be focusing on mechanical seals. There are several types and arrangements of mechanical seals. Single component seals and dual component seals, single cartridge seals, and dual cartridge seals. Depending on your specific application and operating conditions, one of these seal arrangements will likely be specified.
Texas, USA - A thermal power station required a high-wearing, low maintenance bearing alternative for a condensate pump assembly. The line shaft and pump bowl bearings used in this vertical spindle pump operate in pure water conditions at a temperature ranging between 30˚C and 60˚C (86°F to 140°F). Removal and maintenance cost on the pump are high. Vesconite Hilube bearings were manufactured and fitted. Resultant performance has been impressive – the replacement bearings have run without fault for four years, on a pump assembly that has a seven yearly maintenance rebuild schedule.
Texas, USA - A water utility in Texas had over the years experimented with different grades of nylon bearings in its vertical spindle pumps, but with little success. The pumps operated in the abrasive conditions found in pit-wells. The combination of debris and sand would eventually lead to excessive wear of the original bushings and eventual seizure. The original parts were subsequently replaced with Vesconite Hilube, which requires no lubrication, does not swell and can operate in dirty conditions as characterized by the above. The re-fitted pumps have since been running without incident for over a year now.
Vesconite has been used for decades in a wide range of specialized pump bushing applications. The material thrives in water and exhibits excellent dimensional stability, with zero delamination. The result is low downtime and associated hassle factor. Its friction coefficient range of 0.1 – 0.2 allows for dry starting – an issue commonly associated with high wear rates in traditional bushing materials. Corrosion of the bushing is entirely eliminated with Vesconite, Vesconite Hilube is recommended for most pump applications.
Vesconite Hilube is a thermopolymer, designed for particularly difficult operating environments. Hilube is specifically recommended for moist and underwater applications. These include the pump and marine industry, where regular maintenance is not practically feasible or cost-effective. Displaying superior wear life, especially in poorly lubricated and dirty conditions, Vesconite Hilube has been shown to offer up to ten times the life of bronze bushings.
Vesconite Hilube incorporates an internal lubricant that translates into an exceptionally low friction coefficient. Combined with excellent dimensional stability, low wear rates and a high load-bearing capacity. Hilube has a PV rating (pressure x velocity) four times that of nylon bushings.
Vesconite is available in a wide range of rods, bushings, plates, and machined custom parts.
No Water Swell
Fully saturated, Vesconite Hilube has a negligible moisture absorption rate (0.5%). Its linear swell rate of 0.07% allows for fine clearances in the majority of applications. By way of contrast, nylons absorb moisture by as much as 9% of total mass – resulting in high swell rates and critical loss of clearance, which can lead to seizures.
The Orion Engineered Seals patented Bearing Protection Device (BPD) represents state of the art bearing protection technology and is the premier non-contacting bearing protection device offered. The BPD was designed with an understanding of the nature of the bearing housing environment under all operating conditions and utilizes the laws of physics to create what has proven to be the best performing and most cost effective way to protect the bearings of your rotating equipment.
Problem 1: Pumps routinely operate in high humidity and dirty environments. They are also commonly operating batch processes meaning the pump is cycled on and off. These operating conditions results in contamination ingress into the bearing housing, which is the primary cause of shortened bearing life.
Solution: The BPD – Designed for the conditions encountered by centrifugal pumps
Non-metallic bearings may not be the best answer in every case but have been an excellent choice for many applications worldwide. In general, these product-lubricated bearings preclude additional contaminants (oils, greases) infiltrating the pumped fluid.
Non-metallic bearing materials include rubbers, synthetic rubbers (elastomers), plastics, graphite based materials, ceramics and lignum vitae. Thordon XL, Thordon SXL and Thordon Composite (GM2401) are elastomeric grades that offer exceptional wear life, low friction, reduced starting torque and dry start-up capability (SXL only). The inconvenience of pre-lubricating with water and the failures that can result if the flow of liquid is interrupted are eliminated. These elastomeric grades perform particularly well in dirty water and in applications where shock loading is a factor. These grades have high resilience, readily restoring to original shape from impact or localized deflection caused by passing minor particulate. In addition, the high toughness of the material enhances the natural resistance to abrasion damage.
ThorPlas is a proprietary, engineered thermoplastic bearing material. While the range of high performance elastomer bearing grades clearly offers superior performance in the applications in which they can be specified, there are technical limits, such as maximum temperatures and pressures beyond which they cannot be used. To address these limitations, this new grade significantly expands the range of applications where bearings can be specified while still maintaining many recognized elastomeric performance advantages.