Diamond Coated Centrifugal Pump Mechanical Seals
Pump Seals: Ultrananocrystalline Diamond« Mechanical vs. Conventional
Ultra-hard, low-friction surface coating made of synthetic diamond material used to seal pumps used in particularly harsh environments, improving friction losses by roughly 75%.
Synopsis:
Diamond coatings for mechanical pump seal surfaces have been commercialized during the last decade, including both polycrystalline diamond and an amorphous carbon called diamond-like-carbon (DLC). Coating thickness ranges from 0.1 to 10 microns and greatly affects the production costs. When the coating thickness is small, good adhesion must be obtained so the coating does not delaminate from the seal face. The Oak Ridge National Laboratory developed and licenses the ultra-thin Ultrananocrystalline Diamond (UNCD) coating technology which has been shown to reduce friction losses in pumps by 75%.
Mechanical seals should be custom-designed for each industrial application, taking into account the best combination of materials and seal designs to provide the most effective solution. Materials selection and design are based upon pumping pressure, temperature, pumping liquids other than water, pump speed, corrosion resistance and wear resistance. Advanced seal face designs contain groves that provide "upstream pumping" that creates a full liquid film and reduces horsepower losses.
Coefficients of friction for seal face materials varies greatly based upon both sliding and stationery material selection. Silicon carbide to tungsten carbide has a friction factor of 0.05 with a water seal while carbon-graphite (resin filled, rotating) to silicon carbide converted carbon has a friction factor of 0.01 5 --- approximately 70% lower. Mechanical seals with diamond coatings can result in an additional reduction in friction energy losses (depending upon the baseline they are compared with), resulting in energy savings. Seal surfaces, however, should only be in contact during "lift off" when a pump starts. Seals are designed to form a lubricating liquid film between the sealing gap between the rotating seal ring and the stationary seat. Diamond coated mechanical seals have a reduced friction coefficient and provide added protection against "dry running" (which is not a normal operating condition). This reduced friction factor may result in negligible energy savings, however, as the initial seal losses may amount to only a small fraction of pumping horsepower requirements.
Energy Savings: 1%
Energy Savings Rating: Concept not validated
What's this?
| Level | Status | Description |
| 1 | Concept not validated | Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts. |
| 2 | Concept validated: | An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles. |
| 3 | Limited assessment | An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
| 4 | Extensive assessment | Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
| 5 | Comprehensive analysis | Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications. |
| 6 | Approved measure | Protocols for technology application are established and approved. |
Simple Payback, New Construction (years): 666.7
What's this?
Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:
Simple Payback = Incremental First Cost / Annual Savings
The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.
For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.
For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.
Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.
The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.