Managing plant operations and guaranteeing on-time output requires a high degree of predictability that’s hard to ensure – especially in chemical processing environments. Designed to achieve long-term repeatable performance, Flowserve’s reverse vane impeller makes Mark 3 ANSI pump operations as close to future-proof as you’ll get.
Reverse Vane Impeller Advanced Design
Installed standard on all Durco Mark 3 ANSI pumps, the reverse vane impeller is engineered to deliver repeatable pump performance throughout the life of the pump through:
Low, predictable seal chamber pressure and thrust loads achieved by reverse vane pumping action and balance holes
- Lowest required NPSH of any ANSI standard pump
Abrasive wear shifted to the rear cover rather than the more expensive casing
- The only impeller design that takes full advantage of the back pull-out feature. The critical running clearance is set between the rear of the impeller and the rear cover plate.
This allows for the impeller clearance setting and mechanical seal installation to be made in the shop instead of under adverse field conditions
External micrometer impeller adjustment accurately sets impeller clearance in 20 seconds – in the shop or in the field.
These features facilitate routine maintenance and work to extend bearing and seal life, thus increasing uptime and reducing the total cost of pump ownership.
Reverse Vane versus Open Style Impellers
Reverse Vane: Unlike open impellers, the Durco reverse vane impeller offers predictable, repeatable, like-new performance each time it is adjusted. Here's how:
A reverse vane impeller has only one set of pumping vanes and one critical tolerance. This single tolerance — between the impeller and the rear cover — establishes:
- Seal chamber pressure
- Thrust loads
Wear between the reverse vane impeller and the rear cover causes axial thrust loads to decrease as the seal chamber gap widens. At the same time, seal chamber pressure increases. By adjusting the setting of the reverse vane impeller against its single tolerance location, the original seal chamber pressure and axial thrust loads are re-established. The result is consistent, like-new performance.
Open Style: A front vane open style impeller has two sets of pumping vanes and two critical tolerance locations:
- The front vane clearance to the casing – establishes performance and efficiency
- The pump out vanes clearance to the rear cover – establishes seal chamber pressures and seal life, as well as thrust loads and bearing life
Wear causes axial thrust loads and seal chamber pressure to increase as the seal chamber gap widens. But the impeller cannot be adjusted to both tolerance locations at the same time. Seal chamber pressure and bearing loads increase after each adjustment. Performance is diminished and seal and bearing life suffers as a result.
Compare the effects of wear and impeller readjustment: