D_LTF – Proven wastewater pump performance

What does “Non-clog wastewater pump” really mean?

Many manufacturers claim to offer wastewater or non-clog pumps. For a long time, however, there has been no uniform, industry-wide definition of what “non-clogging” truly means in real operation. As a result, performance claims were often difficult to compare, verify, or objectively assess under realistic wastewater conditions.

To overcome this challenge, independent scientific research conducted at TU Berlin established the foundation for standardized testing methods specifically designed for wastewater pumps. Based on this work, the D_LTF (Degree of Long-Term Functional Performance) test was developed—bringing transparency, comparability, and reliability to wastewater pump evaluation.

The D_LTF testing principle – performance proven under real conditions

Unlike short-term laboratory tests, D_LTF testing focuses on realistic operating scenarios. Pumps are exposed to defined fibrous materials under controlled and repeatable conditions.

The D_LTF test simulates continuous wastewater operation over a period of one hour. During this test, hydraulic performance, efficiency, and operational stability are monitored continuously.

The resulting D_LTF value serves as a reliable indicator of long-term clog resistance and overall operational robustness of the tested equipment.

To assess performance under different loading conditions, three defined load levels are tested on the D_LTF test loop using laboratory-prepared wastewater containing wipes:

Light load: 25 wipes per m³
Medium load: 50 wipes per m³
Heavy load: 100 wipes per m³

Each load condition represents an increasing solids challenge and allows a systematic evaluation of performance and reliability under realistic and progressively demanding wastewater scenarios.

According to market experience and the DWA-A 120-2 guideline, D_LTF values above 0.7 indicate stable and reliable wastewater pump operation.

Market-leading results with ANDRITZ ASD / ASW Pumps

ANDRITZ does not rely on undefined marketing terms—we rely on measurable performance.

Our ASD and ASW pump series, equipped with non-clogging (N) and vortex (V) hydraulics, have been successfully tested using D_LTF methodologies. In standardized testing according to DWA-A 120-2, ANDRITZ ASW pumps consistently achieve D_LTF values above 0.9, placing them at the upper end of the market.

This confirms exceptionally low clogging tendency, stable hydraulic performance, and high operational reliability under real wastewater conditions.

Proven technology you can trust

By applying scientifically developed and standardized test methods, ANDRITZ provides full transparency and confidence in pump performance. With ANDRITZ ASD and ASW wastewater pumps, non-clogging performance is no longer a claim - it is proven, measurable, and repeatable.

Do you have questions? Get in contact with us!