Establishing Baseline Performance for Off-the-Shelf Nitrile Seals for the India Mark II Hand Pump System

Accessing clean water is a persistent, and life threatening, challenge for millions of people in the world. Mechanical hand pumps have a long history of helping people access clean ground water for drinking and daily use. Among the most ubiquitous are the India Mark II and III pump systems, for which there are more than 4,000,000 installed across the world. These are estimated to serve between 600M and 1B people. All pumps degrade in performance over time, requiring service; many do not receive it causing pumps to become dysfunctional. The purpose of this paper is to establish a baseline for nitrile seal performance of India Mark II hand pump systems. Understanding off-the-shelf performance and using it as a baseline is an important step toward understanding degradation of performance over time, which is the focus of a much larger study to understand — mechanically and socially — how hand pumps perform, degrade, and ultimately meet human needs. In this paper, 110 off-the-shelf nitrile seals that were purchased in Uganda were tested and the following was characterized: (i) geometric variation, (ii) material variation, (iii) leak performance, and (iv) correlation between these. The seal leak performance was found to be very robust to variations in geometry and material at zero cycles. This important baseline supports our future work to understand how and to what degree seals become sensitive to geometric and material degradation during use.