Cup Seal Research Articles

Use of simulation and wear prediction to explore design improvements to the cup seal in the India Mark II/III hand pump system

The India Mark II/III hand pump system is now over 40 years old and has become a staple in how water is retrieved in many rural areas across India and Africa. With over 4 million installations, it is estimated that 10% of the world’s population is using one on a daily basis. One of the components that fails most frequent is the nitrile cup seal found in the under-ground pump cylinder, often causing the pump to become derelict for undesirably long periods of time. This paper’s focus is on this cup seal and how the wear and life of the seal can be predicted. A test rig was created to evaluate and test cup seals. From this, seal performance and the nitrile cup seal wear coefficient were found. A two-dimensional finite element model of the seal and the pump cylinder was then developed and used to calculate the pressure distribution and wear of the seal. Archard’s wear law was used to simulate the wear. From this, models for pump performance and seal wear prediction were created. This data was then used to explore possible design improvements to the cup seal. By combining this data with engineering tools such as ANSYS, MATLAB, and JMP, a new seal design was generated that has the potential to last 12% longer than the original cup seal.

Nitrile cup seal robustness in the India Mark II/III hand pump system

Accessing clean water is a persistent and life-threatening challenge for millions of people in the world. Each hour, 400 children under the age of five die because of the lack of clean water. To help people get access to clean ground water, mechanical hand pumps are often used. Among the most ubiquitous is the India Mark II/III hand pump system, of which there are more than 4 million installed across the world. These are estimated to serve between 600 million and 1 billion people. But as with most mechanical systems, they degrade over time–leading to pumps becoming dysfunctional due to lack of required service. The pump's nitrile cup seals are the most common cause of dysfunctionality. The purpose of this paper is to analyze the robustness of the cup seals in the India Mark II/III hand pump system. In this paper, 110 off-the-shelf nitrile cup seals purchased by the authors in Uganda were tested and characterized. Leak and pump performance tests were performed in both static and dynamic settings and the correlations between performance and geometry and material properties of the cup seals were determined. This important baseline evaluation for the seals supports our future work to improve the longevity and robustness of the India Mark II/III hand pump system, with a focus on the cup seals. We believe that by finding the baseline of a product, engineers and designers will be able to improve its performance.

Assessment of an Alternative Army Aircrew Eyewear.

Currently, Army aircrews needing refractive correction are issued the HGU-4/P aviator spectacles. However, a recently published survey found dissatisfaction with the current spectacle frame. The Aircrew Flight Frame (AFF) has been used by the Air Force for over 14 yr, with the AFF-OP (Operational) style used the longest. The purpose of this study was to evaluate AFF-OP performance and compatibility among U.S. Army aircrew under operational conditions. At 1-, 6-, and 12-wk intervals, 73 Army aircrew members wore the AFF-OP eyewear and completed a Likert scale survey. There were 14 outcome measures surveyed, with the main outcome measure being frame preference. The AFF-OP was preferred significantly more than the HGU-4/P spectacle. Overall, 94% of aircrew responses preferred the AFF-OP and the three highest subjective reasons for AFF-OP preference were: 1) comfort around the ears without helmet or headset; 2) comfort around the ears with helmet or headset; and 3) the effect on ear cup seal. There were no statistically significant differences in responses over the three surveyed time intervals. Army aviation aircrew preferred the AFF-OP over the current HGU-4/P spectacles. Two of the top three highest subjective reasons for AFF-OP preference coincided with two of the top three operational eyewear problems reported in the recently published survey. If Army aircrew do not wear their issued eyewear, they may purchase their own frame "out of pocket." However, this can lead to use of a frame that has not been tested for compatibility and may compromise performance of aircrew life support equipment.

Complementary products and devices

The design of a contactless seal for use in collars of pump impellers of high-speed units is described. A cup with an unconventional scheme of loading and deforming (straining) of the cup body has been used in the design of the seal unit. At low differential pressures, the cup seal functions as a conventional cup seal, but at high differential pressures it turns into a slit seal. The maximum positive effect in terms of influence on the dynamic characteristics of the rotor is achieved at fixed ratios of the dimensions of the deformed cup and parts that form the seal unit. The data obtained by comparative experimental study of the cup-slit and conventional seal units are provided. Use of cup-slit seals having fluoroplastic (Teflon) cups in oxygen pumps will help reduce expenditures for finding a solution to the problem of safe operation of such pumps.

Bilateral vocal cord immobility caused by a plastic slice: Image and anesthetic management

Abstract This article will describe a rare case of bilateral vocal cord immobility caused by a foreign body and its successful anesthetic management. A 15-year-old adolescent boy presented dysphonia that appeared suddenly while drinking a beverage. According to the flexible laryngoscopy, a one-centimeter circular plastic slice from the cup seal was found stuck in the anterior commissure, making both of his vocal cords unable to move and blocking almost half of his airway. We removed the plastic slice through the rigid laryngoscopy where transtracheal catheter with jet ventilation was used to maintain oxygenation over a critical period. In this kind of case, transtracheal catheter with jet ventilation may be an alternative ventilatory technique to maintain the airway for further laryngomicrosurgery.

Cup seal and master cylinder using the same

Cup seal and master cylinder using the same