Air problems in pipelines - a design manual

Escarameia, M. (2005) Air problems in pipelines - a design manual. Manual. HR Wallingford Ltd, Wallingford.

PDF Air-problems-in-pipelines.pdf Download (3MB)

Abstract

The entry, control and release of air from pipelines is a major, though often hidden, problem in pipelines used for water supply, foul water drainage and effluent discharge. Considerable costs are incurred in providing air release valves and chambers, and in deepening pipe trenches so as to provide the minimum gradients that are thought necessary to enable air bubbles and pockets to move towards the valves. Air valves require regular maintenance, but in practice this is rarely undertaken and there are numerous instances of their leaking and/or failing to operate correctly. In certain cases, vibration of the valves during start-up or shut-down of pumps can cause air to be drawn into a pipeline – the exact opposite of what is intended. Where effluent and water transfer pipelines need to be laid under water in coastal or tidal areas, air valves cannot be used at all and the bed topography may result in very flat pipe gradients. Also, air valves cannot be used on potable water systems in situations where they might admit ground water into the pipeline. It is therefore very important for professionals involved in the design and construction of water and wastewater pipelines to understand the potential problems caused by the presence of air (either as bubbles or large pockets), identify its sources and then take measures to reduce or eliminate as much as possible the presence of air. Since the removal of all sources of air may prove impossible in many cases, it will be necessary for practitioners to know how to design for air/water mixtures and minimise air’s detrimental effect. This manual aims to provide engineers with concise and up-to-date advice. However, it is realised that much is not yet known in this complex field of multi-phase flow and the guidance provided represents a simplification of what is an extremely complex, though fascinating, subject.

Actions (for site administrators only - login required)

View Item