Vacuum Drainage Systems Guidance

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Vacuum Drainage

Transcript of Vacuum Drainage Systems Guidance

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    A design guide for vacuum drainage systems, for use in conjunction with EN 72709: Vacuum drainage systems inside buildings

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  • Contents

    1 1.1 1.2 1.3 1.4

    2 2.1 2.2 2.3

    3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11

    4 4.1 4.2 4.3 4.4

    INTRODUCTION ...................................................................................................................... 3 Scope .......................................................................................................................................... 3 Background ................................................................................................................................ 3 Vacuum drainage systems compared to gravity drainage .......................................................... 3 Applications ................................................................................................................................ 3

    SYSTEM DESCRIPTIONS .................................................................................................... 4 Definitions of terminology ........................................................................................................ 4 The vacuum transport process .................................................................................................... 5 Operation of system .................................................................................................................... 5

    BASIC COMPONENTS .......................................................................................................... 6 Interface units ............................................................................................................................ 6 Vacuum toilets ............................................................................................................................ 8 Collection tanks and vacuum generation .................................................................................. 8 Ejector unit ................................................................................................................................ 8 Vacuum station .......................................................................................................................... 9

    Controls .................................................................................................................................... 10 Column tank ............................................................................................................................ 10

    Check and isolation valves ...................................................................................................... 11 Pipework .................................................................................................................................... 12

    Vacuum generating and forwarding pumps ............................................................................... 9

    Combined vacuum generator and forwarding pump .............................................................. 11

    DESIGN .................................................................................................................................. 12 Design requirements ................................................................................................................ 12 Design criteria ................................... : ...................................................................................... 12 Maintainability ........................................................................................................................ 15 Noise control ............................................................................................................................ 15

    BIBLIOGRAPHY .................................................................................................................................... 16

    DESIGN EXAMPLES

    In the course of producing this guidance. the following sites in the UK have been studied:

    m The Earth Centre. Doncaster

    m Lords Cricket Ground. London

    m McAlpine Stadium. Huddersfield

    m Sainsbury Supermarket. Sevenoaks

    m Waitrose Supermarket. Gloucester Road. London .

    0 Institute of Plumbing 2001 Published by Institute of Plumbing . Produced by BRE

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    Parameter

    Pipe size (mm)

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    Conventional

    Branches 32-100 Stacks 100-150

    (gravity)

    1 INTRODUCTION

    Branches 32-100 Stacks 100-150

    To a fall

    Regular planned servicing of pumps and interface units

    1.1 Scope The aim of this publication is to act as a guidance document for vacuum drainage systems, for use in conjunction with EN1 2109: Vacuum drainage systems inside buildings. This guide is aimed at designers, installers and building services students and lecturers who may be considering using a vacuum drainage system or who wish to know more about them.

    This document covers vacuum drainage systems within buildings, and does not cover their use outside buildings, or vacuum sewerage. The principles of vacuum drainage are covered, however the design details, such as pipe sizing, are not dealt with as such matters would be designed by a vacuum drainage system specialist.

    The terms used in this document are as defined in EN12109. However, a few of the definitions from the European Standard are included in section 2 to aid the reader's understanding.

    Discharge from valves 32-50 Service connection 38-90

    Flexible arrangements, with minimal gradients or sawtooth profile. Vertical upward flow sections 'lifts' can be used

    Regular, planned servicing of pumps and interface units

    1.2 Background Generally, the modern vacuum drainage system is believed to have been started by the development of the vacuum toilet of Mr Joel Liljendhal in the mid 1950s. The concept of his system was to separate the heavily polluted waste and the lightly polluted water (black and grey water) for separate treatment. The vacuum toilets used only about 1 litre of water per flush, improving the efficiency of the system and making treatment easier. This two-pipe system, although environmentally friendly, met with quite a lot of resistance because houses needed to be re-plumbed and the vacuum toilet required more maintenance than a conventional toilet. This lead to the development of the single-pipe vacuum drainage system generally employed today.

    At time of installation and throughout lifetime of building

    May require additional Pumps

    7.5 litre flush WC

    1.3 Vacuum drainage compared to gravity drainage Table 1 summarises the differences between conventional drainage systems and a vacuum drainage system.

    At time of installation and throughout lifetime of building

    Flexible layout makes installation simple

    N/A

    1.4 Applications Particular consideration should be given to the use of vacuum drainage in the following circumstances: 0 water shortage or other reasons for reducing

    water consumption 0 limited sewerage capacity 0 where separation of black and grey water is

    desired, e.g. where grey water is reused 0 where separation of wastewaters is desired,

    e.g. for different treatments

    Conventional water consumption WCs

    Low water consumption WCs

    Loading of sewerage system

    7.5 litre flush WC

    6 litre flush WCs

    Dependant upon appliances installed

    Pipeline gradient

    ~~~~

    Dependant on pumping rate

    To a fall

    Discharge from forwarding pumps can be times to coincide with low flow periods

    Maintenance requirements

    Energy requirements

    Whilst the original systems were developed for domestic sewerage transportation, the systems evolved in two different areas; transportation and land-based systems. The majority of work has been in the transportation sector, and the marine industry continues to be the major user of the system, where the need to conserve wholesome water, and the problems of confined pipework runs and sewage disposal are paramount. For the same reasons, this technology was adopted by the other forms of mass transport, i.e. airlines and railways. Today some SO00 ships, from yachts and cargo vessels to ocean going cruise liners, SO major airline companies, and over 1000 train installations use vacuum drainage systems.

    The building sector has been slow to adopt this new technology, but with the restrictions placed on new projects such as small conduit, ceiling voids and service ducts, and the growing awareness of the need to limit water consumption, the system is finding a place in the building sector.

    Negligible, only after

    At time of installation

    Retrofit or extension of system within building

    May be difficult to accommodate pipework and falls

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    I Vacuum Conventional (DumDed)

    6 litre flush WCs 1.5 to 3 litre flush vacuum toilets

    Table 1 - differences between different types of drainage systems

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  • 1 Advantages I Disadvantages Low installation costs

    Environmentally safe

    Electrical power only required at vaciiiim station

    Always self cleansing

    ,

    High component costs

    Mechanical components - possibly for failure

    Skilled design, installation and maintenance required

    Regular maintenance required

    No possibility of vermin in pipelines Possible water saving technique if vaciiiim toilets are used

    Standby facilities required

    Require area for situation of vacuum tanks and vaciiiim generation