Does Plumbing Research Exist?
Research is defined for the review, due next in April 2001, as original investigation undertaken in order to gain knowledge and understanding. It includes work of direct relevance to commerce and industry, as well as the public and voluntary sectors; the invention and generation of ideas where these lead to new or substantially improved insights; and the use of existing knowledge in experimental development to produce new or substantially improved materials, devices, products and processes, including design and construction. It excludes routine testing and analysis of materials, components and processes, e.g. for the maintenance of national standards.
Historic plumbing research may be assessed against this criterion. Early U.S. work in the 1930s detailing the relationships between annular film thickness in vertical stacks and the applied discharge qualifies, as does Hunter's seminal work at the National Bureau of Standards (NBS). Hunter's work is doubly interesting as he recognised the limitations of his proposals, admitting that his analysis only applied to steady flow conditions that are highly unlikely in drainage networks due to the time dependency of the flow, arising from the combined effects of appliance user patterns, discharge profiles and wave attenuation within the horizontal network branches. Hunter recognised that solutions were possible, but his lack of fast numerical analysis techniques made them impractical-50 years were to elapse before computing made advances on Hunter's solution possible. Hunter's work provided a usable design technique that survives to the present day, despite the fact that the majority of users have no comprehension of the inherent limitations he identified.
In the U.K., Wise made equivalent advances at the Building Research Establishment (BRE) in the 1950s. The need to rebuild following the end of the Second World War led to a wide range of construction initiatives; several initially thought of as short term (such as pre-fabricated housing) have survived to the present. At BRE, Wise concentrated on reducing the complexity of vent systems to economize on both materials and time. This in-depth analysis of the operation of vent systems convinced Wise that conventional venting was over-provided and led to the introduction of the Single Stack system, where careful choice of horizontal branch slope and diameter prevents trap seal loss, forming the basis for U.K. design practice. Wise's work, including laboratory and site investigations, demonstration projects and dissemination to industry, would undoubtedly meet the present day research criterion.
Hunter's work continued during the 1960s through Wyly and his co-workers, their papers demonstrating a research ethos that conforms to the definition chosen for this discussion. The final fully funded research effort at NBS was the water conservation program headed by Galowin in the early 1980s. Internationally, the research effort in drainage was carried forward by contributors to the Conseil International du Batiment Working Commission 62 'Water Supply and Drainage for Buildings,' whose first annual meeting was organized by Wise at BRE in 1972. These meetings continue; my own department hosted the last of the 20th Century in September 1999 in Edinburgh. The first of the new millennium will appropriately take place in Brazil in September 2000. Up to the 1980s, the national building research laboratories dominated, although much of their work would be excluded by our definition as being 'routine testing' or 'in support of national standards.' Most of their work could be described as being for the common good, a traditional and necessary role for governmental research organizations. However, in both the U.K. and U.S., the political climate represented by Thatcher and Reagan turned increasingly away from such funding support, not only in built environment but across a whole range of socially responsible research areas. Drainage research died away in these traditional venues, the NBS effort was closed down, and BRE scaled down its activity. Similar results could be seen across Europe.
Plumbing research might also be expected in universities and industry, in common with other engineering disciplines internationally. Unfortunately, the construction industry in general, and its drainage and water supply arm in particular, is unlike aerospace or electronics where it is recognized that advances come from the acceptance and adaptation of fundamental research, more often than not with a secure mathematical base.There is an inability to appreciate that research can provide both solutions and pointers to valuable new market potential. Industry-based research is rare, with some notable exceptions, such as Toto in Japan, Caroma in Australia and Geberit in Switzerland. Close interaction with university research is rarer still. The culture that 'if it's math, it must be either difficult or irrelevant, or perhaps both' prevails.
One example that swims against this tide, of interest due to recent pronouncements by ASPE and others, is the Air Admittance Valve saga. Work on AAV design falls within the research definition as it transfers ideas from the surge relief field into vent system applications. The inclusion of AAVs within vents substantially reduces complexity, especially when combined with Wise's Single Stack system. The provision of parallel paths by distributing AAVs up the stack reduces stack diameter above the highest discharging appliance and limits the suction pressures generated by traditionally drawing air down the whole stack. AAVs have only been cautiously accepted, with many of the objections having nothing to do with their efficiency. The statement that an AAV cannot deal with the positive air pressure transient following a stack surcharge fails to recognize that due to parallel path venting, the positive air pressure transient is likely to be lower in an AAV-equipped system than in a conventional system, where the entrained airflow rate is higher. An analysis of transient propagation could enhance the operation of AAVs and remove some of these problems. The design of current AAVs has depended on industrial initiative; however, a recent development of a waterless trap by a U.K company demonstrated the value of a combined industry/university approach. The trap featured a sheath that opens to allow water to pass from the appliance to the drain. Normally, the sheath is self-closing. A cursory inspection of the device identified immediately that the device was also a highly efficient AAV-solving two problems at a stroke.
University research funding in the U.K. is highly competitive. Plumbing research has had to adapt to meet the requirements of the competition, leading to a concentration on the application of mathematical methods to simulate installed systems and model validation programs. Sewer research is better provided for in a number of centers, but plumbing is only represented at one or two establishments. The fact that this department rated an international grade 5 in the 1996 Research Assessment proves that it is possible to undertake high quality work in this area, but it is rare.
In conclusion, therefore, it may be seen that plumbing research has existed within the criterion proposed at the start of this column. Its survival into the coming century depends on a radical re-alignment of relationships between industry and the research community, whether governmental- or university-based. In my next column, I will analyze the steps necessary to bring together both industry and the research community so that a common vocabulary can be developed for the common good.
And finally, it would be accurate to say that not all these thoughts are from abroad, as I have just spent an extremely pleasant week skiing in Breckenridge and Vail. However, it was with some trepidation that I approached immigration at Denver Airport, as last year our research reports on the application of AAVs were placed in evidence before the Colorado Court of Appeals, and I wondered for a moment if I would be whisked away to explain our maths-happily, just a fantasy.