WATER SYSTEMS Grey water collection
The Jets vacuum drainage system also allows collection of grey water from basins and showers via special interface tanks, one of which my hosts showed me, mounted below a washbasin in the Otter Vacuum Systems showroom. Once the water reaches a preset level, a valve opens, and the resulting vacuum then ‘flushes’ the water into the pipework. Jets manufactures, and Otter Vacuum Systems can thus supply to UK healthcare customers, an extensive range of both wall and floor-mounted ceramic toilets, urinals, and ‘Asian-style’ toilets and bidets; stainless steel models are also available. Pipes made of a stainless steel, PVC, ABS, HDPE, and polypropylene, are all compatible, while, depending on the type selected, jointing methods including push-fit, heat fusion, and solvent welding.
Pipework design ‘essentials’ While Jets and Otter Vacuum Systems cite numerous advantages for the former’s vacuum drainage systems, they stress that, to derive the maximum benefits, ‘it is imperative that the associated pipework is designed correctly’.
Key requirements include:
n The location of the vacuum generator, ‘as a general rule’, should always be at the lowest part of the vacuum system. For building applications, a 100% redundancy in vacuum generation should be allowed. Pipework dimensions vary, but 50 mm pipework is common, and 75 mm pipes may need to be used in installations involving large numbers of toilets or high levels of grey water. Rising pipes from individual toilets should be DN50, and for grey water interfaces, DN32. Each rising pipe can only serve one interface. An optimally constructed piping system is designed to contain as little water as possible during normal operation. This is aided by making horizontal pipes as short, and with as few bends, as possible.
n While pipework can rise vertically from
n Completed installations can be tested under pressure, ‘only before any interfaces have been fitted’.
n The pipework should be tested under vacuum, either before the interfaces have been fitted – where the acceptable leakage is from 60% to 50% vacuum over one hour, or after, when the comparable figure is from 55% to 40% vacuum over 20 minutes.
The Jets 15MB Vacuumarator pump is a ‘powerful and versatile’ model available in two variants – one for low and medium intensity, and the other for high intensity use.
toilets to carry waste at high level, gravity is always present, and thus all horizontal pipes should have a minimum fall of 1:200.
n If possible, toilets should discharge downwards.
n Bends should always be created with a large radius, or two 45° degree bends. The only place that a 90° bend is allowed is directly connected to the toilet or grey water interface.
n Connecting branches must always be made at a maximum angle of 45˚ in the direction of transport. T pipes, even swept, must never be used.
n Branch pipes, when connected to horizontal pipes, must be from above.
n To avoid any risk of backflow, rising pipes should always be vertical, and should be connected to the upper side of the horizontal, with a goose neck at an angle of 45° to the direction of flow.
n The diameter of a rising pipe must not be increased in the rising part.
n Connection of horizontal branches to downward collecting pipes must always be carried out with a downward 45° connection, and never directly opposite each other. In larger systems, Jets recommends shut-off valves for each branch.
n As with all sanitary systems, scaling will occur. The system will thus need de- scaling, either as part of a normal cleaning programme, or automatically, using dosing pumps.
Wider deployment?
Given the range of benefits that Jets and Otter Vacuum Systems cite for the vacuum sanitation technology, I asked Andrew Hay why he thought there had not been greater take-up in healthcare to date. He said: “That’s a difficult question. In some hospitals I guess there is still a degree of conservatism, in that gravity toilets have been used for many years and are very well-established, despite their substantial water consumption, the need for regular maintenance, and propensity for blockages. We are conscious that some potential users may worry about blockages in, say, the Vacuumarator apparatus, but we know, from our own tests, that the system’s design makes frequent blockages extremely unlikely, coupled to which the Jets vacuum technology’s reliability has been proven over more than 40 years.” I wondered how the system costs compared with traditional gravity sanitation equipment. Andrew Hay said: “Generally a vacuum drainage system will cost more. However, the Jets technology offers very considerable savings in water consumption, lower installation costs, and less disruptive fitting, especially during ‘refurb’ work, plus low maintenance. Add to this the more flexible pipework configuration, and less penetration of walls and ceilings, and while the initial capital costs may be higher, these will be easily recouped medium to longer term. “While we have only – in the past few months – looked really seriously at targeting the Jets technology at the UK healthcare sector, we are very excited at the commercial potential there.”
hej
August 2018 Health Estate Journal 49
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