Warnings of failures of flexible tap connectors recently aired on channel 7NEWS. The hoses which are reported to save plumbers time and money need to be maintained as described in the interview.
The hoses are corroding or fraying before they fail. Is it the material that is at fault or is it an underlying issue within your plumbing system? Unfortunately the industry seems to be focusing on the symptom and not the cause and many believe that it is the grade of stainless sheathing or the type rubber hose that is causing the problem. Where these hoses are exposed to the elements like connecting toilet cisterns or wall basins that is a distinct possibility, but where they are located in vanity cupboards or sinks where the environment is a little more controlled we need to look a little deeper into what could be causing the problem.
Materials Engineer Trevor Rowlands from Materials Solutions Australia has conducted many flexible braided hose failures over years for lawyers, insurance companies and plumbing suppliers, Trevor disclosed the following to PWH.
“I can say with a high degree of certainty that changing the 304 to 316 is only treating the symptom and not the cause. The same goes for changing the rubber hose to a polymeric material. Whilst it would be expected that 316 would take longer to corrode and fail, it will still occur over time. Depending on the severity of the service environment, in fact it may be that corrosion and failure rates may still be very similar.”
Given what I believe is going on as far as leakage past the seal interface in the connections, the data presented below suggests that dynamic pulsation may be a factor. I also think that stress relaxation of the seal over time is real a contributor.
The transient pressure surges generated in rigid piping materials by fast acting tapware such as flick mixers, solenoids and trigger sprays can generate pressure shock waves in piping systems many times over the static pressures.
This above chart displays that the closing of a tap can raise the pressure at the outlet to over 500kpa even when both static and dynamic pressures are below 350kpa.
This dwelling had plastic cold water pipes installed in the ceiling space which helped reduce the effects of the pressure spike.
What dynamics are occurring in your plumbing system?
Sometimes underlying pressure issues go undetected for many years.
I like following quote from Prof. Dr. Hans-Kurt Flemming
Drinking water is the most rigorously monitored class of all foodstuffs. In Germany, the quality of drinking water is excellent – but only until the water meter. Beyond the meter, however, a poorly-studied area of occasional hygienic uncertainty begins: the household installation.
In my opinion it is not just the hygienic side that is poorly studied.
See a copy of his research paper in our .
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