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DESIGN : DEAR MR PLUMBER
Dear Mr Plumber
By
Vollie Brink
SANS 10400-P is the standard for the design and construction of the sanitary drainage system of buildings and for housing and office buildings , this you now know very well .
This Standard is a very clear and easy to understand document and easy to apply , yet so many plumbers and others have problems interpreting the requirements . The first place many people go wrong is to interpret the total SANS 10400-P as ‘ Regulation ’, which it is not .
One of the very important ‘ principles ’ is that you must never combine wastewater and soil-water in a single horizontal branch pipe or in the horizontal collector discharge pipe and the simple reason for this principle is to prevent effluent overflow through the shower or bath or floor drain , which is a horrible experience .
Vollie Brink is one of the industry ’ s longest-serving wet services engineers . He continues to serve on SABS committees and has been involved in the Green Building Council ’ s Green Star rating system . Brink continues to consult for various organisations while enjoying a wellearned retirement .
Only P1 , P2 , P3 , P4 , P5 , P6 and P7 are regulations , and these regulations are compulsory .
A ‘ rule ’, such as the ‘ deem-to-satisfy-rules ’ ( DTSR ), is not compulsory , unless the designer chooses to use it for the design , then it becomes compulsory , and then in this case the legal definition of deem-to-satisfy is ‘ compulsory ’.
The plumber the engineer and the building inspector must be careful with the definition of regulation , rule , standard , by-law , and what is compulsory and what is not , and what trumps what .
The ‘ thou shall ’ part is P1 to P7 and P2 is the only ‘ regulation ’ that specifies the ‘ performance ’ of any sanitary drainage system .
Over and above the standards , regulations , and rules there is also what I call ‘ principles ’, and this is basically the theory of drainage and this is extremely important for a rational design . The engineers talk about the ‘ first principles ’ on which the design is based .
When the Engineer submits an application for professional registration , then the engineer must demonstrate that his / her design is based on ‘ first principles ’, in other words on basic theoretical knowledge and not a standard set of rules .
Therefore , the engineer must think differently and from first principles and comply with the performance specifications . The other professions are allowed and required to apply standards and regulations and rules .
It is very important to understand the above-mentioned . It is also very important to understand the elements or parts of a drainage system and how and why you can ‘ mix-and-match ’ these parts to form a complete sanitary drainage system – and therefore I refer to the ‘ principles ’.
It is also very important to understand that the deemto-satisfy-rules are only a simple ‘ recipe ’ and that if you apply it , your installation will ‘ deem-to- comply ’ with the regulations , namely P2 .
You must note that this ‘ recipe ’ does not always satisfy in all conditions such as soil and even in weather conditions and topography . The recipe was developed for ‘ housing ’ and for ‘ office ablutions ’ and the proof is the pipe elements .
There are two types of important elements or parts namely : A ‘ group of fixtures ’ and ‘ ranges of fixtures ’. The group of fixtures are all the fixtures you will find in a house or a flat which are used privately , and ranges of fixtures what you will find in the ablutions of an office or other public facilities . A group of fixtures must then be connected to a stack pipe or stack pipes or to a drain and the same with the ranges . A range consist of a range of WCs or a range of urinals , or a range of wash-hand-basins or showers .
The group or the range is the core of a drainage system and the pipe configuration around this , which must cater for the hydraulic actions in the piping to convey the waste and soil water through the piping from the fixtures horizontally and vertically and via a drain to the municipal sewer or to an onsite disposal facility .
There are no other ‘ design regulations ’ other than P1 to P7 , which are performance specifications , and these same regulations ( not the dtsr ) are applicable for hospitals , retirement homes , shopping centres , industrial complexes , prisons , police stations – basically all other buildings except for housing and office buildings .
In the 1970s when the new NBR were promulgated , all government , provincial and peri-urban buildings had their own rules and design standards , which is perhaps why they were exempted from having to comply with the new NBR of 1977 .
www . plumbingafrica . co . za @ plumbingonline @ plumbingonline @ PlumbingAfricaOnline March 2021 Volume 27 I Number 1