AU2013101666A4 - Pipe system and building design - Google Patents

Abstract

A method of determining pipe size in a pipe system used to service a plurality of fixtures including: determining one or both of a loading unit and fixture unit for each of the fixtures, based on a water efficiency rating of the fixture; and determining the required pipe size for one or both of a supply pipe and drain pipe on the basis of a sum of the loading units and fixture units, respectively. The invention also relates to a pipe system with supply and drain pipe diameters determined using the method, and to an apartment or building with a plurality of fixtures and that pipe system. -1/2

Description

PIPE SYSTEM AND BUILDING DESIGN FIELD OF THE INVENTION [0001] The present invention relates to a method of designing a pipe system and a building incorporating the pipe system. BACKGROUND OF THE INVENTION [0002] A construction such as an apartment building includes many water using fixtures such as a shower, water closet, kitchen sink and washing machine. Each fixture has a specific optimal flow rate. Building codes specify the flow rates for each type of fixture and ascribe an associated Fixture Unit and a Loading Unit. [0003] A Fixture Unit is a nominal unit used in the calculation of drain pipe diameters. The unit is equal to 0.0283 cubic metres of water drained in a 32mm pipe over one minute. A Fixture Unit is not a flow rate unit but a design factor. [0004] A Loading Unit is a factor that takes into account the flow rate, length of time in use, and frequency of use of the fixture or appliance. A Loading Unit is used to determine a required supply pipe diameter for any given fixture. [0005] For the domestic environment, for example, the Building Code AS/NZS 3500.1:2003 specifies the flow rate of a water closet is 0.10 L/s and applies a loading unit of 2; the flow rate for a shower is 0.10 L/s with a loading unit of 2, and the flow rate of a washing machine is 0.20 L/s and the associated loading unit is 12. [0006] The loading units for an apartment building or any given apartment in the building are tallied to determine an overall loading unit total for the building or apartment. The total is representative of the water usage requirements and is used to determine the -2 supply pipe diameter. Similar calculations are made to determine the drain or sewer pipe diameter for the apartment or building, based on the total Fixture Units of the building. 10007] With regard to the water supply pipe diameter, if the water usage is less than expected, the inlet pipe diameter may be too large for the actual loading requirements, which can result in reduced flow rate through the pipe. Higher flow rates are known to reduce the likelihood of biofilms forming in the water pipe, so a low flow rate may present health risks in allowing dangerous biofilms to develop, such as those responsible for Legionnaires disease and the like. [0008] For new building projects constructed on existing lots, with multiple apartments, it is likely the original sewer pipe connection to the mains sewer will not be large enough to satisfy the larger drain pipe requirements under existing building codes. If a large dimension sewer pipe needs to be installed for the building, the original mains sewer connection will need to be closed and substantial works required to install a new sewer connection and manhole. The additional works add considerably to the cost of a building project and the level of occupational health and safety risks associated with construction of the building. OBJECT OF THE INVENTION [0009] The present invention seeks to provide a new method of determining required pipe sizes in a pipe system used to service a building. The invention also seeks to provide a related building with such a pipe system.

-3 SUMMARY OF THE INVENTION [0010] In accordance with the invention, there is provided a method of determining pipe size in a pipe system used to service a plurality of fixtures including: determining one or both of a Loading Unit and Fixture Unit for each of the fixtures, based on a water efficiency rating of the fixture; and determining the required pipe size for one or both of a supply pipe and drain pipe on the basis of a sum of the Loading Units and Fixture Units, respectively. [0011] Preferably, the rating in a water efficiency labelling scheme (WELS) rating. [0012] Preferably, the method includes providing a cross-referencing tool to correlate the WELS rating with an associated loading unit for the relevant fixture. [0013] Preferably, the cross-referencing tool is a table. [0014] Preferably, the method is used to determine a water supply and drain pipe diameter of an apartment or building. [0015] In another aspect, there is provided a pipe system with water supply and drain pipe diameters determined using the above described method. 10016] In another aspect, there is provided an apartment or building with a plurality of fixtures and a pipe system as described above.

-4 BRIEF DESCRIPTION OF THE DRAWINGS [0017] The invention is described in more detail, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of a building incorporating a pipe system designed in accordance with current building codes; and Figure 2 is a schematic plan view of a building incorporating a pipe system designed in accordance with the invention. DETAILED DESCRIPTION OF THE INVENTION [0018] Referring firstly to Figure 1, a building 1 is represented in plan view. The building I is located on a property lot 2 that adjoins an existing mains sewer 3. A legacy drain pipe 4 is shown to illustrate a previous sewer connection 5 used for the lot [0019] The building 1 is a new development and, for ease of explanation, only the external walls 6 are shown in solid lines. The building has 29 apartments in total with five being on the Ground Floor, designated by reference numbers 7 to 11. The level shown has additional commercial units/facilities on the Ground Floor (and the three levels over that), designated by numeral 12. [0020] Each apartment 7 to 11 has a collection of water using fixtures (not shown) with associated outlets 13 that connect into a pipe system that includes a common sewer or drain pipe 14. The building is illustrated as a single level but multiple levels can be provided, with similar apartment layouts and pipe systems, all connected to the drain pipe 14.

-5 [0021] As may be appreciated, the different fixtures may all have different flow requirements. In order to determine the size of drain pipe require to accommodate all the fixtures, an arbitrary unit is used for pipe sizing which takes into account the likelihood that all the fixtures will not be used at the same time. This unit is called a Fixture Unit (FU), as mentioned above in the Background of the Invention section. [0022] Fixture Unit values can be determined using charts from the International Plumbing Code or similar codes in local jurisdictions. In the present case, reference may be had to Table 6.1 of the Australian Standard AS 3500.2:2003, entitled 'Fixture Unit Ratings'. [0023] Each one bedroom apartment in the above building may have the following fixtures and associated Fixture Units (and a two bedroom apartment may have additional water closet, shower and basin fixtures and associated Fixture Units); 1. Water Closet (WC) 4 fixture units (FU) 2. Shower (Shr) 2 fixture units (FU) 3. Basin (B) 1 fixture units (FU) 4. Laundry Trough (L) 5 fixture units (FU) 5. Kitchen Sink (S) 3 fixture units (FU) Total FU 15 fixture units (FU) [0024] AS 3500.2:2003 provides a further Table 3.1, entitled 'Maximum Fixture Unit Loading for Vented Drains', which can then be used to determine the appropriate size for the drainage pipe 14, based on the total Fixture Units associated with the building. [0025] As can be derived from Table 3.1, a nominal size drain pipe of 100mm diameter, at a minimum gradient of 1.65%, can cater for a total fixture unit load of 165. In the scenario above where one type of each fixture exists within each apartment, this equates to a total number of 11 apartments.

-6 [0026] Upon exceeding 11 apartments the drainage size must be increased to 150mm diameter. The building 1 has a total of 29 apartments plus two commercial spaces over four levels. [0027] A nominal size drain pipe of 150mm diameter, at a minimum gradient of 1.00%, can cater for a total fixture unit load of 855. A drain pipe of this size would accommodate the drainage requirements of a total number of 57 apartments, if each apartment included all of the above listed fixtures. [0028] Upon exceeding 57 apartments the drainage pipe size would need to be increased to 225mm diameter. [0029] A nominal size drain pipe of 225mm diameter, at a minimum gradient of 0.65%, can cater for a total fixture unit load of 3250. Again, if each apartment in the building had every one of the above listed fixtures installed, this would equate to a total number of 216 apartments. [0030] Upon exceeding 216 apartments the drainage pipe size would need to be increased to 300mm diameter. [0031] A nominal size drain pipe diameter of 300mm, at a minimum gradient of 0.40%, can accommodate the drainage requirements of a total Fixture Unit load of 6780, which is equivalent to 452 apartments, assuming each apartment included all of the fixtures listed above. [0032] By way of illustrative example, with reference to Figure 1, it is apparent from the above that if the number of apartments in the building exceeded 11, it would be necessary to install the new 150mm drain pipe 14 since the legacy sewer pipe diameter 4 is too small at only 100mm. As illustrated in Figure 1, a new tie 15 to the sewer is required, in order to satisfy AS 3500.2:2003 design requirements.

-7 [0033] To install the tie 15, a trench firstly needs to be dug to a depth of about 4500mm and a sewer manhole 16 needs to be installed over the existing mains sewer 3 at the intersection of the tie 15 and the sewer 3. The digging and constructions works required are labour and time intensive. The works also pose substantial occupational health and safety risks, not just from machinery use but also as the trenching and pipe laying occurs in a region where many other utility cables and lines are located, such as for power, gas, data, etc. Further, expensive traffic diversion procedures need to be put in place while the works are underway which further increases the costs associated with the building project. [0034] The inventor has found the abovementioned Fixture Unit Table is based on traditional fixture water requirements and no account is taken of more contemporary water fixtures with differing water conserving efficiencies. Indeed, fixtures are designed and marketed on the basis of water saving characteristics, to assist in reducing water usage and utilities bills. However, apartment buildings are still designed as if the fixtures had no such water conservation improvements. [0035] The present invention seeks to provide an alternative Fixture Unit calculation, determined on the basis of water efficiency of the relevant fixture. [0036] Table 3.1 in AS3500.2:2003 will still be used to size the drain pipes however an alternative table 6.1 will produce reduced Fixture Unit loadings where water conserving fixtures are installed within buildings. [0037] Pipe sizes can then be designed to cater for the actual flows emanating from fixtures, both individually and collectively, allowing for reduced pipe diameters.

- 8 [0038] By way of further explanation, Fixture Unit ratings in AS 3500.2:2003, Table 6.1, are derived from fixture types of many years ago, when flow rates were similar e.g. Water Closet (WC) 11 litres full flush Shower (Shr) 20 litres per minute Basin (B) 20 litres per minute Laundry Trough (L) 20 litres per minute plus washing machine (top loader) Kitchen Sink (S) 20 litres per minute plus dishwasher [0039] Water conserving fixtures are now available that have the following profiles: Water Closet (WC) 4.5 litres full flush/3.0 litres half flush Shower (Shr) 6 litres per minute Basin (B) 6 litres per minute Laundry Trough (L) 6 litres per minute plus water conserving five star washing machine (front loader) Kitchen Sink (S) 6 litres per minute plus water conserving five star dishwasher [0040] A rating system known as the Water Efficiency Labelling Scheme (WELS) provides a rating for all types of fixtures in a plumbing system. [0041] The present invention correlates the WELS rating system with a modified Fixture Unit calculation, which is tabulated below for use is determining appropriate drainage pipe sizing. [0042] Prior to presenting the table, attention also needs to be drawn to how a water supply pipe size is traditionally determined and the manner in which Loading Units can also be modified with the WELS rating to effect the size determination of a supply pipe.

- 9 [0043] In that regard, reference is made to the table below, where each fixture is allocated a Loading Unit rating. As explained in the Background of the Invention section, a loading unit is a factor that takes into account the flow rate, length of time in use, and frequency of use of the fixture or appliance. When installed in a domestic situation, Loading Units for fixtures/appliances may be determined by reference to Table 3.1 of the AS 3500.1:2003 Standard, entitled 'Flow Rates and Loading Units'. [0044] From the abovementioned Table, a rating can be applied to each fixture in an apartment e.g. 1. Water Closet (WC) 2 Loading units (LU) 2. Shower (Shr) 2 Loading units (LU) 3. Basin (B) I Loading units (LU) 4. Laundry Trough (L) 3 Loading units (LU) 5. Kitchen Sink (S) 3 Loading units (LU) 6. Dishwasher (DW) 3 Loading units (LU) 7. Washing Machine (WM) 3 Loading units (LU) Total LU 17 Loading units (LU) [0045] Referring now to Table 3.3 of AS 3500.1:2003, entitled 'Probable Simultaneous Flow Rates (PSFR)', this table is used to calculate probable simultaneous flow rate (PSFR) based on water loading units. For example, assuming one apartment has 17 loading units which equates to a probably simultaneous flow rate of 0.35 litres per second. [0046] Reference is now made to Table C1 of AS 3500.1:2003, entitled 'Pipe Sizing for Maximum Velocity of 3 Metres/Sec'. This table is used to calculate the pipe size for PSFR based on length of pipe and allowable pressure drop. By way of example, with a pressure drop of 10 metres head, pipe length of 20 metres at a PSFR of 0.35 litres per second, the pipe size required is a 20mm nominal bore.

-10 [0047] If three apartments have 51 loading units that equates to a probable simultaneous flow rate of 0.62 litres per second. Table CI can then be used to calculate the pipe size for PSFR based on length of pipe and allowable pressure drop. Again, for a pressure drop of a 10m head, pipe length of 40 metres at a PSFR of 0.62 litres per second, the pipe size required is a 25mm nominal bore. [0048] With the present invention, the abovementioned Table 3.1 in AS2500.1:2003 will be replaced with an alternative cross-referencing tool in the form of a modified table, with Loading Units altered to take into account the WELS rating of a fixture. More specifically, the invention will use an alternative Table 3.1 which indicates alternative water loading units that take into account water conserving fixtures that are now common in the Australian market. [0049] Tables 3.3 and C1 will still be used to size the water pipes however the alternative Table 3.1 will produce reduced water loading units where water conserving fixtures are installed within buildings. [0050] Pipe sizes can then be designed to cater for the actual flows required to supply water to fixtures, not a common number applied to all fixtures. [0051] The following Table embodies the modification of the various Fixture Unit drainage ratings and Loading Unit supply ratings for fixtures, as modified by the WELS rating: Fixture WELS rating LirsPer Fixur Unit Loading Unlit (star) midnute rating rating Sewer Water Basin 0- 20 1 1.5 ___________1 16 0.8 1.25 2 _2 0.6 1 3 9 .50.8 __ __ __ __ _4 7.5 0.375 0.6 _______5 6 0. 045 Clothes washing 0 N~/A S 3 Machine __ _ _ _ _ _ __ _ _ _ ___ _ _ _ _ _ 1 23 5 1 3 __ __ __ __ _2 18 4 2.4 3 16 3.52. 4 14 3 I 1.85 5 12 2.6 1.6 Dishwashing 0 N/A 3 3 M ci e1 23 3 3 2 18 2.4 2.4 3 16 2.1 2.1 4 14 1,85 1.85 __________5 12 1.6 1.6 -12 Fixture WELS rating Litres Per Fixture Unit Loading Unit (star) minute rating rating Sewer Water Shower 0 20 2 4 1 16 1.6 2.5 2 12 1.2 2 4 7.5 0.75 1.6 5 6 0,6 1.2 Sink 0 20 3 4.5 1 16 2.4 3,75 2 12 1.8 3 3 9 1.35 2.4 4 7.5 1.2 1.8 5 6 0.9 1.35 LaundryTrough 0 20 5 3.9 1 16 4 3.25 - 2 12 3 2.6 3 9 2.25 2A 4 7,5 1.9 1.8 5 6 1.5 1.3 Water Closet 0 11 3 2 1 5.5 15 2 2 5 14 2 3 4 1.2 2 4 3.5 1 2 5 3 0.8 0 (basin over [0052] Using the above Table, the supply pipe and drain pipe requirements of the building 1 shown in Figure 1 can be recalculated and, for the same number of apartments, it is found that only a 100mm diameter drain pipe is required, as shown in Figure 2. [0053] As a result, the original or legacy sewer pipe connection 4 of the building lot 2 can still be used, which accounts for a substantial saving in time and labour associated with the building project.

- 13 [0054] Further calculations of the Fixture Units and Loading Units of a standard two bedroom apartment are provided below to illustrate the additional number of apartments that can be accommodated in a building before pipe diameters need to be increased, using the WELS modified table. IU WR~ MuM . R . 5 II

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9WI -14 ~1U1P;OVl Ln ~ ~ ~ jg~ S4J o 1 q to0n. aac - 15 [00551 Additional calculations are tabulated below to show the pipe sizes required for an equivalent number of one bedroom apartments. 3 c; c;d dAr i 4 r 4 r Li 3 3 msiiis '33 i 5s ammca gs m sa .! _L9* I * D, I- L R I I I~~ ~~~~ I ""1 111 11 Ws s w V~- A Li~f Dc; ma, -17 [0056] As may be appreciated from the above, the invention allows for reduced pipe sizes to be used in the construction of buildings with multiple water using fixtures by modifying existing Fixture Units and Loading Units by a WELS rating, take into account improved water efficiencies of modem fixtures. By reducing the pipe sizes, high fluid flow through the supply pipes can be maintained, as a preventative measure against biofilms. Smaller drain pipes also means the existing sewer connections can be utilised, instead of requiring new sewer connections to be installed, which reduces project costs and occupational health and safety risks. [0057] The invention has been described by way of example only and many modifications and variations may be made without departing from the spirit and scope of the invention.

Claims (7)

1. A method of determining pipe size in a pipe system used to service a plurality of fixtures including: determining one or both of a loading unit and fixture unit for each of the fixtures, based on a water efficiency rating of the fixture; and determining the required pipe size for one or both of a supply pipe and drain pipe on the basis of a sum of the loading units and fixture units, respectively.

2. The method of claim 1, wherein the rating is a water efficiency labelling scheme (WELS) rating.

3. The method of claim 2, further including providing a cross-referencing tool to correlate the WELS rating with an associated loading unit and fixture unit for the relevant fixture.

4. The method of claim 3, wherein the cross-referencing tool is a table.

5. The method of claim 1, wherein further including determining a supply and drain pipe diameter of an apartment or building.

6. A pipe system with supply and drain pipe diameters determined using the method of any one of claims 1 to 5.

7. An apartment or building with a plurality of fixtures and the pipe system of claim 6.