TERRAIN SDP piping system made in PB for chilled water application

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1 TERRAIN SDP piping system made in PB for chilled water application Air conditioning in residential and commercial buildings are offering an important quality of life to people. Therefore the use of chilled water for the secondary circuit made in Polybutene PB is having a very positive trend. Polybutene (PB) has been applied for cooling (chilled water) in many big and small projects in the last decades. The main advantages of PB compared to traditional steel pipes are: Absolutely corrosion free (inside and outside of the pipe) No additional post-treatment required e.g. anti corrosion treatment on the external pipe surface of steel pipes Much less condensation on the pipe surface Very low thermal conductivity (0,22 W/mK) and therefore less energy loss No issues if the pipes are bad insulated as no outside corrosion can occur Big temperature range; from minus -30ºC up to 95ºC (for cooling and heating) Zero maintenance cost and long lifetime High chemical resistance (generally antifreezing or anticorrosion agents are not affecting the PB, brass or the rubber joints) Very high pipe flexibility which offer comfortable and easy installation, especially when installed inside false ceilings and shafts Very low noise transmission of PB due the extreme low E-Modulus (450 N/m2) Easy and safe assembly technologies available e.g. PushFit and Electrofusion Less pressure drop due to the smooth pipe surface and therefore less pump energy cost Big range of adaptors or connectors to other piping systems e.g. special flange connections, screwed male/female connections from ½ up to 6, etc. Possibility to manage the expansion and contraction in the installation method by rigidly fixing! Only PB offers this possibility. High service pressure rate for cold water which is PN22 (bar) Last but not least; PB offers the lowest environmental impact when compared to other plastics or metallic s e.g. copper, steel, stainless steel which define PB as a Green Product

2 Formation of condensation The typical temperature range for the supply pipe of chilled water is between 2 7ºC (Fan Coil Units) but in some cases it is also 16-18ºC as per instance the so called radiant cooling which is often used in ceiling panels. Because of the potential for condensate formation on the cold radiant surface of the pipes (resulting in water damage), radiant cooling systems have not been widely applied. Condensation caused by humidity is a limiting factor for the cooling capacity of a radiant cooling system. The surface temperature should not be equal or below the dew point temperature in the space. But however, above point is rather a problem with ceiling panels made in copper pipes but it s less problematic for pipes made in plastics with a low thermal conductivity. This is one of the reasons why many manufacturers are offering Ceiling Panes made in pressure resistant plastic. Example: Copper has a thermal conductivity of about 407 W/m K while PB only has 0,22 W/m K. Anyhow, Nueva Terrain always proposes to insulate the chilled water pipes which are supplying the cold-energy to the Fan Coil Units respectively to the Ceiling Panels because of two main reasons: 1. Avoiding condensation and 2. Reducing cold-loss (energy loss). Regarding the first point; an insulation thickness of 6mm would be enough to avoid condensation on PB pipes considering the following parameters: Fluid temperature (5ºC) Ambient air temperature (28ºC) Relative air humidity (60%) Type of insulation (soft rubber with -value 0,035 W/mK) Fluid flow velocity in the PB pipe (0,5 m/s) Therefore a 13mm insulation thickness, which is often a standard thickness, is an ideal compromise as it also has enough thickness to safe energy costs. Remark: It is important that the insulation in cold water pipes is made closedcell insulation with a low water vapour transmission. Otherwise the insulation will get wet and useless.

3 Calculation of the DEW POINT temperature In order to know if condensation would occur on the cold pipe surface we have to know the exact outer surface temperature of the pipe. This can be calculated with the below basic formula: Where is: Q Heat quantity (W/m) l Length of pipe (m) t1 Water temperature (ºC) t2 Outer pipe surface temperature (ºC) tl Ambient air temperature (ºC) αk Heat transfer coefficient (W/m2 K) Thermal coefficient of the pipe material (W/m K) r1 Inner pipe radius (m) r2 Outer pipe radius (m) Example: TABLE-A Criteria PB pipe Steel pipe Copper pipe Thermal conductivity (W/m K) 0, Ext. Heat transfer coeffi. (W/m2 K) Ambient air temperature (ºC) Water temperature (ºC) Pipe diameter 26,9x2,65m 25x2,3mm 22x1,5mm m Outer pipe surface temp. (ºC)

4 Examination if condensation would occur For this purpose we will have to use the h-s Mollier diagram (psychrometric chart). According this example with the below parameters the minimum pipe surface temp. shall be 15,8ºC as otherwise condensation occur. Ambient air temp. 25ºC Example: Given project data Pipe diameter (in this case it s a PB pipe d25x2,3mm) Ambient air temperature: 25ºC Relative air humidity: 60% Fluid temperature: 15ºC How to check? Start at 25ºC air temperature (1) till the 60% humidity curve (2) and at intercept point (3) go to the DEW POINT temperature scale (4) Conclusion: Due the pipe surface temperature is 17ºC and therefore higher than 15,8ºC no condensation will occur (see TABLE-A on previous page). Note: in this example the steel or copper pipe would produce condensation.

5 Positioning of PB vs. black steel and copper pipes in chilled water application Total Cost Comparison Corrosion free material Time saving installation technology PB Mild Steel Copper Lifetime (min. 50 years) Insulation / Th. contuctivity 10 years warranty Need of inhibitors Less friction loss Fire hazard during installation Service pressure and temperatures: PB TERRAIN SDP piping system, which consist in PB pipe and fittings (PushFit & E-Fusion), can be used for the transport of cold water (with glycol) till -30 ºC. PB is ideal for chilled water application due its very big working window which is from -30ºC till 95ºC temperature at high pressures. We have been testing our piping system (PushFit and Thermo/Electro fusion unions) in our laboratory with our special test device which works as following: Fluid temperature: (minus) - 40ºC (glycol) Pressure cycling test: water hammering each 2 seconds from 0,5 to 25bar Number of cycles: Test Result: without any damages or leakages (see pictures on last page) At the following temperatures the service pressure is as following: -30ºC till +20ºC 22 bar (continuous) during at least 50 years lifetime with an included Security Factor of 1,25 (25%). 70ºC 10 bar (continuous) during at least 50 years lifetime with an included Security Factor of 1,5 (50%). 90ºC 6 bar (continuous) during at least 25 years lifetime with an included Security Factor of 1,5 (50%)

6 Due the extreme high pipe flexibility of PB it don t burst even when fully freeze (laboratory test -40ºC) PB is able to absorb the freezing expansion without breaking the pipe or fitting

7 Material and System Characteristics Sr. No Characteristics Posibility to use one system for the whole project Fittings made in the same material as pipes Velocity of the assembly technique (quick & easy) Unit Criteria Product range 4 Jointing technique: - PB PEX Iron/Steel (black) Remarks mm All sizes available Very important in big projects comprehensive product range Yes/No Yes NO Yes The Fittings for the PEX system are quite expensive - Very fast Middle Low The PushFit systems is very quick, tool-less and easy installed PushFit Socketfusion Butt Welding Electrofusion Compression Welding 5 Product range - Big Middle Very big 6 Less pressure drop in Pipes mbar Low Thanks the very smooth surface Low Thanks the very smooth surface High More friction loss Solder unions need a lot of working time (labour costs) and skilled people. The brass fittings for the PEX system needs more labour cost than the PB fittings and especially in the bigger sizes they are very expensive. Very important especially regarding the possibilities to connect to other materials or valves, etc. Comparing to PEX; PB is better because of its thin wall thickness and therefore more inner diameter 7 Corrosion free Yes/No Yes Yes No The iron pipes must be post-treated with special anti corrosion paints, etc., which makes it quite expensive without really resolving the problem. Iron pipes have the additional disadvantage that they have external corrosion, especially when the pipes are not well insulated (because of the condensation). 8 Heat expansion mm/mk 0,13 0,20 0,012 PB has much less expansion than PEX and is the only one were has the possibility to install by Rigidly Fixing. 9 Thermal conductivity W/mK 0,22 0, PB is best 10 Heat loss of pipe W/m Low Low High In case of cooling systems the goal is to avoid that the cold (energy) get lost. Therefore PB is best. 11 Weight Kg Low Low High Plastics are much lighter than metallic pipes Does the antifreezing agent affect the system? Need of special brackets for cooling application? Yes/No NO NO Shall not... Yes/No NO Brackets with rubber liner are OK NO Deepens the temperature The antifreezing agent which sometimes are added to the chilled water are not affecting to the system material e.g. pipes, fittings, brass or rubber gaskets. When the water temperature is lower than 0ºC the need of special cooling brackets is required for steel pipes to avoid energy loss through them. PB don t need such special brackets. Normal ones with rubber are OK. 14 Noise transmission m/s PB has the most flexible pipe and therefore the lowest noise transmission 15 E-Modulus N/m PB has the lowest E-Modulus and therefore the lowest noise transmission and the most flexible pipe 16 Water Hammering Thank the extreme high flexibility of PVB the water hammers are not - Very little Little High transmission forwarded through the piping system. 17 Environmental impact - Excellent/Best Good High The main disadvantage of PEX is that due the cross linking of the HDPE the PEX cannot be recycled anymore. J.Eiriz Page 7 de 7