For MIS Procedure and charts for designing the hydraulics and associated pumping power of closed loop GSHP systems under MCS.

Transcription

1 For MIS 3005 Procedure and charts for designing the hydraulics and associated pumping power of closed loop GSHP systems under MCS Geo En er gy This document was developed and written on behalf of MCS by GeoEnergy a division of Mimer Energy Limited, Falmouth Business Park, Brickland Water Road, Falmouth, TR11 4SZ.

2 TABLE OF CONTENTS 1. INTRODUCTION LIMITATIONS DESIGN REQUIREMENT DESIGN APPROACH THE PROCEDURE FLOW CHARTS NOTES TO ACCOMPANY FLOW CHARTS Appendix 1- Formulae Appendix 2 - Pipe types currently supported Appendix 3 - Antifreezes Appendix 4 - "Active Element" Pressure drop charts Appendix 5 - Header Pipe Pressure Drop Charts Appendix 6 - GSHP Hydraulics Worksheet Appendix 7 - Useful conversions AMENDMENTS ISSUED SINCE PUBLICATION Date: 23/03/2012 Page 2 of 39

3 1. INTRODUCTION Closed loop ground source heat pumps (GSHPs) include a ground loop circulation pump to circulate an antifreeze solution around the sealed ground loop circuit and through the heat pump. This circulating fluid captures the thermal energy from the ground and transfers it to the heat pump where it is extracted and upgraded. The electrical energy consumed by the ground loop circulation pump is an energy 'cost' that has to be incurred to make the system work. It is important that this electrical energy consumption is minimised, to avoid degrading the overall efficiency of a GSHP system. Hydraulic sizing is an area of GSHP design that can be overlooked, resulting in very high pressure drops in the ground loop, poor thermal performance, and high pumping cost penalties. The method presented here is a paper based system, with flow charts providing a step-by-step, iterative approach to achieving the design target required by MIS A set of design charts provide the pressure drops for a variety of pipe sizes, and antifreezes over a range of appropriate flow rates. A GSHP hydraulics worksheet is provided (Appendix 6) that can be used as a final record of how the hydraulic design has been accomplished. It is recommended that this, or an equivalent sheet, should be completed and retained on the project file for every MCS GSHP project. The data and basis for the pressure drop calculations are provided in the Appendices, and designers may choose to use pressure drop calculation software that can be demonstrated to reproduce the pressure drop charts included here. 2. LIMITATIONS The MCS scheme covers heating only heat pumps in sizes up to 45kW thermal output. This document only applies to the hydraulic design of closed loop, ground source heat pump systems that circulate an antifreeze solution around a sealed ground loop. (DX systems and open loop systems are not dealt with). Date: 23/03/2012 Page 3 of 39

4 The method used here can be applied to borehole based systems, Slinky systems and horizontal loop systems. It also applies to pond/lake loop systems. There is no provision for computing pressure drops for compact collectors. The currently available antifreezes, freeze protection levels and pipe types are listed in Appendices 2 and 3. These will be updated as new options are made available. 3. DESIGN REQUIREMENT MIS 3005 requires the maximum ground loop circulating pump electrical power to be less than 2.5% of the thermal power of the heat pump. (para ) eg 10kW thermal output heat pump. Circulating pump to consume less than 2.5% x 10kW = 0.25kW = 250W(electric). There are three major components to the pressure drop that arises in the ground loop circuit. i) the pressure drop through the ground heat exchanger within the heat pump. ii) the pressure drop in the "active" elements of a ground loop array - viz boreholes, slinkies, horizontal loops. iii) the pressure drop in any header pipework running between the heat pump and the ground array. In addition there will be pressure drops in manifolds, valves, pipework bends etc. Figure I shows schematics of these elements for borehole, horizontal, and Slinky systems. Date: 23/03/2012 Page 4 of 39

5 In this note, the term "Active Element" is used. This refers to the main elements of a ground loop circuit that are responsible for extracting the heat from the ground. ie the U-tubes in a borehole system, the Slinky coils, and the horizontal loops. The objective for the designer is to minimise the pressure drop that is caused by pumping the antifreeze fluid through the ground loop circuit, whilst maximising the thermal performance of the "Active Elements". Note that this limit is quite generous. For example, for a heat pump with an SPF of 3.5, (excluding the ground loop pump), a circulating pump meeting the required MIS 3005 limit will reduce the SPF by ~8%). Wherever possible, the designer should seek to keep the circulating pump power to a minimum. Date: 23/03/2012 Page 5 of 39

6 4. DESIGN APPROACH There are several fixed requirements that serve as starting points for the hydraulic design: 1) The selected heat pump will have a minimum, or required, flow rate through the ground loop heat exchanger (sometimes referred to as the "brine" flow rate by European manufacturers). This rate is specified by the manufacturer. 2) The heat pump ground side heat exchanger will have a specified pressure drop at the flow rate defined in 1) above, with a specified antifreeze solution. 3) MIS 3005 requires that the design of a GSHP system will lead to a minimum entering water temperature (EWT) into the heat pump from the ground of 0 C over the lifetime of the installation. Assuming a possible temperature difference of 3 C, an average minimum ground loop fluid temperature of -1.5 C has been adopted here. This temperature defines some of the properties of the antifreeze solutions. 4) MIS 3005 requires that the antifreeze solution will have a freeze protection temperature of -10 C. Some manufacturers require a lower temperature of -15 C. This defines the concentration of the antifreeze solutions, and also defines several antifreeze properties. The designer will have already carried out an initial sizing of the amount of active element required, ie/eg number and depth of boreholes, number and length of Slinkies, and /or number and length of horizontal loops. To minimise the hydraulic power, the designer is left to vary any or all of the following: - The diameter of the pipework in both the active elements and the headers. - The number and pipe length of the active elements - eg more boreholes to shallower depths, less Slinkies in longer trenches etc. - Alternative pipework configurations, eg twin U-tubes vs single U-tubes. Date: 23/03/2012 Page 6 of 39

7 - The type of antifreeze to be used. - The overall efficiency of the type of circulating pump to be used. It is generally accepted in the GSHP industry, that to minimise the size of the ground loop array, whilst achieving good thermal performance, the flow rate in the active elements should be "turbulent". MIS 3005 defines the transition from laminar flow to turbulent flow as being at a Reynolds Number, Re of However, turbulent flow increases the pressure drop in the system. The designer therefore needs to balance the requirement to be turbulent in the active elements, whilst keeping the overall pressure drop to a minimum. Note that in the design charts included here, the Active Element pressure drops have been based on a Reynolds Number of 2500, to be consistent with MIS (Note - The ground loop sizing tables in MIS 3005 are based on the assumption that flow in the active elements is turbulent. If the designer has sizing tools for laminar flow in the active elements (ie more pipe) then care still has to be taken to keep the pump circulation power to the limit imposed by MIS 3005) The designer should be aware that the process of optimising the hydraulic performance of the system may result in a different configuration of active elements, using different pipe diameters to the initial design. This can result in an iterative process, in which the designer needs to check that any new layout of active elements, still results in the required long term thermal performance of the system. Flow in the header pipes of a GSHP system can be turbulent or laminar. Once again the designer will endeavour to minimise the required pumping energy by keeping the pressure drop low, consistent with achieving a cost effective system. 5. THE PROCEDURE The design procedure is outlined here using three flow charts, Figures 2, 3, and 4. Figure 2 shows the overall design sequence, Figure 3 shows the sequence for the active elements, and Figure 4 the sequence for header pipework. Date: 23/03/2012 Page 7 of 39

8 Each of the flow charts has a series of "Notes" as indicated. These notes follow (section 7) the flow charts and should be referred to for clarification of each step. Before starting it will be necessary to have selected a heat pump, the proposed antifreeze and the required freeze protection temperature. The main sequence, (Figure 2). From the manufacturer's literature, look up the MCS approved thermal output of the heat pump at B0/W35. Also look up the minimum ground side flow rate (F l/s), and pressure drop of the heat pump heat exchanger. (Php kpa) Decide on the "type" of circulating pump to be used, ie "standard" efficiency, or "high" efficiency. This will provide an initial estimate of the allowable total permissible pressure drop (PPD) in the ground loop circuit. Use the Active Element Pressure Drop flow chart (Figure 3) to determine the pressure drop in an active element. (Pac) Use the Header Pressure Drop flow chart (Figure 4) to determine the pressure drop in the headers. (Ph) Compute a total Pressure Drop (PD) as the total of Php + Pac + Ph multiplied by 1.15 to allow for a 15% factor for U-bends, Slinky curvature, valves, fittings etc. If PD is less then PPD then proceed to a pump manufacturer's selection (data sheets or software) to size a suitable chilled water ground loop circulation pump that will meet the required duty point of F l/s at a pressure drop of PD. Check that the electrical power of the pump at this duty point is less than 2.5% x H. Date: 23/03/2012 Page 8 of 39

9 If PD is greater than PPD then the designer will need to iterate the process, by changing the pressure drop in either the active elements, and/or the headers. An overall reduction in pressure drop can be achieved by using a less viscous antifreeze. A lower electrical input can be achieved by moving to a more efficient pump, or a different pump selection, eg to a different pump speed on a different pump. Note - if for any reason it is desirable to increase the flow rate in a system, for example to achieve turbulence, then it will be necessary to check what the new, (increased) pressure drop through the heat pump will be (Ph). Date: 23/03/2012 Page 9 of 39

10 6. FLOW CHARTS Figure 2 Closed loop GSHP Hydraulic Sizing Flow Chart Date: 23/03/2012 Page 10 of 39

11 Figure 3 Flowchart to compute Active Element Pressure Drop Date: 23/03/2012 Page 11 of 39

12 Figure 4 Flowchart to compute Header Pressure Drop Date: 23/03/2012 Page 12 of 39

13 7. NOTES TO ACCOMPANY FLOW CHARTS A Heat pump thermal output. This is can be taken as the manufacturer's MCS approved quoted output at B0/W35. B For the UK domestic market there are currently two distinct offerings in terms of efficiency of chilled water circulating pumps that are suitable as ground loop pumps. These are the "standard" offerings which have an efficiency that can range from ~ 25 to ~ 35% overall efficiency, and the newer "high" efficiency pumps that range from ~40 to ~60%. Here we choose a figure of either 30% or 50%. The latter are more expensive than the former. It should be the general intention of a designer / installer to use the newer pumps where possible, and where affordable. However, they can also be used to meet the MIS 3005 pump power requirement with a higher ground loop pressure drop, because of their higher efficiency. At this point in the hydraulic design it is necessary to choose the approximate efficiency, and work through the design. Only when a final pump selection is done at the end of the process, will the actual pump efficiency become apparent. It may be necessary to re-iterate the process if the MIS 3005 design criteria is not met, or to select a different circulating pump to meet the required efficiency. (Note that the smaller high efficiency pumps, with automatic control, should generally be set up at a fixed operating point. The usual automatic control philosophies of these pumps do not aim to produce a constant flow rate under all conditions, which is what is generally required for smaller domestic, (single, fixed speed compressor) heat pumps.) C Heat pump pressure drop. This is specified by the heat pump manufacturer and is the pressure drop through the ground (brine) side heat exchanger at a quoted flow rate. This may be quoted in a various units (eg bar, millibar, psi) and needs to be converted to kpa for use here. (Note - manufacturers generally quote a minimum required flow rate, and the equivalent pressure Date: 23/03/2012 Page 13 of 39

14 drop. If the designer chooses to increase the flow rate, a check should be made with the manufacturer as to the increased pressure drop that will result. The latter needs to be used here as Php) D Active Element graphs. Appendix 4 of this design note, includes the Active Element graphs for several different pipe diameters, pipe types, and antifreezes with different levels of freeze protection. The user needs to ensure that the correct chart is selected. The procedure for determining the pressure drop in each active element (Pac) is described in Flow Chart 2 (Figure 3). E Header graphs. Appendix 5 of this design note includes the Header pipe graphs for several different pipe diameters, pipe types, and antifreezes with different levels of freeze protection. The user needs to ensure that the correct chart is selected. The procedure for determining the pressure drop in Header pipes is described in Flow Chart 3 (Figure 4). F The total pressure drop in the ground loop array comprises the total of the pressure drop in the heat pump Php, the header pipework, Ph, and the Active Elements, Pac. (Note that as long as the active elements are all connected in parallel, then only one value of Pac has to be used. Similarly, if there is more than one pair of header flow and return pipes, (in parallel) then the pressure drop in only one pair is used. In addition, a "contingency of 15% has been added to allow for pipe bends, U bends, Slinky curvature, manifolds and valves. The designer should strive to minimise these extra pressure drops, ensuring that full flow valves and low pressure drop manifolds are used, and that elbows and pipe bends are kept to a minimum wherever possible. G If the total pressure drop (PD) is greater than the allowed pressure drop (PPD) then the designer needs to iterate the process. Reductions in the active element pressure drop or header pressure drop should be investigated. This could be done by increasing header pipe diameters, or the number of pairs of headers. The Active Element pressure drop may be reduced by altering the number of active elements and/or the pipe diameter used - whilst still maintaining turbulence. Overall, change to a less viscous antifreeze fluid, or the use of a higher efficiency pump could lead to achieving the required target. Date: 23/03/2012 Page 14 of 39

15 H If PD is less than the allowed pressure drop (PPD) then the user can proceed to manufacturers' selection software / procedure to choose an appropriate chilled water circulating pump that can meet the required flow rate and pressure drop (ie the duty point). This may require the selection of an appropriate speed setting on the pump to meet the duty. The designer should obtain the electrical power required at the duty point, and check that this meets the 2.5% MCS requirement. (ie electrical power of pump < 2.5% of thermal output at B0/W35). I no note I - to avoid confusion! J Heat pump flow rate - ground (or brine) side. This is the manufacturer's recommended (usually a minimum) flow rate. May be quoted in various units, eg m3/hr, litres/min. Convert to litres/second for use here. K Decide on the antifreeze that is being used. The antifreezes currently provided in this design guide are detailed in Appendix 3. The properties have been calculated at a mean ground loop fluid temperature of -1.5 C. It is generally preferable to use antifreezes with the lowest viscosities that still exhibit good heat carrying and transfer properties. They must also meet UK environmental standards and requirements and have the relevant COSHH information. L Select the required freeze protection temperature of the antifreeze solution that is going to be used. MIS 3005 states this to be -10 C. However, some manufacturers require a lower protection level. The graphs in the appendices have in some cases been prepared for different freeze protection temperatures. Ensure that the correct one is selected. N From the initial ground loop sizing exercise, the number of active elements (N) and their individual (equal) Lengths (L - metres) will have been determined. These active elements will be individual boreholes, Slinkies, or horizontal loops. It is assumed here that these are connected in parallel. If any subsets are connected in series, then the number and length of the equivalent parallel active elements must be used. Date: 23/03/2012 Page 15 of 39

16 Note: - for boreholes the Length is the total pipe length per borehole (= 2 x depth). Care needs to be taken when considering double-u borehole installations - depending on how the double U's are connected - ie whether in parallel or series. - for Slinkies the Length is the total pipe length (not trench length) including the "return" length. - for horizontal loops the Length is simply the total pipe length in a loop (not necessarily the trench length). O Make sure that the appropriate Active Element chart is used from Appendix 4, ie correct antifreeze, at correct freeze protection, with selected pipe type. P Compute the flow rate in each active element. This is the total flow rate required by the heat pump in litres/second divided by the number of parallel active elements. Q On the appropriate active element chart, locate the flow rate determined as at Note P above. Taking a vertical line through this flow rate, check that it intersects the required pipe diameter curve, and that the intersection lies outside of the shaded "laminar" zone. If there is an intersection, on this chart, this will ensure that the flow is turbulent. If there is no intersection, ie the flow rate is too high, then any resulting pressure drop will be too high. If the intersection is in the laminar zone, the flow rate is too low. R If there is a suitable intersection, take a horizontal line from the intersection to the vertical axis and read off the pressure drop per metre of pipe (kpa) If there is no suitable intersection, then, using the same chart, the designer can try changing the active element pipe diameter, or the number of parallel elements. To do this the product of the number of elements and their total "active" length needs to remain the same, eg change 4 x 100m (400m total) boreholes to 5 x 80m (400m total) boreholes to reduce the flow rate per Date: 23/03/2012 Page 16 of 39

17 active element. Or, conversely, change 5 x 40m Slinkies (200m trench) to 4 x 50m (200m trench) to increase the flow rate. Alternatively the designer can try changing the type of antifreeze, and/or freeze protection level, and will need to select the appropriate active element chart. S To compute the total pressure drop in one Active Element, multiply the total length of pipe in the element by the pressure drop/metre obtained in R above. NB this is the total length of pipe in the element, not the borehole depth, or the trench length. T Is the total pressure drop in the active element less than the permitted pressure drop PPD minus the heat pump pressure drop, (ie less than PPD - Php)? Judgement is required here. Allowance has to be made for the header pipe pressure drop - which has yet to be calculated. If the Active Element pressure drop exceeds PPD- Php, or is very close to it, then it will be necessary to iterate the process to get a lower pressure drop in the Active Element. If the Active Element pressure drop is lower than PPD-Php, then proceed to the next step of calculating the Header pipe pressure drop. U In the header pipe work there is no requirement to be turbulent. Generally the objective is to keep the pressure drop as low as possible, which will occur with laminar flow. However, it may be the case that an adequately low pressure drop will be obtained with turbulent flow. If there are several active elements, they will generally be connected together and brought back to the heat pump using one or more pairs of flow and return headers. These will generally be in a larger diameter than the active element pipework. The larger the diameter of the header pipework, the lower the pressure drop. V It may be decided for a variety of reasons to use more than a single pair of header pipes. These need to be of equal length, or flow/pressure balancers need to be introduced to ensure equal flow to each active element. Decide on the number of parallel pairs of headers, and their length. Date: 23/03/2012 Page 17 of 39

18 W Select the appropriate header sizing chart from Appendix 5, based on antifreeze type, pipe type, freeze protection. As per Note U above - there is no requirement to be turbulent or laminar in the header pipework. Laminar flow will result in lower pressure drops. X Compute the flow rate in each pair of headers. If there is only one pair, then the flow rate will be the heat pump flow rate, ie F litres/second. For two pairs the flow rate will be half of this, for three, a third, and so on. Y Having located the relevant pressure drop per metre on the sizing chart, the total pressure drop in the header in kpa, Ph will be 2 x Length of header pipework x pressure drop/metre. The factor of 2 allows for the flow and return. If there are multiple pairs of equal length headers in parallel, it is only necessary to take into account the pressure drop of a single pair. Z Is the total pressure drop through the heat pump, header, and active element x 1.15 less than the permitted pressure drop PPD? If not then it will be necessary to iterate to try to lower the header pressure drop further. It may be necessary to go back and reduce the active element pressure drop as well, or to change to a different antifreeze in the system, or select a higher efficiency pump. Date: 23/03/2012 Page 18 of 39

19 Appendix 1- Formulae The formulae used to compute pressure drop in this design note are as follows: Reynolds Number Re = ρ v D / µ where: ρ = density, v = velocity, D = internal diameter, µ = viscosity Pressure drop: For laminar flow (ie Reynolds number < 2500) P = 2 f ρ L v 2 / D where: f = Fanning friction factor = 16 / Re ρ = density, v = velocity, D = internal diameter, L = length of pipe For turbulent (transition) flow (ie Reynolds number > 2500), the Darcy Weisbach formula is used: P = f' L v 2 / (2 D g r) where: f' is Colebrook friction factor, and is obtained iteratively r = roughness, v = velocity, D = internal diameter, L = length of pipe, g = gravitational acceleration. Date: 23/03/2012 Page 19 of 39

20 Appendix 2 - Pipe types currently supported (Note SDR: Standard Dimensional Ratio = Pipe Diameter / Pipe wall thickness OD = Outer Diameter) 1) Polyethylene pipe, PE 100, SDR 11, Roughness = As "Active elements": OD = 25mm, 32mm, 40mm As headers: OD = 25mm, 32mm, 40mm, 63mm, 90mm 2) Polyethylene pipe, PE 100, SDR 17, Roughness = As "Active elements": OD = 25mm, 32mm, 40mm As headers: OD = 25mm, 32mm, 40mm, 63mm, 90mm Date: 23/03/2012 Page 20 of 39

21 Appendix 3 - Antifreezes All properties computed at a temperature of -1.5 C 1) Ethylene glycol/water. Freeze protection to -10 C Glycol concentration (wt%) 22.9 Freezing point C Density (kg/m 3 ) 1042 Viscosity (Pa.s) ) Ethylene glycol/water. Freeze protection to -15 C Glycol concentration (wt%) 28.6 Freezing point C Density (kg/m 3 ) 1051 Viscosity (Pa.s) ) Propylene glycol/water. Freeze protection to -10 C Glycol concentration (wt%) 24.2 Freezing point C Density (kg/m 3 ) 1031 Viscosity (Pa.s) Date: 23/03/2012 Page 21 of 39

22 Appendix 4 - "Active Element" Pressure drop charts Ethylene glycol charts Date: 23/03/2012 Page 22 of 39

23 Active Element Chart. SDR-11 Ethylene Glycol Freeze Protection to -10C Pressure Drop (kpa/m of Pipe) SDR11 Active Element -Ethylene Glycol (-10 C) Laminar Flow Zone Flow Rate (l/s) Date: 23/03/2012 Page 23 of 39

24 Active Element Chart. SDR-11 Ethylene Glycol Freeze Protection to -15C Pressure Drop (kpa/m of Pipe) SDR11 Active Element -Ethylene Glycol (-15 C) Laminar Flow Zone Flow Rate (l/s) Date: 23/03/2012 Page 24 of 39

25 Active Element Chart. SDR - 17 Ethylene Glycol Freeze Protection to -10C Pressure Drop (kpa/m of Pipe) Laminar Flow Zone SDR17 Active Element -Ethylene Glycol (-10 C) Flow Rate (l/s) Date: 23/03/2012 Page 25 of 39

26 Appendix 4 - continued "Active Element" Pressure drop charts Propylene glycol charts Date: 23/03/2012 Page 26 of 39

27 Active Element Chart. SDR-11 Propylene Glycol Freeze Protection to -10C Pressure Drop (kpa/m of Pipe) Laminar Flow Zone SDR11 Active Element -Polypropylene Glycol (-10 C) Flow Rate (l/s) Date: 23/03/2012 Page 27 of 39

28 Active Element Chart. SDR-17 Propylene Glycol Freeze Protection to -10C Pressure Drop (kpa/m of Pipe) Laminar Flow Zone SDR17 Active Element -Polypropylene Glycol (-10 C) Flow Rate (l/s) Date: 23/03/2012 Page 28 of 39

29 Appendix 5 - Header Pipe Pressure Drop Charts Ethylene glycol charts Date: 23/03/2012 Page 29 of 39

30 Header Pipework Chart. SDR-11 Ethylene Glycol Freeze Protection to -10C SDR11 Header Pipework -Ethylene Glycol (-10 C) P r e s s u r e D r o p ( k P a / m o f P i p e ) Flow Rate (l/s) Date: 23/03/2012 Page 30 of 39

31 Header Pipework Chart. SDR-11 Ethylene Glycol Freeze Protection to -15C SDR11 Header Pipework -Ethylene Glycol (-15 C) P r e s s u r e D r o p ( k P a / m o f P i p e ) Flow Rate (l/s) Date: 23/03/2012 Page 31 of 39

32 Header Pipework Chart. SDR-17 Ethylene Glycol Freeze Protection to -10C SDR17 Header Pipework-Ethylene Glycol (-10 C) P r e s s u r e D r o p ( k P a / m o f P i p e ) Flow Rate (l/s) Date: 23/03/2012 Page 32 of 39

33 Header Pipework Chart. SDR-17 Ethylene Glycol Freeze Protection to -15C SDR17 Header Pipework-Ethylene Glycol (-15 C) P r e s s u r e D r o p ( k P a / m o f P i p e ) Flow Rate (l/s) Date: 23/03/2012 Page 33 of 39

34 Appendix 5 - continued Header Pipe Pressure Drop Charts Propylene glycol charts Date: 23/03/2012 Page 34 of 39

35 Header Pipework Chart. SDR-11 Ethylene Glycol Freeze Protection to -10C 1.20 SDR11 Header Pipework -Polypropylene Glycol (-10 C) 1.00 P r e s s u r e D r o p ( k P a / m o f P i p e ) Flow Rate (l/s) Date: 23/03/2012 Page 35 of 39

36 Header Pipework Chart. SDR-17 Ethylene Glycol Freeze Protection to -10C SDR17 Header Pipework-Polypropylene Glycol (-10 C) P r e s s u r e D r o p ( k P a / m o f P i p e ) Flow Rate (l/s) Date: 23/03/2012 Page 36 of 39

37 Appendix 6 - GSHP Hydraulics Worksheet Date: 23/03/2012 Page 37 of 39

38 Appendix 7 - Useful conversions Flow rates To convert to litres/second (l/s) Multiply: Cubic metres per hour (m 3 /hr) by litres/minute (l/min) by Pressure drop To convert to kilopascals (kpa) Multiply: bar by millibar by 0.1 metres of water by 9.81 psi by Date: 23/03/2012 Page 38 of 39

39 AMENDMENTS ISSUED SINCE PUBLICATION Document Number: Amendment Details: Date: 1.0 First Issue 23/03/2012 Date: 23/03/2012 Page 39 of 39