Page 1Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Technical Overview Features Specification Product Codes The VC-Q range of balancing valves are a unique genera- tion of dual-function valves, which can be used separately as an automatic flow limiter valve or as a combined flow limiter and control valve when fitted with an actuator. In addition, the setting is extremely user-friendly and reliable, making the VC-Q maintenance free. The VC-Q valve is the obvious choice for balancing and controlling terminal units such as fan-coils, chilled ceilings and air handling units. For the user it is straightforward to set the maximum designed flow – just turn the presetting scale at the desired flow. A built-in diaphragm keeps a constant low differential pressure across the valve, ensuring the maxi- mum set flow is not exceeded. • Compact design • No control calculation • Flow is the only parameter to be considered Materials: Valve bodies Brass Membranes EPDM O-rings EPDM Flat gasket NBR Sealing agent Dimethacrylate Ester Media Water and water mixture with cool ants for closed systems Connections (not included): 10mm valves – VC-PC10 ⅜" BSP male (2 required per valve) 15mm valves – VC-PC15 ½" BSP male (2 required per valve) 20mm valves – VC-PC20 ¾" BSP male (2 required per valve) 25mm valves – VC-PC25 1" BSP male (2 required per valve) 32mm valves – VC-PC32 1¼" BSP male (2 required per valve) Max. operating pressure 16 bar Media temp -10°C to 120°C Stroke length: 10mm to 20mm valves 2.25mm 25mm to 32mm valves 4.5mm Max. static pressure PN16 (16 bar) Leakage max. 0.01% of k v at 250N Control characteristic Linear Rangeability 50:1 Country of origin Slovenia Balancing val ves, without measurement points VC-QW10 ⅜” Automatic valve 275l/h maximum flow VC-QW15A ½” Automatic valve 275l/h maximum flow VC-QW15B ½” Automatic valve 450l/h maximum flow VC-QW20 ¾” Automatic valve 900l/h maximum flow VC-QW25 1” Automatic valve 1700l/h maximum flow VC-QW32 1¼” Automatic valve 3200l/h maximum flow Balancing val ves, with measurement points VC-QM10 ⅜” Automatic valve 275l/h maximum flow VC-QM15A ½” Automatic valve 275l/h maximum flow VC-QM15B ½” Automatic valve 450l/h maximum flow VC-QM20 ¾” Automatic valve 900l/h maximum flow VC-QM25 1” Automatic valve 1700l/h maximum flow VC-QM32 1¼” Automatic valve 3200l/h maximum flow Pipe connectors (2 required with each val ve) VC-PC10 Tailpiece for use with VC-Qx10 valves VC-PC15 Tailpiece for use with VC-Qx15 valves VC-PC20 Tailpiece for use with VC-Qx20 valves VC-PC25 Tailpiece for use with VC-Qx25 valves VC-PC32 Tailpiece for use with VC-Qx32 valves Page 2 Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Applications Air handling unit (AHU) / fan coil unit (FCU) A VC-Q with an actuator can be used as a combined flow limiter and control valve with full authority for an AHU (Air Handling Unit). The VC-Q ensures the required flow on every AHU and simplifies the hydronic balancing of the sys- tem. Because of the integrated differential pressure control- ler the control valve always has 100% authority which means that partial load in the system has no influence on temperature regulation, as it will have with normal control valves. By installing a VC-Q, the whole system is divided in independent control loop zones not influencing each other. The flow setting is very simple. Just set the required flow for the AHU direct at the VC-Q. There is no special method needed for balancing the whole systems. This means a lot of savings in working hours, not forgetting that the combination of several functions in one valve body means less valves and installation work. For temperature control the VC-Q can be equipped with different actuators (on/off, 3-point, 0 - 10Volt) as required. Chilled Ceiling: A VC-Q in systems with chilled ceilings are used to achieve the required flow in the system and to control the tempera- ture. An VC-Q is installed at every chilled ceiling limiting the flow. The integrated control valve is used for temperature control by mounting an actuator. Different types of actuators can be used. Constant flow systems: A VC-Q can be used as an automatic flow controller if a system with an AHU/fan coil is run with constant flow (system with 3-way valve). There is no special balancing method needed. The flow can be set directly at the VC-Q. Alternatively the system can be changed into a system with variable flow because the VC-Q is also able to work as a control valve with full authority which means no problems with partial load. In a one pipe heating system the VC-Q can be installed as an automatic flow controller in every riser. The VC-Q limits the flow to the set value, thus automatically achieving hy- dronic balance in the system. There are numerous applications in which VC-Q can be used. In principle it can be used every time you need an automatic flow controller or a control valve with full authority. For example, systems with heating/cooling with concrete core activation or small substations. Page 3 Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Operation Principle The VC-Q is a control valve combined with a differential pressure controller. The differential pressure controller main- tains a constant pressure over the control valve independent of varying conditions in the installation. Because of this con- struction the flow is automatically limited to a specified value and the control valve has an authority of 100%. Flow limitation If you have a constant differential pressure across an orifice with a known resistance (k v value) you can determine the flow with the formula: Q = k v x √Δp Because the VC-Q limits the differential pressure (Δp) across the control valve to a constant level it follows that the flow through the VC-Q is also limited. To function properly the VC-Q needs a pressure difference of at least 16 kPa. By limiting the stroke of the control valve, the maximal flow through the valve can be adjusted. If the k v -value of the control valve is halved, the flow is also halved. Because the VC-Q has a nearly linear characteristic to have half the flow you need half the stroke. Authority The valve authority can be defined as: The resistance across the fully opened control valve, divided by the total resistance in the system (valve, pipes, heat exchanger etc.). A= Usually the authority should be 0,3 (30%) as high as possi- ble to guarantee sufficient control quality. The resistance in the system is variable because it depends on the flow. If the flow is reduced, the resistance in the system also drops. Normally the control valve would have to compensate for this by closing even further, thus causing a distortion in the valve characteristic. Because the VC-Q has a built in differ- ential pressure controller that keeps the differential pressure across the control valve constant, the effect of this decrease is compensated. It is therefore possible to assume that Rsystem is zero. The formula then becomes: A = =1 (100%) The VC-Q therefore always automatically ensures 100% authority, which provides stable control and therefore in- crease comfort and saves time consuming calculations to check the valve authority. As an example, take two valves in a normal HVAC system, one close to the pump (position 1) and the most distant valve (position 2). Both valves have the same differential pressure potential (the pump head) but the pressure drops between: • Control valve (abbreviated as CV), • Balancing valve (abbreviated as BV) and • Other elements (abbreviated as OT; such as pipe, terminal units etc.) are distributed differently. With the valve closer to the pump the pressure drop in the pipes (OT) is much smaller. The differential pressure controller (BV) ensures however that the working conditions for both control valves (CV) are the same. If we look at a situation where we need only 20%, we can see that the pressure drop in the pipes (OT) becomes smaller when the flow is decreasing. This effect is much bigger for the distant valve because the pressure drop in the pipes (OT) is bigger to begin with. The differential pressure controller (BV) compensates for the difference and ensures identical working conditions for both control valves across the total range. If you compare that with a situation with traditional balancing valves you can see that, because the balancing valve is static and doesn’t react to the system conditions, the pressure drop across the control valve in- creases significantly which puts the control valve (CV) to a challenge to provide comfort and stable temperature control. 100% 80% 50% 50% 80% 100% Q, k v Stroke R valve R valve + R system R valve R valve Page 4 Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Design (continued) Design 1. Differential Pressure Controller BV The differential pressure controller maintains a constant differential pressure across the control valve. The pressure difference (p2-p3) on the membrane is balanced with the force of the spring. Whenever the differential pressure across the control valve changes (due to a change in avail- able pressure, or movement of the control valve) the hollow cone is displaced to a new position which brings a new equi- librium and therefore keeps the differential pressure at a constant level. 2. Control Val ve CV The control valve has a linear characteristic. It features a stroke limitation function that allows adjustment of the k v value. The percentage marked on the scale equals the per- centage of 100% flow marked on the pointer. Changing the stroke limitation is done by lifting the blocking mechanism and turning the top of the valve to the desired position, showed on the scale as a percentage. A blocking mecha- nism automatically prevents unwanted changing of the set- ting. Sizing Example 1: Variable flow system Given: Cool requirement per unit : 1000W Flow temperature in the system: 6°C Return temperature in the system:12°C Required - control and balancing valves: VC-Q and actuators type for BMS system. Solution: Flow in the system: Q (l/h) Q = 0,86 x 1000 / ( 12-6 ) = 143 l/h Selected: VC-QW10 with Q max = 275 l/h presetting on 143 / 275 = 0,52 = 52 % of maximum opening. Actuator: VT-AMV130-24. Remarks: required minimum differential pressure across the VC-QW10 - 16kPa. Operation Principle (continued) Position 1 Position 2 Position 1 Position 2 Position 1 Position 2 CV BV QT CV BV QT P P P P CV BV QT CV BV QT 20% of design flow Design flow 20% of design flow Design flow 20% of design flow Design flow 20% of design flow Design flow Pressure drop in a system with VC-Q Pressure drop in a system with tradi- tional valve set (manual balancing valve & control valve Q Q Q Q 1 5 6 7 8 2 3 4 P1 P2 P3 P1-P3 P2-P3 1. Stuffing box 2. Spindle 3. Plastic ring 4. Control valve’s cone 5. Membrane 6. Main spring 7. Hollow cone (pressure controller) 8. Vulcanized seat (pressure controller) Page 5 Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Sizing (continued) Sizing (continued) Example 2: Constant flow system Given: Cool requirement per unit : 4000W Flow temperature in the system : 6°C Return temperature in the system : 12°C Required - automatic flow limiter: VC-Q and presetting. Solution: Flow in the system : Q (l/h) Q = 0,86 x 4000 / ( 12-6 ) = 573 l/h Selected: VC-QW20 with Q max = 900 l/h presetting on 573 / 900 = 0,64 = 64% of maximum opening. Remarks: required minimum differential pressure across the VC QW20 - 16kPa. Example 3: Sizing VC-Q according pipe dimension Given: Flow in system 1, 4 m3/h (1400 l/h = 0,38l/s), pipe dimension DN 25 mm Required - automatic flow limiter: VC-Q and presetting. Solution: In this case we can selected VC-Q with Q max = 1700 l/h In this case it will be recommended to check the maximum velocity in the pipe. For this we calculate velocity in the pipe for condition: DN 25 mm – Di 27,2 mm Dimension and condition acceptable, velocity below 1,0 m/s. Presetting on the valve VC-QW25 1400 / 1700 = 0,82 = 82 % of maximum opening. Remarks: Required minimum differential pressure across the VC-QW25 DN 25 - 16kPa. Pump Optimising / Troubleshooting The VC-QM features measuring nipples that allow measur- ing of the pressure difference (p2-p3) across the control valve. If the pressure difference exceeds certain value (7- 14kPa) it means the differential pressure controller is opera- tional and the flow limitation is achieved. The measuring function can be used to verify if enough pressure difference is available and thus verify the flow. Q(l/h) 3500 3000 2500 2000 1500 1000 500 0 DN10LF DN10 DN15 DN20 DN25 DN32 DN15LF 3200 640 1700 340 900 180 450 90 275 55 150 30 Blue Red P2-P3 P1 P2 P3 P2-P3 P1-P3 P2-P3 P1-P3 7.5kPa 16kPa (20kPa) Q≠Const. Q=Const. Q=Const Pump optimization Q≠Const Q Q Page 6 Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Pump Optimising / Troubleshooting (continued) Installing It can also be used to optimize the pump head. The pump head can be decreased until no more than the minimal re- quired pressure (7-14kPa) is available on the most distant valve (in terms of hydronic). This optimal point is to be found when proportionality between pump head and measured differential pressure cease to exist. Presetting The calculated flow can be adjusted easily without using special tools. To change the presetting: 1. Remove the blue protective cap or the mounted actuator. 2. Raise the grey plastic ring and turn to the new presetting. 3. Release the white plastic ring and the presetting is locked. The presetting scale indicates a values from 100% flow to 0% closed. Counter clock wise turning would increase the flow value while clock wise would decrease it. When valve is set to 80% or more the red ring (below “DN max flow “ sign) becomes visible. If the valve is a DN 15 then the max flow = 450 l/h =100% presetting. To set a flow of 270 l/h you have to set: 270/450 = 60%. Sontay recommends a presetting/flow from 20% to 100%. Factory presetting is 100%. The VC-Q valve is mono-directional, meaning that the valve operates when arrow on the valve body is aligned with flow direction. When this rule is disobeyed the valve acts like variable orifice that cause water hammer at sudden closing when available pressure has increased or valve have been set to lower value. In case when system condition allows backflows it is strongly recommended to use a backflow preventer in order to avoid possible water hammer that can damage the valve as well as other elements in the system. 100% 10% Red Page 7 Balancing Valves VC-Q Data Sheet Ref: 90501220 Issue: 5.0 International Tel: +44 1732 861225 UK Sales Tel: 0845 345 7253 International Fax: +44 1732 861226 UK Sales Fax: 0845 345 7353 www.sontay.com Whilst every effort has been made to ensure the accuracy of this specification, Sontay cannot accept responsibility for damage, injury, loss or expense resulting from errors or omissions. In the interest of technical improvement, this specification may be altered without notice. 90800066 Issue 1 Dimensions L1 L2 L2 L3 H 2 H 1 H 3 b H 4 Part number L1 L2 L3 H1 H2 H3* H4 b Weight (mm) (mm) (mm) (mm) (mm) (mm) (mm) (ISO 228/1) (kg) VC-Qx10 53 36 79 20 73 105 140 G ½ A 0.38 VC-Qx15 65 45 79 25 75 110 145 G ¾ A 0.48 VC-Qx20 82 56 79 33 77 115 150 G 1 A 0.65 VC-Qx25 104 71 79 42 88 130 165 G 1¼ A 1.45 VC-Qx32 130 90 79 50 102 145 180 G 1½ A 2.21