CONSTANT FLOW REGULATOR (CFR)

Transcription

1 CONSTANT FLOW REGULATOR (CFR) CFR991 GENERAL NOTES The Crane CFR991: Can be used in variable volume heating and chilled water systems. Has a double regulating feature, allowing the valve opening to be set with a 3mm Allen key. Is operated by means of the handwheel with position indicator or with recordable set position. Has a linear control characteristic across setting operating range. Has built-in Differential Pressure Control. Has a maximum working = 4 bar Has built in pressure test points to verify operational differential pressures. Fig.1 DN25 / DN32 Style (left) and DN40 / DN50 Style (right) LIMITS OF USE These valves have been categorised in accordance with the Pressure Equipment Directive 2014/68/EU. The fluid to be transported is limited to group 2 liquids i.e. non-hazardous. On no account must these valves be used on any group 1 liquids, group 1 gases, group 2 gases or unstable fluids. Note: Valves are classified as SEP (sound engineering practice) and as such cannot be CE marked and do not require a declaration of conformity.

2 INSTALLATION These instructions are issued as guidelines only and do not cover all installed conditions. If unsure please contact our Technical Helpline on , before installation. It is advised that the valve should be installed in a run of pipe of the same nominal size. Crane Fluid Systems products are designed for installation and use within suitably designed systems reflecting CIBSE, BSRIA and HVAC guidelines. Particular care should be taken with regards to; o Accessibility to valve for setting/adjustment o Tube cutting after cutting and threading, the end must be deburred or reamed before fitting to the valve. o Jointing no thread jointing materials must be allowed to protrude inside the bore. o Bracketing/supports the piping system shall provide suitable support and must be carefully aligned and at the correct distance between centres for the size and type of valve. Orientation: The CFR991 can be positioned in any orientation. Normally installed on return pipework, i.e. after the equipment it is controlling, but can be installed in flow if required. Ensure direction of flow is correct - indicated by an arrow on the valve body. CFR991 operates between a minimum and maximum pressure drop across the valve - see commissioning section on page 4. CFR s are not designed as isolation valves. Dedicated isolation valves should be installed to isolate against system pressure, i.e. for maintenance etc., when disconnecting/draining pipework. Care should be taken to not exceed maximum operating differential pressure, to prevent damage to the internal components. Systems should be installed with strainers to protect the CFR and other installed items. Straight lengths of pipework are not required for CFR s but some straight lengths are recommended to create a more stable flow pattern. FLUSHING Control valves, like the CFR, are sized to give good control over the system water, therefore, have been designed with a small convoluted flow path. These water ways may not allow adequate water velocities for flushing of the coil, even when fully open. Therefore, in line with BSRIA recommendations, it is recommended that a flushing point be located between the coil and the CFR. This allows the coil to be flushed without the water passing through the CFR. Please refer to BSRIA Guide BG for guidance. 02

3 VALVE SETTING INDICATOR CFR991 valves operate from closed to fully open with 4 complete turns of the handwheel. The Microset handwheel indicates the valve setting by means of digits appearing in outer (black) and inner (red) windows. The digit in the outer window indicates tenths of a turn. The example to the right shows a valve setting of 4-0 turns (fully open). REGULATION regulation is achieved by adjusting the valve setting until the required flow rate is obtained. The Microset handwheel will indicate the final valve setting. See table 1 on page 4 for flow rate setting. SETTING FACILITY The valve setting at which the required flowrate is achieved may be retained as follows: 1. Remove cap in centre of handwheel 2. Using the Allen key provided tighten the centre screw until it stops. Do not over-wench. 3. Replace centre cap in handwheel. The valve is now set and be adjusted and re-set to the original set point. PRESSURE TEMPERATURE RATING TEMPERATURE C -10 to 120 PRESSURE (BAR) 16 03

4 COMMISSIONING The CFR991 controls the flow rate depending on its set position, therefore, removing the need to measure the flow rate. The CFR991 maintains a constant differential pressure across its internal seat, any excess pressure being removed by the internal differential pressure controller. To ensure that sufficient pressure is available for the differential pressure controller to control the flow rate correctly, a differential pressure reading should be taken using the test points provided. When taking differential pressure readings, it is important that the system is running at full load, i.e. with CFR s set to design flow rate. This ensures that differential pressure readings are carried out in the most unfavourable conditions, guaranteeing optimum performance in normal running conditions. To ensure that all CFRs are working at the required differential pressure, it is necessary to check the least favoured / index CFR. By verifying the least favoured CFR is set correctly then all other CFRs must have a higher differential pressure. However, we would also recommend that a selection of other CFRs are tested along the circuit to verify this. H/W Setting DIFFERENTIAL PRESSURE REQUIREMENTS At each % setting option all sizes require a specific constant (Differential Pressure) to ensure the CFR is within its working range: Table 1 - CFR Setting Table % Opening FLOW RATE DN25 DN32 DN40 DN

5 For flow rates between settings, interpolation of position can be used. Please note that DN25 and DN32 test points measure the differential pressure across the seat, not overall pressure drop. Please note for the DN40 and DN50 the test points measure the overall differential pressure drop across the valve only. The pump speed should be set to ensure that the required differential pressure is always available. By setting the differential pressure across the least favoured CFR to the value stated in the above table, it ensures that minimum pump energy is used, therefore, reducing system running costs and CO2 emissions: DN25 & DN32 To set pump speed to achieve this: whilst measuring (across test points), increase pump speed until a constant is achieved, however please note that the typical value, as shown in the table above, can differ but in itself is not critical to operation. DN40 & DN50 To set pump speed to achieve this: whilst measuring (across test points), increase pump speed until a value greater than the minimum stated in the above table is achieved. As the measured is the total pressure drop across the PICV, the measured value will continue to rise as pump speed is increased. Any value above the minimum requirement will increase running costs, therefore, reducing system efficiency. The optimum setting is achieved when there is sufficient, but not excessive, pump pressure available. rate verification should be carried out using separate Measurement Devices (FMD) where fitted. In line with CIBSE & BSRIA recommendations, we recommend that as a minimum requirement, FMDs are installed in all branches. 05

6 CRANE HOUSE, EPSILON TERRACE, WEST ROAD, IPSWICH, SUFFOLK IP3 9FJ TELEPHONE: +44 (0) FAX: +44 (0) FM311 ISO 9001 Designed and manufactured under quality management systems in accordance with BS EN ISO 9001:2008 Every effort has been made to ensure that the information contained in this publication is accurate at the time of publishing. Crane Ltd assumes no responsibility or liability for typographical errors or omissions or for any misinterpretation of the information within the publication and reserves the right to change without notice. CFS_CFR_CFR991_1117 IOM_ R01_v1