Terminator Valves
Terminator Commissioning Valve
The Terminator is a combined venturi measuring device and regulating ball valve.
Each valve size comes with an option to interchange venturi’s depending on the flow.
Each is supplied with flow information, such as Kv values and flow charts.
Patent GB2297374.
Integrated Union
Whenever a terminal unit is installed it requires unions on the inlet and outlet to allow for servicing. To save time, space and cost, Marflow have included a union in the design of the valve.
Tagging
Since the valve needs identifying within the system Marflow supply a pre-fitted valve tag free of charge so that the valve number, and indicator position can be recorded when commissioning is complete. Tags can be factory fitted marked with the valve number to simplify installation.
Air Vent Tapping
In making the most comprehensive featured commissioning valve available today, Marflow Hydronics took advantage of the low velocity area which surrounds the ball, and placed an air vent tapping on it.
TCV Selector
Marflow supply Excel based software called TCV selector that is dedicated to the selection of balancing and flow regulating devices. Starting from a minimum of information, the programme is able to suggest an individual venturi to measure flow. Selection is made by reference to 4 interrelated criteria.
- Line size
- The capability of the manometer used to measure the signal
- The excess pressure (headloss) that the valve will be required to remove from the circuit.
- The design flow rate
Commissioning Data
The Terminator Commissioning Manual provides convenient methods of selection using tables and formulae as well as the necessary data for commissioning.
End Connections
Standard end connections are female BSP from 1/2” to 2”
Venturi Options
A wide range of flows can be accommodated as at least two options are available for each valve size.
Commissioning Set
A commissioning valve installed in heating and cooling circuits is primarily used to measure flow using a differential pressure manometer. It allows the commissioning engineer to see how the flows within the circuit are distributed. Once the flows are established and the Index circuits identified, then the secondary use of the commissioning set, that of regulation, adding resistance to circuits that have too much flow. The amount of resistance added to circuits is dependant on many variables such as the flow, the resistance and layout of the fan coil, the pipe and the pipe lengths between fan coils.
Sizing for flow
Sizing of commissioning valves is usually carried out to give differential pressure readings between 1 and 4.6 kPa on a fluorocarbon Manometer. Historically this very general rule was acceptable as it allowed a mercury ‘U’ tube manometer to be filled with fluorocarbon in place of the mercury and so allow quite accurate readings to be taken of smaller pressure differentials.
The development of accurate electronic differential pressure measurement devices has meant that some consultants prefer design signals above 2 kPa as readings on the index circuit might not be visible or accurate enough if sized to 1 kPa signal.
Low loss venturi’s as fitted in Marflow balancing products give high signals with low losses and are becoming the preferred option of some designers.
The Marflow interchangeable venturi system allows the designer to over size mains pipework to reduce the pump head required for the system. By fitting a smaller venturi the flow can be still be accurately measured without the typical and expensive reduction pipework as is common with most manufacture’s fixed orifice devices.
Variable Volume
This principle can be put to very good use on variable volume systems. Pipe sizing on variable volume systems where the pump head is required to be kept at a minimum can be designed using a size larger pipework with Marflow's Flow Measuring Venturi’s FMV80. The pump head required is reduced because the pipe losses are reduced. The smaller pump means that differential pressure through out the system is not as significant. Two port control valves typically affected by high differential pressures might not require differential pressure control valves.
Marflow FMV80’s fitted with a smaller venturi allows pipe sized (lined sized) valves to be used with time and money saved in not reducing pipework.
Using Venturi’s to remove head
The 15mm and 20mm Marflow Terminator Commissioning Valve has five different sizes of venturi’s which may be fitted. These interchangeable venturi’s create different amounts of resistance depending on flow rates.
If resistance can be added using a venturi rather than regulating a valve then the system could be more self balancing. This would allow DRV valves to be more open and less likely to block as is the case with low flow valves currently found on the market.
The interchangeable venturi can also be used to take out a significant amount of the resistance when designed into the system. This only then leaves the commissioning engineer fine tuning on the ball valve.
Quick Selection Table
This table provides a quick look up, at each end of a range of flows, for the headloss at 100% open and at 30% open, the difference being the excess pressure that the valve will remove. The flow range selected provides signal to a standard low loss manometer (0 to 4.6 kPa range).
| Headloss of Valve (kPa) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Product Code |
Thread Size (Pipe size) |
Venturi Size (mm) |
Signal Coefficient Kvs |
Flow in l/s | Minimum flow | Maximum flow | Valve Kv | ||||
| Minimum @0.5kpa |
Maximum @4.6kpa |
100% Open |
30% Open |
100% Open |
30% Open |
100% Open |
30% Open |
||||
| TCV9404.03 | 1/2” | 3 | 0.36 | 0.007 | 0.021 | 0.45 | 0.6 | 4.13 | 5.5 | 0.38 | 0.33 |
| TCV9404.04 | 1/2” | 4.25 | 0.71 | 0.014 | 0.042 | 0.20 | 2.2 | 1.80 | 19.8 | 1.12 | 0.34 |
| TCV9404.06 | 1/2” | 6 | 1.38 | 0.023 | 0.070 | 0.21 | 3.2 | 1.92 | 29.8 | 1.81 | 0.46 |
| TCV9004.09 | 1/2” | 9 | 3.04 | 0.060 | 0.181 | 0.14 | 18.5 | 1.31 | 170 | 5.7 | 0.5 |
| TCV9004.12 | 1/2” | 12 | 5.30 | 0.104 | 0.316 | 0.11 | 24.3 | 1.03 | 223 | 11.2 | 0.76 |
| TCV9006.06 | 3/4” | 6 | 1.38 | 0.023 | 0.070 | 0.21 | 3.2 | 1.92 | 29.8 | 1.81 | 0.46 |
| TCV9006.09 | 3/4” | 9 | 3.04 | 0.060 | 0.181 | 0.14 | 18.5 | 1.31 | 170 | 5.7 | 0.5 |
| TCV9006.12 | 3/4” | 12 | 5.30 | 0.104 | 0.316 | 0.11 | 24.3 | 1.03 | 223 | 11.2 | 0.76 |
| TCV9008.10 | 1” | 10 | 3.69 | 0.072 | 0.220 | 0.22 | 4.9 | 2.00 | 45 | 5.6 | 1.18 |
| TCV9008.14 | 1” | 14.5 | 7.88 | 0.155 | 0.469 | 0.12 | 31.0 | 1.10 | 285 | 16.1 | 1.00 |
| TCV9010.13 | 1 1/4” | 13 | 6.60 | 0.130 | 0.393 | 0.13 | 5.4 | 1.19 | 50 | 13.0 | 2.00 |
| TCV9010.19 | 1 1/4” | 19 | 14.30 | 0.281 | 0.852 | 0.13 | 21.1 | 1.20 | 194 | 28.0 | 2.20 |
| TCV9012.15 | 1 1/2” | 15 | 8.60 | 0.169 | 0.512 | 0.11 | 7.0 | 1.05 | 64 | 18.0 | 2.3 |
| TCV9012.22 | 1 1/2” | 22 | 20.00 | 0.393 | 1.192 | 0.08 | 34.7 | 0.74 | 319 | 50.0 | 2.4 |
| TCV9016.18 | 2” | 18 | 12.50 | 0.246 | 0.745 | 0.11 | 5.4 | 0.99 | 50 | 27.0 | 3.8 |
| TCV9016.31 | 2” | 31.5 | 42.00 | 0.825 | 2.502 | 0.16 | 30.2 | 1.44 | 278 | 75.0 | 5.4 |
Headloss
The headloss (Δp) attributed to a Terminator Commissioning valve inserted into a pipeline can be calculated by the reference formula:
Where:
Q = flow in litres/sec,
Δp = headloss in kPa,
Kv is provided from the table above (valve Kv)
Application & Installation Guidance
Marflow recommend that the design, installation and commissioning of heating and chilled water systems be carried out in accordance with established codes of practice including BSRIA Application Guide, The Commissioning of water Systems in Buildings and CIBSE Commissioning Code W.
