The UVM takes a 0 V to 10 V scaled CFM command signal from the room level controller and interprets it as a 0 CFM to xxxx CFM request signal. Each Venturi valve comes factory mounted with a UVM, which is characterized with the unique flow curves associated with the valve. The UVM moves the valve’s actuator to the correct position for the requested CFM.
There is a fitted electronic position sensor on each valve. The sensor provides actual valve position feedback signal to the UVM processor. This feedback signal is non-linear and has a random 0% and 100% position voltage.
The UVM converts the position sensor signal to a physical feedback position on the valve and then translates that position to a CFM value. The CFM value is in turn output from the UVM as a 0 V to 10 V feedback signal at the same scaling as the CFM request signal.
For more information on basic UVM functionality, see the following image.
- You can configure and adjust the UVM1000 module in the field.
- Ganged Venturi air valves have a single UVM module. This is because multiple Venturi characterizations are linearized to a single command and control curve. All the valves in the gang assembly are treated as one unit.
UVM position feedback and scaling
The following table shows the default signal voltage scaling relative to valve size:
| Unit size | Ganged units | Minimum CFM | Maximum CFM |
|---|---|---|---|
| 8 in. (203 mm) | 1 | 0 | 800 |
| 10 in. (254 mm) | 1 | 0 | 1100 |
| 2 | 0 | 2200 | |
| 3 | 0 | 3300 | |
| 4 | 0 | 4400 | |
| 6 | 0 | 6600 | |
| 12 in. (305 mm) | 1 | 0 | 1600 |
| 2 | 0 | 3200 | |
| 3 | 0 | 4800 | |
| 4 | 0 | 6400 | |
| 6 | 0 | 9600 | |
| 14 in. (356 mm) | 1 | 0 | 2300 |
| 2 | 0 | 4600 | |
| 3 | 0 | 6900 | |
| 4 | 0 | 9200 | |
| 6 | 0 | 13,800 |
- Multiply the single size scaling factor by the ganged value for ganged valves.
- Exhaust air valves are configured in the factory to fail open. Supply air valves are factory configured to fail closed.
- Fail Open Valves require the configured control signal to be Reverse Acting. 10 VDC and 0 VDC = 0% to 100% AO% = 0 CFM to 800 CFM. The 0 VDC control signal results in maximum calibrated CFM. 10 VDC closes the valve to 0%.
As the valve moves to position, the position feedback sensor moves as well. The signal from this sensor is processed by a sensor voltage to position calibration section. The output of this section provides an accurate position value. The position value is applied to the position to CFM mapping table and an equivalent CFM value is outputted.
This CFM value is passed through CFM to voltage scaling factor and converted to a voltage value. The voltage value is passed through the factory set output calibration section and made available to the voltage output for use by the third-party equipment as the actual valve CFM.
In certain circumstances, the feedback signal does not match the requested CFM signal. If 0 CFM is requested, the input is 0 V and the valve is closed to the minimum CFM that it can attain. This value is not 0 CFM and for a 12 in. valve is approximately 90 CFM. In this case, the feedback signal is the equivalent of 90 CFM or 0.56 V for a 10 V = 1600 setting.
If a UVM for an 8 in. valve is set with a scale of 10 V = 1100 CFM (or 110 CFM/V), and a request signal of 9 V (or 990 CFM) is input into the unit, the actuator increases to 100%, as the maximum is 800 CFM. The voltage feedback output signal uses the same scale and is approximately 6.4 V. The actual valve CFM is approximately 700 CFM.