Data Sheet for Product

CA1N4028E / 11.1998 Siemens Building Technologies
6/12 Landis & Staefa Division
Relationship between flow rate and heat quantity
When the Landis & Staefa magnetic valve is used as a simple straight-
through valve (port 2 closed) the disc provides throttle control in response to
the positioning signal from the controller.
When used as a three-port control valve, water from two temperature
sources is mixed in a proportion determined by the positioning signal from
the controller.
The correct hydraulic circuit and the correct installation of the valve are vital
factors for control quality.
Another important criterion for the quality of a control loop is the minimum
controllable heat quantity. The behaviour of the Landis & Staefa magnetic
valve in the low opening / closing range, as described in this article, enables
very small heat quantities to be controlled.
Conclusion
1) The Landis & Staefa magnetic actuator has an outstanding life expectancy,
thanks to its simple construction.
2) The special behaviour of the modulating valve in the low opening range –
no jump on start-up, a concave “starting curve” – ensures precise control,
down to the smallest flow rates.
3) The virtually friction-free construction results in a high stroke resolution,
allowing extremely accurate control of the flow rate.
4) The design characteristics of the magnetic actuator allow very quick travel
through the full stroke range (1 to 2 seconds) and thus an almost
immediate response to any changes in the input signal.
These special features of the Landis & Staefa magnetic valve enable even
difficult HVAC control loops to be controlled.
Advantage Main reason
Accuracy No static friction
Wide application range Linear stroke/voltage
characteristic, high
resolution in low
opening range
Fast start-up response Positioning speed
Efficient damping Positioning speed
94.0211
Fig. 12: Control characteristics