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hysteresis

Hysteresis

Hysteresis arises from friction and an acute strain on elastic components. This results in different outlet pressures at a predetermined set point depending on whether the previous value was higher or lower.

Sensitivity

Sensitivity


The minimum change in a setpoint which leads to a change in the outlet pressure is called sensitivity. Expressed as a percentage of the maximum outlet pressure, this value is merely 0.5 % for ASCO Numatics‘ SENTRONIC valves, thus allowing for extremely sensitive adjustments of the outlet pressure.

Linearity  
 

Linearity


An outlet pressure shown in dependence on a setpoint should result in an almost straight (linear) characteristic curve (dotted line) so that the pressure to be expected at a given setpoint can be predicted as precisely as possible. The divergence is calculated from the maximum deviation from the ideal characteristic curve as related to the maximum outlet pressure.

Repeatability
 

Repeatability


Control components are more precise in repeating a previously determined value than in adjusting to absolute values. The reason is that– under this aspect – the divergence from the linearity is of no importance. Moreover, the repeatability is positively influenced by a low hysteresis.

Zero Adjustement
 

Zero Adjustment


By way of zero adjustment, the proportional valve can be assigned to a predetermined starting point, and /or a definite pressure or flow can correspond to a previously established setpoint.

Span Adjustement
 

Span Adjustment


If the user’s operative range is only a part of the valve’s total adjustment range, span adjustment can be used to assign the setpoint range(0 - 10 V) to the user’s operative range. This provides for the highest-possible resolution.

Ramp Function
 

Ramp Function


The ramp function transforms a setpoint step into an internal gradual increase of the setpoint signal. This allows slow opening and closing of proportional valves.