I am dealing with a pressure switch datasheet which has a process pressure range of 0 t 3.5 barg. Please someone tell me how can i calculate its differential pressure range? and the significance of on measurement increase switch and the orientation of the switch?
You don't calculate what a pressure switch (non-adjustable) deadband is. The (non-adjustable) deadband is what it is for any given pressure switch, due to design and mechanical tolerances. Every major manufacturer lists the deadband range for a given switch. Two identical pressure switches could have different deadbands due to mechanical tolerances.
There are pressure switches with adjustable deadband, sometimes an option for "close deadband". Depends on manufacturer.
This blog explains further:
A typical mounting suggestion is:
Should the control be installed where condensation is expected, vertical mounting is recommended as a means of keeping water away from switch terminals.
I'm not sure what you mean by this, but the setpoint adjustment is done in terms of rising/increasing pressure or falling/decreasing pressure because of the effect of hysteresis.
The setpoint is repeatable within its spec, for example, for a trip on rising pressure, but would shift on falling pressure.
If you want a 'high alarm', then the setpoint would be adjusted for increasing/rising pressure.