One is that the pressure difference is fixed by the switch itself, and only the automatic shutdown pressure is adjusted, the highest pressure. There are two flat-head screwdriver debugging buttons on the switch, and the two buttons must be adjusted uniformly (otherwise, they will stop moving together, stop and start, and burn out the appliance).
The other is an adjustable starting pressure (low pressure), an adjustable stopping pressure, (high pressure) this is relatively difficult to adjust the former.
No matter which method should be adjusted in the switch housing or cover, you look carefully.