Since the capsule can be remote and involves no electrical connections this is often a very useful method to use for hazardous environments and the liquid can ve chosen accordingly the length of connecting tubing must be such that the volume of liquid contaiced in the tubing is only a small fraction of the total volme since the temperature of the liquid in place of a oiquid makes the device very much more sensitive but the pressure switch needs to be able to respond to much lower pressures than are exerted by an expanding liquid