There are many gas pipelines buried around the world. Many of these have liquid separators built into them at remote locations (normally in geographically low spots). Their function is to allow water and heavier hydrocarbons that condense out, to be collected and removed from the pipeline.

Frequently these remote locations have no power. Modified Style E (top-mount) magnetic level gauges have been used to monitor and control these separators. Since they are underground and pressurized the LG series gauge operates very well and no power is required, because the PS-1 pneumatic switches can be operated by gas pressure (from a step down pressure regulator).

As the tank fills with liquid, the float rises and operates the top switch. The output from this switch actuates a pneumatic latching relay and opens the dump valve. The normal pipeline pressure forces the liquids into the slop tank.

As the liquid level drops the lower PS-1 is actuated and the dump valve closes. The slop tank is another good place to use a standard LG series gauge.