With oil level indicators GN 656, the fluid level can not only be viewed, it can also be monitored using an electric contact.
A float with a magnet is located within the indication range which closes or opens a contact at a certain fluid level (REED switch).
The table values for the maximum allowable pressure are based on the use of mineral oil (according to ISO 3498) at a temperature of 23 °C. Use under different conditions will influence the compressive strength and requires prior consultation.