A new type nuclear device for measuring the oil-water interface level as well as the total liquid level was presented. A series of new methods

such as non-linear fitting of the level

automatic compensations for the deviation caused by the decay of radioactive source

the medium’s temperature

etc.

were employed. Comparing with other non-nuclear techniques

this device has the following advantages: non-contact surveying

anti-interference of paraffin wax coagulating and a little of repairing. The measuring range is 0—200cm for total liquid level and 0—100cm for oil-water interface level respectively. The measurement precision is 1% for total liquid level and 2% for the interface level respectively. The respond time is ≤10s

the long time stability ≤ 0.5% FS / 48h and the temperature influence ≤0.01% FS /℃. The gauge can be used in surveying oil-water interface level and total liquid level in oil-water separation tanks on oil fields. It is also suitable to measure the interface level of two kinds of liquids as well as the total liquid level in various storage tanks.