A separator

A separator arrangement comprising a tank 3 for receiving a water-oil mixture and a separator device 15, such as a coalescer, located inside the tank for separating water and oil from the mixture. The separator comprises an outlet for discharging the separated water and one or more oil drain apertures 21 in the sidewall 11 of the tank. A mechanism may adjust the level of the oil drain apertures in relation to the base 9 of the tank; this may comprise a movably mounted plate 39 comprising the oil drain aperture 21, overlapping with an auxiliary aperture 47 in the tank sidewall. The tank may have several consecutively arranged partitions 25 defining oil retention chambers 27, where the oil draining apertures 21 are provided in each chamber. The tank may comprise a levelling arrangement for adjusting the tilt of the tank base, such as adjustable legs.