of the present invention the tank vent assembly is designed to fit in the valve assembly in the vent tank 10 as described above the tank vent assembly includes a probe 100 with a lower gas outlet section 101 a middle section 102 and an upper gas inlet section 103 at the upper section 103 there are gas inlet slits 104 around the probe circumference the gas inlet slits 104 extend into the inner hollow of the probe 100 which forms a gas inlet channel 107 there is also a gas inlet bleed opening 105 at the top of the probe 100 the gas inlet bleed opening 105 leads to a gas inlet bleed channel 106 extending down the probe below the gas inlet slits 104 is an upper part of a ball rack lock mechanism 50 a ball race outer collar 54 has six rotatably mounted ball bearings 55 in its circumference there should ideally be at least three ball bearings the collar 54 and ball bearings 55 can be rotated with respect to an inner shaped collar 56 in a locked position as shown in fig6 a the ball bearings 55 rest in grooves of the inner collar 56 in a locked position shown in fig6 b the ball bearings rest in mini grooves on the top of spokes of the inner collar 56 hence in the unlocked position the ball bearings 55 are nearer the centre and in the locked position the ball bearings 55 are further outwards the outer collar 54 is connected to and can be rotated by a lever collar 52 at the lower section 101 of the probe 100 the lever collar 52 is connected to a lever 51.