Air entrainment in concrete can improve its durability. Recommended limits vary between 3% and 6.5%. The Tinius Olson TO 340 air entrainment meter available from Power Parameters provides an accurate means of air concentration measurement by means of a cylindrical stand pipe, graduated in per cent air.
The air entrainment device comprises of a pressure-tight flanged, cylindrical measuring bowl with a removable conical cover assembly complete with air valve and cock for bleeding of water. The required pressure is applied by means of a pressure bulb. The Tinius Olson TO 340 Type A has a capacity of 5 litres with a maximum aggregate size of 38mm. Larger volumes are accommodated in the Tinius Olson TO 341 (10 litres, maximum aggregate size 76mm) and the Tinius Olson TO 342 (100 litres, maximum aggregate size of 150mm). The latter model is supplied with a foot pump instead of a pressure bulb.
The Tinius Olson TO 340 B is designed for on-site analysis. The instrument has a 7 litre capacity and weighs 6.8kg. Measurements up to 22% entrained air can be made with a maximum aggregate size of 50mm.