The stainless steel King Instrument 7430 / 7440 series rotameter utilizes a float and tapered tube design. As a result, these rotameters have longer and more linear scales, better pointer stability, and 40% greater accuracy than competitively priced products. Both the 65mm and 150mm scaled models feature borosilicate glass tubes and all stainless steel frames. They are available in either horizontal (7430) or vertical (7440) connection orientations .

Accuracy is determined by the scale length: the 65mm scale has an accuracy of ±6% of full scale flow and the 150mm scale has accuracy of ±4% of full scale flow. Repeatability is 1% with turndown ratios from 10:1 to 12-1/2:1 unless otherwise indicated. Flow ranges cover 0.72 to 1800 cc/min for water and 66 to 70000 cc/min for air .

The maximum temperature rating is 250°F (121°C) for gas applications and 200°F (93°C) for liquids. Maximum pressure depends on fitting material: 200 psig for 316L SS fittings, 130 psig for PVC, and 150 psig for PVDF. Ambient temperature range is 33°F to 125°F (1°C to 52°C).

Alarm options include inductive ring sensors and fiber optic sensors. Inductive ring sensors detect the metal float via an electromagnetic field and are available in proximity or latching format. Fiber optic sensors housed in a junction box use emitter/receiver pairs to detect float position, providing NPN or PNP transistor outputs compatible with all float types .