• Horizontal (7430) or vertical (7440) fitting orientation
  • 0.72 to 1800 cc/mn (Water)
    • 200°F (93°C) max (liquids)
  • 66 to 70000 cc/mn (Air)
    • 250°F (121°C) max (gases)
  • 65 or 150mm direct reading, detachable scale
    • ±6% full scale accuracy (65mm scale)
    • ±4% full scale accuracy (150mm scale)
  • 10:1 to 12-1/2:1 turndown (unless otherwise indicated)
  • 1% Repeatability
  • Maximum pressure depends on material
    • 200 psig (SS)
    • 130 psig (PVC)
    • 150 psig (PVDF)
  • 33°F to 125°F (1°C to 52°C) ambient temperature


The stainless steel King Instrument 7430 / 7440 series rotameter utilizes a float and tapered tube design. As a result, the King Instrument 7430 / 7440 series 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 of the King Instrument 7430 / 7440 series rotameters feature borosilicate glass tubes and all stainless steel frames. They are available in either horizontal or vertical connections. Accuracy of the King Instrument 7430 / 7440 series rotameter is determined by the scale of the rotameter – the 65mm scale has an accuracy of ±6% of full scale flow and the 150mm scale has accuracy of ±4% of full scale flow.

The maximum temperature rating of the King Instrument 7430 / 7440 series rotameter is 250°F (121°C) when used in gas applications and 200°F (93°C) when used for liquids. The maximum pressure for 316L SS fittings is 200 psig, 130 psig for PVC fittings, and 150 psig for PVDF fittings.

Alarm Options for the King Instrument 7430 / 7440 Series Rotameter

  • Inductive Ring Sensor: Inductive ring sensors are designed to be used with a remote intrinsic safety barrier / switch isolator. These sensors are able to detect the metal float by producing an electromagnetic field within the ring. Ring sensors are available in either proximity or latching format for the King Instrument 7400 series rotameter.
  • Fiber Optic Sensor: The fiber optic sensor is housed in a junction box attached to the side of a King Instrument 7400 series rotameter. The sensor uses a pair of fiber optic cables, an emitter, and receiver to transmit the light across the metering tube and back to the sensor. If the light beam is blocked by the float, the sensor output will change. The sensor provides a transistor output that switches the common or negative voltage (NPN) or positive voltage (PNP) to the load. The fiber optic sensor is compatible with all King Instrument 7400 series rotameter float types.


This product can be used in the following applications:

Here's how some of our customers use this product...

Ozone Metering for an OEM

The Background: Our customer is an OEM that seeks a way to monitor and control the flow of ozone for a water treatment system they produce

The Problem: Ozone is commonly used as a disinfectant in water treatment systems as very small amounts of it are very effective at killing bacteria and viruses. It is generally used in such small amounts that metering it is difficult.

The Solution: We recommended a King Instrument 7430 series rotameter. The 7340 features extremely small glass tubes, made on-site by King Instruments, which are ideally suited for low flow applications of both liquid and gas. The scales can be customized to compensate for all gases and process conditions (pressure and temp). The 7430 is also available with a needle valve to finely adjust the ozone flow if needed. The typical meter wetted materials of 316SS and borosilicate glass make the meter suitable for use with corrosive ozone gas.

In Stock

Part Number Price Available
74C-214G021-5-2-1-8-3-0 [Custom Gas]
$248.00 1 in stock

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