CDI Meters

Flowmeter Overview

CDI flowmeters represent a radical departure from conventional designs. The meter clamps around a pipe with its flow-sensing probes projecting into the pipe through drilled holes. The low cost of the meters makes them ideal for installation throughout an air distribution system.

All of our meters:

  • Install in minutes
  • Measure mass flow by thermal dispersion
  • Have built-in LED displays
  • Are CE certified and RoHS compliant
Thermal Mass Flowmeters
Thermal mass flow meters employ a simple, direct method of measuring flow without imposing a significant pressure loss. They work by sensing the temperature of air in a pipe and the amount of heat required to maintain a heated sensor at a fixed temperature difference above the air temperature. The faster the air flows, the more heat is required. The heat requirement depends on the mass velocity of the air, so the meter is measuring the mass of the air going by rather than its volume. As long as the compressed air has been filtered to remove lubricating oil and dried to remove water droplets, thermal mass flowmeters provide accurate flow data independent of temperature and with little dependence on pressure.
Our Design

We separate the heated, flow-sensing element from the temperature-sensing reference element and place them in two probes that enter a pipe through small drilled holes. The probes are mounted in one or two rings, and the rings clamp around and seal to the pipe. Installation consists of drilling two holes, using a drill guide, and clamping the meter in place. Each meter is designed and calibrated for a specific type and size of pipe, so no adjustment or configuration is required during installation. The meters have large, bright LED displays, milliamp and pulse outputs, and an optional wired serial output for networking.

Recommended Placement
To perform properly, our meters must be installed where the air is free of oil and water droplets; thus in a compressed-air system, they must be downstream of a dryer. They also must be installed with sufficient straight pipe upstream that the air will have a well-developed, uniform flow profile. A length equal to 20 times the pipe diameter is sufficient in most cases; more is recommended after long-radius elbows and other items that could distort or concentrate the flow. For additional application limitations, please refer to the data sheet for the meter.
Flow metering is useful and cost-effective at a range of locations in the typical compressed-air system. At the plant-wide level, it assesses compressor-room performance and plant-wide air-use efficiency and leakage. At the department level, it assigns responsibility for air usage and gives credit for progress in reducing air usage. At the point of use, it pinpoints leakage and inefficiency. Leading companies in several industries have found it cost-effective to install dozens or hundreds of meters at individual pieces of equipment and use them to determine where maintenance is required.
Flowmeter Options and Modifications

We can easily modify our standard flowmeters to accommodate various units of measure, various display features, wired communication, high-pressure applications, and calibration adjustments for non-standard piping or tubing. You can find more information about these modifications here.