A revolution in airflow measurement technology.

Traditional technology has inherent performance limitations. A brief list of common occurrences that can impact traditional outdoor airflow measurement device accuracy include:

• Wind gusts
• Low air velocities
• Ambient weather variations (temperature and humidity)
• Airborne particulate matter (dust, dirt, pollen, waste)
• Damper blade deterioration and system hysteresis
• Mechanical system bends or restrictions (that affect airflow)

Other common concerns include:

• Physical equipment limitations
• Unrepeatable, inconsistent measurements
• Prohibitive cost of implementation and maintenance

Many airflow measurement technologies exist, but few provide accurate, repeatable results for all types of equipment. Most devices have strict installation requirements, limiting where they can be used.

• Differential pressure (using a pitot tube) is a standard method for measuring airflow, but it’s not suitable for duct systems with bends or low velocities.
• Thermal dispersion sensors are good for low-velocity airflow but can be affected by pollutants like dust, dirt, and animal waste. They also don’t perform well with bends or restrictions in the ductwork and require regular maintenance and recalibration.
• Conditioned orifice plates are effective but can be costly and require system modifications. They also struggle to accurately measure low velocities because they need to increase differential pressure, which reduces accuracy.

The cost to install the KMC Airflow Measurement System is often much lower than traditional technologies. Many existing systems require expensive modifications to ductwork or equipment to meet factory standards for accurate measurements.

To achieve a good return on investment, an airflow measurement solution must be affordable and reliable. The KMC AFMS uses inclinometer technology and a characterized system method, providing an economical way to improve performance. Real-time measurements, KPIs, and diagnostics can be displayed locally or integrated into a building automation system.

Ongoing maintenance costs are low because supply airflow measurements are taken in filtered air. Additionally, existing sensors and actuators can be reused for calibration, lowering installation costs. A hard-wired sensor connection is recommended for better reliability.

System diagnostics are performed regularly using automated methods (ASHRAE standards 62.1, 111, and 189.1). If needed, the system can be recalibrated to maintain long-term accuracy.

Recently, ESSER funding has been made available by the federal government to improve Indoor Air Quality (IAQ) in educational facilities. The amount of funding and qualifying activities vary by state. The amount of funding and qualifying activities vary by state and are listed in the State Plan. For details, consult your state’s Department of Education website. ESSER funds have been used for installing airflow measurement stations and improving ventilation, including products like KMC CommanderAQ.

Using a characterized damper airflow measurement system makes proper ventilation achievable in nearly any building.

The patent pending KMC Airflow Measurement System is a revolutionary approach to measuring outside airflow. The system uses a characterized system method to measure outside, return, and supply airflow.

A high-precision inclinometer monitors the outside air damper blade position, ensuring performance is unaffected by weather, wind gusts, low air velocities, pollutants, turbulent airflow, or duct bends and restrictions—issues that commonly impact traditional airflow measurement technologies.

The KMC Airflow Measurement System measures airflow by characterizing outside air damper performance, similar to how a pump performance curve is created.

This method helps the system determine the composition of supply air at any damper position.

The system creates the characterization curve automatically using a Learn Mode sequence. It uses an inclinometer mounted on the damper actuator blade and the Temperature Ratio Equation. As an alternative, a qualified TAB technician can manually create the curve.

During Learn Mode, the damper is moved to several known positions. At each position, airflow and temperatures (outside, return, and mixed air) are allowed to stabilize before being sampled, averaged, and stored in the curve.

ASHRAE standard 111 requires 25⁰-50⁰F temperature difference (∆T) between Return Air (RA) and Outside Air (OA) temperature for the most accurate calculations.

The KMC AFMS Learn Mode can automatically start when there is a temperature difference greater than 15°F between OA and RA for at least two hours.

This includes time for temperature sensor stabilization and multi-sampling.

The requirements for initiating Learn Mode are minimal.

Execute when:

• Building can maintain >15⁰ ∆T between RA and OA for minimum 2 hours
• Typically at night (less thermal variance due to Sun & reduced occupancy / less need for system override)
• There is no possibility of mechanical or environmental faults
  • E.g. Freezing, over-pressurization, excessive humidity, etc.

The outside air damper characterization curve is the foundation for all measurements on the KMC AFMS.

A high-precision inclinometer (compliant with AHRAR Standard 189.1) is attached to the damper blade to measure its position with accuracy up to 0.001°. This helps reduce errors caused by damper blade wear or linkage issues that can’t be detected through actuator feedback.

The characterization curve defines the composition of supply fan airflow using the Temperature Ratio Equation in ASHRAE Standard 111, similar to how a TAB technician balances the equipment.

Characterizing damper performance also ensures accuracy, regardless of intake configuration, non-laminar airflow, or leaks in the mechanical system.

Many equipment manufacturers include features like filters or air bypass streams in mixed air chambers. As the equipment operates, these components can affect outside airflow being drawn into the equipment.

To monitor these conditions, the KMC AFMS uses a Pressure Assist feature. This feature can be used on any system but is specifically recommended when:

1. 1. Relief fan that is variable speed OR operating independent of mixed air damper position
   2. Return fan that is NOT controlled by a Supply / Return Fan offset
   3. Bypass damper for a heat recovery system
   4. Return VAV boxes
   5. Supply to return bypass (or bypass damper is used in place of a VFD)

Pressure Assist corrected airflow rates are determined by the OA damper characterization process and aggregation of variables affecting airflow through the mixed air chamber

If the KMC AFMS controller is being used to manage equipment operation, it may be configured for four basic modes:

• Pass Through
  • Damper is controlled by an external source (existing BAS, etc.)
• Mixed Air Temperature
• OA Volume
  • Air changes / hour
• Damper Position

NOTE: Customized control modes / equipment sequences can be accomplished through additional programming

The KMC AFMS natively monitors the following properties, to ensure accuracy and equipment performance:

• Sensor Faults
  • Outside Air, Mixed Air, Return Air, Differential Pressure
• Damper Faults
• OA Flow Status
• Active Control Mode Faults
  • Position, Mixed Air, OA Volume
• Title 24 Faults

These diagnostics may be viewed locally or reported through a building management system.