Introducing NJK Precision Airflow Measuring Stations

Transcription

1 Introducing Precision Airflow Measuring Stations A new and unique airflow measuring station that accurately measures airflows at very low flow rates and can operate in physically restrictive applications Airflow Measurement Products

2 Airflow Measuring Stations Inspired by proven aviation and automotive technologies, Precision has developed a new airflow measuring station that is completely different from the methods that have been used in the HVAC industry for a generation. has developed an airflow measuring station technology that includes 21 patented claims. The result is an airflow measuring station that is not subject to the same inaccuracy, placement restrictions, low flow limitations, pressure drop issues, and size restrictions that are inherent in other airflow measurement methods. This airflow measuring station provides a unique, robust, and patented method of measuring airflow, even in the most challenging HVAC applications. The Precision airflow measuring station has an airfoil profile that installs in the perimeter of a duct or an outdoor air opening. The Flow Frame (FF) has a patented, Dual Chambered, Airfoil design. There is a precision formed linear slot opening on both the front and back side of the airfoil chambers running the length of the FF. Like an airplane wing, the momentum of air flowing over this anodized extruded aluminum frame creates a pressure differential. On an airplane wing this is called lift. And just like a wing, the heavier or denser the air, the greater amount of lift and the greater mass of air movement. This is the principal at work in the airflow measuring station. This dual chamber airfoil Flow Frame (FF) has three functions. The chamber induces a differential pressure that is proportional to the mass of air flowing through it. Second, it averages flow samples from the perimeter of the duct. Lastly, the FF dynamically normalizes the turbulent flows inherent in a duct. These functions improve measurement accuracy. The chambers are connected through the Flow Measuring Module (FMM). The lift or momentary pressure change created by air passing through the Flow Frame induces air to flow through the frame and through the FMM. Flow Frame Cutaway Flow Frames and Flow Measuring Modules

3 Manufacturers typically recommend installing an air measuring station as far away as possible from an elbow, branch, transition, or fan. The more equivalent duct diameters away from these air distribution components, the better the measurement. This is because the air velocity profile becomes more uniform the further it travels down a straight section of duct. achieves this uniform velocity profile when air enters the Flow Measuring Module (FMM) through a half inch diameter communication hole. The air then flows 7.5 equivalent duct diameters before reaching the advanced thermal dispersion technology thin film resistor which measures the mass flow of the air. The FMM simulates a desirable duct run. This is the same sensor technology used to measure the mass flow rate of air entering a fuel-injected combustion engine. Each airflow measuring station from Precision is calibrated and scaled for accuracy from the minimum flow through the maximum flow on a primary IST Certified Airflow Test Stand. The Flow Measuring Modules with 7.5 Equivalent Duct Diameter Sensing Tube result is a Flow Measuring Module reading within a 2.0% uncertainty and at a 95% confidence interval. The result is a calibration accuracy of 0.19% uncertainty at a 95% confidence interval. This means high accuracy and repeatability of airflow readings at all temperatures and humidity conditions. BEEFITS The taming of the turbulent airflow results in more accurate measurements, which means the Precision airflow measuring station can be placed in more physically restrictive situations. There are a number of products on the market that will accurately measure airflow at less than the ASHRAE Standard 111 recommendation for equivalent duct diameters away from an elbow, branch, transition, or fan. The airflow measuring station sets a new, smaller equivalent duct diameter standard for station placement. For example, instead of requiring that an air measuring station be located 3 equivalent duct diameters downstream from a 90 degree elbow, the station can be placed just one equivalent duct diameter downstream of the elbow. (For details, consult the Precision Application Guide.) Being able to place the Precision station in tight locations increases the number of applications where you can apply an airflow measuring station. The station is suitable for new construction and existing buildings. The Precision station design also allows for some of the lowest measurements of flow on the market. The station can measure airflow amounts with velocities as low as 50 feet per minute. This provides a greater range of measurement and can be used for applications like ventilation, building pressurization control, and critical applications by a building automation system. The Flow Frame (FF) of the Precision airflow measuring station comes in two sizes to minimize the cross sectional area inside the duct. For rectangular air stations where both the height and width are less than 18 inches, the smaller FF profile (only 2.75 inches wide) is standard. For rectangular air stations where either the height or width is 18 inches or greater, the larger FF profile (only 5.5 inches wide) is standard. The airfoil shape and proportionally small cross section have a very low pressure drop and create very little fan pressure loss. There are no sampling tubes traversing the cross section of a duct or outside air opening. Right Angle w/o Turning Vanes Mounting Single Input Dual Output Mounting Right Angle w/ Rounded Elbow Mounting 2D 1D D/4

4 COMPOETS AD ASSEMBLY The Precision Airflow Measuring Stations are built to order. Measuring stations are shipped unassembled to reduce shipping costs and to prevent damage. Field assembly is fast and simple. The Flow Measuring Module is already factory mounted onto a Flow Frame section. The sections are connected together with slip fit, field adjustable corner pieces that are tightened by a screw. Because field provided dimensions are not always exact, each frame is built 0.5 inch smaller than the requested duct dimension. In the event of an incorrect duct dimension, the small profile frame is adjustable +0.5 inch and the larger profile frame is adjustable inch. This allows secure and proper fit inside the duct or outdoor air opening. Round air sensing stations, available in 2019, have mounting bracket adjustments so that a single station can fit into a range of duct diameters. Flow Frame and Slip Fit Corner Pieces In applications where you are placing a measuring station at the opening of an outdoor air hood or measuring flow from an open plenum, offers perimeter edge extension pieces. These one inch wide pieces go on the outside edge of the air opening. This simple addition makes accurate airflow measures in a rain hood, plenum, or other unducted installations a reality. The Flow Measuring Module (FMM) can be mounted inside or outside the duct. Measuring stations come with a Signal Processing Unit (SPU-S) that includes a display. The display readout from the SPU is in cubic feet per minute at standard air conditions (SCFM). Signal Processing Unit with Display Maintenance is also simple. The Flow Frame needs to be clear of debris that can affect sensor operation which can occur in an unfiltered outdoor air application. While particulates like Cottonwood will have little effect, items like leaves, straw and litter can plug the Flow Frame and affect operation. Rain hood and unfiltered outside air installations may require periodic cleaning. Every year the Flow Measuring Module should be removed and the sampling port be cleaned with a small amount of air, water, or electric contact cleaner. The Flow Measuring Module can be cleaned by removing the four mounting screws that attach the module to the Sensor Flow Frame and flushing the sampling port with either a small amount of air or electrical contact cleaner. Air pressures in excess of 110 psig may damage the Sensing Probe. It is recommended that the rubber sealing gaskets be replaced whenever the Flow Sensing Module is removed / replaced. Recommended cleaning interval is two years for a standard application.

5 MULTIPLE SESOR APPLICATIOS For multiple sensor installations, Precision offers an economical option not available from competitors. Instead of requiring a dedicated display unit for each airflow measuring station, offers a Multi Sensor Hub and a multiple sensor Signal Processing Unit (SPU-M). This combination saves on hardware and installation costs. Up to eight stations can be connected to a multiple sensor SPU (SPU-M) through this Multi Sensor Hub. From one location you can simultaneously monitor four airflow values at a time or view all eight air station measurements individually. MULTIPLE SESOR APPLICATIOS The Signal Processing Unit (SPU) is powered by 24 volts either AC or DC. The multiple sensor Signal Processing Unit (SPU-M) provides four 1-10 VDC output values to the Building Automation System. Airflows can be summed together for a totalization of airflows. SIGAL PROCESSIG UIT - MULTIPLE (SPU-M) REQUIREMETS Multiple sensors (up to 8) can be monitored from a single SPU-M Three sensors per channel or group can be added together on each channel Overall cable length is limited to 300 feet per SPU-M and Multi Hub Sensors added to each channel will be viewed at BAS as one flow signal only Each sensor in the channel or group can be viewed and modified at the SPU-M The Multi Hub and sensor flow modules are all powered from the SPU-M SIGAL PROCESSIG UIT - MULTIPLE (SPU-M) ADVATAGES Multiple (Like) sensors can be added to create one flow signal to the Building Automation System Unlike sensors (outside, return, supply and exhaust air) can be viewed from a single SPU-M Equipment cost savings Installation cost savings

6 APPLICATIOS The Patented Dual Chamber Airfoil Design requires minimal equivalent duct lengths. With the addition of the perimeter edge strips, the Precision air station is a perfect solution for outdoor air intakes on package rooftop equipment and air handling units. The station can also be applied to the measurement of supply, return, and exhaust airflows. The extreme accuracy of the device also makes this airflow measuring station a great solution in applications where you need precise airflow information as in laboratories and clean rooms. The Precision airflow measuring station is not subject to pressure span accuracy errors. It has an operating range from -25 F to 160 F and operates in humidity levels from 0% to 95% relative humidity. When mounted correctly, moisture in the Flow Frame, as from snow or rain, has no effect on the measurement accuracy. Wind gusts are anticipated and dealt with in the Signal Processing Unit. And the accuracy is consistent through the entire velocity range from 50 to 3,000 feet per minute. The Precision Airflow Measuring Station Flow Frame, Flow Measuring Module, Multi Sensor Hub, and Signal Processing Unit all come with a 3-year factory parts replacement warranty. If you need to accurately measure airflow: to prevent wasting energy by over ventilating, to make sure you are providing the proper amount of ventilation, in critical airflow applications, in order to maintain and control building or room pressure, or when having problems finding a suitable location for a typical airflow measuring station, Precision has the airflow measuring station solution for you. Precision Airflow Measuring Station Mounted in the Outdoor Air Intake of a Custom Air Handler Contact your nearest Precision Representative or contact Precision directly at: Airflow Measurement Products 402 East Haven Street, Suite H Eaton Rapids, MI sales@njkprecision.com (517) Precision 402 East Haven Street, Suite H Eaton Rapids, MI sales@njkprecision.com (517)