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Air Duct/HVAC Air Flow

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Eldridge Products, Inc.’s patented* Flow Averaging Tubes (FAT™) were designed to provide accurate flow measurement in large pipes and ducts without the expense and complexity of traditional multipoint systems by offering a cost-effective solution for Heating, Ventilation, and Air Conditioning (HVAC) and Variable Air Volume (VAV) applications. Because they also provide accurate, repeatable readings in applications with very limited upstream straight run this list has been expanded by our customers over the years to now include almost any gas measurement requirement, with particular emphasis on natural gas usage and submetering.

The Master-Touch™ FAT™ probes utilize a flow averaging tube to give a stable flow signal in applications where the flow profile is less than ideal, such as downstream of a bend, valve, tee or obstruction. The flow averaging tube has a number of large diameter (0.125”) inlet ports along the length of the upstream impact surface. The impact pressure at each inlet port is averaged inside the tube to create the axial flow through the tube and across our flow sensor. The gas flow then passes back into the main flow stream through the gas return ports located near the flow sensing elements.

fat animation

Anomalies in the actual flow profile or installations in non-circular ducts may require a C-Factor adjustment for the best accuracy. The velocity impact pressure follows a square root function. Therefore, the average velocity pressure in the FAT™ probe may vary slightly from the average of the velocities at each inlet port. The Master-Touch™ electronics easily accommodate the C-Factor adjustment.

The FAT technology is available in the same range of physical configurations as the other Eldridge Products' instruments. Inline style averaging tubes are available for pipe sizes 2" and greater with flanged ends; insertion style FAT probes can be as small as 2" or as large as necessary (90+" to date!). Integral and remote electronics with approvals for hazardous or non-hazardous locations allow the FATs to meet most installation requirements.

The Master-Touch™ MP Series Flow Averaging Tubes are approved by CSA/CUS, ATEX, IECEx and KOSHA for use in hazardous area locations.

The Master-Touch™ MPNH Series Flow Averaging Tubes are approved by CSA/CUS for use in general purpose (Ordinary) area locations.

MPNH Series Flow Averaging Tubes

FAT MPNH group

*U. S. Patent No. 6,883,389 Other U.S. & foreign patents pending

Specifications

 Linear signal output   Flow: 0–5 VDC & 4–20 mA
 Temperature: 0–5 VDC & 4–20 mA 
 Relay Output  Two 1-amp @ 30 VDC, user-selectable alarm functions 
 Signal Interface  LCD (flow rate, flow total, gas temperature)
 RS232 & RS485 Modbus RTU
 Optional HART or Profibus DP
 Accuracy including linearity (Ref.: 21°C):   ±(1.0% of Reading + 0.5% of Full Scale + GTC) 
 Repeatability  ± 0.2% of Full Scale 
 Sensor response time   1 second to 63% of final value 
 Turn down ratio  100:1 @ 15,000 SFPM/76 NMPS minimum FS
 Ambient electronics temperature range   -40° to 120°F (-40° to 50°C)
 Gas temperature range  40° to 150°F (5° to 65°C)
 Gas temperature coefficient (GTC)  0.05% Full Scale/°C @ 40° to 100°F (5° to 40°C)
 0.10% Full Scale/°C @ 100° to 150°F (40° to 65°C)
 Gas pressure effect  Negligible over ±20% of absolute calibration pressure
 Pressure rating maximum:  
 Inline flowmeters  500 PSI Std., >500 special
 Insertion flowmeters  
 .500” OD  125 PSI Std., >125 special
 .750” OD   55 PSI Std., >55 special
 1.000” OD  30 PSI Std., >30 special
 Transmitter power requirements  5 Watts or less
 Input power requirement  24VDC @ 250mA
 115 VAC 50/60 Hz optional
 230 VAC 50/60 Hz optional
 RAM Back-up  Lithium Battery, 2.5–3.5v, >10 years
 Wetted materials:  316SS, including sensor
 Standard temperature & pressure (STP)  70°F & 29.92" Hg
 (Air .075 lb/cubic foot)  
 NIST traceable calibration  Standard

Specifications subject to change without notice.

Approval

 MP Series Flow Transmitter — 

 For use in hazardous area locations
 CSA/CUS, ATEX, IEC Ex, KOSHA

 MP Series Flow Transmitter Approvals

 MP Series Remote Enclosure —  For use in Ordinary(Non-Hazardous) area locations:
 Type 4X, IP66

 Optional ACEX/DCEX
 Remote Enclosure —

 For use in hazardous area locations
 CSA/CUS, ATEX, IEC Ex, KOSHA
 MPNH Series —  For use in Ordinary(Non-Hazardous) area locations:
 Type 4X, IP66

If you require further information on this product or would like a quotation, please contact dp-flow on:

Supplied by DP-Flow