The SEMTECH EFM4 is Sensors, Inc.'s 4th generation of proprietary rugged, compact Electronic Flow Meters specifically designed for the measurement of total raw exhaust mass flow from either compression or spark ignition engines and vehicles.

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SEMTECH EFM4

SEMTECH EFM4: Electronic Flow Meter

Operating under the Bernoulli principle and laminar flow theory, EFM4 employs five high performance, dual-stage, differential pressure transducers which allow operation over an extremely wide dynamic range.

SEMTECH EFM4 can be attached directly to SEMTECH SCS or electrically and pneumatically connected via harness and heated line, respectively if the SEMTECH LDV unit is installed inside the vehicle. Five flow tube diameters: 1”, 1.5”, 2”, 2.5” and 3”, are available to accommodate various engine sizes depending upon exhaust flow.

 

  • Features
  • Specifications
  • Accessories

The SEMTECH EFM4 is the first generation of EFM where all measurement components are completely self-contained in a single module mounted directly on the flow tube, eliminating the need for transport lines, and continues to offer the following benefits:

  • High Speed Sampling: The EFM4 internally samples the differential pressure channels at up to 5 kHz, accounting for every pressure pulse from an engine, from idle to maximum rpm. Standard output rate is 1 Hz.
  • Back Purge: A software-controlled back purge pump is included in the heated sampling flow tube assembly, along with solenoids that route high pressure air backward through the Pitot tube, purging contaminants and any condensation in the pressure lines. No dismantling is required
  • Autozero: With a single software command, internal solenoids open the pressure sensors to ambient air, allowing fast and easy zeroing while the engine is still operating.
  • Sampling tube assemblies come with two elbow extensions to facilitate installations.

Product Views for EFM4

Specifications
Exhaust temperature range
-5 to 700° C
Exhaust temperature accuracy
± 1% of reading or ± 2° C, whichever is greater
Flow measurement linearity
|xmin x (a1 - 1) + a0 | ≤ 1% of max
Slope a1 between 0.99 and 1.01
Standard Error of Estimates (SEE) ≤ 1% of max
Coefficient of Determination r2 ≥ 0.990
Flow measurement accuracy
± 2% of reading or ± 0.5% of full scale, whichever is greater
Warm up time
≤ 5 minutes at 20° C ambient
System response
time (T0 – 90)
≤ 2.5 seconds; synchronized to match rise time of gaseous analyzers
Data acquisition rate
5 Hz standard
Resolution
0.1 kg/hr
Power requirements
12 VDC
Communications
≤ 10 seconds with rise time ≤ 2.5 seconds
Box dimensions
W x D x H
35.8 cm x 11.2cm x 9.1cm
14.1 x 4.4 x 3.6 Inches
Flow tube dimensions
OD X L
(mm)
25 x 508 25 x 508 38 x 508 51 x 508 64 x 640 76 x 640
OD X L
(in)
1.0 x 20 1.3 x 20 1.5 x 20 2.0 x 20 2.5 x 25.2 3.0 x 25.2
Flow tube weight
kg (lbs)
3.7 (8.2) 3.7 (8.2) 3.7 (8.2) 3.8 (8.4) 3.8 (8.4) 3.9 (8.6)

 

Flow Rates
Temp
100˚C
400˚C
Nominal Tube
Diameter (in.)
Min Flow (kg/hr) Max Flow (kg/hr) Min Flow (kg/hr) Max Flow (kg/hr)
1
6.9 85.0 10.4 64.0
1.3
8.9
217.0 13.4 162.0
1.5
10.9 276.0 16.4 208.0
2
15.8 535.0 23.9 402.0
2.5
18.9
890.0 28.4 670.0

3

22.5 1250.0 34.0 930.0

 

EFM4 Flow Rates

Each heated tube assembly includes the following accessory kit (unique to each size):

  • Marmon Flange Clamps (2)
  • 90° Flow Tube Extension Inlet (1)
  • 90° Flow Tube Extension Outlet (1)
  • Heat Shield
  • Gaskets (2)
  • Extension Cable (POE)
  • Hard case for Flow Tube and harness
  • Pneumatic capacitor (for 1.0”,1.25”, 1.5”, 2.0” gasoline vehicles only)