D-FL 220 Volume Flow Measuring

General Details

Volume Flow Measuring System

Ultrasonic sensor system to measure the velocity and the volume flow of flue gas or process gas in pipes or ducts.

Suitable for velocity and volume flow measurement:

  • at incinerators in general
  • at facilities for cement production
  • at power stations with gas, oil, coal or co-firing
  • at installations for the incineration of biomass




Two identical sensors transmit and receive ultrasonic pulses alternately. The flow velocity of sample gas is precisely calculated from the transit time difference dependant on the direction. Taking into account the cross-section of the stack, the gas temperature and absolute pressure the flow rate is calculated in parallel. 
D-FL 220 performs automatic check cycles and requires extremely low maintenance.

  • In situ measurement, continuous measurement
  • Measurement even in wet or dust-laden flue gas
  • Allows calibration to measure the volume flow
  • Also suitable for thick-walled stone / insulated ducts
  • Automatic zero and reference point check
  • Sensors are purged and are therfore not in contact with sample gas
  • Easy installation, adjustment and maintenance
  • No separate control unit required
  • Normalization of the flow measurements as an option
  • Very low maintenance

D-FL 220 Application Data

measurements flow velocity
volume flow, at operating conditions or normalized
sample gas air, flue gas, non flammable process gas
flow velocity 0 .. 10 / 20 / 40 m/s   (0 … 32.75 / 65.5 / 131.25 ft/s)
duct diameter** 0.5 – 13 m   (1.75 – 512 in)
sample gas temperature** -20 to 120 / 150 / 200 / 250 / 300°C (-4 to 248 / 302 / 392 / 482 / 572°F), others on request
sample gas pressure
(relative to ambient pressure)
-50 to +20 hPa, others on request
sample gas moisture 0 – 100 % rel. humidity, condensation allowed
ambient temperature -20 to 50 °C (-4°F to 122°F), others on request

D-FL 220 Technical Data

measuring principle evaluation of transition times of ultrasonic pulses dependent on direction and subsequent calculation of flow speed and volume flow
type mounted at stack, measurement cross stack, purged sensors are not in contact with sample gas
system components D-FL 220 MK measuring head
D-FL 220 SPF purge flange
D-FL 200 E mounting pipe with flange
D-TB 100 Terminal Box
D-BL purge air unit
measuring path** 1 – 15 m
orientation of the measuring path 30 – 60° to flow direction, typically 45°
measuring range 0 to 40 m/s, 
0 – 4…5,000 * 1000 Nm3/h
any range within the measuring range can be assigned to the analog output
delay time > 1s … 180s, programmable
resolution 0.1 m/s
process connection D-FL 200 E mounting pipe with flange, 
similar to DN80 PN6, pipe DI=100

D-FL 220 MK2 measuring head

ambient temperature -40 … 70°C
measurement output 1x 4-20mA, 400 Ohm, isolated, can be assigned by any measured component and output range
1 x RS 485 Modbus RTU, bi-directional to control room
status output 2 x relay NO, max. load 48V, 0,5A
function can be assigned. typically: failure, maintenance
signal transfer 1x Intercom RS 485 Master-Slave communication
service interface USB 1.1
service software D-ESI 100, requires laptop with Windows XP ™ OS
check cycle automated routines, self test, automatic or on request
supply 24 VDC +- 10%, 0,5 A
protection IP 65
dimensions (h x w x d) 110 Ø x 410…2450mm
the length is depending on version
weight depending on version
material housing 1.4571/316Ti, polyamide, ca. RAL5017
fire class: B1 (UL 94 V0)
process parts: 1.4571
transducer: PA6.6, PBT, FRP
fire class: B1 (UL 94 V0)

D-FL 220 SPF purge flange

weight 4.5 kg
material 1.4571 / 316Ti
dimensions (od x l) 190mm x 90mm
flange similar to DN80 PN6
purge air connection od=40mm
purge air requirements 10 … max. 40 m3/h for each measuring head

D-FL 200 E mounting pipe with flange

weight depending on version
 material  1.4571 / 316Ti
FRP (Durabest 180)*
 flange  similar to DN 80 PN 6
 pipe  id=100mm, L=335 … 2135mm (steps 200mm)

 D-TB 101 A terminal box

 ambient temperature  -25 to 55°C, others on request
 power supply  90 – 264 VAC, 48 – 62 Hz, 30 VA
includes 24VDC supply for 2 x D-FL 220 M
 dimensions (h x w x d)  ca. 160 x 160 x 110 mm
protection  IP 66
 weight  ca. 1,5 kg
 material  polycarbonate, ca. RAL 7035
fire class: B1 (UL 94 V0)
fixation  4 x bolt od= 8 to 10 mm

D-BL blower unit

 ambient temperature -20 to 50°C, others on request
 purge air supply max. 40/60 m3/h at dPtot 50/25 hPa, 
others on request
 supply  115 / 230 VAC, 50 / 60 Hz, 0,37 / 0,43 kW, 
others on request
 protection  IP 55
dimensions (H x B x T)  480 x 450 x 320 mm
 weight  12 kg
 material  1.4301


* Variants
** max. measuring path length depends on the sample gas temperature.
Subject to technical modifications!