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Helical Rotor Positive Displacement Meter

Two highly accurate cycloid-shaped screw spindles mesh and rotate inside a cylindrical housing with two overlapping holes in the form of a figure 8, which forms the measuring chamber. Liquid flows in axial direction and rotates the spindles; it is forced along the measuring chamber bores by the profile of the spindles. This occurs without pulsation and with minimum leakage. An inductive pickoff will detect the speed of the spindle pair through the housing via a pole wheel with a high number of gears. The speed of the spindles is directly proportional to the volumetric flow rate over a very wide range. This sensor will output a highly accurate pulse train or an analog 4-20 mA signal when used in conjunction with the ALVTM local display unit. All units come factory calibrated under conditions that match the end user's operating viscosity as closely as possible in order to determine the optimal K-factor (pulses per unit volume).

Process Connections ¼"-1½" FNPT
Operating pressure 5800 psig (400 bar) max.
Process temperature up to 300°F (150°C); higher upon request
Flow rates 0.002 to 105 GPM (0.01 to 400 LPM)
Viscosities 30 up to 1,000,000 cSt (below 30 cSt with restricted measuring range and vertical mounting)
Material SS DIN 1.4571/1.4435 (SS316 Ti/316L)
Linearity ±0.50% of actual flow value (from 30 mm²/s up)±0.25% of actual flow value (from 100 mm²/s up)
Weight Flowmeters : 0.5 to 77 lbs (2.5 to 35 kg)Electronics : 0.5 to 5.5 lbs (0.25 kg to 2.5 kg)
Supply Voltage VB (blind pulse amplifier) +8.5 up to 29 VDC, regulated; < 5 mA current draw
Frequency Range (blind pulse amplifier) 2 up to 4,000 Hz
Repeatability ±0.10%
Max. process temperature (blind pulse amplifier) 250 °F with a distance of at least 1" between flowmeter and electronic housing; 300 °F w/ at least 2½"
Integral LCD display option 8 digits (14 segments), digit height ¼" (7mm) for real-time value, totals and programmable
Supply Voltage (LCD display option) 14-30 VDC controlled,VB = (Rload x 20 mA) + 14 V
Analog output (LCD display option) 2-wire (4-20mA); 12 bit (3.9 µA) resolution
Frequency output (LCD display option) fmax: 3,000 Hz, duty cycle: approx. 1:1,
Process temperature (LCD display option) -40~ 248 °F (-40~120 °C) w/ a distance of ≥ ½" (15 mm) between flowmeter and electronics
Ambient temperature (LCD display option) -40 up to 158 °F (-40 up to 70 °C)
Housing IP 65, aluminum AlMgSiPb, blue anodized
Ex-protection II 2 G Eex ia IIC T4, BVS 03 ATEX E 205
Related Files:
  • High accuracy and wide turndown ratios; up to 400:1
  • Suitable for pressures up to 5800 psig (400 bar)
  • Low pressure drop compared with other positive displacement meters
  • Double pulse rate and reverse-flow detection possible
  • Pulsation-free measurement, readings unaffeted by pulsating flows
  • High quality materials and bearings provide superior corrosion resistance
  • Low operating noise
  • Ex-protection EExiaIICT6 for zone 1

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