Nova-Tech RITEFLOW FLOWMETERS AND KITS - Manual (Page 4)

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BEL-ART RITEFLOW ® FLOWMETERS
Bel-Art Flowmeters feature precision formed glass flowtubes and are available in three formats:
Plain Ends which is a glass flowtube with floats and Teflon
® end plugs; Guarded, which has a plastic
safety guard over the flowtube; and Mounted, which has an anodized aluminum frame to hold the
flowtube and facilitate mounting the unit on an instrument panel or use with a base, free-standing
on a lab bench.
PRINCIPLE OF OPERATION
Bel-Art Flowmeters are fabricated from heavy walled, shock resistant, borosilicate glass with per-
manently fused ceramic scales. Bores are uniformly tapered with internal rib guides. Floats are
retained by Teflon
® plugs. Useful metering ratios are 10:1 or better. Ratio can be increased to
20:1 by replacing the glass float with stainless steel float or Carboloy (heavy gauge steel) for size
5 (150mm), size 6 (65mm).
Flowmeters must be installed in a vertical position in the line carrying the gas or liquid to be
measured. Gas or liquid enters through the opening at the bottom end, and exits through the
opening at the top end. Upward pressure causes the float to rise. Flow takes place through the
circular area between the float and the inside surface of the Flowmeter. As the float rises, the
flow area increases, due to the tapered bore of the Flowmeter. Dynamic equilibrium results when
the upward force, due to the air or liquid pressure, balances the weight of the float.
The vertical position of the float at equilibrium corresponds exclusively to one flow rate.
This flowrate is obtained by reading the scale etched on the flowtube calibration chart for the
particular fluid.
Flow rates are determined by reading the scale graduation at the center of the spherical float. To
increase the accuracy and reproduction of the metering a vertical locator line is incorporated into
the geometry of the scale graduation.