Operation Manual

6-3
IM 1F5B2-01E
6. PREPARING FOR OPERATION
6.2 Pressure Loss and Cavitation
When changing the range, ALWAYS make sure the line’s back pressure level will not
lead to adverse effects due to pressure loss or cause cavitation.
■ Pressure Loss
• The pressure loss is calculated by
∆P=108 × 10
-5
× ρf • υ
2
........................ (1)
or
∆P=135 × ρf •
Qf
2
D
4
..................................... (2)
where
∆P = pressure loss (kPa)
Qf = volumetric flow rate under operating conditions (m
3
/h)
D = inner diameter of ULTRA YEWFLO (mm)
υ = flow velocity (m/s)
ρf = density under operating conditions (kg/m
3
)
■ Cavitation (Minimum Back Pressure of the Line)
IMPORTANT
Cavitation may occur in fluid measurements if the line pressure is too low and the flow
velocity is too high, resulting in failure to measure the correct flow rate. Before
measurement, ALWAYS make sure the line’s back pressure level will not cause
cavitation.
No cavitation occurs if the minimum back pressure of the line at the maximum flowrate
is sufficiently low compared with the actual line pressure.
• The minimum line pressure is calculated by
P=3.8 × ∆P + 1.3 × Po ......................... (3)
where
P = line pressure at a point two to seven times the nominal
diameter downstream from the ULTRA YEWFLO (kPa
abs)
∆P = pressure loss (kPa)
Po = liquid’s saturation vapor pressure under operating
conditions (kPa abs)
6.3 Zero Adjustment
No zero adjustment is necessary since the zero point does not shift.
6.4 Resetting totalized Value
•On the Brain Terminal (BT200), choose EXECUTE from the menu in parameter E10
(TOTAL RESET).
•Or, press the RESET switch located on the indicator/totalizer component.