Emerson Daniel 788DVC, User Manual

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8 Operation parameters
8.1 Control valve normal operation
The most common application of the Daniel Model 788DVC Digital Control Valve is for
truck loading of petroleum products. The valve may be used with a variety of flow meter
types, including Daniel series 1200 Turbine Meters and Coriolis.
Table 8-1: Typical opening/closing speed
Line
size
inches Typical
dead
time
setting
(secon
ds) Recommended low flow set-point Typical
openin
g speed
adjust
ment
(turns
open) Typical
openin
g time
(shut-
off to
full
open)
second
s Typical
closing
speed
adjust
ment
(turns
open) Typical
closing
time
(full
open to
shut-
off)
second
s
Turbine PD meter
gpm K-
factor gpm K-
factor
2-3 0.015 100 50 100 100 0.25 5.0 0.75 2.0
4 0.015 150 25 150 25 0.25 5.0 0.75 2.0
6 0.030 150 25 150 25 0.75 5.0 1.25 2.0
8 0.030 150 25 150 25 0.75 5.0 1.25 2.0
8.2 Operation accessories
• Opening speed control: Device installed in the Y port of the valve to control opening
speed
• Thermal relief: It is the pressure differential safety device use to eliminate excessive
pressures caused by thermal expansion.
• Block or isolation valve for X, Y, Z ports
• Manual override: Device used to by-pass the pilot module
• Valve position indicator
• Limit switches: The sequential switches convert the mechanical motion of the batch
controlling mechanism of the preset counter to electrical signals used to control the
solenoid pilots of the control valve for low flow position-shut down and/or start-up.
It is recommended to ensure that both the line and the product are clean before the valve
is installed. Small particles of foreign material usually will not effect the performance of
the valve, although larger particles may damage the valve piston and its seat.
8.3 Operation overview
Operation of the Model 788DVC Digital Control Valve is based on a balanced piston
principle.
User manual Operation parameters
P/N 3-9008-556 October 2019
User manual 71