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CONTROL VALVES 762, 763, 765, 766 AND 767
Volume displacement (Main valve piston)
6"
66
15"
1,207
Example:
(12" valve, set point 640 psi and over-pressure is 40 psi)
Solving V
1
Equation 5-2:
1
=
576.74779
0.041061
= 14, 046.12
3
1
=
14, 046.121
231
= 60.80 . . 𝀵𝀵𝀵𝀵 𝀵 𝀵𝀵 𝀵 𝀵𝀵𝀵𝀵𝀵
Note
Valve is fitted with light piston spring which provides:
•
4 psi Preload with valve close
•
6 psi Preload with valve open
This 4 and 6 psi Preload must be subtracted from P
1
& P
2
, respectively, to arrive at actual gas
pressure.
Conditions assume adiabatic compression.
5.9
Nitrogen system panel
A nitrogen control panel may be advantageous if there are large variations in ambient
temperature or if it is not practical to bury the nitrogen plenum underground.
The control panel can be used to provide a precise output which is used to regulate the set
point of the gas loaded relief valve.
The Nitrogen Supply Cylinders shown in Figure 5-2 are used as a source of the nitrogen and
the control panel will use this to replenish the nitrogen pressure within the valve anytime it
falls below the desire set point. Conversely if the set point at the valve is higher than the
desired set point, the control panel will relieve the excess pressure from the valve.
Since the Daniel valve does not consume nitrogen, unlike competitive valves, the need to
adjust nitrogen is normally due to changes in pressure due to ambient temperatures.
The nitrogen set point pressure is measured using a pressure transmitter, which can be
transmitted to a remote control room. The system nitrogen set point is field adjustable by
authorized personnel. A complete
Daniel
control valve system can be furnished that will
include the surge relief valve, inlet/outlet piping, nitrogen control panel, supply cylinders
and the plenum. The system is carefully designed, engineered and assembled onto a
structural skid with a lifting facility (as shown below in Figure 5-2 ).
Installation prerequisites
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Daniel Models 762, 763, 765, 766 and 767 Control Valves