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MODEL 700 CONTROL VALVE
The Daniel Model 700 Control Valves have the following characteristics:
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Modular construction: All internal parts including seat ring can be removed with the
cylinder assembly without disturbing line connections.
•
No diaphragms or stuffing boxes
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45° body design assures high capacity
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Positive shut-off
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Uniform speed-of-response
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Linear control
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O-ring plus metal-to-metal seat
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Pilots and other optional accessories enable the valve to perform a variety of control
functions such as back pressure control, regulating rate-of-flow, pressure relief, surge
control, etc.
1.6.2
Control valve applications
This is the starting point for unlimited control applications. The basic valve needs to
incorporate a pilot control loop, which is mandatory for it to function, see
Daniel Liquid
Control Valves Technical Guide (P/N DAN-LIQ-TG-44)
for specific applications.
1.6.3
Operation overview of the control valve
The basic valve operates on a balanced piston principle, spring biased (loaded). Refer to
Figure 1-1
. The term balanced piston means that the exposed area on the spring side (P3)
of the piston and the bottom side (P1) are equal in area. The spring is the differential force
that closes the piston when (P1) and (P3) pressures are equal.
To open the valve, the pressure against the bottom of the piston (P1) must exceed the
pressure on the spring side of the piston (P3) plus spring force.
Closed position
Figure 1-1
illustrates the closed valve. Y-port (P3) to Z-port (P2) is closed. X-port (P1) and
Y-port (P3) pressures are balanced. The differential force created by the main valve spring,
closes the piston and keeps it seated.
Therefore, total pressure equals 40 psi @ (P1) and 45 psi @ (P3) or (P3 minus P1) - 5 psid.
The needle valve/strainer controls the speed of the closure by controlling the flow through
the X-port.
Introduction
User manual
November 2020
P/N 3-9008-553
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Daniel Series 700 Control Valve