DANIEL 700 User Manual page 8

MODEL 700 CONTROL VALVE
Introduction
November 2020
The Daniel Model 700 Control Valves have the following characteristics:
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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
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
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.
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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
45° body design assures high capacity
Positive shut-off
Uniform speed-of-response
Linear control
O-ring plus metal-to-metal seat
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.
1-1. The term balanced piston means that the exposed area on the spring side (P3)
illustrates the closed valve. Y-port (P3) to Z-port (P2) is closed. X-port (P1) and
User manual
P/N 3-9008-553
Daniel Series 700 Control Valve