Data Sheet

Pilot-Operated Regulators
Pilot-Operated regulators are preferred for high flow rates
or where precise pressure control is required. A popular
type of pilot-operated system uses two-path control.
In two-path control, the main valve diaphragm responds
quickly to downstream pressure changes, causing an
immediate correction in the main valve plug position.
At the same time, the pilot diaphragm diverts some of the
reduced inlet pressure to the other side of the main valve
diaphragm to control the final positioning of the main
valve plug. Two-path control results in fast response and
accurate control.
Pressure Reducing Regulator Selection
The majority of applications require a pressure reducing
regulator. Assuming the application calls for a pressure
reducing regulator. The following parameters must
be determined:
• Outlet pressure to be controlled
• Inlet pressure to the regulator
• Capacity required
• Shut-off capability required
• Process fluid
• Process fluid temperature
• Accuracy required
• Pipe size required
• End connection style
• Material requirements
• Control line needed
• Overpressure protection
Regulators are self-contained, control devices which use
energy from the controlled system to operate whereas
control valves require external power sources, transmitting
instruments, and control instruments.
Pressure Reducing Regulators
A pressure reducing regulator maintains a desired outlet
pressure while providing the required fluid flow to satisfy
a downstream demand. The pressure which the regulator
maintains is the outlet pressure setting (setpoint) of
the regulator.
Pressure Reducing Regulator Type
The two main types of regulators:
1. Direct-Operated
2. Pilot-Operated
4
Direct-Operated
Pilot-Operated
Pressure Reducing Regulators
Figure 1. Direct-Operated Regulator
SPRING
DIAPHRAGM
VALVE
Figure 2. Pilot-Operated Regulator
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
LOADING PRESSURE
MAIN
REGULATOR
PILOT
REGULATOR
Direct-Operated Regulators
Direct-Operated regulators are the simplest style of the
regulators. At low set pressures, typically below 1 psig /
0.07 bar, they can have very accurate (±1%) control. At
high control pressures, up to 500 psig / 34.5 bar, 10% to
20% control is typical.
In operation, a direct-operated, pressure reducing
regulator senses the downstream pressure through either
internal pressure registration or external control line. This
downstream pressure opposes a spring which moves the
diaphragm and valve plug to change the size of the flow
path through the regulator.
Direct-operated regulators have many commercial and
residential uses. Typical applications include industrial,
commercial, and domestic gas service or instrument air.
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE