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简单介绍：
Double-acting or single-acting service accommodates installation in a variety of environments
Field reversibility reduces downtime and simplifies maintenance
Choice of continuously adjustable standa
详情介绍：
Features & Benefits
Double-acting or single-acting service accommodates installation in a variety of environments
Field reversibility reduces downtime and simplifies maintenance
Choice of continuously adjustable standard stroke ranging from 1/4" to 48" and continuous span and zero adjustability
within range spring limits provide application versatility
Extra high capacity pilots ensure maximum frequency response and optimum stroking speeds for all actuator sizes
Negative feedback pilot circuit allows the positioner to operate with a push-pull gain of more than 900:1 (using 100 psig supply) with no sacrifice in stability (gain of 650:1 with 74S models)
Description
The Model Series 74 Valve Positioners are universal positioners that provide versatility, dynamic performance,
and high positioning accuracy. They use the piston or diaphragm in a pneumatic actuator to position a valve to
what is required by a control instrument and hold that position, regardless of the presence of forces that change
valve position. As such, supply pressure variations have little or no effect on the positioner output, which eliminates the
need for a supply pressure regulator.
These valve positioners are two-stage, pilot-operated instruments. The pilot circuit activates dual-output boost-
ers, which perform opposite actions (when one booster is supplying air, the other is exhausting air.) This “push-pull”
action applies to a full differential (supply pressure to atmosphere) across the actuator to drive the valve to the position required by the control instrument signal.
Model 74 Valve Positioners can also be used for single-acting service on a spring-loaded actuator. In this case, one
of the pilot-booster connections is plugged. See below for rotary-type actuators.
Specifications
Input Ranges：3-15, 3-9, 3-27, 0-15, and 0-30 psig including split ranges within these basic ranges
Valve-Stroke Ranges：1 1/4" minimum ； 48" maximum
Supply Pressure：3 psig above full actuator pressure minimum；150 psig maximum
Air Consumption：0.2 scfm (in balanced condition with 20 psig supply)
Overload Protection：150 psig at any connection
Response Level：Output is sensitive to control signal changes as small as 0.1% of full range
Ambient Temperature Range：-40 to 180°F (-40 to 82°C)
Materials of Construction：Aluminum, brass, stainless steel, and Buna-N
Rotary Actuators Kit
The Series 74 Rotary Actuator Kits allows for compact instal-lation of a complete assembly (positioner and mounting) to
fit inside a 5"x 5"x2-2/3" envelope. The kit’s direct connected feedback spring eliminates error-prone connections and
levers, while its spiral feedback spring provides inherent reliability.
Response Level：0.1% F.S.
Linearity：±1.5% F.S.
Input Range：3-9, 9-15 , 3-15 psig
Actuator Motion：90° Rotation
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Double-acting or single-acting service accommodates installation in a variety of environments
Field reversibility reduces downtime and simplifies maintenance
Choice of continuously adjustable standard stroke ranging from 1/4" to 48" and continuous span and zero adjustability
within range spring limits provide application versatility
Extra high capacity pilots ensure maximum frequency response and optimum stroking speeds for all actuator sizes
Negative feedback pilot circuit allows the positioner to operate with a push-pull gain of more than 900:1 (using 100 psig supply) with no sacrifice in stability (gain of 650:1 with 74S models)
Description
The Model Series 74 Valve Positioners are universal positioners that provide versatility, dynamic performance,
and high positioning accuracy. They use the piston or diaphragm in a pneumatic actuator to position a valve to
what is required by a control instrument and hold that position, regardless of the presence of forces that change
valve position. As such, supply pressure variations have little or no effect on the positioner output, which eliminates the
need for a supply pressure regulator.
These valve positioners are two-stage, pilot-operated instruments. The pilot circuit activates dual-output boost-
ers, which perform opposite actions (when one booster is supplying air, the other is exhausting air.) This “push-pull”
action applies to a full differential (supply pressure to atmosphere) across the actuator to drive the valve to the position required by the control instrument signal.
Model 74 Valve Positioners can also be used for single-acting service on a spring-loaded actuator. In this case, one
of the pilot-booster connections is plugged. See below for rotary-type actuators.
Specifications
Input Ranges：3-15, 3-9, 3-27, 0-15, and 0-30 psig including split ranges within these basic ranges
Valve-Stroke Ranges：1 1/4" minimum ； 48" maximum
Supply Pressure：3 psig above full actuator pressure minimum；150 psig maximum
Air Consumption：0.2 scfm (in balanced condition with 20 psig supply)
Overload Protection：150 psig at any connection
Response Level：Output is sensitive to control signal changes as small as 0.1% of full range
Ambient Temperature Range：-40 to 180°F (-40 to 82°C)
Materials of Construction：Aluminum, brass, stainless steel, and Buna-N
Rotary Actuators Kit
The Series 74 Rotary Actuator Kits allows for compact instal-lation of a complete assembly (positioner and mounting) to
fit inside a 5"x 5"x2-2/3" envelope. The kit’s direct connected feedback spring eliminates error-prone connections and
levers, while its spiral feedback spring provides inherent reliability.
Response Level：0.1% F.S.
Linearity：±1.5% F.S.
Input Range：3-9, 9-15 , 3-15 psig
Actuator Motion：90° Rotation
