Model 711A

SKU: 711A

Float Switch, Top Inserted, Two Point, Wide Separation

Operation: A float is carried up and down by variations in liquid level or interface position.

Uses: Provide high and / or low level alarm, pump control, etc.

Insertion: Up to 10 feet below the flange face

Switch Action: From 1 to 4 points of alarm and/or differential; up to 60″ differential available with Type 711

Specific Gravity: From 0.35 to 2.40 SGU

Temperature: From –150 to 750°F (-100 to +400° C)

Pressure: From –15 to 1200 PSIG (-1 to +80 BAR)

Process Connection: 1″ to 4″ NPT threaded; 1″ to 12″ flanged, up to 900# rating; ASA, DIN or JIS equivalents


Model 711A Product Diagram - Delta Controls Corporation

The Delta Controls Model 711 provides switching action at field selected liquid level elevations. The switch stations are isolated from the process liquid by the barrier tube. The output of the control consists of two alarm switching actions as the liquid level varies. Two switch stations are operated. Switching action occurs as the float carries the attractor in front of each switching station magnet. The barrier tube isolates the switch stations from the process liquid.


The Delta Controls Model 711A should be mounted on top of the process vessel containing the liquid level to be detected. It should be located with the float and rod down into the vessel so that the desired switching points are located between the upper and lower maximum collar positions on the stroke rod. Use the collar clamp screws to position the setpoint collars to the desired liquid level switching points.

Setpoint Collar Adjustment

The setpoint collars are locked in place by a socket head setscrew. The collars my be repositioned as desired to achieve switching action at various liquid elevations. Do not position the upper collar so high that the collar strikes the guide. No additional float or stroke rod movement can occur after the fluid level lifts the collar up against the lower guide. SUPPORT SPRING The spring supports the weight of the attractor/stroke rod assembly in the middle of its stroke, which is the neutral position. The position of the spring collar is adjusted so that the attractor is positioned in the center of its travel when the float is floating on the liquid surface, is being supported by the liquid, and is not in contact with either setpoint collar.

Sliding Float

The float has a hollow tube through its centerline. The tube is generously larger than the stroke rod which passes through the tube and maintains the floats horizontal position. The float is normally supported by the liquid and moves up and down on the stroke rod as the liquid level varies. An upper and lower setpoint collar are positioned on the stroke rod. The float pushes against one of the collars when the fluid level rises (or falls) to one of the setpoint collar elevations. The force produced by the float moves the stroke rod and positions the attractor in front of a switch station magnet. The magnet is attracted and that output signal switch is operated.

Alarm Action

Two independent switch stations are mounted on the sealing tube. On/Off switch action with minimum liquid level change occurs as the float contacts the upper and lower collars.

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