The Delta Controls Model 710A provides output switching at two points based on a varying liquid level. The unit is located on top of the vessel with the primary element extending down into the vessel. The float rides on the surface of the liquid and is carried up and down as the liquid level varies. The attractor is coupled to the float by the float rod and also moves up and down as the level varies. The attractor is located inside of the barrier tube and is in contact with the process fluid. The switching stations are located on the outside of the tube and are isolated from the process fluid. Each station contains a magnet which is magnetically attracted to magnetic materials such as the attractor. The attractor is lifted into the magnetic field of the bottom switch station. The magnet is pulled in against the barrier tube, an output switch is connected to the magnet and is actuated. Additional increases in the liquid level lift the attractor into the magnetic field of the top switch station and its output switch also actuates. Falling liquid level sequentially pulls the attractor out of the field of the switch station magnetic fields and each output switch deactuates. Separation between the two output switch actuation points is 2" - 3", depending on the actual SPG of the liquid.

INSTALLATION

The Delta Controls Model 710A should be mounted vertically on top of the vessel. The guide tube/float rod must be long enough so that the float centerline extends down approximately 2" below the point where switch action is desired. A baffle or stilling well is required if the fluid is agitated or has surface turbulence; otherwise, the switching action may be erratic. The switching points are fixed by the length of the float rod/guide tube. The process connection should be large enough to admit the float into the vessel. If not, then the float must be unscrewed from the float rod and installed from inside the vessel after the body/attractor assembly has been mounted on top of the vessel.

MODEL 710D - Single Point On/Off Adjustable Differential Control

The Delta Controls Model 710D provides switching action at two points, based on a varying liquid level. The unit is located on top of the vessel with the primary element extending down into the vessel. The float rides on the surface of the liquid and is carried up and down as the liquid level varies. The attractor is coupled to the float by the float rod and also moves up and down as the level varies. The attractor is located inside of the barrier tube and is in contact with the process fluid. The switching station is located on the outside of the barrier tube and is isolated from the process fluid. The station contains a magnet which is magnetically attracted to magnetic materials such as the attractor. The attractor is lifted up into the switch station magnetic field. The magnet is pulled in against the barrier tube by the attractor. The magnet is connected to an output switch which actuates as the magnet is pulled in against the tube. The attractor is "captured" and held up by the magnet. The output switch stays actuated until the liquid level falls enough to lower the top collar against the attractor and then to pull it out of the magnet field. The attractor then falls to the lower collar by gravity. The guide is always located just above the float. This improves reliability and helps to prevent rod bending, binding, and friction hang-ups. The differential may be increased (up to 2") by resetting the top collar to a higher position on the rod. The spacing between the top collar and the attractor is the increased amount of liquid level change required to deactuate the switch station.

INSTALLATION

The Delta Control Model 710D should be mounted vertically on top of the vessel. The guide tube/float rod must be long enough so that the float centerline extends down approximately 2" below the point where switch action is desired. A baffle or stilling well is required if the fluid is agitated or has surface turbulence; otherwise, the switching action may be erratic. The switching point is fixed by the length of the float rod/guide tube. The process connection should be large enough to admit the float into the vessel. If not, then the float must be unscrewed from the float rod and installed from inside the vessel after the body/attractor assembly has been mounted on top of the vessel.