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The Agar System 2 provides automatic monitoring and indication of accumulated hydrocarbon in API skimmer systems. When used in conjunction with mechanical or pneumatic actuators, the system provides complete automatic control of the oil recovery process. When utilized in manually controlled systems, it provides visual feedback for skimmer operation.


The use of any control system can be evaluated by the improvement in the operation of the controlled process and the economic benefits derived. The benefits derived from the Agar System 2 in Oil Skimmer Applications can best be summarized as follows:

1. Elimination of Waste Water Recycling

Recovered hydrocarbon is generally routed to recovered oil or “slop” tankage. There, the hydrocarbon is allowed residence time for further separation (dehydration) before reprocessing. The free water from this separation is commonly returned to intermediate storage via slop tank dewatering. When free water is recovered at the API skimmer, a cycle is established with the same water incrementally recovered and processed over and over again. This increases the load on the waste water system, requiring more work to manage the recovered oil tankage. The System 2 breaks this cycle by stopping free water recovery at the oil skimmer.

2. Higher Quality Recovered Hydrocarbon

Adjustable relay control points allow control of the water content of the recovered fluid and can significantly reduce the potential for free water recovery at the skimmer. The elimination of free water drastically reduces the total oil volume recovered, (manuallyoperated systems commonly recover more than fifty times more water than oil). The reduced free water volume allows for a longer retention time in slop oil tankage producing a much “drier” hydrocarbon for reprocessing.

3. Decreased Chemical Usage

The amount of chemical demulsifiers used to enhance slop oil dehydration is determined by the volume of fluid transferred to the slop tanks. Reducing the total fluid recovered (by eliminating free water) will proportionally decrease consumed chemicals.

4. Improved Wastewater Quality

The System 2 ensures that free-phase floating hydrocarbon cannot escape with the water phase. This reduces the oil load on downstream "polishing" systems (e.g., IAF and DAF). The result is a higher quality effluent with lower operating costs.


The Agar System 2 offers complete control flexibility in two ways:

  • The position of the sensing element (point of measurement) of each ID-201 can be adjusted to read at any level below the skimmer.
  • The relay set point of each ID-201 can be adjusted to trip at any point in the 0-100% range. This allows flexibility in determining the amount of water and oil that will activate the relay.

In manual mode (indicating lights only), the use of the Agar System 2 allows the operator to properly determine the control of the skimmer. The operator can then prevent the recovery of free water and control the water content of the recovered hydrocarbon.

At the same time, the system controls the volume (depth) of hydrocarbon allowed to accumulate so the effluent water is not contaminated. In automatic operation, the same control benefits are realized without operator intervention.

System 2 Logic Table
ID-201 Probes Pipe Lights
High Low Action Oil Yellow Water Blue Alarm Red
Water Water Open Off On Off
Oil Water Open Off On Off
Oil Oil Closed On Off Off
Oil Water Closed On Off Off
Water Water Open Off On Off
Water Oil Closed Off Off On


The AGAR System 2 is a simple and cost-effective means to improve the efficiency of hydrocarbon recovery from the API separator. By providing a way to monitor water content of oil/water emulsion below the surface, the system controls the volume and % water of the skimmed oil. The benefits of this more sophisticated control are economically significant reducing the total volume and water content of the recovered emulsions.