Any process which involves chemistry that puts something into solution (i.e. dissolving, etching) or takes something out of solution (i.e. plating, precipitating), dilutes or concentrates a solution can benefit from precision specific gravity control. When solution density deviates from the desired set point a replenishment pump FEEDS a suitable replenisher and the excess spent solution BLEEDS into a collection tank.
FEED
AND FEED controllers are available as an option for processes which
reduce
solution volume by loss mechanisms such as evaporation or drag out. A
second
relay is added to the Power Module to control a solution FEED pump
which
maintains solution level. The other relay continues to control solution
replenishment FEED to maintain steady state constant specific gravity.
The figure at left shows the Level Sensor Assembly used with a feed and feed system. The unit conveniently hangs on the inside of the solution drum or tank. When the bottom sensor detects low solution level it activates the solution feed pump. The upper sensor detects overfill and shuts down all pumps should the solution level get too high. On the standard unit shown the upper level sensor is set at 5 inches and the lower level sensor is 11 inches down from the tank rim. These are convenient dimensions for the standard 5 gallon bucket. Other sensor depths are available by special order.
The Level Sensor Assembly is weighted at the bottom to keep it down in the solution. The attached cable is 12 feet long with a sealed plug on the end to attach to the Power Module. The 3/8 inch tube down the side is for the solution control pump pickup.
Level Sensor Assembly for feed and feed process: $116.
Controls are available for use in different chemical environments - one version for corrosive alkaline solutions, another for corrosive acidic solutions. Each control's materials have been optimized to resist the harmful effects of that particular chemical solution. These controls are capable of operating with solution specific gravity from 1.0 to 1.4 since the hydrometer float is adjustable. Specific gravity control points beyond the standard 1.0 to 1.4 range can be special ordered at no extra charge. Furthermore, the adjustable control point provides flexibility for smaller changes. With the control properly calibrated the specified performance will be achieved.
The system diagram below shows a typical FEED AND FEED specific gravity control system.
