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SMS2000 - Soap and Liquor Interface System




As you are well aware, Kraft soap can be a valuable by-product to the modern mill’s bottom line but it can also be an expensive and aggravating nuisance to the operating people that need to manage it.  After working in the Electrical & Instrumentation field for over 16 years in the pulp and paper industry I have taken this experience to be the original designer of a soap and liquor interface level system.  Based on the first original design I have greatly improved the system to provide a second generation system.


RTS Installations is pleased to present to you the SMS 2000 – a revolutionary instrument package that allows the accurate measurement of the soap/liquor interface as well as the height of the soap head on a continuous basis. This information can then be displayed in the control room to allow operators to track exactly how much liquor as well as soap is present in the weak liquor storage, heavy liquor storage, soap storage etc. These level inputs can be “alarmed” to give early warning of impending problems such as pulling soap into the suction of weak liquor evaporator feed pumps, or the over – flow of soap from a liquor storage.




The liquid interface measurement is detected by the use of a transmitter, flexible/rigid stainless steel sensor hose and interface float.  The end of the sensor hose is supported by a weighted anchor or stop plate at the opposite end.  Traveling up and down the sensor hose is a specially engineered float that follows the two liquids particular interface.  As the float position changes along the sensor hose it closes very small reed contacts within its magnetic field through the wall of the flexible sensor hose. The closed reed switches provide an uninterrupted measurement voltage from a resistance chain (a potential divider) to the transmitter and this voltage is proportional to the liquid interface level.  This variable voltage is then converted into a standard 4-20mA analog level signal.  The interface float has the ability to be accurately adjusted to provide the needed buoyancy, based on calculations and the customer’s process data.  Depending on the process application the float size and shape will change. 

The SMS2000 interface system is modular in design, offering you a selection of electronic housing styles, float sizes/shapes and sensor hose styles.  The interface system features a removable sensing element and electronics that can be removed without disturbing the operation of your process saving time and money. 

Up to two 4-20mA loops are available for analog indication of interface and temperature.  Set-up, calibration and diagnostics are available from any point on the loop using a standard HART hand-held terminal.


The trend below is a great example of how differential pressure transmitters are very ineffective in measusuring liquor levels within a tank.  As you can see as the soap surface(red) increases the true liquor level is decreased(blue).  Ultimately the red and blue trends cancel each other out.  By having a proper interface level witin the tank the operators are able to see what is really happening to the tank liquor levels.




Three dimensional view of the SMS2000 installed into a tank. 

Another view of SMS2000 interface installed into a tank. 

View of SMS2000 interface float and suspended anchor being lowered into a tank roof top opening.  System can be installed while tank is in operation.

View of interface transmitter(on left) and radar gauge (on right).  Both can be installed on the same manway lid opening.

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