To change the full scale blind setting on the transmitter, you must use the magnetic pushbuttons on the transmitter (Figure 5).
Figure 5. Magnetic pushbuttons.
First use pushbutton M to cause Mode 6 to show in the display window. Then use the other two pushbuttons to set the numerical value for the full scale blind setting.
Remember, the only configuration parameter that you can use to reset specific gravity is the full scale “blind setting” or Mode 6. Do not change any other parameter!
DISPLAY LEVELS VS. GALLONS
As already noted the transmitter displays levels in inches. You may need to know how many gallons of material that various levels represent.
Some error is unavoidable when measuring levels and converting them to gallons of asphalt stored in the tank. Such determinations are not reliable substitutes for metering and calibration equipment.
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It is important to note that pressure transmitters on Heatec tanks are now set up to display the height of the asphalt above the inside bottom of the tank. In the past the transmitters were set up to display the height of the asphalt above the location of the transmitter sensor.
You should not change the position of the transmitter or the location of its sensor. Doing that would cause all indications to be wrong.
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The sensor of the transmitter is installed 11 inches above the bottom of the tank. (This distance may vary plus or minus 1/4-inch.) Consequently, the transmitter displays 11 inches when the asphalt level is at the same height as the sensor. And when the asphalt level is 11 inches there are approximately 647 gallons of material in the tank.
But note that the transmitter does not actually indicate asphalt levels lower than 11 inches, even though the display shows 11.00. So remember, any time the transmitter display shows 11.00, the amount of asphalt in the tank is somewhere between 0 and 647 gallons.
Figure 6. Controller used to indicate levels.
The table shown in Figure 9 enables you to convert levels to gallons. The column labeled “inches” refers to the numbers that are displayed on the transmitter (Figure 3) and on the level controller (Figure 6).
FILLING THE TANK
The pressure transmitter works in conjunction with the controller (Figure 6) to automatically shut off the unloading pump when the material in the tank reaches a level approximately 24 inches from the inside top of the tank.
The tank is also equipped with a high level float switch. It functions as a backup system for the shutoff provided by the pressure transmitter. It will shut off the unloading pump at a level of approximately 7 inches from the inside top in case the pressure transmitter fails to shutoff the unloading pump.
Only two settings can be reset in the field. One is the Full Scale Blind setting, which should be set according to the specific gravity of the material as explained earlier.
The other is the zero setting. This setting corrects for transmitter tilt. The transmitter is installed at Heatec with the display facing straight ahead with no tilt. If the transmitter is installed with the display facing up, the zero setting should be reset according to instructions in the Siemens manual under the heading 6.2.5 Zero Adjustment (Position Correction). We do not recommend installing the transmitter with the display facing up.
