Tec-Note 10-06-180: Setting Siemens Pressure Transmitter used on Heatec vertical asphalt tanks (page 2)

Tec-Note 10-06-180: Setting Siemens Pressure Transmitter used on Heatec vertical asphalt tanks (page 2)

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Pages: 1, 2, 3, 4, 5, 6, 7

FACTORY SETTINGS
The transmitter is normally set at Heatec before the tank is shipped. It is set to display the level of the liquid material in the tank in inches (Figure 3). This setting cannot be changed in the field by plant personnel.

Siemens pressure transmitter used on Heatec vertical asphalt tanks
Figure 3. Display on transmitter.

Heatec also sets the transmitter based on the specific gravity of the material that is to be stored in the tank. The customer provides this information and we use it to determine the proper setting. However, the transmitter can be reset in the field by plant personnel for a material with a different specific gravity.

NOTICE

You should check the transmitter to make sure it is set for the specific gravity of the material actually stored in the tank. If its specific gravity is either higher or lower than that set on the transmitter, the transmitter will not provide accurate level indications.

To determine the transmitter specific gravity setting, set the transmitter to Mode 6, which is the Full Scale Blind Setting. Read the numerical value shown. Now find that same value in Figure 4, where you can see the specific gravity for that value.

Remember, specific gravities vary with the type of asphalt. And the specific gravity of a particular type of asphalt varies with its temperature. So if you decide to store a different material, or if you change its storage temperature, you need to reset the transmitter as explained below.

If you don’t know the specific gravity of the material at the temperature you plan to store it, ask your supplier.

RESETTING THE TRANSMITTER
NOTE: You cannot directly enter the numerical value for specific gravity when resetting the transmitter. The setting you actually set on the transmitter is known as the Full scale blind setting, which you should obtain from Figure 4. It consists of a four digit number that includes one decimal point.

Figure 4. Specific Gravity vs Full Scale Blind Setting
Specific Gravity	Full Scale Blind Setting	Specific Gravity	Full Scale Blind Setting
1.140	671.5	1.015	597.8
1.135	668.5	1.010	594.9
1.130	665.6	1.005	591.9
1.125	662.6	1.000	589.0
1.120	659.7	0.995	586.1
1.115	656.7	0.990	583.1
1.110	653.8	0.985	580.2
1.105	650.8	0.980	577.2
1.100	647.9	0.975	574.3
1.095	645.0	0.970	571.3
1.090	642.0	0.965	568.4
1.085	639.1	0.960	565.4
1.080	636.1	0.955	562.5
1.075	633.2	0.950	559.6
1.070	630.2	0.945	556.6
1.065	627.3	0.940	553.7
1.060	624.3	0.935	550.7
1.055	621.4	0.930	547.8
1.050	618.5	0.925	544.8
1.045	615.5	0.920	541.9
1.040	612.6	0.915	538.9
1.035	609.6	0.910	536.0
1.030	606.7	0.905	533.0
1.025	603.7	0.900	530.1
1.020	600.8
The full scale blind setting is equal to a tank height of 600 inches minus the sensor height of 11 inches multiplied by the specific gravity of the asphalt.

Thus, to obtain a full scale blind setting for an asphalt with a known specific gravity, simply choose a specific gravity value shown in Figure 4 with a value closest to your known value. Then note the full scale blind setting shown alongside the specific gravity listed. Be sure the specific gravity you use is for the actual storage temperature of the asphalt and not its temperature at 60 degrees F.

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