Hydrometer Analysis (lab testing)

 

HYDROMETER table (none are Modifiable):

Field Name

Lookup

Description

PointID

 

 

Depth

 

 

Wt_Dry_Specimen

 

Grams

Percent_Of_Total

 

Percent of the total specimen that is represented by the hydrometer test specimen, e.g., if hydrometer specimen split on #40 sieve, this field contains the % passing the #40 sieve.

Specific_Gravity

 

 

Temperature_Units_Test

Lookup!

lab temp units

 

HydrometerID

Libtbl!

Hydrometer calibrations

 

Type

Lookup!

lab hydrometer type

Can be input manually or program will read it from the HYDROMETER CALIBRATIONS table using the HydrometerID field. New calibrations can be input in Data Design►Library Data.

Temperature_Units_Calibration

Lookup!

lab temp units

Can be input manually or program will read it from the HYDROMETER CALIBRATIONS table using the HydrometerID field. New calibrations can be input in Data Design►Library Data.

Calibration_Intercept

 

Can be input manually or program will read it from the HYDROMETER CALIBRATIONS table using the HydrometerID field. New calibrations can be input in Data Design►Library Data.

Calibration_Slope

 

Can be input manually or program will read it from the HYDROMETER CALIBRATIONS table using the HydrometerID field. New calibrations can be input in Data Design►Library Data.

Calibration_2ndOrderTerm

 

Can be input manually or program will read it from the HYDROMETER CALIBRATIONS table using the HydrometerID field. New calibrations can be input in Data Design►Library Data.

 

HYD READINGS table (none are Modifiable or have an associated Lookup):

Field Name

Description

PointID

 

Depth

 

Reading

Arbitrary counter.

Time

Minutes

Hydrometer_Reading

For hydrometer type 151H, this is the digits after "1.0", e.g., input 1.013 as 13, 1.0135 as 13.5.

Temperature

Blank fields will take the values of the reading above it.

Particle_Size

 

Percent_Finer

 

 

If only final results are to be input, all of the parent record information (except Depth) can be left blank.

 

To perform calculations, you must supply the following:

  1. The Weight of Dry Specimen (Wt_Dry_Specimen) is the net (just soil; no tare) weight in grams of the specimen that was actually used in the test.

  2. The total specimen percentage that is represented by the hydrometer test specimen (Percent_Of_Total), for example, if hydrometer specimen split on #40 sieve, this field contains the % passing the #40 sieve.

  3. The Specific_Gravity is that of the hydrometer specimen and is not necessarily the same as the specific gravity given in the LAB SPECIMEN or FINE SG tables.

  4. The temperature units used in the test (Temperature_Units_Test). This may or may not be the same as the calibration units (see below).

  5. The composite correction (see ASTM D422) is applied to the readings calculations. Each hydrometer/dispersing agent combination has its own correction versus temperature characteristics. You define each in Data Design►Library Data under the HYDROMETER CALIBRATIONS table. Each hydrometer is identified with a unique name. The list of defined hydrometers from the HYDROMETER CALIBRATIONS table appears in the drop-down list when on the HydrometerID field.

On supplying a HydrometerID and saving, the program will copy the calibration parameters from the HYDROMETER CALIBRATIONS table to the corresponding fields in the parent record if you leave all four of the required calibration fields empty.

The HydrometerID is not required. You could input the parameters manually.

However, if you supply values in some but not all four of the required fields, the program will use the stored values for the empty fields if a stored hydrometer identification is given.

If you do supply all four fields and a hydrometer identification, and if they do not match what is in the calibration Library Table, the program will indicate the differences and allow you to use the stored values or the manually input values.

In the readings table, supply the time in minutes, the temperature in the specified testing temperature units, and the hydrometer reading. The particle diameter (mm) and percent finer will be calculated. Note that only the first temperature is required. If a temperature field is blank, the value from the record above is used.

Note:

The hydrometer calibrations may have a 0 value for the intercept. The reason for this is that some clients enter corrected hydrometer readings, therefore, there is no calibration correction necessary. In this case, the hydrometer calibration intercept would be 0 and the slope would also be 0.