www.perthscientific.com.au

Perth Scientific Pty Ltd is a Western Australian company with over 35 years experience in the scientific field. We are renowned

for our quality service and specially trained staff.

Perth Scientific Pty LtdUnit 2 / 11 Narloo StreetMalaga WA 6090

PH: 08 6240 5600Email: sales@perthscientific.com.au

Salinity, Conductivity and Total Dissolved Solids

CONDUCTIVITY TABLE FOR WATER

Absolute Water 0.055 uS/cm

Distilled Water 0.5 uS/cm

Spring Water 1.9 uS/cm

Domestic Water 500 - 800 uS/cm

Brackish Water 5 mS/cm

Sea Water 53 mS/cm

CONDUCTIVITY CONVERSIONS

mS/cm uS/cm mS/cm TDS/ppm

1 1,000 100 500

20 20,000 2000 10,000

200 200,000 20,000 100,000

1000 ppm = 1 ppt = 77 grains per gallon

Salinity is an important measure of industrial and natural waters and is the measure of the mass of dissolved solids in a given mass of water. The direct method to do this is time consuming and

cannot yield the precision for accurate work. Therefore to determine salinity practicably, indirect measurements such as conductivity is used.

Conductivity is a numerical expression of the ability of a substance to carry an electric current and is determined by the motion of the ions in solution. As temperature greatly affects molecular motion, it is necessary to consider temperature when accurate measurements are needed. Normally, for comparative measurements, the standard temperature is 20oC or 25oC. To correct for the effect of temperature, a compensation factor is used and expressed in % per degrees C and it varies accordingly to the solution being measured. In most applications, a value of 2% per degree C is used. The unit of measurement commonly used for Conductivity is the Siemens /cm (S/cm). Conductivity is measured in water with relatively low levels of dissolved ions and is expressed in terms of micro-Siemens/cm (μS/cm).

Total Dissolved Solids is the term applied to that portion of fluid which passes through a filter and the residue left behind after evaporation of the sample is the Total Dissolve Solids. Conductivity measured in water with relatively high levels of dissolved ions is expressed in terms of milli-Siemens/cm. In aqueous (water) solutions, conductivity is directly proportional to the concentration of dissolved solids, therefore the higher the concentration of solids, the greater the conductivity. The relationship between conductivity and dissolved solids is given approximately by: 2 μS/cm = 1ppm where: 1 ppm = 1mg/L and is the measuring unit for dissolved solids.

www.perthscientific.com.au

Perth Scientific Pty Ltd is a Western Australian company with over 35 years experience in the scientific field. We are renowned

for our quality service and specially trained staff.

Perth Scientific Pty LtdUnit 2 / 11 Narloo StreetMalaga WA 6090

PH: 08 6240 5600Email: sales@perthscientific.com.au

Conductivity TDS and Water Hardness

uS/cm ppm mg/L Hardness

0 -140 0 - 70 0 - 70 Very Soft

140 - 300 70 - 150 70 - 150 Soft

300 - 500 150 - 250 150 - 250 Slightly Hard

500 - 640 250 - 320 250 - 320 Moderately Hard

640 - 840 320 - 420 320 - 420 Hard

Above 840 Above 420 Above 420 Very Hard

Conductivity and Water Hardness

The main cause of hard water is the presence of dissolved Calcium or Magnesium ions and hardness of water is usually given in ppm of calcium carbonate.

Measurement of water hardness by either conductivity or dissolved solids meters must be performed before water softening treatments. During the water softening processes, carbonates are substituted by sodium, which does not alter the total concentration of dissolved solids, but diminishes the hardness of the water

Who should Measure Salinity, Conductivity?

Wherever quality of water needs to be maintained, conductivity measurements need to be made to ensure appropriateness of water quality. As mentioned earlier, conductivity measured in water with relatively low levels of dissolved ions is expressed in terms of micro-Siemens (uS/cm) or milli-Siemens (mS/cm). Similarly, Total Dissolved Solids is measured in water with relatively high levels of dissolved ions and is expressed in terms of parts per million (ppm) or parts per thousand (ppt), i.e.

• Readings in the range uS/cm or mS/cm refer to conductivity;• Readings in the range ppm or ppt refer to TDS.

A range of portable, accurate and inexpensive equipment is available formost applications from Perth Scientific Equipment.

AD31 AD32

RangeEC

TDSTemp

0 to 3999 µS/cm0 to 2000 ppm

0.0 to 60.0oC / 32.0 to 140.0oF

0.00 to 20.00 mS/cm0.00 to 10.00 ppt

0.0 to 60.0oC / 32.0 to 140.0oF

ResolutionEC

TDSTemp

1 µS/cm1 ppm

0.1oC / 0.1oF

0.01 mS/cm0.01 ppt

0.1oC / 0.1oF

Accuracy(at 25oC / 77oF)

EC/TDSTemp

±2% f.s.±0.5oC / ±1oF

±2% f.s.±0.5oC / ±1oF

AD31 - AD32

AD31 and AD32 are waterproof Conductivity, TDS and temperature testers. The housing has been completely sealed against humidity. All Conductivity and TDS readings are automatically temperature compensated (ATC), and temperature values can be displayed in °C or °F units. The Conductivity/TDS conversion factor (CONV) can be selected by the user, as well as the coefficient ß (BETA) for temperature compensation. The instruments can be calibrated at one point. Measurements are highly accurate with a unique stability indicator right on the LCD. The models are also provided with a low battery symbol which warns the user when the batteries need to be replaced.

The AD32P probe supplied with the meters, is interchangeable and can be easily replaced by the user. The encapsulated temperature sensor allows fast and accurate temperature measurement and compensation.

www.perthscientific.com.au

Perth Scientific Pty Ltd is a Western Australian company with over 35 years experience in the scientific field. We are renowned

for our quality service and specially trained staff.

Perth Scientific Pty LtdUnit 2 / 11 Narloo StreetMalaga WA 6090

PH: 08 6240 5600Email: sales@perthscientific.com.au

Group A HIGHLY SALT SENSITIVE PLANTS Pastures CloverFruit Strawberry, Raspberry, Avocado, Loquat, stone-fruit, Citrus Fruits, Apples, PearsVegetables Beans, Parsnips, Celery, Peas, Squash, Peas, Onion, Carrot

Group B MILDLY SALT SENSITIVE PLANTS Pastures Clover, Maize, Oats, Wheat, Rye, LucerneFruit Strawberry, Mulberry, GrapeVegetables Cucumber, Capsicum, Lettuce, Sweet Corn, Rockmelon, Onion Potato, Cauliflower, Cabbage, Watermelon, Broccoli, Pumpkin, Tomato

Group C SLIGHTLY SALT SENSITIVE PLANTS

Pastures Perennial Rye-grass, Barley, Kikuyu, Couch Grass, Tall Wheat GrassFruit Olive, Fig, PomegranateVegetables Spinach, Asparagus, Garden Beets

Group D SALT TOLERANT PLANTS

Pastures Saltwater Couch, Sand CouchFruit Date Palm

More than 20 mS/cm TOO SALTY FOR IRRIGATION

Approximate Upper Salinity Limits For Suggested Plants

SALT CONTENT

uS/cm mS/cm ppm gr/gl

1000 1 550 38.5

2000 2 1100 77

3000 3 1650 115.5

4000 4 2200 154

5000 5 2750 192.5

6000 6 3300 231

7000 7 3850 269.5

8000 8 4400 308

9000 9 4950 346.5

10000 10 5500 385

11000 11 6050 423.5

12000 12 6600 462

13000 13 7150 500.5

14000 14 7700 539

15000 15 8250 577.5

16000 16 8800 616

17000 17 9350 654.5

18000 18 9900 693

19000 19 10450 731.5

20000 20 11000 770

21000 21 11550 808.5

22000 22 12100 847

To Convert ppm to grains/gallon gr/gl = ppm x 0.077

To Convert ppt to grains/gallon gr/gl = ppt x 77

To Convert mS/cm to grains/gallon gr/gl = mS/cm x 38.5

To Convert uS/cm to grains/gallon gr/gl = uS/cm x 0.0385

To Convert grains/gallon to mS/cm mS/cm = gr/gl x 0.026

To Convert grains/gallon to uS/cm uS/cm = gr/gl x 26

To Convert grains/gallon to ppm ppm = gr/gl x 13

To Convert ppm to mS/m mS/m = ppm x 0.2 (approx)

To measure soil salinity, make a suspension of 1 part soil to 5 parts with distilled water, shake vigorously and allow to sediment. Then

measure the salinity in the aqueous phase and log the result.Conductivity Conversions

GROUP B

GROUP C

GROUP D

GROUP A

www.perthscientific.com.au

Perth Scientific Pty Ltd is a Western Australian company with over 35 years experience in the scientific field. We are renowned

for our quality service and specially trained staff.

Perth Scientific Pty LtdUnit 2 / 11 Narloo StreetMalaga WA 6090

PH: 08 6240 5600Email: sales@perthscientific.com.au

Approximate Upper Salinity Limits For Animal & Domestic Use

SALT CONTENT

uS/cm mS/cm ppm gr/gl

1000 1 550 38.5

2000 2 1100 77

3000 3 1650 115.5

4000 4 2200 154

5000 5 2750 192.5

6000 6 3300 231

7000 7 3850 269.5

8000 8 4400 308

9000 9 4950 346.5

10000 10 5500 385

11000 11 6050 423.5

12000 12 6600 462

13000 13 7150 500.5

14000 14 7700 539

15000 15 8250 577.5

16000 16 8800 616

17000 17 9350 654.5

18000 18 9900 693

19000 19 10450 731.5

20000 20 11000 770

21000 21 11550 808.5

22000 22 12100 847

Hot Water Systems (1.6 mS/cm)

Human Consumption (Tolerate up to 2.5 mS/cm)

Poultry (Tolerate up to 4.7 mS/cm)

Dairy Cattle (Tolerate up to 5.5 mS/cm)

Shower and Baths (Tolerate up to 6.2 mS/cm)

Pigs (Tolerate up to 7 mS/cm)

Horses (Tolerate up to 10 mS/cm)

Lambs, Weaners, Breeder Ewes (Tolerate up to 11 mS/cm)

Beef Cattle (Tolerate up to 15.5 mS/cm)

Adult Sheep (16.5 mS/cm - 22 mS/cm) {Salinity is an important property and is

a measure of the mass of dissolvedsalts in a given mass of solution...

Conductivity in Water and/or Soilshould be regularly monitored along

with pH and oxygen content to accountfor changes occurring the various

seasonal and farming cycles.