conversion chart 3

[elcamino]

Where can I obtain a conversion chart for microohms to ppm? This is for checking conductivity for my plant water samples.Thanks, Joe

 

[PELS]

I doubt you will find a chart anywhere that directly converts micro-ohms to parts per million (PPM). "Micro-ohms" is a measure of electrical resistance (ER), which is the inverse, or reciprocal of electrical conductivity (EC). EC is expressed in "siemens" (sometimes called "mho", ohm spelled backwards) per centimeter or "s/cm". The EC of a solution is measured by a meter that converts EC (s/cm) to TDS in units of PPM.

Nutrient concentration of a solution is expressed as "Total Dissolved Solids" (TDS) and the higher the quantity of nutrient ions present, the higher the EC . Electrical Conductivity Meters are used to estimate TDS by measuring EC and converting that number to TDS, expressed in PPM. I say "estimate" because meters use a linear conversion factor to calculate it. Nutrient mixes are all different so no factor will be exact, but I have read they can range from 0.50 to 0.72 depending on the meter manufacturer.

So sadly you see, there is no direct conversion from micro-ohms to PPM.

 

[bimr]

In the future, one should only post on one forum. This was also posted on the water forum. I am replying here to PELS comments regarding "So sadly you see, there is no direct conversion from micro-ohms to PPM.".

http://www.lenntech.com/unit-conversion-calculator/tds_engels.htm

http://www.onlineconversion.com/

 

[PELS]

bimr:

There seems to be some confusion created. I'm not sure what you are trying to say to me. You are the one who posted in both forums. I did not post in the water forum.

The thread in the water forum you linked asked how to, "convert microohms to microsiemans".

This thread asked how to convert "micro-ohms to PPM". I was responding to this thread and was not aware of the one you linked.

Why are you directing your comment to me? The converter you linked does not convert micro-ohms to PPM. It converts siemens/cm (a measure of EC) to TDS in PPM. This thread asked how to convert micro-ohms to PPM.

 

[bimr]

The comment "In the future, one should only post on one forum. This was also posted on the water forum." was directed to el camino, as he essentially posted the same thing on two different forums.

The comment "I am replying here to PELS comments regarding "So sadly you see, there is no direct conversion from micro-ohms to PPM.""

http://www.lenntech.com/unit-conversion-calculator/tds_engels.htm

http://www.onlineconversion.com/"

was directed to PELS since there is a direct conversion of micro-ohms to PPM as shown on the conversion chart.

http://www.lenntech.com/tds-ec_engels.htm

Dissolved solids will conduct electricity by the movement of positive and negative ions of the dissolved solids thus carrying current or conducting. Conductivity meters measure conductivity. The readout may be in microseimens (The same thing as inverse of micro ohms resistivity) or in PPM TDS.

Regarding "Nutrient concentration of a solution is expressed as "Total Dissolved Solids" (TDS)"

When one says nutrients, one is usually referring to phosphorus and nitrogen, not dissolved salts.

Also, in water treatment, mg/l is essentially the same thing as ppm.

 

[shahyar]

There is no conversion between microohm/microsiemens to ppm. The online calculators are based on "standard sea water", which is not the case alawys.

 

[bimr]

Really.....then perhaps you can explane this chart?

http://www.lenntech.com/tds-ec_engels.htm

It calculates mg/l to microsiemens from cation and anions.

mg/l to ppm to tds to mmol/l to meq to EC to ?S (microSiemens)

 

[PELS]

According to the text below the chart, EC measured with a TDS meter yields a 1EC value that corresponds to +500ppm while EC measured with a NPK meter yields a 1EC value that corresponds with +700ppm.

In other words, there is not an exact conversion of micro-ohms to ppm because the method of measuring EC depends on the device used to measure it.

 

[bimr]

Really....you must work in agriculture to know about a Nitrogen Phosphorus Potassium (NPK) meter.

http://www.agrifam.com/product_information.php?product=6&title=NPK Meter

Of course you must also be aware that the NPK meter is not used to measure water conductivity, but rather the nutrient level in soils.

"If your water analysis indicates the TDS and the electrical conductivity, then it should be possible to establish the following relation:

+ 500 ppm correspond to 1000 ?S / cm"

With an range of error of only 2-3%, this is most certainly accurate enough for any application in water/wastewater treatment.

 

[shahyar]

Just I tried to answer the poster question;
EC--> TDS ppm : no exact formula
Water analysis--> EC: simple formula (as it is mentioned by bimr).