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supporting the Water Treatment Community since 1990. qualicam offers some of the
best formulation expertise in the industry quala Kim offers a wide array of house formulations or qualicam can
help you with your own formulations at quala Kim we never sell direct to the end user so you’ll never have to worry
about competing with your blender to find out more about quala Kim go to scalinguph2o.com forward slash qualikim
once again that’s scalingup h2o.com forward slash qualikim at quala Kim we
know the blender matters thank you [Music]
you’re listening to the smooth sounds of water treatment knowledge with scaling
up H2O your host Trace Blackmore what the heck did you just tune into
sorry folks having a little fun with our intro of course this is the scaling up
H2O podcast and it’s still the podcast where we’re scaling up on knowledge so
we don’t scale up our systems and I am still Trace Blackmore certified water
technologist and your host for this awesome podcast and of course it’s
always awesome because of our listeners I’m here in the studio and I just wanted
to have a little fun with the intro I’m sure that’s probably not your favorite intro but I thought I would have a
little fun with it so thank you for going on me with that journey and today is going to be a journey because this is
a pinks and blues episode where we are opening up the scaling up mailbag to
answer your questions that’s right the questions from the scaling up Nation
and we’ve picked one specific question out that we are going to talk about
today but I’m going to leave you in suspense just a little bit there are a few items
that I want to make sure you know are available for your educational enjoyment
and that is a few organizations are having some events that you might want
to know about first up is the water environment Federation and International Water Association they are holding their
Innovations in process engineering conference June 6 through June 9th in
Portland Oregon so this is where process Engineers come together for a Cutting
Edge showcase on everything that is innovative around new practices in water
resource recovery this conference will focus on a large range of topics
including to resource recovery treatment efficacy efficiency and enhancements to
learn more about this we’re going to have all of that information for you on our show notes page the water
environment Federation is also holding their collection systems conference June 27th through 30th in Kansas City
Missouri we will have all that information for you on our events page
and then finally the national Rural Water Association is having their water Pro conference September 25th through
27th in Aurora Colorado more information is available on this right on our show
notes page a nation speaking of our show notes page I know we mention a lot of
conferences on this show but we make it so easy for you to find everything we
talk about not just the events but everything we talk about is searchable
on scaling up h2o.com so many people are learning that
that search feature is their gateway to so much much knowledge about whatever
they want to learn more about so I urge you if you have not been to scalinguph2o.com please navigate over to
that page and I know you will be glad that you did something else that you
will be glad that you did is listen to this latest installment of periodic
water table with James hello and welcome to the periodic water
table with James where we think and learn about water chemistry drop by drop please use your week to search online
ask your colleagues or even pick up a book to learn more about each week’s periodic water table topic if you do at
the end of the year you’ll be 52 water chemistry smarter so let’s raise the water table of
knowledge together and get started today’s topic is
http you might already know that HTTP is a phosphonate but what does that mean
what does http stand for what is its molecular formula what
percentage of atdp is phosphate is HTTP used for scale control corrosion
control or both is HTTP synergistic with anything else
does pH have an impact can HTTP precipitate with anything
if so how might this be controlled do oxidizing biocides such as chlorine
have an impact upon http how does this impact compare to that of
other phosphonates do you use any products with http remember knowledge is power and taking
the time to learn more about water chemistry each week will help make you a force to be reckoned with
be sure to post what you learn to social media and tag it with hashtag water table23 and hashtag scalingup H2O I look
forward to learning more from you as always thank you James for bringing
that to us each and every week a nation there’s not a week that doesn’t go by hardly where I am not asking for what
your ideas are for what your questions are and today I am going to answer those
questions we call that a pinks and blues episode and today we are taking multiple
questions about what is the difference between conductivity and total dissolved
solids lots of people have asked questions about this lots of people are asking questions that they have meters
that have both buttons to read conductivity and tedious and what
exactly is the difference there and that’s what we are going to talk about
first off I want to talk about conductivity so let’s start out with
talking about what conductivity is and think about that word I love using words
to Define itself to Define that word so
conduction how are we conducting a
current through water so you’ve either done this experiment that I’m getting ready to talk about or you’ve seen an
illustration of it so if we have Ultra Pure Water so let’s say we’ve distilled
water so it has nothing dissolved in it we put that in water and we put a
current across that pure water and we stick a light in that water it will not
illuminate it will not illuminate because there is not enough solids
dissolved in that water to conduct the current across the water so we can
complete the circuit now you’ve also seen in that same experiment where
they’ve dissolved solids in that water and it’s those solids which are creating
little bridges for that current to go across the water and connect the circuit
this is conductivity we’re able to conduct the current across the water so
now think of your conductivity meter that has that button that you hit that
says conductivity on it what exactly is going on there so you put your water
sample in that little cup and in that little cup you’re going to see two metal
pieces probably one on the bottom and one that sticks out from the side well
whether you knew it or not what that is is an anode and a cathode one is
positively charged one is negatively charged and we’re going to put a current
across the water and we are measuring how easily that
current goes from point A to point B and whatever that is that is now translated
into conductivity we’re actually able to conduct that electrical current from
point A to point B the more solids that you have in the system equals the easier
it is going to be to get that current from point A to point B that’s what
conductivity is and then through years of measuring conductivity we’ve been
able to equate that in industrial water treatment so we know that we can set our
controllers up to measure so much conductivity before it opens up a bleed
solenoid and we know that the solution to pollution is dilution and what’s
going on there is that high solids water that high conductivity water that’s in
say a cooling tower is now being bled out and it’s being replenished by low
solids low conductivity water so the solution to pollution is dilution well I
guess we can also say the solution to concentration is dilution but that doesn’t rhyme so we’re not going to say
it that way so that’s what conductivity is now conductivity alone doesn’t tell
us a lot conductivity tells us the sum of the parts if you will conductivity
tells us that all of the things that are dissolved in the water equal the
conductivity so what’s dissolved in the water well that’s why you are running
your tests so you might run a chlorides test you might run a hardness test you
might run an iron test a copper test a phosphate test whatever it is all of
those things are dissolved in the water and they are contributing to
conductivity now what we have done is we’ve taken our products and we know our
products are able to hold so much of stuff those things that we’re measuring
into solution until there’s an issue so we know that as long as we stay under
certain concentrations of say calcium or certain concentrations of silica and you
name it that’s what our technical directors are doing they’re figuring out how much we can hold of a particular
substance in solution and then that allows us to equate that to conductivity
and we say that we don’t want our overall system conductivity to exceed
and I’m just going to throw out a number there say it’s a thousand so whenever we
get to a thousand and maybe your number is three thousand it really doesn’t matter it’s whatever the number is that
tells us to do something specifically that’s the controller being told to do something and that’s where the solution
to pollution is dilution comes in all right well that’s all sounds well and
good but the question is what’s the difference between conductivity
and total dissolved solid so we know what happens when you press the button
that boom conductivity button pressed and we know that a charge is sent from
point A to point B and we know that the water depending on how much stuff is dissolved in it the easier it’s going to
be to get from a 2B so how do we involve TDS into all of this well that’s what
we’re going to talk about next so let’s start by defining TDS well that stands
for total dissolved solids and what is that well that’s the total amount of
dissolved solids in your solution I love it when terms define themselves well
that doesn’t really help us with our question here today so total dissolved
solids has also a TDS button on our meter so we hit that button and what’s
happening with that let’s talk about if we were in the lab so if we’re in the
lab not using our meter there’s a very well defined procedure on getting total
dissolved solids so we’re going to have a predetermined volume of sample that
we’re going to bring back to our lab we’re going to ensure that that sample
is as well mixed as possible and after we well mix this we’re going
to weigh a filter paper and then we’re going to draw that sample through that
pre-weighed filter paper and we are going to dry it specifically the
procedure is we put it in an oven at 105 degrees Celsius for one hour and then
we’re going to place that in a desiccator for one hour to cool and then we are
going to re-weigh that filter so we have how much the filter weight in the
beginning and then we have how much the filter weighed when we passed our sample through it and we allowed all the water
to evaporate out so now all we have left are the dissolved solids in that filter
paper well we’re going to take that and put it into this equation so the filter the
final weight minus the original weight in grams times 1 million divided by the
sample volume we put through it will actually equal the TDS value how many
total dissolved solids were in that filter paper so that’s the procedure maybe you knew that maybe you didn’t
know that but I do know you know when you hit that button on your meter that
says TDS that is not happening I assure you little elves do not live inside your
meter and they are doing this procedure so what exactly is going on inside your
meter well it’s just a percentage of conductivity so it’s putting that same
electrical charge through the water sample and then it’s taking a percentage
of that now typically 65 percent of whatever your conductivity is is what
your meter is going to take a percentage of so different meters might be a little
bit different but I think you can feel safe with 65 percent of conductivity is
what your meter thinks total dissolved solids are we know that there is no way your meter
can actually do that because we now know the procedure involved with total
dissolved solids so why is there a button on our meter for TDS well it
might make you feel good to do that and I bet if you were to do the math consistently if you were to go into the
lab run the procedure as we just said and compared that to conductivity most
likely you’re roughly going to get all of your data within that 65 to 75
percent range and that’s why your meter does that so in order to answer the
questions around total dissolved solids and conductivity that our listeners have
written in for us to answer on this episode we know what that procedure
actually is we now know what our our meter is doing and we can take that
information for however we want to use it now let’s talk about that because why
do we even want to know about conductivity or total dissolved solids now we already talked about setting up
our controller and the solution to pollution is dilution but how do we also
know how to use that and that’s what I want to talk about calcium carbonate for
those of you that have heard me speak on calcium carbonate before I call it the
water treaters Nemesis and it’s because we are heat transfer efficiency managers
and I say that on this podcast all the time and because we are dealing with
heat the thing that impedes heat the most that we deal with is calcium
carbonate and that’s where five things come together in order to create calcium
carbonate well that’s calcium hardness alkalinity temperature total dissolved
solids and pH those are the five things those are the five ingredients a chef
knees in order for calcium carbonate to be on the menu and trust me on the water
Traders restaurant we do not want calcium carbonate on the menu so I want
to talk about calcium carbonate just a little bit so you understand it and then we’re going to relate that back to Total
dissolved solids and conductivity and which one that you need to use for that equation so here is the example or here
is the equation that we have for calcium carbonate it’s 12.3 minus the quantity
of the log of the calcium hardness plus the log of the M alkalinity plus the
quantity of .025 times the temperature in celsius
minus the quantity of .011 times the
square root of the total dissolved solids okay what that gives us is the
saturation pH now that’s a term that tells us at what PH are we neither
dissolving or precipitating calcium carbonate and that’s the number that we
just derived through that crazy equation yes there’s calculators and all sorts of
things that you can use so you don’t have to plug that into a scientific calculator but if you did you would get
the same number and I also know that by knowing that information whatever number
you’re getting on whatever tool that you are using You Now understand it better
making that a better tool well have you ever seen one of the slide rules that
that used to be used in the water treatment industry as a tool to find calcium carbonate and the slide rule is
it has a bunch of different numbers on it and it has a window for each one of
the five ingredients and you adjust the slide to make sure everything lines up
and then you read the card and it tells you what your saturation pH is and then
ultimately it will tell you what your LSI RSI and psir which I will cover in a
second but what I want you to notice if you can Envision one of those slide
rules is that conductivity is the smallest window I mean it is Tiny
compared to everything else that takes up the entire card so all that being
said if you were trying to calculate calcium carbonate the best way to do
that is by total dissolved solids because it’s the solids that we’re
worried about coming out of solution you now know what the procedure is you know
you’re not doing that in the field so you can hit that TDS button and use that
number to figure out saturation pH and really you can hit the conductivity button and figure out saturation pH
because it’s not really going to matter what does matter is you understand
what’s going on with that and now you know exactly what the difference is
between conductivity and total dissolved solids now I promised I was going to go
through what LSI RSI and PSI are since we’re talking about calcium carbonate I
call that the water treater’s Nemesis because it wants to come out of solution the hotter it gets and we are heat
transfer efficiency managers and we want to make sure that those surfaces are as
clean as possible and calcium carbonate wants to scale there making them not
clean so with all of that knowledge LSI the longer stability index so this
is now taking the saturation pH that we already talked about and now we’re
adding another number to it in this case it’s pH and in fact we’re subtracting it
from that so here’s how it goes LSI is equal to the system pH
minus the saturation pH and the scale is between negative 3 and 3 and that
anything that is less than zero has a non-scaling tendency and anything that’s
above zero has a scaling tendency notice how I said that I did not say that any
anything below zero has a corrosive tendency and everything above zero has a
scaling tendency that is not what these indices indicate what they indicate is
whether the water is scaling or non-scaling because they are a measure
of calcium carbonate so with this we know all waters are corrosive water is
called the universal solvent for this reason now granted the more stuff that
the water’s dissolved the less ability it has to be aggressive to dissolve that
but trust me over time it will so all waters are corrosive and now you know
what LSI is so now let’s talk about RSI RSI is the Reasoner stability index and
that equation is the quantity of two times the saturation PA H minus the
system pH now this scale is between 0 and 12 and anything below 6 has a
scaling tendency where everything above 6 has a non-scaling tendency maybe you
use RSI and now you know where that comes from now the last one is the
pecorius scaling index and sometimes I hear that as the Practical scaling index
and that equation there’s actually two equations to it so the first one it’s two times the saturation pH so just like
RSI but then we subtract the pH of equilibrium well what is the pH of
equilibrium well that’s another equation and that equation is 1.465 times the log of the M alkalinity
and then we take that quantity and we add 4.54 to it now what that does that gives
us a scale just like RSI of 0 to 12 and
just like RSI we have a scaling tendency below six we have a non-scaling tendency
above six so what’s the difference between the PSI and the RSI well the PSI
Paul pecorius who I so badly wanted to get on this podcast unfortunately I was
not able to do that before he passed he came up with this formula and what he
did he took his years of experience in water treatment to say hey we’re not
just treating any water here we are treating treated water and we are
treating this water to extend the ability for water to hold calcium
carbonate into solution and he wanted to add that to the
equation so he came up with the pH of equilibrium
now I don’t know where the 1.465 came from I wasn’t able to ask him
but I did ask Brent shettle at an awt conference who used to be president of
awt he was actually the original author of the certified water technologist
examination I asked him the same question and he said I don’t know where the 1.465 comes from but I’m going to
tell you where the plus 4.54 comes from and that was the numbers
didn’t line up Paul got all of his information and he said you know what it
doesn’t line up to the RSI scale and he looked at all of his numbers and found
out that he needed to add 4.54 and then he had a very similar scale to the RSI
and that was one that people were already familiar with so now you know a little bit more more about LSI RSI and
PSI and you might be wondering which one is better for us to use and honestly
it’s been my experience in years of water treatment it doesn’t really matter
you know on the surface it sounds like the PSI should be the ones that we use but I have to tell you it really doesn’t
matter as long as you’re consistent so you shouldn’t run one that somebody else
in your company is not running you should decide as a company which one of
these indices that you are going to use and be consistent and that information
is now telling you information about your system so you’re already testing
calcium hardness you’re already testing M alkalinity you know what the
temperature is and I want to talk about temperature in a second and then you know what either the conductivity or the
TDs is and you know the pH so with all of that together you’re now able to
figure out what’s happening to all the things that are dissolved in the system when it comes to calcium carbonate the
water treaters nemesis use whichever one you decide that you
want to use but make it Universal throughout your company now let’s talk about that temperature and the reason
that we’re saying temperature is important is because
where you take the temperature really does matter now let’s think of a comfort
cooling system so in your mind’s eye I want you to go to the mechanical room
that you were last in now maybe you’re listening to this in a mechanical room and you can actually walk through it so
you’ve got a chiller you’ve got some condenser water and you’ve got a cooling
tower so of all of those different pieces of equipment of all the different places that water seas in that equipment
where should you take your temperature and I really want you to do this
experiment so whatever tool you’re using whatever indices you are using for that
tool I want you to do this on all these different places I want you to figure
out the temperature of the bulk water now maybe you can just simply go to your controller and see that it’s 90 degrees
or whatever it is go ahead and run LSI RSI or PSI with a 90 degree water now
maybe then you’ve got a heat exchanger and that’s at 100 degrees go ahead and
run it there and then I want you to go to the user interface and I want you to
record the hottest temperature of the refrigerant
and that number is probably going to be about a minimum of 120 degrees that is
the hottest temperature that your water is going to come in contact with where
that hot refrigerant is on the other side of that heat exchange tube and
that’s the first place that you are going to get scale if you’ve ever
wondered why the entire system is clean but the chiller is only scaled in a
certain spot you run this experiment and you will see that’s where calcium
carbonate is coming out of solution so that’s the first place that comes out
and then of course it builds from there and that’s how we lay down calcium
carbonate so I hope all that information is allowing you to see why it’s
important we do know the difference between conductivity and the difference
between total dissolved solids we realize how we get conductivity and how
we get total dissolved solids but more importantly we know why we use that we
know why that is important a nation I am here to tell you that when you just
follow procedures that is awesome for efficiency that is awesome for
consistency but that stinks to motivate you to become better and wiser about
what it is that you do now you have to walk before you run so you do need to
know those procedures before you understand the why but everything that I
just told you is the why behind that and I hope that that has unlocked this need
for you to learn more why about out everything that you do and this is just
one topic this is just from one question asking about what the difference was
between conductivity and total dissolved solids Nation what is the next why that
you have to go out there and find that information for yourself I want to tell
you that has been the key to my success that has been the key to me never being
bored in this industry because I’m always trying to learn more why and I
can’t think of another industry that allows us to learn more why than this
industry and I’ve said before if you are bored in this industry you are doing it
wrong challenge yourself each and every day if
you are going through servicing all of your accounts the exact same way no
wonder you’re bored if you’re going through your service thinking about the
same things you always think about no wonder you are bored so I’m going to
challenge the way that you are thinking and just add one word and that word is
why now for all you people out there that are worried I’m saying hey change your procedures I am not I am saying
understand your procedures at a level your procedures are never going to teach
you ask why about everything and then
explore it now you probably have why about a hundred things now if you research a hundred things at the same
time you are not going to be successful but just like we did right here we took
conductivity and total dissolved solids that was the only why we talked about
and how much information were we able to uncover and folks there’s way more
beyond that but that’s how to do it we might want to know why is there all this
information on the chiller interface and how do we use that well maybe we then
talk with somebody that knows a little bit more about how to use the chiller interface and then we talk with somebody
in our companies that know how to use that data just like we did here to
figure out what temperature we needed to use with our calcium carbonate
calculations so with that what is your next why how are you going to improve
what you know and how are you going to make this job more fun each and every
time you do it it all starts with y Nation I can’t thank you enough when you
let me know what questions you want me to answer on the scaling up H2O podcast
my favorite episodes to do are pinks and blues because we just do just that we
answer your questions and I need your questions well Trace how do you get our
questions and I know it’s probably the first time you’ve ever listened to this show if that’s what you’re asking
because each and every show I’m always asking about that it is going to scaling up h2o.com and going to our show ideas
page and there you have it folks another installment of Pinks and blues join us
next week where we will have a brand new episode for you and until then have a
great week folks please [Music]