The Magic Button

Posted by 13 Jun, 2014

The magic button says:

“Give resale pricing to those who enter the code “GIMMERESALE” at checkout.”

Thus spake the magic button.  Good until June 30, 2014 on Ultrameters only.

Categories : Uncategorized

Using MyronLMeters.com

Posted by 28 May, 2014

 

Use MyronLMeters.com Wisely

We have a lot to offer (if you know where to look)

MyronLMeters.com can tell you most of what you need to know…if you know where to look,  Want to know how to calibrate? Take a look in our videos OR manuals section. Want to send a meter in for repair? Click on the REPAIRS tab and you’ll find out how. Have a discontinued product?  We can tell you the new part number. Don’t know what solutions to use – there are several places you can find them.

Keep this email handy for reference and it will save you a phone call. Also, if you have suggestions to improve our website, please let us know! We want to make MyronLMeters,com as easy to use as the meters we sell.

 

Click this image on the home page OR click the OPERATIONS MANUALS page and you’ll find not only operations manuals, but material safety data sheets for solutions, product datasheets, and application bulletins.

 

Click this image on the home page OR click the REPAIRS tab and you’ll find out how to send your meter in for repair or calibration AND some of the most popular repair videos.

 

Click this image on the Myron L Meters home page OR click the VIDEOS tab OR visit our YOUTUBE channel and view the latest product overview and maintenance videos.

 

Click this image on our home page OR click TECHNICAL SUPPORT at the top of the home page and you’ll find Frequently Asked Questions, a handy contact form, links to MANUALS, REPAIRS, VIDEOS, terms, discontinued products, conversion charts and industry applications.

 

Want to know how to CALIBRATE? Check the OPERATIONS MANUALS page for your meter and open or download OR check out our VIDEOS OR search our BLOG for calibration. Check your OPERATIONS MANUAL for the proper solution.

 

Need help finding a product? Browse our sections on the HOME PAGE OR click PRODUCTS to search by category or parameter OR use the SEARCH box in the upper right of the page.

 

 

Categories : Company News, MyronLMeters.com Service

Meter Maintenance: Myron L Meters

Posted by 13 May, 2014

 


Protect Your Ultrameter

With Regular Maintenance

When you spend a thousand bucks for a meter, you want it to last. That’s why you bought a Myron L meter in the first place. And, while Myron L meters are renowned for durability, they need care: cleaning, calibration, storage solution, sensor replacement, and sometimes repair. Keep this blog post as a handy reference guide to Myron L meter maintenance.



Maintenance of the Ultrameter 6PFCE
These procedures apply to the Ultrameter, PoolPro, TechPro, and D-6 Dialysate meter. 

 READ MORE ABOUT ULTRAMETER CARE

DOWNLOAD AN OPERATIONS MANUAL

pH Calibration of the Ultrameter 6PFCE
This procedure applies to the Ultrameter, PoolPro, TechPro, and D-6 Dialysate meter. 

READ HOW TO CALIBRATE

BUY PH BUFFER SOLUTIONS

VIDEO: Ultrameter II Cleaning the pH Sensor

BUY SENSOR STORAGE SOLUTION

VIDEO: Ultrameter II Replacing the pH Sensor

 

BUY A REPLACEMENT PH SENSOR

Repair And Maintenance of Myron L Meters

Need to have your meter repaired?
READ HOW TO SEND YOUR METER FOR REPAIR

Time to get a new meter?

GET YOUR NEW ULTRAMETER HERE
Facebook
Facebook
Twitter
Twitter
Website
Website
Email
Email
Tumblr
Tumblr
Google Plus
Google Plus
Pinterest
Pinterest
YouTube
YouTube
Copyright © , All rights reserved.Our mailing address is:

Myron L Meters

3460 Marron Road #103-341

Oceanside, CA 92056

 

 

Categories : Care and Maintenance, MyronLMeters.com Service, Technical Tips, Videos

UltraEasy Ultrapens: Myron L Meters

Posted by 7 May, 2014

 


Make your work life UltraEasy.



The Benefits of an Ultrapen

Portable, Durable, Accurate, and Easy

Perfect for field testing.
Same accuracy and range as an Ultrameter.
Tough.
Light.
Use as backup for your Ultrameter, or as field replacement.

Click Here to Find Your Ultrapen Now


Your Ultrapen Options

Ultrapens: PT1 (Conductivity, TDS, Salinity), PT2 (pH), PT3 (ORP), PT4 (Free Chlorine)

Ultrapen Sets: The Ultrapen Combo (1&2), The Ultrapen Set (1,2,3), The Ultrapen Complete (1,2,3,4), The Ultrapen Splash (for pool pros:1,2,4)

Ultrapen PT1 Product Overview – MyronLMeters.com

Ultrapen PT2 pH Pen Product Overview – MyronLMeters.com

Facebook
Facebook
Twitter
Twitter
Website
Website
Email
Email
YouTube
YouTube
Pinterest
Pinterest
Tumblr
Tumblr
Google Plus
Google Plus

Copyright © , All rights reserved.

Our mailing address is:

Myron L Meters

3460 Marron Road #103-341

Oceanside, CA 92056

 

Categories : Product Updates, Videos

Real-Time Field Water Analysis with an Ultrameter III 9P: Myron L Meters

Posted by 30 Apr, 2014

tumblr_mrw572B3Q81qgr3lpo4_250

The Ultrameter III 9P Titration Kit allows for fast, accurate alkalinity, hardness & LSI titrations in the field.

The Ultrameter III 9P is based on the tried and tested design of the Ultrameter II 6P and measures conductivity, resistivity, TDS, pH, ORP, free chlorine and temperature quickly and accurately. The 9P also features new parameters that allow the user to perform titrations in the field. The Ultrameter III 9P has a unique method of performing alkalinity, hardness and LSI titrations that makes field monitoring fast and feasible.

How does it work?

The 9P titrations are based on conductometric titration methods that are possible with the 9P’s advanced conductivity cell and microprocessor based design. Titrations are chemically equivalent to standard methods using colorimetric techniques, but replace color change identification of equivalence points with changes in conductivity, thereby replacing a subjective, qualitative assessment with a quantitative one. This means the instrument determines the equivalence point instead of the user and the method of analyzing the equivalence point is objective, rather than subjective.

What is a conductometric titration?

A conductometric titration is performed just like a colorimetric titration, only the equivalence point is determined by a change in conductivity rather than a change in color. This is based on the fact that changes in ionic concentration that occur as constituents react with reagents change the electrical conductivity of the solution.

A simple example can be given of the titration of a strong acid with a strong base. The acid solution, before the addition of the base, has a very high conductance owing to the concentration and mobility of the small hydrogen ions.

With the addition of the base, the hydroxide reacts with the hydrogen to form water, thus reducing the hydrogen ion concentration and effectively lowering the conductivity of the solution. The conductivity continues to decrease until all the hydrogen ions are consumed in the reaction, but then sharply increases with the next addition of base, which contains highly conductive hydroxide ions. The solution conductivity then continues to increase with each base addition. The equivalence point in this example would be a clearly defined minimum point of lowest conductivity (see Figure 2).

Not all solutions will give a plot with an equivalence point that is as easy to distinguish as the sharp upturn found in a strong acid-base titration, however. The 9P plots several reagent additions beyond any changes in conductivity and matches the derived curve to the behavior of solutions of known concentration.

Is a conductometric titration a standard method?

(Standard method comparison to methods listed in the Standard Methods for the Examination of Water and Wastewater published by the American Public Health Assn., the American WaterWorks Assn. and the Water Environment Assn.)

Myron L’s conductometric titration methods are chemically equivalent to standard methods that use the same procedure, but with pH indicators. That means that they use the same reagents in the same sequence with the same theoretical approach. The difference lies in the 9P’s ability to determine the equivalence point based on numerical data, rather than subjective observation of a color change.

The alkalinity titration is modeled after standard method 2320. The sample is titrated with sulfuric acid and conductivity changes are recorded at each titration point.

The hardness titration is modeled after standard method 2340. To reduce the affects of high alkalinity in the form of bicarbonate, acid is first added to the sample. This shifts the bicarbonate toward carbonic acid, then carbon dioxide (reference the carbonic acid equilibrium), which is gassed off the sample. The sample is buffered above pH 10 (effectively pH 12) by the addition of sodium hydroxide. EDTA reagent is then added incrementally, with conductivity measured after each addition.

The LSI titration uses a simplified version of the thermodynamic equations for the determination of the scaling tendency of water developed in 1936 by Dr. Wilfred Langelier. The user simply titrates for alkalinity and hardness, then measures pH and temperature, and the 9P generates the saturation index value automatically.

Conductometric vs. Colorimetric

The benefits of determining the equivalence points by conductometric titrations are that the user does not have to interpret any results. The 9P does it for you using objective measurements. And the 9P is a faster method. For example, a typical colorimetric titration for hardness can take up to 30 drops of reagent, while the 9P method for the same concentration only requires six to eight drops. Colorimetric distinctions are sometimes hard to make, as well, especially when adding reagents drop by drop while trying to carefully observe the precise point at which the color changes—and that can lead to inaccurate data. This is especially true in colored or turbid solutions.

The conductometric method can also be used with very dilute solutions or for solutions for which there is no suitable indicator. The conductometric titration method gives you empirical results that are calculated for you, eliminating potential sources of error. And the measurements can be stored in memory for later data transfer using the optional U2CI software and bluDock Bluetooth hardware installed on the 9P . This makes data analysis and reporting seamless.

What else can the Ultrameter III 9P do?

Alkalinity, hardness, pH and temperature values used to compute the saturation index of a sample can be manipulated in the LSI Calculator function, allowing you to perform on the spot analysis of water balance scenarios. You can use historical or theoretical data to populate the required values in the calculator.

And the 9P titration kit comes with all required accessories, reagents, and calibration solutions (see Figure 6). Streamline your field testing with an Ultrameter III 9P from MyronLMeters, where you can save 10% when you order online.

Myron L Meters is the premier online retailer of accurate, reliable, and easy-to-use Myron L meters like the Ultrameter III 9P.  Save 10% when you order online at MyronLMeters.com. Find out more about the Ultrameter III 9P in our Myron L Meters – Ultrameter III 9P Titration Kit Overview video.

 

Categories : Case Studies & Application Stories, Product Updates

Water Industry News: MyronLMeters.com

Posted by 19 Apr, 2014





 



Water Industry News
from MyronLMeters.com


Published by
Myron L Meters
18 April 2014


Read paper →


Environment


Health


Science


World


Stories

 


California’s Governor Wants Water Tunnels. Antitax Group Wants to Know Who Pays – Businessweek


avatar
Shared by
Myron L Meters


thumbnail

www­.businessweek.com

– California has a $25 billion plan to transport snowmelt from the northern Sierras through a pair of 37-mile tunnels to farms and cities in the south. But there’s no indication of how much water use…


On the real performance of cation exchange resins in wastewater treatment under conditions of cation competition: the case of heavy metal pollution – Online First – Springer


avatar
Shared by
Imen Ayed


link­.springer.com

– Sorption performance of cation-exchange resins Amberlite® IRN77 and Amberliteâ„¢ IRN9652 toward Cs(I) and Sr(II) has been tested in single-component aqueous solutions and simulated waste effluents co…


China seeks solution to providing clean drinking water supplies


avatar
Shared by
news.google.com


thumbnail

www­.scmp.com

– Large colonies of micro-organisms – some capable of causing serious disease – have been discovered inside pipelines carrying drinking water to homes in most major mainland cities, the South China M…


City moves to secure $27.5M for wastewater treatment plant


avatar
Shared by
news.google.com


thumbnail

thetandd­.com

– Orangeburg City Council gave first reading Tuesday night to a series of ordinances that will help finance the Department of Public Utilities’ $27.5 million wastewater treatment plant overhauls and …


Reaping the benefits of a composting toilet


avatar
Shared by
Water.org


thumbnail

water­.org

– Composting toilets are a win in rural India. Improved sanitation means better health for the owners and their neighbors. After the pit has been used for about a year and is getting full, they seal …


The Power of Water


avatar
Shared by
Water.org


thumbnail

water­.org

– The water and sanitation problem in the world is far too big for charity alone. At Water.org, we are driving the water sector for new solutions, new financing models, greater transparency, and real…


Portland, Ore., is dumping 38 million gallons of drinking water because of a urinating teenager


avatar
Shared by
Myron L Meters


thumbnail

www­.washingtonpost.com

– Portland, Ore., is dumping 38 million gallons of drinking water because of a urinating teenager By Mark Berman April 17 at 2:49 pm More Comments It took one teenager urinating in a reservoir for th…


Desalination Plant Said to Be Planned for Thirsty Beijing – NYTimes.com


avatar
Shared by
Myron L Meters


thumbnail

www­.nytimes.com

– BEIJING — A coastal desalination plant planned for east of Beijing could provide a large portion of the drinking water for the parched Chinese capital by 2019, the state news media quoted officials…


How to Build a Rain Garden and Curb Water Pollution (VIDEO)


avatar
Shared by
Myron L Meters


thumbnail

www­.onegreenplanet.org

– Have you ever heard of a rain garden? Building a rain garden, which helps reserve stormwater and keep it out of neighboring rivers, lakes, and ponds you want to help keep clean, can help curb water…


Chinese court dismisses water pollution lawsuit


avatar
Shared by
Myron L Meters


www­.reuters.com

– BEIJING (Reuters) – A Chinese court has rejected a lawsuit filed by five residents from a major northwestern city after authorities said a cancer-inducing chemical had been found in tapwater at 20 …


Government Agency Takes On Non-Revenue Water


avatar
Shared by
Myron L Meters


www­.wateronline.com

– Trenton Water Works is struggling with the problem of non-revenue water.  A new report “tracks the amount of water lost before it gets to the tap in Mercer County — and leading the pack with the mo…


The Stream, April 16: Scientist Says Deforestation, Not Dams, Caused Massive Flood in the Amazon


avatar
Shared by
Myron L Meters


www­.circleofblue.org

– Extreme Weather Extreme flooding along the Madeira River in the Amazon basin, which killed 60 people and displaced 68,000 families this year, was the result of massive deforestation in Bolivia and …




Environment


U of C Nurses for Clean Water


avatar
Shared by
Water.org


Local Vendors Make a Fast Buck Using Water Scarcity – The New Indian Express


avatar
Shared by
Water.org


How a facebook group from Pune brought aid to drought affected Maharashtra


avatar
Shared by
Water.org


Governor’s Coal Ash Action Plan Favors Duke Energy, Threatens Drinking Water


avatar
Shared by
Waterkeeper Alliance


Waterkeeper.Org » McCrory’s Coal Ash Plan a Failure


avatar
Shared by
Waterkeeper Alliance


Restoring Louisiana’s Coast Will Require Restoring Its Democracy—Governor Jindal Is Trying to Undermine Both


avatar
Shared by
Waterkeeper Alliance



More Environment →



Health


Waterkeeper.Org » Splash Series Events


avatar
Shared by
Waterkeeper Alliance


Natural Cleansers – NRDC


avatar
Shared by
NRDC


NRDC: Chemical Index


avatar
Shared by
NRDC


If you think FDA knows what chemicals are in our food, think again. | Maricel V. Maffini, PhD’s Blog


avatar
Shared by
NRDC


Water Quality > Town of Devon


avatar
Shared by
Canuck | MacLeod


NYCWasteLess – Spring 2014 SAFE Disposal Events


avatar
Shared by
NYC Water



More Health →




Photos


thumbnail


avatar
Shared by
Myron L Meters


More photos →



Science


Ocean Acidification Could Make Fish Lose Their Fear Of Predators, Study Finds


avatar
Shared by
NRDC


BBC News – Guernsey beach fails water quality standard


avatar
Shared by
TweetingCrapaud


LI Sound water quality improvement on target


avatar
Shared by
Long Island News



More Science →



World


News across the East Coast


avatar
Shared by
The Beach


Water district proposes taking over leaky, empty Ten Mile Creek project » TCPalm.com


avatar
Shared by
Treasure Coast News



More World →

 


Environment • Health • Science • World • Stories
Read paper →
 

This email was sent to


Water Industry News was originally published on Myron L Meters Blog

Categories : Company News, Water Industry News

Water Quality Parameters: MyronLMeters.com

Posted by 15 Apr, 2014

Water Quality Parameters

Measuring Key Water Quality Parameters

The right meter is essential for measuring any of several key water quality parameters:

Conductivity is the ability of water to conduct an electrical current and is an indirect measure of the conductive ionic mineral concentration. The more conductive ions that are present, the more electricity can be conducted by the water. This measurement is expressed in microsiemens per centimeter (µS/cm) at 25º Celsius. Myron L Meters carries a complete line of conductivity meters, including the Ultrameter II 4P.

Resistivity is the inverse of conductivity. Electrical conductivity is a measure of water’s resistance to an electric current. Water itself has a weak electrical conductivity. Electric current is transported in water by dissolved ions, making conductivity measurement a quick and reliable way to monitor the total amount of ionic contaminants in water. Myron L Meters carries a complete line of resistivity meters, including inline monitor/controllers like the 753II Resistivity Digital Monitor/Controller. Read more about Measuring Key Water Quality Parameters

The Ultrameter III 9P is the most comprehensive water meter on the market, measuring 9 parameters with a single instrument: Conductivity, Resistivity, TDS, Alkalinity, Hardness, Langelier Saturation Index,
ORP/Free Chlorine, pH, Temperature. Three parameters – LSI, hardness, and alkalinity require titration. Find out more about the Ultrameter III 9P

. Facebook Facebook Twitter Twitter Website Website email Email Google Plus Google Plus Pinterest Pinterest YouTube YouTube Tumblr Tumblr Watch the Myron L Meters – Ultrameter III 9P Titration Kit Overview Partners in Success
Would you like to become a Myron L Meters featured partner?  Our upcoming program will allow our customers to be featured on our website, offer them special discounts, custom branded training videos, and more.  Interested? Click here to join our Partners in Success program. Copyright © , All rights reserved.Our mailing address is:

 

Water Quality Parameters: MyronLMeters.com was originally published on Myron L Meters Blog

Categories : Uncategorized

FDA Warning: MyronLMeters.com

Posted by 14 Apr, 2014

 

FDA Warning

Are You FDA Compliant?

In recent news “A warning letter sent to (a dialysis clinic operator) by the US Food and Drug Administration (FDA)”… “FDA said the company needs to take “prompt action to correct the violations addressed in the letter,” and that failure to comply could lead to more serious regulatory enforcement actions, up to and including seizure, injunction and civil penalties.”

Are your devices FDA 510K compliant? Click here to learn about the FDA 510K compliant D-6 and D-4 from Myron L Meters. Order online and save 10%. ‘Digital Dialysate Meter D-6

                                   
D-6               Click to view product details                 D-4
Facebook
Facebook
Twitter
Twitter
Website
Website
Email
Email
Google Plus
Google Plus
Pinterest
Pinterest
YouTube
LinkedIn
LinkedIn

Want to see how it works?  Click the link above.  

Like a training video custom branded for your company?  Let us know!

Ready to convert all your clinics to a D-4 or D-6?  Let us know and we’ll send you a coupon code for extra savings.

Copyright © , All rights reserved.Our mailing address is: 

 

Categories : Case Studies & Application Stories, Company News

Measuring Key Water Quality Parameters: MyronLMeters.com

Posted by 12 Apr, 2014

The right meter is essential for measuring any of several key water quality parameters:

Conductivity is the ability of water to conduct an electrical current and is an indirect measure of the conductive ionic mineral concentration. The more conductive ions that are present, the more electricity can be conducted by the water. This measurement is expressed in microsiemens per centimeter (µS/cm) at 25º Celsius. Myron L Meters carries a complete line of conductivity meters, including the Ultrameter II 4P.

Resistivity is the inverse of conductivity. Electrical conductivity is a measure of water’s resistance to an electric current. Water itself has a weak electrical conductivity. Electric current is transported in water by dissolved ions, making conductivity measurement a quick and reliable way to monitor the total amount of ionic contaminants in water. Myron L Meters carries a complete line of resistivity meters, including inline monitor/controllers like the 753II Resistivity Digital Monitor/Controller.

Total Dissolved Solids (TDS) is also a measurement of the amount of dissolved minerals in the water. In this instance they would be called solids in solution. The quantity of dissolved solids in the solution is directly proportional to the conductivity. In this case, conductivity is the measurement but it is used to estimate TDS. It is measured with a conductivity meter but is reported as TDS in parts per million (ppm), via a complex algorithm. Myron L Meters carries a complete line of TDS meters, including the Ultrapen PT1.

pH is a measure of the concentration of hydrogen ions in the water, indicating the acidity or alkalinity of the water. On the pH scale of 0-14, a reading of 7 is considered to be neutral. Readings below 7 indicate acidic conditions, while readings above 7 indicate the water is alkaline or basic. Naturally occurring fresh waters have a pH range between 6 and 8. Myron L Meters carries a complete line of pH meters, including the Ultrapen PT2

Temperature is expressed in degrees Celsius (C) or Fahrenheit (F). Most digital handheld Myron L Meters include a temperature function.



Oxidation reduction potential (ORP)can correlate millivolt readings to the sanitization strength of the water. Microbes can cause corrosion, fouling, and disease, and oxidizing biocides are usually used to keep microbial levels under control. ORP is expressed in millivolts (mV). Myron L Meters carries a complete line of ORP meters, including the Ultrapen PT3

Free Chlorine refers to both hypochlorous acid (HOCl) and the hypochlorite (OCl–) ion or bleach, and is commonly added to water systems for disinfection. Free chlorine is typically measured in drinking water disinfection systems to find whether the water system contains enough disinfectant.  Myron L Meters Ultrameter II 6PFCe and Ultrapen PT4 can both be used to measure free chlorine.

Salinity is simply a measure of the amount of salts dissolved in water, a measurement useful to pool service technicians and others.  You can measure salinity with a Myron L Pool Pro PS6.

Alkalinity is a measure of the capacity of water or any solution to neutralize or “buffer” acids. This measure of acid-neutralizing capacity is important in figuring out how “buffered” the water is against sudden changes in pH. Alkalinity is a titration function of the Ultrameter III 9PTKA.

Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals.  As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water “hard.” Hardness is a titration function of the Ultrameter III 9PTKA.

LSI or Langelier Saturation Index helps you determine the scaling potential of water. LSI is a calculated number used to predict the calcium carbonate stability of water. It indicates whether the water will precipitate, dissolve, or be in equilibrium with calcium carbonate. LSI is a titration function of the Ultrameter III 9PTKA.

MyronLMeters.com is the premier internet retailer of accurate, reliable Myron L meters.  Save 10% when you order Myron L meters online at MyronLMeters.com. You’ll find reliable instruments for every water quality parameter mentioned above.



 

 

 

Categories : Uncategorized

Measuring ORP: MyronLMeters.com

Posted by 12 Apr, 2014


Ultrapen PT3 ORP tester Ultrapen PT3 ORP tester



Though the measurement of free chlorine concentration is often indicated for the disinfection of water and disinfectant byproduct control, there is a better way. Because free chlorine works through oxidation, ORP instrumentation can be used to monitor and control its effectiveness. ORP measures the actual oxidation power of the solution, specifically the strength and number of oxidation and reduction reactions in solution. This yields a clear picture of the efficacy of the chlorine present, regardless of the concentration or ratio of chlorine species in solution.
Measuring ORP directly reflects the sanitizing power of free chlorine or any other oxidizing or reducing chemicals. The measurement of ORP is precise, empirical and requires no user interpretation, making it ideal for water quality and industrial process control.
What is ORP?
ORP stands for Oxidation Reduction Potential, sometimes called REDOX. ORP is a differential measurement of the mV potentials built up when electrodes are exposed to solutions containing oxidants and reductants. ORP describes the net magnitude and direction of the flow of electrons between pairs of chemical species, called REDOX pairs.
In a REDOX pair, one chemical loses electrons while the other chemical gains electrons. The chemical in the REDOX exchange that acquires electrons is called the oxidant (HOCL, OCl-, ClO2, bromine, hydrogen peroxide, etc.). The chemical in the REDOX exchange that gives up electrons is called the reductant (Li, Mg2, Fe2+, Cr2, etc.). Oxidants acquire electrons through the process of reduction, i.e., they are reduced. Reductants lose their electrons through the process of oxidation, i.e., they become oxidized.
How is ORP measured?
ORP sensors are basically two electrochemical half-cells: A measurement electrode in contact with the solution being measured and a reference electrode in contact with a reservoir of highly concentrated salt solution.
When the solution being measured has a high concentration of oxidizers, it will accept more electrons than it loses so that the measurement electrode develops a higher electrical potential than the reference electrode. A voltmeter placed in line with the two electrodes will display this difference in potential between the two electrodes. Once the entire system reaches equilibrium, the resulting net potential difference represents the ORP. A positive reading indicates an oxidizing solution, and a negative reading indicates a reducing solution. The more positive or negative the value, the more powerful the oxidants or reductants, the greater their concentrations or both.
What does ORP measure?
ORP can be used to determine the efficacy of chemical disinfectants that work via the oxidation or reduction of the structures of microbial contaminants. For example, chlorine, an oxidant, will strip electrons from the negatively charged cell walls of some bacteria. Because ORP measures the total chemical activity of a solution, ORP measures the total efficacy all oxidizing and reducing disinfectants in solution: Hypochlorous acid, monochloramine, dichloramine, hypobromous acid, sodium hypochlorite, UV, ozone, peracetic acid, bromochlorodimethylhydantoin, etc.
ORP indicates the effectiveness of only those disinfectants that work through oxidation and reduction. ORP cannot be used to detect the presence of any one particular chemical or chemical species. Nor can it alone be used to determine the concentration of a known species of chemical in solution. This means that although ORP is the best way to know whether or not your sanitizer is working, it can’t tell you how much or what kind of sanitizer is working.
What factors affect ORP measurement?
While the accuracy of ORP sensors is relatively stable, which is why they do not require calibration, there are factors that affect their response time. Changes in temperature can affect response times by altering the kinetic rates of the reactions being measured, for example. Low temperatures reduce the kinetic rates and lengthen sensor response times.
The condition of the electrode will also alter response times by changing the “exchange current density” (the amount of electrons exchanged per unit area of exposed electrode). The lower the exchange current density, the more sluggish the sensor response. The typical measurement electrode is made from pure platinum (Pt) because it is a noble metal and, therefore, highly unreactive, i.e., the potential being measured is most likely due to the activity of the chemicals in the water and not reactions between the solution and the Pt itself. Even though Pt is a noble metal, it will form a thin oxide layer on the surface of the platinum when exposed to dissolved oxygen. This oxide layer facilitates the ORP measurement when it is very thin, one molecule thick, by attracting, or “adsorbing,” hydrolyzed oxidant or reductant molecules to the surface of the electrode.
Unfortunately, when the oxide layer becomes more than one molecule thick, the resulting lowered exchange current density offsets this benefit. Also, the adsorbed molecules cause a “memory effect.” If a sensor is placed in a less oxidizing solution after measuring a more oxidizing solution, it can take a very long time for the sensor to equilibrate to the new sample. Though the sensor response time is much slower, the final ORP reading will be the same.
ORP electrodes never require recalibration because there is no drift in zero point (as is the case with pH sensors). Any deviation from expected readings is most likely due to surface contamination of the electrodes or buildup of the oxide layer, both of which can easily be remedied by cleaning with a light abrasive, such as Softscrub®. Exposing the sensor to an “ORP conditioning solution” will help reduce the memory effect due to adsorption.
Can ORP be used as a surrogate parameter for free chlorine?
Yes. ORP measures the oxidizing power and, therefore, the actual residual sanitizing strength of the solution being tested. Simply counting how much chlorine is present is misleading because certain changes in water chemistry, such as pH or the addition of cyanuric acid, dramatically alter the oxidizing power of chlorine and, therefore, its efficacy, without changing how much chlorine is present.
When correlated with established disinfection control parameters, measurements and bacterial plate counts, this type of measurement gives a very accurate picture of the sanitizing activity. For this correlation to be valid, the water undergoing treatment must be characterized so that all chemical constituents are known. The pH and temperature values should be reported and held constant. ORP will report an empirical value or a hard number that indicates how active the sanitizer is. However, you have to make certain that microbial contamination is responding to the treatment. Once a correlation is established in a stable system, ORP is a very efficient and effective way to monitor microbial control.
ORP has long been used in bathing waters as the only means for automatic chemical dosing. In fact, the World Health Organization (WHO) suggests an ORP value of between 680-720 mV, depending on the sensor and the particular context, for safe bathing water. In the disinfection of drinking water, an ORP value of ~800 mV is required for oocyst inactivation.
For the purpose of pretreatment screening to detect chlorine levels prior to contact with chlorine-sensitive RO membranes, influent must first be screened to determine which chemicals besides chlorine are present that contribute to the ORP value. With these interferants characterized and pH and temperature held constant, ORP can be correlated to specific sanitizer concentrations, such as chlorine, in their known forms. Some manufacturers of RO membranes and other water quality treatment equipment will also specify an ORP tolerance value for prescreening and influent control. The same holds true of effluent screening.
Why ORP?
ORP is a faster, simpler empirical measurement than titration with DPD or other methods, and in many cases it gives the most accurate picture of the effect of all oxidizing and reducing chemicals in solution. No in-depth knowledge or training is required to obtain accurate repeatable results. User error is virtually eliminated because ORP readings require no subjective, visual interpretation, nor do they require calibration.
Using ORP disinfectant control can be automated because the measurement produces an electrical signal that can trigger switches when outside established control parameters. And ORP sensors are relatively low-maintenance. If you’re not using ORP to monitor and control chemical additions that work through REDOX, you should. You’ll save yourself time, hassle and money.
Myron L Meters is the premier internet retailer of accurate, reliable Myron L meters like the Ultrapen PT3, ORP pen tester.
Categories : Case Studies & Application Stories