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“Tomorrow’s Instruments Today” — “For Good Measure” ® |
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A Leading South African Test and Measurement Instruments Supplier |
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“For Good Measure”® |
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TMI, Established—1982 |
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Test and Measurement Instruments C.C. |
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Test our Service and Measure with our Instruments. |
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CK 85/07464/23 |
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Please contact us by phone, fax, email or visit us at the details given above. We look forward to hearing from you. |
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Product List |
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All brands, trade names, trade marks, and logos are the property of their respective owners. |
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Brand Names |
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T + M ® |
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English, Afrikaans and Portuguese Speaking No Credit Card Payments yet. |
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Ph: +27 (011) 683 4365 Fax: +27 (011) 683 4461 E-mail: t.m.i@iafrica.com
Physical Address: 1st Floor, TMI House, 37 Garden St, Cnr 160 Bellavista Rd, Turfclub, Johannesburg, 2135 SOUTH AFRICA
Postal Address: P.O. Box 1416, Southdale, Johannesburg, 2135, SOUTH AFRICA
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T.M.I. |
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This Month’s Special |
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Excess Stock to be cleared while stocks last. > Click for More... |
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Thermography—Thermal Imager— Infrared Camera. FLIR i3 — Smallest , Lightest, most affordable camera “point-shoot-detect”. Introductory Nett Price of R 11 990.00 + VAT while stocks last. |
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pH Meters |
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pH Meters |
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Part No: PH-201 |
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pH Meter : 0 to 14pH Economical Pocket size, Needs Electrode. |
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Part No: PH-202 |
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pH Meter,Bench Type: 0 to 14 pH,(0.01)pH, Water Resistant Front Panel. Ideal for Schools, Laboratory and Industry. |
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Lutron |
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Lutron |
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Accessories & Adaptors |
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Part No: PE-01 |
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pH electrode. 0 to 14 pH Professional High Quality pH Electrode, Epoxy body, 9.5mm dia. X 130mm. |
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Part No: PE-06HD |
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Spear tip pH electrode. 1 to 13 pH (Typical 0—14 pH) General purpose electrode, ideal for piercing into meat, sausage, cheese. Durable glass in rugged epoxy body. |
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Lutron |
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Lutron |
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Part No: YK-200PCD |
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Conductivity Probe for YK2001PH, 2/20 ms 2 Ranges, 0 to 60 deg C, C/F, ATC (Automatic Temperature Compensation) |
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Part No: YK-200PCT |
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Conductivity / TDS Probe for YK2001PH, 2/20 ms 2 Ranges, Total Dissolved Solids,132 to 20000PPM |
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Lutron |
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Lutron |
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Part No: YK-200PDO |
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Dissolved Oxygen Probe for YK2001PH, 0 to 20 m/L Diaphragms and Electrolyte included. |
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Part No: YK-200PATC |
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ATC probe for YK 2001PH, 0 to 65 degC, C/F, to gain maximum possible accuracy |
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Lutron |
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Lutron |
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Part No: YK-2001PH |
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pH Meter : Intelligent pH Meter/mV, 0.00to 14.00 pH, +/-19999mV, C/F, Record-Min/Max, Memory, Data Hold &RS232. With Optional Probes also covers Conductivity and TDS, as well as Dissolved Oxygen. |
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Lutron |
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T + M ® |
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Part No: PH-209G |
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Green Hybrid Generator Powered pH Meter. RS232, Professional pH/mV Meter, 0 to 14 pH x 0.01 pH, -1000 mV to 1000 mV, for use with ORP probes
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Lutron |
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Notes on pH and ORP Electrodes. pH is the Unit of Measure used to express the degree of acidity of a substance. pH electrodes and ORP electrodes are analytical sensors for measuring pH and oxidation-reduction potential (ORP). These electrodes can be for measuring either pH or ORP, or both. pH is the negative logarithm of the hydrogen ion activity in solution. The pH value of a substance is directly related to the ratio of the hydrogen ion [H+] and the hydroxyl ion [OH-] concentrations. It is one of the most common laboratory measurements because many chemical processes are dependent on pH. Oxidation-reduction is a type of chemical reaction in which electrons are transferred from one substance to another. The oxidized species loses electrons and the reduced species gains electrons. Both species must be present for the reaction to occur. Important specifications for pH electrodes and ORP electrodes are measuring ranges and accuracies, as well as response time, which is typically given as time to reach 95% of final value. pH electrodes and ORP electrodes are available as either single cells or combination cells. Single cells, one part of an electrode pair, require separate reference electrode and are the best choice for colloidal suspensions, iodides in sample, and high percentage of solids in fluid. Combination electrodes are composed of two parts, the measuring electrode and the reference electrode. This is the most common configuration and is best for laboratory or field applications. Reference electrodes can be either refillable or sealed. The trade-off between the two is amount of maintenance versus length of product life. Refillable electrodes obviously need more maintenance, but also last longer and typically have higher accuracies. Sealed electrodes, while not requiring refilling, have a limited life, as the chemicals inside get used up and not replaceable. Two types of reference cell junctions are common. Single junction reference electrodes contain a single electrolyte. The electrolyte provides a constant level of the ion sensed by the reversible reference element and forms a low potential liquid junction with the sample solution. Double junction reference electrodes have an additional reference cell in front of the potassium chloride cell, which screens the sample from the potassium chloride reference cell. Double junction cells typically have a longer time response. Handheld or portable configurations allow pH electrodes and ORP electrodes to be used with ease in laboratories, where the operator may be testing several different samples. Insertion style electrodes are often inserted into process piping through a tapped hole in a pipe or bulkhead. Flow-through styles fit directly into the pipeline and become an integral part of it via some connection such as flanges or other fittings. Typical features of pH electrodes and ORP electrodes include temperature compensation, built-in temperature sensor, submersible or water resistant design and a design specially suited for food or sanitary applications.
Additional Notes On pH of general interest. The term pH is derived from the French word, "Pouvoir Hydrogene" which means "hydrogen power". pH is the measurement of hydrogen ions concentration in a solution. As a result of its mathematical formulation, low pH values are associated with solutions with high concentrations of Hydrogen ions, while high pH values occur for solutions with low concentrations of Hydrogen ions. Pure water has a pH of 7.0, and other solutions are usually described with reference to this value. Acids are defined as those solutions that have a pH of less then 7 (ie more Hydrogen ions than water); while bases are defined as those solutions that have a pH greater than 7 (ie less Hydrogen ions than water). The pH levels for drinking water should be pH 6.5 - 8.5. Measurement of pH. Litmus paper may be used for pH measurement, but it only provides a rough indication and is not necessarily accurate. A more accurate method requires a pH meter and a pH electrode that has a Hydrogen ion sensitive glass bulb. The most common sensing element used in the electrode is the glass membrane as it is selective for H+ ions, i.e. H+ ions can permeate through the hydrated layer of glass membrane. The electrode body may not necessarily be glass. Movement of the ions into the hydrated membrane changes the electrochemical effect inside the glass which is measured in mV which is then converted via the pH meter to be reflected as a pH value, thus depending on the concentration of ions in the solution, the mV and thus the pH varies. Geology in Soils. Compounds that are acidic and alkaline can be released into water from different types of rock and soil. When Calcite (CaCO3) is present, Carbonates can sometimes be released, which increases the alkalinity in the water and raises the pH. When Sulfide minerals, such as Pyrite are present, water and oxygen interact with the minerals to form Sulfuric acid. This can drop the pH of water making it very acidic. Drainage from forests and marshes are often slightly acidic, due to the presence of organic acids produced by decaying vegetation such as is the case in the Amazon River turning the water to a dark tea like colour. Drainage from mine sites particularly in Gauteng, South Africa. When mining for silver, gold, and other metals this often involves the removal of sulfide minerals buried in the ground. Water can become acidic from the formation of sulfuric acid, when water flows over or through sulfidic waste rock or tailings exposed at a mine site. Streams that receive drainage from mine sites have low pH levels, in the absence of buffering material, such as calcareous rocks. Air Pollution. Car exhaust pollution and power plant emissions increase the concentrations of nitrogen oxides and sulfur dioxide in the air and may travel far from their place of origin. They react in the atmosphere to form nitric acid and sulfuric acid and fall as acid rain or snow. These acids do affect the pH in streams and thus the fish and eco life. The concentration of carbon dioxide in the water. Carbon dioxide (CO2) enters a mass of water from a various sources, including the atmosphere, runoff from land after rains, release from bacteria in the water and respiration by aquatic organisms. This dissolved CO2 forms a weak acid. Natural, unpolluted rainwater can be as acidic as pH 5.6, because it absorbs CO2 as it falls through the air. pH levels in water can change from daytime to night because plants take in CO2 during the day and release it during the night. Water Quality Standards. The DWAF Requirements for the Purification of Waste Water or Effluent Water, is that the pH should be 5.5 - 7.5. A very high (greater than 9.5) or very low (less than 4.5) pH value is unsuitable for most aquatic organisms. The young fish and immature stages of aquatic insects are extremely sensitive to pH levels below 5 and may die at such low pH values. The high pH levels (9 - 14) can harm fish by denaturing cell membranes. Any such changes in pH can also affect aquatic life indirectly by altering other aspects of water chemistry. The low pH levels accelerate the release of metals from rocks or sediments in the stream. These metals can affect a fish's metabolism and the fish's ability to take in water through the gills and can kill fish fry. Temperature Compensation. In a perfect electrode - one that measures zero at exactly pH7 - there is no temperature effect on the electrode sensitivity at pH7, regardless of temperature change. Most pH electrodes are not perfect, but the errors from changes in temperature are still very minute when near pH7, plus or minus one-tenths of a pH, and can be disregarded. However, the further from pH7 the solution is, the greater the expected measurement error due to changes in the electrode sensitivity. For most electrodes, the error is approximately 0.003 pH / C / pH away from pH 7. For example, if a pH meter is calibrated at room temperature (25C) and is measuring a sample around pH4 at around 5C, Temperature difference: 25C - 5C = 20C pH away from neutral: 7 pH - 4 pH = 3 pH Total error: 0.003 x 20 x 3 = 0.18 pH To overcome this error, pH meters require some form of temperature compensation to ensure standardised pH values. Meters and controllers with Automatic Temperature Compensation (ATC) receive a continuous signal from a temperature sensing element and automatically correct the pH value based on the temperature of the solution. Manual Temperature Compensation requires the user to enter the temperature of the solution in order to correct pH readings for temperature. ATC is considered to be more practical for most pH applications. Storage of pH probes. Electrodes should be kept in a solution of Potassium Chloride at pH = 4 or same acidic calibration buffer. pH probes do not like to be kept in distilled water. Note that probes should be rinsed before placed in the test solution to remove traces of the pH = 4 solution, as this can influence results. Also do the measurement in a static solution without moving the probe around in solution. How pH Meters work. Voltage differences occur when two different metals come into contact with one another, and a similar electric potential exists when a metal comes into contact with a solution of salts or acids, which is how a battery works. A similar potential exists when one solution comes into contact with another solution, and separated by some membrane. A pH meter is basically the electro-chemical potential measured between a liquid inside a glass electrode, or membrane, and a test solution outside. The very thin glass electrode measures the electro-chemical potential of the Hydrogen ions. To accomplish this a reference is used inside thus forming a conducting bridge to the glass electrode. This gives off a voltage and is translated by the instrument into a digital reading. For this reason the probe should not be used in liquids with movement, and best results are achieved with small containers. Readings vary with temperature, and instruments compensate for variations in temperature. Replacement of Probes. Electrodes don’t have eternal life, and should be replaced when taking long to settle or when the drift is no longer acceptable.
We hope that the above is of good use to anyone who has interest in pH Meters.
Copyright © 2009—2012 Test and Measurement Instruments C.C. | All rights reserved Ph Meters
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Part No: PE-03 |
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pH electrode. 0 to 13 pH General Purpose pH Electrode, Epoxy body, 12.3mm dia. X 160mm. |
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Lutron |
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Part No: PH-206 |
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pH Meter : PH/mV/Temp/ 0 to 14 pH (0.01pH),Water resistant front panel. Auto/Manual temp compensation, Large LCD, Built in analog output terminal |
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Part No: PH-211 |
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pH Meter : 0 to 14pH (0.01pH) Economical cost / Pocket Size, General purpose application, Needs electrode. |
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Lutron |
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Lutron |
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Part No: PH-220S |
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Soil, Cheese, Meats pH Meter : 0 - 14 pH, supplied with Separate Spear Tip Electrode and pH7 Standard Solution. Electrode ; 0 - 13pH. Auto Calibration. |
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R 990.00 excl VAT |
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Lutron |
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Part No: PH-220
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Ph Meter, pH probe included: 0 - 14.00 pH, P-65 Waterproof. Auto Calibration. One Buffer solution included. |
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R 820.00 excl VAT |
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Lutron |
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Part No: PE-03K7 |
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pH Electrode with Temp Probe. 0 to 13 pH PE-03 General Purpose pH Electrode, and TP-07 Temp probe for PH-207,PH-207A,PH-208,PH-221,YK-2005WA. |
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Lutron |
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Part No: PH-207 |
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pH Meter : PH/mV/Temp/ 0 to 14 pH (0.01pH),Auto/Dual Function Display, MIN/MAX/AVE Values with Recall, Large LCD, RS232 Interface. Needs Optional Electrode |
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Lutron |
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See also the notes on the page of ORP meters. |
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Part No: ORP-14 |
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ORP Electrode, with BNC Connector& 3 Meter Cable, 12,5 mm X 150mm, (High Accuracy) For use with ORP203, PH206, PH207,PH208, YK2001PH,YK2005WA |
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Lutron |
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pH Meters for soil, food, liquids, water testing, hydroponics, home beer brewing, cheese making, experiments, fish tanks, garden growing, laboratory use, meat, wine making, oil, swimming pools, paint, aquariums, urine and titration are available for sale ex-stock. |