For many research laboratories around the globe, pH meters are considered basic equipment. In fact, it’s common for a single organization to keep multiple types of pH meters on hand for use in different situations. Below, we’ve outlined how benchtop and portable meters are used in the research sector and what features are most important to researchers.
Benchtop meters are the number one choice for pH testing in a laboratory setting. They’re typically rectangular or square in shape and are designed to sit on a flat surface. Much like a calculator, benchtop meters are equipped with buttons that function as controls and an LCD screen that displays calibration and test results. To conduct pH tests, the benchtop meter must be paired with a pH electrode via an electric cable.
Benchtop meters vary in testing range, accuracy, and functional capabilities. For instance, some benchtop meters are multipurpose (designed to test a variety of elements, such as conductivity, oxidation reduction potential (ORP), pH, saline, TDS, and resistivity), while others may specialize in one type of test (such as conductivity) or be limited to a select few. Typically, users who are looking to test pH will choose a meter that can measure pH and provide automatic temperature compensation (ATC) because fluctuations in temperature directly influence pH values.
Different benchtop models may also vary in measurement range and accuracy level. For laboratory measurements, an accuracy rating of plus or minus 0.01 pH is considered standard. The testing range required by the user depends on the substance being measured. For example, if a researcher typically measures highly acidic or basic substances, he or she might need a wider pH testing range of minus 6.0 to plus 20.0. If he or she mostly tests water (such as groundwater or surface water), a more abbreviated testing range of minus 2.0 to plus 14.0 would be sufficient.
Other key features that matter to benchtop pH users include:
A water-resistant or splash proof exterior
Amount of memory storage and backup
The size of the LCD display
Automatic and manual calibration options (some researchers need both)
Battery life
RS output
Number of calibration points available (average range is between one and five)
Data connectivity (Can data be uploaded wirelessly or does it require a cable connection?)
Automatic and manual temperature compensation options for pH readings
Electrode efficiency functionality
Automatic offset and slope recognition (helps ensure consistency between readings as the electrode ages)
The pH display units
Portable meters are ideal for field testing and taking spot measurements in a lab, treatment plant, or manufacturing facility. Because portable meters are meant to travel to a variety of testing sites, it’s important that they’re light, they’re easy to calibrate, and they can be held in one hand. The best portable meters have a longer body that serves as a handle and a backlit, high-resolution screen that is readable in low-lighting conditions.
For users who must venture outdoors to take measurements (such as environmental researchers), features such as long battery life, data time-stamping, and memory storage are exceptionally important. In addition, many researchers opt for portable meters that are shockproof and can withstand exposure to natural elements such as moisture and dirt. In the European Union, portable meters that are used outdoors must be in compliance with Restriction of Hazardous Substances (RoHS) regulations, which prohibit the use of harmful materials such as lead, mercury, or cadmium in electronic equipment. Additionally, European electronics that are compliant with national safety, health, and environmental standards must be marked with the letters “CE” (Conformité Européenne).
Like benchtop meters, portable meters vary in testing range and accuracy. When choosing a portable meter, users typically look at:
Durability (Is the meter splashproof? Watertight? Dirt- or dust-resistant? Shockproof? Does it come with a portable case capable of storing the meter and an electrode probe?)
Amount of memory storage
Automatic backup capabilities (Does data automatically save to the device when the device powers down? Can data be wirelessly uploaded to the cloud?)
Battery life
Manual and automatic temperature compensation options for pH readings
Audio feedback buttons
Number of calibration points available (typically between one and three for portable meters)
Size and readability of screen (high resolution, backlit)
RoHS and CE compliance
In order to use a benchtop or portable meter, you need a pH electrode probe. When choosing between electrodes, there are a few important factors to consider:
To get the most out of your pH meter, it’s important to pair it with the right electrode for the job. Look for a pH electrode that can provide the measurement range and level of sophistication you’re looking for.
Most pH electrodes will also measure temperature because of the effect that it has on pH readings. For users who are planning on testing boiling or freezing substances, it’s important that the electrode they choose can withstand extreme temperatures and has a higher pressure tolerance.
For laboratory use, glass electrodes are often preferred because they’re easy to sanitize and have a wider range of operating temperatures. For field testing, plastic or epoxy-bodied electrodes are more durable but less able to withstand extreme temperatures.
A pH meter can have a rounded or spear tip. A spear tip is essential for penetrating semi-solid and solid substances, whereas a flat or rounded tip is ideal for testing liquids.
The cable refers to the electric cord that connects the electrode probe to the pH meter. A longer cable is important when taking readings in hard-to-reach sites or fully submerging the tester in a substance.
Determining the best type of meters and electrodes for your business (and your end users) is a highly contextual process. If you take the time to understand your customers’ unique needs, you’ll be able to speak to the features that are most important to them. In addition, knowing how your customers intend to use the product will help you identify cross-sell and upsell opportunities. By partnering with a distributor such as Jenco that offers on-demand order fulfillment and case-by-case consultation, your current inventory or expertise won’t ever limit your ability to make a sale.
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