What Is Torque?
Torque is defined as the measure of the force that can cause an object to rotate on an axis. Most commonly, people hear this term used when talking about cars. Cars utilize torque to turn the wheels to propel the vehicle forward.
Measuring Torque
Torque, typically measured in pounds per foot (Ft/lbs) or newtons per meter (Nm), possesses both magnitude and direction. This classifies it as a vector quantity. The direction of the vector depends on the direction of the force on the axis. When opening a door, a users applies force to the side of the door farthest from the hinges. Pushing on the side of the door closest to the hinges requires much more force. Even though the work remains the same in both scenarios, one would generally prefer to apply less force, ergo the typical location of a door handle.
Multiplication of force and distance results in torque calculation. As a vector quantity, it can be tricky to understand at first. Because these calculations involve a vector product, the “right-hand rule” applies. Take your right hand and curl the fingers of your hand in the direction of rotation caused by the force. Your thumb of your right hand now points the direction of the vector.
Static or Dynamic?
When discussing torque there are two types: static and dynamic. The static variety does not produce an angular acceleration. When pushing on a closed door, static torque is being applied because the door is not swinging on its hinges. A bicycle being peddled at a constant speed is classified as static because it is not accelerating.
Your vehicle’s torque, as discussed earlier, is a dynamic form due to its production of an angular acceleration of the wheels at an increased rate of speed. Power tools (pneumatic wrenches, etc.) typically apply dynamic torque.
Everyday Science
There are many reasons we use these measurements in our daily world. For example, when a manufacturer makes a nut and bolt, they define that bolt’s maximum torque value. You use a torque wrench to ensure you tighten that nut down to that exact specification to prevent failure of the nut and bolt. You want to make sure it’s tight, but not too tight! This can make the difference between your car’s wheels rolling down the road for eight thousand miles … or eight minutes.
Mettler-Toledo MCP1-S Pipette Calibration Balances: Calibration Spotlight
The Mettler-Toledo MCP1-S represents top-of-the-line pipette calibration equipment, with capabilities for single and multi-channel pipettes. PTS pairs our system with the Calibry pipette calibration software, fully CFR part 11 and ISO 8665 compliant. This combination ensures accurate, efficient, and precise calibration of pipettes whether in our lab or on a customer site.
Precision Hardware: MCP1-S
The MCP1-S features the ability to calibrate all multi-channel pipettes with a dispensed volume greater than 10 μl. This system greatly reduces the calibration time of a multi-channel pipette. Using the MCP1-S allows all twelve (12) channels to be checked in a single step. Additionally, the system provides quick validation of individual channels. ISO 8655 specifies that up to three hundred and sixty (360!) measurements must be taken using a conventional balance: the MCP1-S needs only thirty (30). When compared to a conventional analytical balance, this fully automatic process improves calibration ergonomics and reduces time requirements by up to ninety (90) percent. This results in improved calibration productivity and reliability.
Swapping the 12-channel transport carriage with the glass evaporation trap places the MCP1-S in single-channel pipette calibration mode. The built-in moisture trap around the weighing vessel ensures evaporation and wind currents do not affect even the smallest volumes. Environmental readings recorded prior to calibration, coupled with a Z factor, ensure accurate measurements unaffected by environmental factors.
Precision Software: Calibry
The Calibry software optimizes pipette calibration according to ISO 8655. Designed with these procedures in mind, the software optimizes data management and guarantees traceability. Additionally, the accompanying database incorporates manufacturer specifications for each pipette type. When the user selects a pipette its specifications immediately show, saving valuable time. Calibry automatically adds pipettes to the calibration task list as the recalibration date approaches. Further, calibration results can be viewed at any time during the procedure. Values outside tolerance limits show clearly in red, allowing technicians to take immediate corrective measures.
Precision Partners: PTS
PTS goes to great lengths to ensure all pipette calibrations are accurate and precise. This includes the design and maintenance of our temperature-controlled PDCL (Pipette/Dimensional Calibration Laboratory). Network-enabled equipment controls and monitors this lab, ensuring ideal conditions within two degrees and three percent humidity. When our partners prefer onsite service, we utilize mobile monitoring devices to ensure complete compliance with required conditions, bringing the precise calibration techniques of our in-house lab to your facilities.
Pipette Testing Guide
You have a favorite pipette. Familiarity with the electronic interface makes its use second nature. Maybe your hand fits it just right, or the smoothness of the action makes it easy to use. Then, one day, your dispensed volume just feels “off”. You try pipetting the liquid again, and again it looks too low or too high. What can you do? Basic pipette testing verifies the accuracy – or inaccuracy – of your equipment.
Fortunately, you can perform basic pipette testing with a few pieces of lab equipment. Let’s get started.
Required Equipment
Collect the following equipment and supplies.
- A weighing device. Balances offer more precision, but a digital scale can suffice for larger volume samples.
- A weighing vessel, such as a beaker.
- A steady and consistent pipette technique.
- An environment with stable temperature and humidity.
- A stable surface.
- Distilled water.
Pipette Testing Preparations
Once you collect the needed items, start by setting up your weighing device on a stable surface in an environment with minimal temperature and humidity variations. If your scale or balance has a leveling bubble and internal calibration, utilize both now. Finally, set your weighing device to read grams.
With your scale or balance ready, place your weighing vessel on the weighing device and either “tare/zero” the unit or record the weight of the vessel to be subtracted from your overall weight later.
Pipette Testing Procedure
With all the preparations made, set the pipette’s volume to the middle of its range. Draw up a sample of water and dispense it into your weighing vessel. The elegance of this procedure lies in the near-perfect conversion of microliters of distilled water to grams of mass. This conversion involves nothing more than moving the decimal three (3) places. To go from grams to microliters, move the decimal to the right. To from go from microliters back to grams, move the decimal to the left.
For instance, fifty (50) microliters of water weighs 0.05 grams: a movement of the decimal from 50.0 three places to the left to 0.05. Similarly, .0485 grams of distilled water translates to 48.5 microliters of water: a movement of the decimal from 0.0485 three places to the right, to 48.5.
So, when you verify a pipette with a range of 10-100 microliters at 50 microliters and the balance reads 0.0487g, then your pipette dispensed 48.7 microliters. If your scale or balance does not have a zero or tare function, subtract the weight of the vessel from the total measured weight after dispensing the water. After verification at the mid-range, set the pipette’s range for its lowest and highest settings and repeat the procedure for the respective ranges.
Conclusion
While this method does not yield the precision results of more in-depth procedures, it provides you with a general idea of pipette performance and accuracy. With that in mind, let’s say you’ve figured out that your pipette is reading too far out of range to be used within your lab. What do you do now? Throw the pipette away and buy new?
Of course not! Send it to the professionals at Precise Technical Solutions. The diagnosis, repair, and calibration of lab instruments such as pipettes forms a core part of our team’s competencies. With a little time in our lab, our technicians will have your favorite pipette operating just like it did the day it was new.
What Is A Pipette?
A simple, critical, instrument in labs across the world, a pipette transports a measured volume of liquid safely and accurately. Pipettes can be as simple as plastic tubes and as complex as precise electronic devices. They generally have a single channel, eight (8) channels, or twelve (12) channels. Dr. Heinrich Schnitger, from Marburg, Germany, invented the first micropipette in 1957. This model measured and transported a fixed amount.
Later, the co-founder of biotechnology company Eppendorf, Dr. Heinrich Netheler, inherited the rights and initiated the global and general use of micropipettes in labs. In 1972, Warren Gilson and Henry Lardy, of Wisconsin, developed the first adjustable micropipette. Micropipettes dispense between one (1) and one thousand (1000) μl (microliters), while macropipettes dispense greater volume. Most pipettes work by creating a partial vacuum above the liquid-holding chamber, or the tip, and selectively releasing this vacuum to draw up and dispense liquid.
The Air Displacement Pipette
Air displacement micropipettes deliver a measured volume of liquid, depending on size. Additionally, they require disposable tips that come in contact with the fluid and operate using a piston-driven air displacement. The vertical movement of a metal or ceramic piston within an airtight tube creates a vacuum. The pipetting liquid around the tip moves into the vacuum and can then be moved and dispensed as needed.
These pipettes have the capability of precise and accurate measurement, but since they rely on air displacement, changing environmental conditions, especially air temperature and user technique, can introduce inaccuracy. Because of this, such equipment requires regular maintenance and calibration. End users should receive training to properly use correct and consistent technique.
The Positive Displacement Pipette
Similar in function to air displacement pipettes, positive displacement pipettes see less common use. Generally, users deploy these pipettes to avoid contamination and to handle volatile or viscous substances, or extremely small volumes, like DNA. The main difference comes in the disposable tip, a microsyringe made up of a capillary and a piston which directly displaces the liquid.
Other Varieties
Volumetric pipettes, otherwise known as bulb pipettes, have a large bulb with a long narrow portion above a single graduation mark. This mark serves as the calibration point for a single volume, similar to a volumetric flask.
A single piece of plastic forms transfer pipettes, also known as beral pipettes. In beral pipettes, the bulb sometimes serves as the liquid holding vessel.
Electronic pipettes were developed to improve ergonomics of pipettes by reducing the necessary force to operate them. A small electric motor powered by an internal battery replaces manual piston movement. Where manual pipettes require a movement of the thumb, electronic pipettes operate by the push of a button. Users employ a digital display on the unit to program settings such as volume.
Modern advancements in science and technology changed the look and operation of pipettes over the years, but not their main purposes. Pipettes, to this day, move a liquid from one place to another accurately and safely.
Calibration Spotlight: Hart Scientific 1590 Super-Thermometer II
What Is a Super-Thermometer?
Metrology laboratories around the world rely on super-thermometers for their reliably accurate, easy-to-take measurements. For instance, the Hart Scientific 1590 Super-Thermometer II reads accurately to 0.00025°C or 1 ppm. This high degree of accuracy makes super-thermometers perfect for calibration of SPRTs (Standard Platinum Resistance Thermometers). Further, they are the best lab instruments to take advantage of SPRT accuracy. They read temperature directly, automate data collection, and calculate constants for ITS-90. Additionally, the large LCD screen of the 1590 Super-Thermometer II features a live graph which records temperature trends during calibration. This allows PTS technicians to see when the temperature has stabilized enough to ensure an accurate reading.
How Does PTS Use the Super-Thermometer II?
The typical benchtop thermometer has an error level twenty to forty times larger than the Super-Thermometer II. However, the resolution of the 1590 with a 25-ohm SPRT is 0.000125°C. Because of this, the 1590 Super-thermometer II can easily calibrate Platinum Resistance Thermometers (PRTs), Resistance Temperature Devices (RTDs), thermistors, thermocouples, and related measurement devices. As a key provider in the scientific services calibration industry, PTS services all manner of temperature devices. As an ISO:17025 accredited organization, we meticulously catalog uncertainty data for our 1590. Customers may request this data as needed.
We paired our 1590 Super-Thermometer II with a quartz-sheathed SPRT Accumac AM1960. This allows accurate measurements up to 600°C. This instrument gives PTS the ability to calibrate all temperature devices in-house. Because of this, we have more time to devote to serving our customers. This ensures our turn around time is quick and efficient to minimize the time you are without your instrument. You won’t wait six weeks (or longer!) to receive your PRT or temperature device back from calibration. You can rest assured knowing your temperature device will be calibrated to its greatest degree of accuracy from PTS.