Industries Information

Data loggers and data recorders acquire digital data from sensors and other signals. They are primarily used to store data for subsequent downloads to a host PC, but may also include real-time features such as monitors and alarms. Important specifications to consider when searching for data loggers and data recorders include differential analog input channels, digital I/O channels, sampling frequency, resolution, and accuracy.  Differential channels use the difference between two signals as an input; common mode is filtered out. In some systems, differential inputs are combinations of two single-ended inputs; in this case, twice the number of differential channels would be available as single-ended inputs.  Digital or discrete channels are used for low-level on-off signals used in applications such as communication, user interface, or control.  Sampling frequency is the frequency of the analog signal sampling and conversion to a digital value.  Resolution refers to the degree of fineness of the digital word representing the analog value. A ten-bit number contains 210, or 1024, increments. A 0-10V signal could therefore be resolved into approximately 0.01V increments. A 12-bit representation would be in 212 (4096) increments, or divisions of 0.0024V for the same signal. Each additional bit doubles the resolution, and one bit is required for the polarity (sign) of a number.  Data loggers and data recorders accuracy depends on the signal conditioning linearity, hysteresis, temperature considerations, etc. It is represented here as percent full scale of measurement range.

Common form factor for data loggers and data recorders include IC or board mount, circuit board, panel or chassis mount, modular bay or slot system, rack mount, DIN rail, and stand-alone.  Applications include general lab or industrial, environmental, vehicular, marine, aerospace or military, seismic or geotechnical, weather or meteorology, and medical or biomedical.  Common signal inputs available for data loggers and data recorders include DC voltage, DC current, AC voltage, AC current, frequency, and charge.  Sensor inputs include accelerometer, thermocouple, thermistor, RTD, strain gauge or bridge, and LVDT or RVDT.  Specialized inputs include encoder, counter or tachometer, timer or clock, and relay or switch.  Transducers and excitation are also important to consider when searching for data acquisition.  Many data loggers and data recorders have integral sensors or transducers.  These sensors can have voltage or current excitation.  Common outputs for data acquisition products include voltage output, current output, frequency output, timer or counter output, relay output, and resistance or potentiometer output.

Considering the user interfaces available is important when searching for data loggers and data recorders.  User interfaces available include no display, front panel and display, touch screens, hand-held or remote programmers, and computer programmable.  Host connection choices include direct backplane interface, RS232, RS422, ST485, USB, IEEE 1394, GPIB, SCSI, TTL, parallel, Ethernet, modem, and radio or telemetry.  The transmission rate of data is important to consider.  Many data loggers and data recorders are web enabled for web addressing.  Additional specifications to consider when searching for data acquisition systems and instruments include application software, memory and storage, network specifications, and environmental parameters.

Data acquisition is the processing of multiple electrical or electronic inputs from devices such as sensors, timers, relays, and solid-state circuits for the purpose of monitoring, analyzing and/or controlling systems and processes.  Data acquisition instrument types include computer boards, instruments or systems, dataloggers or recorders, chart recorders, input modules, output modules, and I/O modules.  Computer boards are self-contained printed circuit board with full data acquisition functionality; typically plugs into a backplane or motherboard, or otherwise interfaces directly with a computer bus.  Instruments or systems are fully packaged with input and output, user interface, communications capability, etc. They may include integral sensors.  Data loggers and data recorders are data acquisition units with instrument functionality with specific capability for data storage. May be for general purpose or application-specific data acquisition.  Chart recorders generate real-time plots, graphs or other visualizations of data.  Input modules are devices (module or card) configured to accept input of sensors, timers, switches, amplifiers, transistors, etc. for use in the data acquisition system.   Output modules are devices with specific functionality for output of amplified, conditioned, or digitized signal.  I/O modules have both input and output functionality. Digital or discrete I/O includes on-off signals used in communication, user interface, or control.

Common form factor for data acquisition devices include IC or board mount, circuit board, panel or chassis mount, modular bay or slot system, rack mount, DIN rail, and stand-alone.  Common device specifications to consider when searching for data acquisition products include differential analog input channels, digital I/O channels, sampling frequency, resolution and accuracy.  Common signal inputs available for data acquisition products include DC voltage, DC current, AC voltage, AC current, frequency, and charge.  Sensor inputs include accelerometer, thermocouple, thermistor, RTD, strain gauge or bridge, and LVDT or RVDT.  Specialized inputs include encoder, counter or tachometer, timer or clock, and relay or switch.  Transducers and excitation are also important to consider when searching for data acquisition.  Many products have integral sensors or transducers.  These sensors can have voltage or current excitation.  Common outputs for data acquisition products include voltage output, current output, frequency output, timer or counter output, relay output, and resistance or potentiometer output.

Considering the user interfaces available is important when searching for data acquisition products.  User interfaces available include no display, front panel and display, touch screens, hand-held or remote programmers, and computer programmable.  Host connection choices include direct backplane interface, RS232, RS422, ST485, USB, IEEE 1394, GPIB, SCSI, TTL, parallel, Ethernet, modem, and radio or telemetry.  The transmission rate of data is important to consider.  Many products are web enabled for web addressing.  Common applications for data acquisition products include general lab or industrial, environmental, vehicular, marine, aerospace or military, seismic or geotechnical, weather or meteorology, and medical or biomedical.  Additional specifications to consider when searching for data acquisition products include application software, memory and storage, network specifications, filter specifications, amplifier specifications, and environmental parameters.

Paper recording charts and consumables consist of circular charts, strip charts, markers, fanfolds, sheets, pens, and pen arms used in chart and strip recording instruments. A chart recorder is an instrument used to record various process and electrical signals. The paper is passed under a pen and the pen is deflected in proportion to the signal. The result is a graph or chart of the data. There are many types of paper recording charts. Examples include circular charts and strip charts. Circular charts are used in circular chart recorders which record data in a circular format. The paper is spun beneath one or more pens. The pens are deflected in proportion to the varying signal resulting in a circular chart. Strip charts are used in strip chart recorders which consist of a roll or strip of paper that is passed linearly beneath one or more pens. As the signal changes the pens deflect, producing the resultant chart. Paper recording consumables refers to various other instruments and materials, such as sheets, paper, and pens, which are used in a chart recorder. Other paper recording charts and consumables are commonly available.

Paper recording charts and consumables are available in various sizes according to the required specifications. Chart recording paper is defined by its part number, which determines its size. Various sheets of paper are used for making a particular type of chart. A specialty paper called strip chart paper is used for making strip charts, which are used with strip recorders. An industrial recording chart is used with an industrial recorder. Generally, industrial recorders have the recording width of 100mm and 180mm. Recorder pens are an important paper recording consumable used in chart recorders. Recorder pens are used to write in style and record the data. Recorder pens may have fiber tip or micro tip. Paper recording charts and consumables are manufactured to meet most industry specifications.

Paper recording charts and consumables are used in many applications. Examples include its use in recording data of a given environment, such as refrigeration, air conditioning, storage, transport, and workplace or home monitoring. Paper recording charts and consumables should adhere to various standards specified by American National Standards Institute (ANSI) and International Standards Organization (ISO) standards.

Chart recorders and strip charts are data acquisition tools used to generate a plot, graph or other visualization of data versus time. Common applications include temperature and humidity measurements, chromatography, spectroscopy graphs, and plots of the output of a wide range of other lab and test equipment.

Chart recorders typically output data in one of four common formats.  These include circular x-y plotter, strip chart, or paperless, video graphing.  Circular charts rotate uniformly while variable is plotted radially. Advantages include relatively compact size and simplicity of operation. Revolution time may span from minutes to days.  In an X-Y plotter two selectable variables are plotted against each other in rectilinear coordinates. The paper source is often a standard size sheet, but can also be a roll or drum. Plotted variables may include mathematical functions of data input.  Strip charts plot variables with regard to time, as the paper strip advances uniformly through the plotter. Strip frequently comes off a roll for space conservation.  In a paperless or video graphing system the plot is displayed on video screen; scaling and mathematical functions possible.  Chart recorders and strip charts can produce multiple plots simultaneously.

Important data acquisition specifications for strip charts and chart recorders are differential analog input channels, digital I/O channels, sampling frequency, resolution, and accuracy.  Differential channels use the difference between two signals as an input; common mode is filtered out. In some systems, differential inputs are combinations of two single-ended inputs; in this case, twice the number of differential channels would be available as single-ended inputs.  Digital or discrete channels are used for low-level on-off signals used in applications such as communication, user interface, or control.  The sampling frequency is the frequency of analog signal sampling and conversion to a digital value.  Resolution refers to the degree of fineness of the digital word representing the analog value. A ten-bit number contains 210, or 1024, increments. A 0-10V signal could therefore be resolved into approximately 0.01V increments. A 12-bit representation would be in 212 (4096) increments, or divisions of 0.0024V for the same signal. Each additional bit doubles the resolution, and one bit is required for the polarity (sign) of a number.  Accuracy depends on the signal conditioning linearity, hysteresis, temperature considerations, etc. It is represented here as percent full scale of measurement range.  Some chart recorders and strip charts come equipped with recorder or datalogger, which has instrument functionality with specific capability for data storage. May be for general purpose or application-specific data acquisition.

Common signal inputs for strip charts and chart recorders are DC voltage, DC current, AC voltage, AC current, frequency and charge.  Typical sensor inputs for chart recorders and strip charts are accelerometers, thermocouples, thermistors, RTDs, strain gauges or bridges, and LVDTs and RVDTs.  Specialized inputs may include encoders, counters or tachometers, timers or clocks, and relays or switches.

Features common to chart recorders and strip charts include transducers and excitation supplies, auxiliary outputs, user interfaces, communications with computers, application software and memory and storage functions.

 Syringes utilize a cylinder and plunger for precise delivery of liquids or gases in analytical, medical, pharmaceutical or biotechnology applications.  A syringe is a device used to inject medications or other liquids into body tissues or other media.  A needle is a slender hollow instrument for introducing material into or removing material from the body parenterally.  It is common for syringes to come with needles attached; it is not the rule, however.

The important parameters when specifying syringes are injection method, needle configuration, syringe volume, syringe scale graduations and pressure rating.  Syringes use one of two injections methods, manual or autosampler.  An injector is a mechanism for accurately injecting a predetermined amount of sample.  The injector can be a simple manual device, or a sophisticated autosampler that permits automated injections of many different samples into the liquid stream for unattended operation.  The needle may have one of two configurations if it is supplied with the syringe.  It may either be removable or fixed.  Syringe volume is the amount of sample the syringe can contain prior to injection.  Syringe scale graduations are the markings printed on the side of the scale for measuring the volume dispensed.  The pressure rating is the maximum pressure the syringe can withstand.

The important parameters when specifying needles are needle gauge, length, inner diameter and outer diameter.  When specifying a needle they range from largest to smallest, the larger the needle’s gauge, the smaller the needle. For example, a 4.0 gauge needle is larger (physical size) then an 8.0 gauge needle.  The important dimensions to consider for needles are length, inner diameter and outer diameter.  The outer diameter is dependent upon the gauge, but this is not true of the inner diameter.

Features common to syringes and needles include replacement needles included with the syringe, interchangeable plungers for the syringes, interchangeable barrels for the syringes, digital display and a Chaney adaptor, which provides a convenient method of performing multiple injections of the same volume of fluid without the need for careful reading of the syringe scale each time.

Pipettes and tips are used for accurate liquid handling in many lab applications. This area includes both pipettors, which are complete devices used to deliver a known quantity of solution to a vessel; and pipette tips, through which fluids are dispensed, which are often sold separately from the pipette or pipettor. Pipettes and tips are either of the classical style (glass) or digital.

There are three main types of pipettes and tips: positive displacement, air displacement, and Pasteur styles. Pasteur pipettes are small glass tubes with a bulb at the end used for dispensing small amounts of fluids. Positive displacement pipettes are used for high viscosity and volatile liquids. Both types of pipettes have a piston that moves in a cylinder, or capillary. In air displacement pipetting, a specified volume of air remains between the piston and the liquid. In positive displacement pipetting, the piston is in direct contact with the liquid.

Selecting air displacement pipettes and tips require special consideration. Air displacement pipetting, which is used for standard pipetting applications, is highly accurate. Even so, conditions such as atmospheric pressure, and the specific gravity and viscosity of the solution can have an effect on the performance of air displacement pipettes. Typically, air displacement pipettes are meant for general use with aqueous solutions.

Positive displacement pipettes and tips are used in applications that require extreme accuracy. These pipettes and tips are also recommended for specialized procedures such as DNA amplification. The microsyringe tips used in positive displacement pipettes are disposable, which helps avoid sample-to-sample and cross-contamination, and contamination due to the aerosol effect.  Positive displacement pipettes and tips are also used for high viscosity and volatile liquids.

Dispensers feed measured amounts of sample material into trays, vessels, microplates, or centrifuges, without human contact with the material. These devices may be operated manually, automatically timed, or computer controlled for more complicated projects.  Dispensers are used instead of simply pouring out materials because they are more accurate, help to cut down on waste, and lessen the risk of sample contamination.

The most common types of dispensers are bottle top and burette dispensers.   Bottle top dispensers portion out small volumes of sample from a bottle safely and reliably without contamination or waste.  Pouring introduces the possibility of contamination each time the bottle is opened and invariably leads to waste.  Burette dispensers are used for the volumetric transfer of reagents for titration.  They consist of a calibrated barrel, a delivery tip, and a valve (stopcock).  There are other far less common types of dispensers, but these tend to be designed for proprietary needs.

When determining which of the many dispenser types is best for a given set of applications, or expected uses, there are a number of criteria that should be specified.  It is important to be aware of the level of accuracy that will be needed.  Most dispensers function with a degree of accuracy between .5 to 1.0% of accepted values.  If the dispenser will be used in very sensitive tests, it may be better to tend towards those devices with a higher degree of accuracy.  Similarly, the volumetric increments to which the dispenser is geared will help to gauge its reliability for certain applications.  While milliliters are the most common increment, they are certainly not the only scale.  Additionally, it is important to be aware of the sample capacity of the device.  If the dispenser is going to be used often to produce or maintain reactions, especially in situations where it will not be directly supervised, or the experiment may take place over a period of days, a large capacity dispenser is suggested.

Diluters are used to simplify the process of sample preparation by diluting samples to standard concentrations. Most diluters come pre-programmed with standard (common) dilutions.  Common dilutions for concentrated samples are 1/4, 1/10, 1/25, 1/50, 1/100, 1/250, 1/500, 1/1000 and greater.  By using diluters, samples can be prepared in less time than standard manual methods, such as mixing solutions in a volumetric flask.  Diluters may also be used to make smaller quantities of a solution, when compared with other analytical techniques, such as atomic absorption spectrometry (AA), gas chromatography (GC), and high performance liquid chromatography (HPLC); thereby limiting solvent consumption and reducing overall waste and disposal costs.

When selecting between diluters, it is important to take the following specifications into account: accuracy, precision, solvent volume, and sample volume.  Accuracy describes the nearness of a measurement to the standard or true value, i.e., a highly accurate measuring device will provide measurements very close to the standard, true or known values.  Precision is the degree to which several measurements provide answers very close to each other. It is an indicator of the scatter in the data. The lower the scatter, the higher the precision.  Solvent volume is the amount of solvent (the substance that is used to dilute the sample) that the diluter can accept.  Generally, solvent volume needs increase, as concentration of the sample decreases.  Similarly, sample volume is the amount of sample material that diluters are designed to accept.

Once the diluters’ performance specifications are determined, the next step is to determine the display or interface options that best suit the given application.  Diluters are available with local interfaces or computer interfaces.  Local interface diluters should be selected if the device will be used for single batches, occasional operation, or if the sample preparation requires close supervision and alteration.  Local interface options include analog and digital panels for reaction information display and input.  Computer interfaces are appropriate for continuous batching of sample, preparations that require numerous steps, or long reaction times, or in laboratory settings where multiple activities are taking place.  Additionally, computer interfaces are useful if careful data tracking and logging is necessary, as well as remote display of data.

Autosamplers are automated sample loaders, usually robotic, used with chromatography, atomic absorption and other analytical technologies. Autosamplers are designed especially for laboratories that process large numbers of samples on a routine basis. They are used for a variety of tasks, ranging from general HPLC needs up to dedicated solutions for high sample throughput.  Most are designed to interface with PC systems, and some autosamplers can be remotely computer controlled.  Complete remote control of all operational parameters such as injection time, number of injections per vial, rinses, three auxiliary contact closures, and internal injection valve actuation are available by means of optional serial or parallel interfaces.

Autosamplers may use a variety of receptacles to accept sample or reagent injection. These include simple vials, wellplates, or graphite furnace sample cups.  Wellplates, also known as microplates, are plastic plates or cassettes containing a specified number (typically 96 or 384) of small wells arranged in rows.  Researchers commonly use them to conduct numerous chemical reactions at the same time. Graphite furnaces are used in atomic absorption spectroscopy to atomize a sample.  The sample crucible is usually a cup cut from hollow aluminum or magnesia tubing.  Syringes or injector valves are the usual methods used to inject materials into the testing receptacles. Some varieties of autosamplers are specifically configured for one type of receptacle platform, while others can use them interchangeably.

Autosamplers are used in a wide variety of applications.  These can range from analysis of Organic Volatile Impurities (OVIs), plastics, polymers, blood alcohol analysis, and flavors, to semiconductor applications and any ultratrace analysis of commonly occurring elements. Clinical applications including drinking water testing, wastewater analysis and reclamation projects, soil composition, toxicity analysis.  In addition, a range of QA/QC control procedures, such as the EPA protocols, can be automated using the optional Intelligent Sequencing Software.

 Vials are small glass or plastic bottles used for storage.  Depending on supplier they can be supplied in amber or clear glass, plastic, with or without markings and in various configurations of features and sizes.  Vials can be used for media, diagnostic, storage, display and sample collection applications.  Vials have different mouth and cap styles to accommodate different types of applications.  The mouth of a vial can either be a standard size or wide mouth for facilitation of adding and dispensing samples.  The connection type for vials is typically one of five standard types, screw thread, crimp, snap seal, snap ring and RAM for robotics.  A screw thread connection is an external threaded connection.  A crimp style connection is not threaded; a cap would "crimp" on.  A snap seal connection is a special style of crimp that allows a seal to snap on.  A snap ring connection is a special style of crimp that allows a ring to snap on to the vial.  RAM for robotics is a special style of thread designed for robotic applications.

Important parameters to consider when specifying vials are volume, drams, outer diameter and height.  The volume of the vial is the maximum amount of sample that the vial can hold.  A dram is a unit of fluid measurement common to laboratory applications; one dram is about 3.7 mL.  The outer diameter of the vial is important in applications where an autosampler would be used.  The height of the vial is important in applications where an autosampler would be used.

Features important in specifying vials include limited volume inserts, high recovery, shell vial, marking spots, and self-centering springs.  Limited volume inserts are used to limit the volume that the vial can contain.  High recovery vials allow for a maximum amount of the sample to be recovered.  A shell vial is an inexpensive thin walled cylinder.  Marking spots are square or graduated spots to denote volumes.  Self-centering springs allow for re-centering when used with an autosampler.