Written by former Delaware Ghost Hunters President, John R. O’Neil
The Diamond State Ghost Investigators always strive to investigate the paranormal with a science based approach. It is our belief that through the applied knowledge of science and technology we can come to an understanding of paranormal and supernatural occurrences. Our goal is to investigate the presence of paranormal phenomena and ghostly hauntings, and document the presence of spirits in our everyday life through evidence collected in a scientific manner.
However, the world of paranormal technology can be more than confusing at times. In such a rapidly emerging field of study, new equipment and theories are presented nearly everyday. To help keep things sorted and give you some insight into the devices which we use on investigations, we present to you information on the science and equipment used during the investigation of the paranormal world. Get comfortable… It’s about to get technical in here!
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EMF
PARANORMAL PHOTOGRAPHY
TEMPERATURE MONITORING
Changes in EMFs are one of the physical conditions believed to contribute to the manifestation of ghostly apparitions. It can also be one of the most misunderstood. Most of the questions asked related to EMFs tend to focus upon the following questions:
1. EMF?
EMF stands for Electro-Magnetic Field. It consists of two distinctly separate fields called electric and magnetic. EMFs are non-ionizing electrical and magnetic waves of energy that radiate from an electrical circuit or device.
2. Fear Cage is the name of a band isn’t it?
No. A Fear Cage Effect is a localized high concentration of EMF contained within a localized area. It is typically caused by faulty or old wiring that causes large amount of leakage of the magnetic leakage field and causes electrical charging of the surrounding air space.
3. How do I differentiate between what is normal or paranormal?
Paranormal Investigators should focus attention on EMF readings that are inconsistent and non-repetitive, and above and 2 and less than 8 milli-Gauss (mG).
4. What types of equipment can be used to detect and measure EMFs?
There are several different types of commercially available EMF detectors and measurement (meter) devices. They are designed to measure the amount of EMF given off by most U.S. domestic household appliances (50 – 60 Hz depending upon the governing market application). Most EMF detectors or meters marketed are affordable for the average paranormal investigator.
Introduction
An Electro-Magnetic Field (EMF) is made up of two distinct and separate fields called electric and magnetic. Electromagnetic fields may also be known as electromagnetic radiation (EMR). EMFs are non-ionizing electrical and magnetic energy (waves) that radiate from an electrical circuit or device. Most of the electromagnetic fields experienced are generated by household or industrial appliances, equipment, or distribution circuitry within the location.
EMF is an invisible byproduct of electricity. When the device’s motor is not plugged in and operating or a switch is left open (device off), the electrons are not free to move through the cable’s wire, therefore, no electromagnetic field exists. After the switch is closed or the device is plugged in (device turned on) the electrons are allowed to freely flow (current) and a magnetic field is created that exists around the circuit and the connected device. The frequency of the wave is dependent upon the device itself. Most of the commercially available EMF detectors or measurement devices are affordable to the average paranormal investigator.
EMF Fear Cage Effect
A phenomenon coined “fear cage effect” occurs when there is a high concentration of EMF contained within a localized area. “Fear cage” effects are typically caused by faulty or old wiring that causes a large amount of magnetic leakage field and electrical charging of the surrounding air space. People walking into the “cage” complain of symptoms such as nausea, paranoia, the feeling of being watched, anxiety, anger, and mood swings. Some people may even feel euphoric. Although non-ionizing radiation is not strong enough to alter atoms, it can be strong enough to heat up human tissue and that can contribute to these types of feelings.
Many people said to have experienced paranormal activity may have felt the same symptoms associated with that of a fear cage. It is recommended before investigating location that client interviews are conducted and EMF measurements are taken.”
The concentrated presence of high EMFs may be contributing to an illusion of paranormalcy. Recently conducted research by researchers shows some individuals’ brains may be highly susceptible to EMF emissions. Their studies have shown has shown a brain sensitive to electrical stimuli may be interfered with by the leaking EMFs causing one to believe they had experienced something “strange” where one or more of the five senses was affected.
When combined, the information acquired can help identify locations where paranormal activity may have occurred and even possibly explain it based upon the physical environment. Investigators should carefully monitor and locate areas where incoming power lines, switch boxes, unshielded wiring (old) or operating air conditioning units, motors, and pumps could possibly be contributing to inordinately high EMF.
Laboratory experiments have indicated the critical frequencies that affect the mind are lower, in the 0.5Hz – 30Hz range. Brain activity is seen typically in ranges referred to by Greek letters: Delta (0.5-4Hz), Theta (5-7Hz), Alpha (8-12Hz), Beta (18-30Hz) and Gamma (30-50Hz). It is the lower ranges – Delta – Beta that typically cause the subject to experience events that they may describe as being paranormal.
Most EMF detectors and meters measure the amount of EMF given off by domestic appliances at 50H – 60 Hz. European electrical circuits operate using 50 Hz whereas American electrical circuits use 60 Hz. Many paranormal investigators suggest that the effects of electricity may be linked to the effects upon the mind and reported paranormal activity.
EMF Detection & Measurement Equipment
An important primary instrument used to conduct paranormal investigation is an EMF detector or meter. There are several different types of commercially available EMF detectors and measurement (meter) devices. Most EMF detectors or meters marketed are affordable for the average paranormal investigator. They are designed to measure the amount of EMF given off by most domestic household appliances.
EMF detectors are mainly used to locate the presence or strength of an EMF field and determined how far it may extend from the source. An exact measurement of the amount of EMF is not usually needed unless one is attempting to quantify the actual amount of leakage occurring or determining the presence of a “fear cage”. EMF detectors are designed to detect electromagnetic emissions from appliances such as microwave ovens, compressors, motors or high voltage power lines and electrical circuits. EMF detectors alert investigators to the presence of EMFs by measuring electromagnetic distortion in the 2 -8 milli-gauss (mG) range. A visual alert such as a light emitting diode (LED) or audible alarm usually exists such as on a KII device.
KII EMF Detector
A detector does not indicate an actual readout of a measured numerical value. Detectors alert the operator that EMFs were detected and exceeded a pre-established threshold. Most standard EMF detector LED lights represent a 1 mG change at the X10 setting. Many paranormal investigators believe reading between 2-8 mG could be possibly indicative of paranormal activity.
EMF meters measure the amount of electromagnetic radiation and display the reading obtained. Some EMF equipment is capable of measuring alternating fields as low as 20 Hz. Frequency is measured in Hz (number of cycles per second). EMF meters and detectors of suitable quality can also be used able to locate extremely low frequency (ELF) and high EMFs (hotspots).
Paranormal researchers should be interested in detecting and measuring extremely low frequency (ELF) magnetic fields. Measurement of electromagnetic fields can be obtained using specially designed sensors or probes. The probes used are antennas that don’t disrupt the electromagnetic field and don’t cause coupling or reflection in order to obtain a precise measurement. The two most common types of EMF measurement devices include:
* Broadband: Measurements are obtained using a broadband probe that senses any a wide range of frequencies and is typically made of using three independent diode detectors.
* Narrowband: Frequency measurements are taken by either a field antenna and a frequency selective receiver or spectrum analyzer that allows monitoring of a specified frequencies within a given interest range.
Single (mono) axis meters are less expensive than tri-axis meters. Single axis meters require more time to complete a survey because the meter only measures one dimension of the field. Single axis instruments have to be tilted and turned on all three axes to obtain a full measurement. The Lutron 822-A Digital EMF Meter is an example of an economical digital low-frequency EMF meter with great sensitivity. It is capable of measuring a range between 0.1 milli-Gauss, and 199.9 mG.
An isotropic (tri-axial) probe simplifies the measurement procedure because the measurement obtained includes the field’s three values (X, Y and Z). The reading displayed is taken simultaneously without changing the sensor’s position. The unit’s three independent broadband sensing elements are placed orthogonal to each other and measure using three consecutive time intervals. These models tend to be somewhat more expensive. The Tri-field Electromagnetic Field Meter is a time tested proven meter used to conduct paranormal investigations. It allows simultaneous independent testing of the electrical and the magnetic fields – both components of electromagnetic radiation.
Tri-Field Meter
EMF measurements obtained using an E-field or H-field sensor can be isotropic or mono-axial, active or passive. A single axis (mono-axial), omni-directional probe senses electric or magnetic field polarity in a single given direction. Single probe designs require the investigator to take three individual separate measurements in the X, Y, Z directions.
The Tri-field meter has both high and low sensitivity range settings that can be used to measure magnetic radiation. It measures EMFs in all three planes simultaneously and sums them electronically into one single reading. It does not require any movement by the investigator. It also measures radio / microwave EMF but lacks sensitivity in this range. The Tri-field meter is a good tool to detect EMF leaks from normal electrical circuits but shouldn’t be used to monitor cell phone tower or radio station antenna, or wireless network EMFs. The Natural EM Tri-Field is an excellent commercially available EMF monitoring device that a paranormal investigator should own and use. It is a hand-held, stand-alone device that enables paranormal investigators to see real time changes in field strength. Other meters, such as the Model 1394 Tri-axial digital meter must be linked to a PC for either real-time or data-logging and can be used for greater degrees of accuracy at a slightly higher cost.
Investigation Application
The best way to use your EMF meter is to hold it in a manner such that the sensors located near the top of the meter are not obstructed. Be advised that metallic objects such as jewelry (e.g. rings, bracelets and watches) may interfere with the meter’s reading. It should be noted EMF meters and detectors can be caused to artificially activate by placing a magnet in the area of the meter or detector. They also can be activated using radio waves such as that from cell phones or walkie-talkies.
Some paranormal investigators believe ghosts can cause EMF readings to vary in strength as EMF energy is absorbed during manifestation. Other investigators believe ghosts emit or give off EMF radiation as they manifest and that condition is measured when their EMF detector is activated or a reading is obtained. Ghosts are not known to radiate electro-magnetic energy. The internet and television shows have contributed to misinformation regarding EMF detectors being used as ‘ghost detectors’.
Paranormal Investigators attention should focus on EMF readings obtained are inconsistent (non-repetitive) in nature and above 2mg and less than 8 mg (>2 mG and <8 mG). Obtained stable EMF readings below 2 mG should be ignored because they are indicative of stray EMFs coming from distant high voltage lines, microwaves, instrument vibration, or ungrounded circuits. Readings found above 8 mg are typically due to environmental conditions due to environmental conditions such as electrical circuits, operating motors, or compressors, etc. One of the biggest mistakes investigators make is conducting a baseline measurement of a location and then never revisiting the baseline during the investigation. EMF detectors and meters should be used throughout the investigation and whenever there is an unusual occurrence. EMF readings obtained should be cross referenced against other evidence obtained from instruments that were in use at the time such as audio recorders, captured photographic evidence, or thermometers. EMF’s , exist within most location environments. Their strength may vary depending upon the age of the location and wiring, appliances used, etc. It is wrong to assume that any EMF reading detected or measured is of an anomalous or paranormal origin without added extensive examination and evaluation. The tools we use as investigators may simply be the wrong type and may not be capable of detecting causal emissions. The information supplied by EMF detectors or measurement devices should only be treated as a tool; a guide to help the paranormal investigator discern between the presence of a fear cage effect or potential subtle changes in a electrically charged environment that may or may not be demonstrating consistent or inconsistent behavior.
Help me Paratech-Geek! What are these things I’m seeing in my paranormal investigation photos?
Visual evidence is one of the most desired forms of documented evidence that can be used to validate the presence of ghostly apparitions. It can also be one of the most misunderstood. As paranormal investigators, we are often shown photos taken by folks wanting to know if what they captured in a picture is ghostly or paranormal in nature. Many times the captured image can be validated or simply explained. There are many photographic terms to which paranormal investigators can refer to help explain the image captured in a photo. The following are a snapshot of the terms DSGI references and utilizes most often.
You may be asking yourself “how can a picture be noisy?” Image noise is similar to that of white noise heard in audio or video. Image noise is the grainy appearance sometimes seen in photos taken with a digital camera. It can appear as multi-colored specks which show up really well in a dark or shadow area of an image. Image noise can also show up as grainy speckles randomly scattered throughout the image. While image noise can sometimes create a nice photographic effect in the picture it usually unwanted; particularly when the image is enlarged.
Most photographs contain image noise to various extents. You may not be able to actually see the noise in your image at the time you take your photograph but there is some form of image noise contained in every picture taken. When using a digital camera light that enters the lens and miss-aligns with the sensors will cause image noise. Steps can be taken to reduce the amount of image noise in your photos.Most folks taking photos in hopes of capturing an image of a ghostly apparition take their photos in darkness or at nighttime. Taking pictures in darkness requires longer exposure times or higher ISO speeds that are more susceptible to pixilation. The sensor intensifies the light taken in through the lens causing bright dots to appear throughout the image.
Using a flash can prevent such a noise. It is also the most inexpensive way to take clear crisp photos and avoid brighter image noise showing up in a photo taken low lighting area.
Orbs
Orbs are the most often found and misunderstood photographic phenomenon existing within the paranormal investigative community. It is a commonly used term in photography and the paranormal community that describes the presence of a circular light forms appearing within a captured image. Orbs are a very controversial topic amongst the paranormal community. Some paranormal enthusiasts believe an orb is a spiritual energy form trying to manifest. Other paranormal investigators believe orbs are merely light reflecting from particulate matter in free air. The term orb used in photography is: “artifact captured during the low-light instances where the camera’s flash is used, such as at night or underwater or where a bright light source is near the camera.” These types of artifacts are especially common with compact or ultra compact cameras and cell phones where the short distance between the lens and the built in flash decreases the angle of the light reflection to the lens. Orb artifacts can result from light being reflected from solid particulate matter such as dust, pollen, insects, and water droplets within a camera lens’s field of view.
Most orb artifacts typically appear as white or semi-transparent circles containing the whole or partial colors of the spectrum. Some orbs seen with photos containing color are actually particulate matter reflecting light of colors within the room or area. For example a room painted yellow may possess yellow orbs, or a green orb may be associated with dust matter in a green carpeted room. Orbs are not normally paranormal in nature they are simply the camera capturing the light being reflected off normally sub visible particles. The best thing to compensate for orbs is to move your flash further from your lens or add a shroud around the outside of your lens. To the right are examples of “orbs” that were taken with digital cameras.
Matrixing
Matrixing is another popular photography term used by paranormal investigators to describe the human mind’s ability to take random sensory data and rearrange it to an orderly form that is recognizable and most familiar. Matrixing anomalies make us see something that really isn’t there, such as a face peering from a tree, or cloud shapes resembling that of a giraffe.
What do you see?
1. Stone
2. Devils face
3. Indian totem pole figure
4. Carved statue
Perhaps each of these answers is correct. This question was asked of several people and these were some of the typical responses received. The image in the circle represents a matrix view of a Devils face.
Motion Blur
Motion blur is typically caused by camera movement or object movement while a picture is being taken. Motion blur is not necessarily a bad thing. Creative photographers oftentimes use it to capture falling water, athletic actions, etc. It is practically impossible for a photographer to hold a camera perfectly still without using a tripod.
A photographer’s movement of the camera can contribute to motion blur. A paranormal enthusiast taking a photo at night should set his or her cameras’ setting properly and then listen for the shutter to open and close after depressing the button to take the picture.
Just because the flash fired does not mean the photo has been taken. Given the slower shutter speeds any movement of the camera before the shutter closes will cause shadows and blurring of the photo.
Conclusion
It never should be assumed that just because a picture doesn’t look normal that the paranormal must be the explanation. This usually happens due to hopes of capturing an apparition image and over-scrutinizing a photo. Evidence of paranormal activity should be able to stand on its own and up to the scrutiny of the paranormal community. Remember a camera is not looking for a ghost when you take the photo, it is attempting to adjust automatically to the best possible settings to take the best possible picture in the environment that the photo is being taken.
TEMPERATURE MONITORING
Help me Para-Tech-Geek- what type of temperature measuring device should I choose to conduct my paranormal investigations?
The best and most common ways of measuring ambient area temperatures are with infrared pyrometers, resistance temperature detectors (RTD) and thermocouples (TC). The choice between them is usually made by determining responses to the following five (5) basic questions:
1. What are the temperature requirements?
If process temperatures are between -328 to 932 °F (-200 to 500 °C), an industrial quality infrared pyrometer and resistor temperature devices (RTD) type are the preferred option. Thermocouples (TC) have a range of -180 to 2,320 °C (-292 to 4,208 °F).
2. What are the time-response requirements?
Infrared and RTD devices should be used to conduct paranormal investigations given it has relatively fast response time to temperature changes—seconds (e.g. 2.5 to 10 s). Thermocouples have the fastest response time- fractions of a second
3. What are the accuracy and stability requirements?
RTDs are capable of high accuracy and can maintain stability for many years, while thermocouples can drift within the first few hours of use. Infrared detectors are subject to the type of material and surface condition due to variations in emissivity.
4. What should be used to measure surface temperature of various types of materials?
Portable “gun type” Infrared pyrometer devices respond quickly and should be selected and used to measure surface temperatures of such things as heating ducts, chairs, windows, doors, etc.
5. Should temperature monitoring be obtained continuously or as needed?
RTD data loggers are an excellent tool to continuously monitor subtle changes in an area’s temperature, and humidity. Infrared portable “gun type” are used to measure surface temperatures of such things as heating ducts, chairs, windows, doors, etc.
Paranormal Premise
Ghostly theory believes sources of potential energy must be drawn upon in order for kinetic energy to occur. Meaning, in order for a spirit to manifest itself into an apparition it needs to have a source of power to draw upon. Sources of energy that can be drawn upon can come from the local environment such as electrical, thermal, or kinetic. Therefore, the transfer of thermal energy from the environment for a manifestation to occur, a communicating voice, tap, object movement would result in a reduction of temperature as that energy is drawn. Like a heating furnace being shut off on the coldest night of the year or a lantern battery going dead unexpectedly the heat leaves the area and is replaced by coldness.
Thermometers can be used to measure the environment’s temperature. It is recommended that temperature – humidity data loggers be used to routinely to capture evidence regularly at set intervals such that subtle changes in the environment can be measured.
Technical Explanation
Temperature measurement may be achieved using several different methods. Most of the methods rely upon measuring some sort of physical property of a working material that varies with changes in temperature. Investigators must be careful when measuring temperature to ensure that the measuring instrument (thermometer, thermocouple, etc.) is actually recording and displaying the same temperature as the thing being measured. Under some conditions heat from the measuring instrument can cause a temperature gradient that causes the displayed temperature to be different from the actual temperature of the region being measured. An extreme case of this effect gives rise to the wind chill factor, where the weather feels colder under breezy conditions than calm conditions even though the temperature is the same. What is happening is that the breeze increases the rate of heat transfer from the body, resulting in a larger reduction in body temperature for the same ambient temperature.
One of the most commonly used devices used to measure temperature is a glass thermometer. Unfortunately, these are not adequate to measure temperature when conducting a paranormal investigation because they are too slow to respond to subtle or rapid changes in temperature. Glass thermometer tubes are filled with mercury or another liquid that acts as a working fluid it takes a while for the fluid volume to expand as the temperature rises, or contract as the temperature drops.
Bimetallic temperature measuring devices take advantage of the difference in rate of thermal expansion between different metals. Strips of two metals are bonded together. When heated, one side will expand more than the other, and the resulting bend is translated into a temperature reading by mechanical linkage to a pointer. These devices are portable and they do not require a power supply, but they are usually not as accurate as thermocouples or RTDs and do not readily lend themselves to temperature recording and are therefore not recommended for investigating. Other types of equipment that can be used to measure temperature changes during our investigations include:
* Thermocouple Sensors (TC)
* Thermistors and Resistance Temperature Detector (RTD)
* Infrared Pyrometer
Thermocouple Sensors
Thermocouple sensors such as the Mel Meter, and the Environment Meter, generally utilize a K connection probe plug to measure temperature.
Thermocouples (TC) are pairs of dissimilar metal wires joined at least at one end, which generate a net thermoelectric voltage between the open pair according to the size of the temperature difference between the ends, the relative Seebeck coefficient of the wire pair and the uniformity of the wire pair. TCs are possibly the easiest temperature sensors to use and obtain and are used widely in scientific and industrial applications. They are “simple”, rugged, need no batteries, and measure over a wide range of temperatures. TCs consist of essentially two strips or wires made of different metals and joined at one end. Changes in the temperature at that juncture induce a change in electromotive force (EMF) between the other ends. As the temperature increases the amount of EMF output rises, though not necessarily linearly.
Resistance Temperature Devices (RTD)
Resistance Temperature Devices (RTD) instruments have the ability to continuously record ambient temperatures and humidity at present intervals. Obtained readings may be downloaded into a computer and graphed using manufacturer supplied software. A disadvantage of using data loggers is highly dependent upon proper location placement. Data loggers provide a retrospective view of the collected information is a reliable way of collecting data and can be used to validate any anomalies having occurred within an investigation’s time frame.
Resistance thermometers are constructed in a number of forms and offer greater stability, accuracy and repeatability than thermocouples in some cases. Resistance thermometers use electrical resistance and require a power source to operate. Resistive temperature devices capitalize on the fact that the electrical resistance of a material changes as its temperature changes. Resistance thermometers are highly accurate (design dependent), reliable (low drift), and cover a wide temperature range
Measurement of resistance requires a small current to be passed through the devise under test. This can cause resistive heating, causing significant loss of accuracy if manufacturers’ limits are not followed. Mechanical strain on the resistance thermometer can also cause inaccuracy. The accuracy of the unit also depends upon the amount of lead wire resistance based upon the two, three or four wire design. The three wire design is sufficient for most applications. If more preciseness is desired by the investigator then it is recommended that a four wire design be used. Resistance thermometers are usually made of platinum because of its linear resistance temperature relationship and chemical inertness.
Data Loggers
Thermistors are based on resistance change in a ceramic semiconductor; the resistance drops nonlinearly with temperature rise. Compared to thermistors, platinum RTDs are less sensitive to small temperature changes and have a slower response time. However, thermistors have a smaller temperature range and are considered more stable. It should be noted that increased EMF due to poorly shielded or unshielded electrical cabling may cause an individual physically ill effects but it can also result in contaminated temperature measurements due to stray currents leaping between the leads.
Infrared Pyrometers
Infrared pyrometers are great for detecting objects that may make the room cooler (drafts) or hotter (heating ducts), and detecting temperature changes in physical objects.
Infrared pyrometers are non-contact temperature measurement devices. They infer temperature by measuring the thermal radiation emitted by a material. Infrared pyrometers are useful for measuring component surface temperatures. Infrared pyrometers with a laser beam are typically used by pointing and shooting at the object being measured. Infrared pyrometers are used to measure temperature where conventional sensors cannot be employed such as moving objects, or non-contact measurements are required because of contamination or hazardous reasons, where distances are too great, or where the temperatures to be measured are too high for thermocouples or other contact sensors. The most basic infrared pyrometer design consists of a lens to focus the infrared (IR) energy on to a detector, which converts the energy to an electrical signal that can be displayed in units of temperature after being compensated for ambient temperature variation. This configuration facilitates temperature measurement from a distance without actually contacting the object to be measured.
When selecting noncontact temperature measurement instruments, it is necessary to take into account not only the target and its emissivity, but also the surroundings and the intervening atmosphere. Readings obtained can be influenced by color and reflection of the surface it is pointed at. The critical considerations for any infrared pyrometer include field of view (target size and distance), type of surface being measured (emissivity considerations), spectral response (for atmospheric effects or transmission through surfaces), temperature range and mounting (handheld portable or fixed mount). Emissivity is defined as the ratio of the energy radiated by an object at a given temperature to the energy emitted by a perfect radiator, or blackbody, at the same temperature. The emissivity of a blackbody is 1.0. All values of emissivity fall between 0.0 and 1.0. Most infrared thermometers have the ability to compensate for different emissivity values, for different materials. In general, the higher the emissivity of an object, the easier it is to obtain an accurate temperature measurement using infrared. Objects with a very low emissivity (below 0.2) can be difficult applications. Some polished, shiny metallic surfaces, such as aluminum, are so reflective in the infrared that accurate temperature measurements are not always possible.
The field of view is the angle of vision at which the instrument operates and is determined by the unit’s optics. To obtain an accurate temperature reading the target being measured should completely fill the instrument’s field of view. The infrared device determines the average temperature of all surfaces within the field of view. If the background temperature is different from the object temperature a measurement error can occur. More accurate readings can be acquired when it is closer to the object being measured. At a distance of 6 inches you will be roughly measuring a spot size of about one inch- the further away you are the wider the spot size.
The pyrometer can be either mounted or portable. Fixed mounted units are generally installed in one location to continuously monitor a given process. They usually operate on line power, and are aimed at a single point. The output from this type of instrument can be a local or remote display, along with an analog output that can be used for another display or control loop. Handheld infrared thermometers are one of the most popular types of infrared pyrometer. They are commonly used for portable applications although some models also feature an integral tripod mount. Battery powered, portable infrared ‘‘guns’’ units have all the features of the fixed mount devices, usually without the analog output for control purposes. Generally these units are utilized in maintenance, diagnostics, quality control, and spot measurements of critical processes.
Conclusion
Temperature measurement may be achieved using several different methods. Most of the methods rely upon measuring some sort of physical property of a working material that varies with changes in temperature.