DSGI To Continue Fort Delaware
Paranormal Adventure Tours!
Diamond State Ghost Investigators are excited and honored to announce that we have renewed our contract with Fort Delaware to continue to serve as the premier paranormal group to host, along with Fort Delaware, the fall Paranormal Adventure Tours for 3 more exciting years. We look forward to continuing to work with the fort to bring you a unique, exciting, and authentic paranormal experience not available through any other group in Delaware.
We hope to see all of you on Pea Patch Island this fall!!
Tickets for all October dates are NOW ON SALE! DO NOT WAIT LONG!! This tickets and dates sell out quickly! http://www.destateparks.com/park/fort-delaware/
We recently experienced some technical difficulties with our email servers. If you have tried to contact us through our website in the past few weeks we were unable to receive your message. We are deeply sorry! The good news is, our email is now up and running again! Feel free to visit our contact us page at: http://diamondstateghostinvestigators.com/contact-us/
and leave us a message! Again, we sincerely apologize for the inconvenience but hope you will drop us a line so we can get back to you as soon as possible!
You can also send us an email at: Contact@delawareghosthunters.com
Gina O’Neil of Delaware Ghost Hunters: The Thirty Second Interview
Gina O’Neil is vice president of the Delaware Ghost Hunters, which bills itself as “Delaware’s foremost paranormal investigating team.” She became interested in the paranormal after she had a vivid dream of her grandmother who had died a couple days before. You can catch O’Neil and the rest of the hunters at Fort Delaware on weekends throughout the month of October.
DT: How did you guys come together?
GO: The group was started back in 2005 by brothers. They had four or five members. They were doing basic investigations of homes and historical places. But nothing major. It was pretty low-key. In 2009 I saw they were recruiting. My husband, John, and I were both interested in joining their group. John hadn’t had any experiences, but I had some experiences in the past that I couldn’t quite place my finger on and just kind of brushed them off. But there were some paranormal TV shows that were gaining popularity and it piqued everybody’s interest. We both applied and were accepted into the group. The group has at least doubled since then. The brothers who originally formed the group are no longer with the group. We’ve lost members and gained a lot of good members. Right now there are 18 members.
DT: How do you recruit? Is it like baseball where they send out scouts to find the talent?
GO: It’s funny. When John and I were originally recruited for Delaware Ghost Hunters, it was just a basic phone interview with the lead investigator at the time. It was no big deal. We changed that format. We have a Web site, delawareghosthunters.com, and we’ll put it out there on the site that we’re recruiting for new applicants. You can click on the link and fill out an application with basic questions. We bring the people into an interview session and we kind of do it like rapid dating. We put a couple members at a couple tables and they have to cycle through all the tables and meet with all of us. We have set questions that we ask them. Then we decide who we like and we go to a second round. For the second part of the interview process, we have them do a mock investigation. We have them bring their own equipment and we pair them up with our members. We watch them investigate. We watch how they interact with each other and how they deal with things that they’re not sure about. We try to get a feel of how they would interact with the public because we do a lot of things with the public. So it’s a two-step process. Then from that second round we determine who we really want to keep going and who we don’t. Once we’ve decided, we put them on a three-month probation. They’re just considered investigators-in-training and that’s it. Once they get through that and there are no issues, then we bring them on as full-fledged members.
DT: Can you talk about the experiences that got you interested in this?
GO: I had an experience shortly after my grandmother passed away. I had a dream of her. It was a very vivid dream. In the dream, she came to me and said, “Please let your mother know (it was my mother’s mother who passed away) that your cousin came to visit me the night before I died and I was not able to communicate with her. I knew that she was upset that I couldn’t speak. But just let her know that I knew she was there and I appreciated that she came to visit me.” Then I woke up and I didn’t think anything about it. I think I was 15 or 16 at the time. The next morning I was eating breakfast and I said to my mother, “I had this crazy dream about Granny last night.” She said, “What do you mean?” So I told her. And my mom just looked at me and she had the strangest look on her face. She said, “How did you know that?” I said, “What do you mean, how did I know that?” I said, “I’m telling you I had this dream and Granny told me that my cousin had come to visit the night before, but she couldn’t talk.” And my mother said, “Well, that’s interesting,” because my cousin had gone down the night before my grandmother passed away. And my grandmother was unconscious at that point. And my cousin wasn’t able to communicate with her and she was upset when she left.
I had no idea that had even occurred. Like I said, the dream wasn’t a typical dream. It was very vivid. It was very real.
DT: What was the other experience?
GO: My father-in-law had passed away very suddenly. It was probably about two weeks after his death and I had a big votive candle burning inside of this candle holder that was on a stand in the living room. I was making dinner. It was in the evening and I was walking between the kitchen table and the stove, and I was putting food out, setting the table, things like that. And I saw this really bright flash of light at the end of the hallway near the living room. And I was like, What is that? I walked up to see if it was a car coming down the street or what it was and then I looked over to my right and there was my son, who was like two years old at the time, and he was looking at the candle and his face was so close to the flame. There was no explanation for what this big flash of light was, but it was something that definitely caught my attention. And I thought, well, maybe it’s my father-in-law saying, Hey, you should pay attention to him because you’ve got this candle burning. So I’ve had two experiences. Were they paranormal? Not necessarily. They were a personal experience. But it always made me wonder what happens to someone after they pass away.
DT: Have you ever seen a ghost?
GO: I have not seen a ghost. That’s one of the things Delaware Ghost Hunters would most like to really, really see—to catch an apparition on film. We’ve had personal experiences. They’ve come mainly over at Fort Delaware where we spend an incredible amount of time. I’ve had footsteps behind me when I’ve been completely alone and nobody else is around. They’re not your typical footsteps of somebody walking up stairs. They were kind of a slow shuffle coming up. I once had my name called. It was actually a nickname that my husband would call me. That was a hair-raising event because it was literally in my ear. It really caught me off guard. We haven’t caught anything on film yet. We would love to, but it hasn’t happened.
DT: I’ve been to Fort Delaware and I’ve heard about the ghost tours. What’s DGH’s role there?
GO: Since 2009, this will be our third year, the whole month of October—every Friday and Saturday night—we host Paranormal Tours over there in efforts to raise funds for Fort Delaware. We have two three-hour tours. One starts at six, one stars at nine. There’s usually about 75 people per tour. They come over on the boat, they enter the fort and then they are broken into groups of 10. Delaware Ghost Hunter members are stationed throughout the fort in areas where the most paranormal activity has been reported. The support staff there, re-enactors and interpreters, take the groups through the fort to these locations. Say I’m in the kitchen. They’ll come into the area and gather for 20 minutes and we’ll do an investigation. We encourage the public that this is their time to investigate, use the equipment and ask questions. I think a lot of times they’re afraid that they’re not going to ask the right question or they don’t want to be the first one to ask a question. So it ends up being one of us doing most of the work. But the first year we did this with Fort Delaware, we raised $70,000 for them in one month. It was such a huge success, they ask us to come back every year. Every year, since 2009, we have raised at least $70,000 for them. All of the tours sell out. There’s usually a waiting list. So we are getting geared up to do that again. We’re going to start at the end of September. And then we ramp it up the very last weekend in October with what we call an extended tour. It’s a six-hour tour. The cost is set up by the state. We don’t set the cost. We don’t get paid by the state to do this. We’re just volunteer for the state. We’re a nonprofit organization. For the extended tours, you get access to parts of the fort that the other tours didn’t get access to.
DT: We were there on a re-enactment weekend and I figured we wouldn’t see any ghosts that day because it was too busy.
GO: Some people come over and I think they think it’s going to be a Frightland experience. That people are going to be jumping out at them and things like that. That’s not the case at all. Some people are like, why doesn’t anything happen? We watch “TAPS” and something happens for 10 minutes. We don’t have the power of editing. This is real time. The paranormal TV shows film for a week. And they have to edit down to a half-hour program. So things are going to happen in 10 minutes. I always say, We cannot make the ghosts come out. We cannot make anything happen. We always say paranormal investigating is like fishing. You throw your line out there and you hope you get a bite. If you do, you do. And if you don’t, it’s OK. You try again. Our tours are nothing of that nature where someone is going to jump out and scare you. No one is dressed in scary clothing. All of the interpreters are dressed in their own clothes. DGH members all have DGH clothing, so there’s no mistaking who’s who.
DT: Both the footsteps and you hearing your name happened at Fort Delaware?
GO: It’s funny because I was doing one of the tours and John and I had been assigned to the kitchen that night. He and I had gone over to the kitchen probably half an hour before the first group came through. We had put equipment out, dowsing rods and EMF detectors, and we were talking about the tours. The nickname he calls me is Murphy. That’s what he had been calling me. So the first group comes in and they all sit down. I told them, You guys came to investigate and that’s what I want you to do. Feel free to ask questions. There are no stupid questions. The group was a really good group. They were really getting into it. Right across from the kitchen area is a large open foyer area and then there’s the officers’ quarters. I could have sworn I heard movement coming from the officers’ quarters. I got myself out of the kitchen. John was still in the kitchen with the group. The officers’ quarters was completely dark. We shut the power off when we do this. There was nobody over there because there were no groups assigned to that area. I walked through to make sure nobody wandered away. I didn’t see anybody. Nothing was out of the ordinary. So I came back toward the kitchen area and since the group was pretty involved in what they were doing, I didn’t want to cut back and disturb them. So I leaned against the door and was watching them. Then John came through the kitchen area. He said, “What’s the matter?” I said, “Nothing. I just thought I heard noises coming from the officers’ quarters, but I don’t see anything over there.” He said, “Let me go take a look. You stay here.” So he goes over to the officers’ quarters. It has several rooms to it. He walks into the room and I’m still watching the group. Then I hear my name, Murphy, being whispered. So I turned and looked because I figured he must be in there calling me to come over. And I look over and he’s not there and there’s nobody standing there calling my name. So I stuck my head in the doorway real quick and I didn’t see him. So I thought, OK. Maybe I just imagined it. So I go back to the kitchen and I’m leaning on the door and I hear it again. But this time it was a little more forceful. So I go back over and just then, I see John coming from two rooms back in the officers’ quarters. I looked at him and I said, “What do you need? He said, What do you mean? I said, You’ve been calling my name. What’s going on?” He said, “I have not called your name.” So I say, OK and go back to the kitchen where the group is finishing up. They leave. He looked at me. “What was going on? You came flying through that room like something was happening.” I said I heard my name being called twice in my ear. I said I thought you were trying to tell me that you saw somebody in the room that shouldn’t have been there. Because every once in a while you get someone from the public who wants to wander through out of the group and go see what it looks like. He said, no. He had been all the way back in a mailroom area. Again, no explanation. No why or who.
DT: What’s the deal with those orbs that people see in photos?
GO: A lot of people feel that orbs are spirits that are trying to manifest themselves. Collectively, as a group, we have looked into this whole situation and analyzed it. Orbs are really nothing more than dust or water or bugs reflecting off a camera. When you’re taking a picture and the flash goes off and you happen to catch a water droplet just as it’s coming down past your lens and the flash hits it, it’s going to reflect it. That’s going to make that circle. Especially at Fort Delaware. You have dripping water, you have dust and you have bugs. So you’re bound to get a so-called orb almost anywhere in the fort. Even outside people take pictures and they catch something they think is an orb near a graveyard or whatever. Again, you probably just caught a random bug flying by the lens just as you took the picture. Do Delaware Ghost Hunters think orbs are spirits? No, we don’t.
DT: If I were a ghost at the fort and all of these people came out at once, I would feel like I’m being forced to perform. I would probably just hang back. Does that make sense?
GO: Absolutely. It’s funny because we’ve investigated a lot of private places, businesses and historical places. We’ve done Bellevue Hall, Rockwood Mansion. We’ve done Pachette House in Delaware City. It’s one of those things that when you least expect it, something’s going to happen. At Fort Delaware, we do two tours a night for six weekends. We joke that on the last night, the ghosts are saying, “Thank god they’re leaving.” It’s exciting to the public because they really, really, really want to see something. But it gets a little mundane for us by the last weekend. But there are times when we have not planned to hear anything or see anything and something happens. And it’s usually when we don’t have our audio running or we don’t have cameras running. For instance, one time we were investigating Rockwood Mansion. The headquarters where the main monitor was, we had that set up downstairs in the foyer. And one of our female investigators was pregnant at the time and her husband didn’t want her climbing up and down the stairs so we left her to sit and watch the monitors. It was one or two in the morning and four of us decided we were going to head up into one of the offices that’s located underneath the servants’ quarters. It was just going to be us girls and we were going to go up and investigate and the guys were going to hang back on the ground floor and sit with Lesley, who was pregnant, and watch the monitors with her. So we were up there and we had been asking serious EVP (electronic voice phenomenon) questions like “Are you here?” and “Can you make noise?” Then we got off-topic, talking about family and kids and general stuff. Nothing to do with paranormal. We heard the doorknob to the servants’ quarters turn. That door is located right next to this office. We thought somebody must have come up. We looked and there we didn’t see anything or hear anything. So we go back to talking. Again, off-topic conversation. Then we heard the door open and shut. We thought, somebody’s got to be up here besides us. I went downstairs and they said no one had gone up there. So we went back and sat down and started talking again. Then we heard clear footsteps walking above the floor above us in the servants’ quarters. So a couple of us went upstairs and we walked the length of the servants’ quarters while the other two stayed downstairs to see if we could repeat the same sound. It was the same sound as someone walking through the servants’ quarters. What it was we could never figure it out.
DT: What’s the top spot for paranormal activity in Delaware?
GO: Fort Delaware is definitely haunted. We had a really interesting experience at Bellevue Hall. The reports that we had gotten from the staff there were that people feel weird when they go up to the servants’ quarters, they’ve heard noises, they’ve seen children in the window, the whole nine yards. We did a private investigation and we actually came up with an EVP that we got from the basement. The basement is where the men of the family would hang out after dinner and drink scotch and smoke cigars. And four of our female investigators were down there alone to see if we could get any kind of response. We were asking questions and Stacey, one of our investigators, said, “Have you ever done naughty things down here?” And very clearly, a very harsh male voice said, “No!” We caught it on tape and we tried debunking it. At the time, the guys were three floors up. We tried the talking through the vent type thing. We tried to debunk it and we could not debunk it. When we presented it to the staff at Bellevue Hall, they were like, Oh, wow, because they weren’t thinking basement. They were thinking servants’ quarters because that’s where they felt most uncomfortable. But Fort Delaware definitely offers up the most interesting stuff to happen of all of the places we’ve been to.
DT: How did the expo go?
GO: We had our first paranormal expo this past May 4-5 in Delaware City. It was our first time out. We didn’t know what we were going to come out with, but it turned out to be really successful. We had some really great guest speakers there. We had Dave Schrader of “Darkness Radio.” He was one of the judges when “Ghost Adventures” had their paranormal challenge. We had David Roundtree. He’s a big technical guy. The equipment he makes and the things he talks about, some of it is beyond comprehension. We had Bill Bean who had very horrific childhood memories of being tortured by some sort of demon spirit that attached itself to him and his family. People had a chance to come out and just listen to the lectures that were held all day Saturday. Or they could attend one of the investigations. We invited other groups and they set up tents in the park. It was our first time out, it took over a year to plan it. Overall, we got positive feedback. We’re definitely going to do it again next year. Because we are a nonprofit organization, we were able to present Delaware City a $1,500 check on Delaware City Day. It was a good experience.
DT: What kind of training does one have to have to be a ghost hunter? Do you have to have a doctor of ghostology or something?
GO: You don’t necessarily need training. If you have previous experience, it’s good. We like to have people on our team who think with an open mind and not think that everything is paranormal. We like people who take more of a scientific approach and think logically about what could be causing something to happen. For instance, one time we were doing a private investigation at Bellevue. Two of our male investigators were upstairs investigating and one of our other male investigators was coming up the stairs to see if they needed anything. He tripped on something and he whispered, “dammit.” And that got caught on the recorder. So when they went back to listen to their audio, one of the investigators said, “I want you guys to listen to this. I don’t know if it’s anything or not.” Whenever we think we have something, we always bring it to the team to review. We all listened to it. And as soon as I heard it, I thought, No. That’s John whispering “dammit.” Then John said, “Yeah, that was me.” So you don’t really need to have any kind of experience. You have to have a lot of patience. It does take time out of your schedule. We all work full time during the day, so this is technically a hobby. But sometimes it can come off like a part-time job. You just have to think out of the box a little bit. You don’t even need a lot of expensive equipment. You can just have a recorder and paper and pen. Just common sense is really what we’re looking for.
DT: When you’re investigating, do you guys ever punk each other?
GO: We always try to be serious and professional when we’re out some place. Especially at a private home or a business. One time we were investigating a theater in Kent County. It was on the ground floor and it had all of these costumes and props hanging and there was all sorts of stuff down there. One of the things we do is buddy up. So we’ll send two people into one area and send another two into another area. Then we try to keep the rest of the team out of the area so we don’t have any contamination. There was this big Elvis cut-out there. One of the team members had moved it so when Jason and I were walking through the costume area where all of these costumes are just hanging from the ceiling, all of the sudden you come around the corner and you see this cut-out. It just stopped you dead in your tracks. We both kind of screamed a little bit because we really weren’t expecting it. So I said, “You know what? Payback’s a bitch.” There was a staircase where you go down, then there’s a landing to turn, then you go down again. We had moved it to the landing. Again, we’re investigating in pitch black. Later on another group had gone through. You could hear talking as they’re going down the stairs and then you just hear a scream. For the most part we try to stay serious, but we kind of get punchy after two or three in the morning.
DT: When you actually do see a ghost, do you think it will be scary, cool, fun?
GO: I think it’s going to be a combination of things. I think at first, if we ever get the opportunity to actually see something, I think we’ll be like, What the heck was that? The final thing will be, Wow, that was really cool. We need to see that again. I think it will really drive the group to investigate even more.
DT: Do outsiders tease you or make fun of you?
GO: No. When I first told my family what I was doing, they were like, “You do what?” People will come up to you after they know what you do and say, “Hey, I had this experience.” People will start telling you these stories. They come out of the woodwork. When they realize we’re not some seat-of-the-pants group and that we try to de-bunk things, then they’re more open to tell you their stories. It’s pretty cool.
DT: Do people bring up “Ghostbusters” a lot?
GO: Some people who come to our events wear the T-shirt with the ghost with a line through it. They’ll play the theme song from “Ghostbusters.” We usually try to do a group Christmas party at one of our homes. One year our team members, they’re husband and wife, gave us all an ornament of the car that they drove in “Ghostbusters.”
DT: Do you relate to any of the characters in that movie?
GO: No. I don’t. If you ask other team members, they probably do. I liked the movie.
DT: What’s the best movie about ghosts?
GO: I don’t really watch them. I’ll watch TV shows like “Ghost Adventures.” I like those guys. There’s a new show called “Haunted Highway.” I haven’t seen it, but a couple of our members said it’s pretty good. I don’t really have a favorite scary movie.
DT: Who’s cooler, Casper or Slimer?
GO: I like Casper.
On Saturday July 21st Delaware Ghost Hunters was honored to present all the proceeds from our 2012 Paranormal Expo, a total of $1,500 to Delaware City. As an official 501 (3) (c) non-profit organization, DGH was excited to have an opportunity to give back to the community. The Delaware Paranormal Expo was held in May in Delaware City, DE and was the first of its kind in the Delaware Valley. It featured several speakers, lectures, investigations, and vendors all geared towards the world of the paranormal. Working in conjunction with DGH, the city and people of Delaware City were a tremendous help in pulling of this fantastic event that brought so many people together. 100% of the proceeds went back to helping the City grow, and we hope to see the expo grow in size in the following years! It was an incredible inaugural event and Delaware Ghost Hunters were honored to be able to give back to such a wonderful and supportive community.
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.
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.
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 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|
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 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.
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.
Written By: DGH President, John R. O’Neil