Cooking with a thermometer
Why do I get different readings when I test my food in different places?
The temperature of food can be different in different places at the same time. It is not unusual for the internal temperature of a large roast to vary by as much as 10°C to 15 (20°F to 30°F ) due to texture, thickness and oven positioning. Even a steak or a boneless chicken breast may show differences of many degrees as you move the tip of your thermometer probe from the surface toward the center of the piece, or from end to end.
My thermometer suggested my steak was medium but it ended up overdone, why?
Meat will continue to cook after you take it off the heat. This is called "resting." Cooked meat should be allowed to "rest" after cooking and before cutting. This permits the juices to be reabsorbed into the fibers of the meat. If you skip resting, you will lose more juices when the meat is cut. The temperature of the meat will always continue to rise a little during the resting period, referrd to as carryover cooking.
Typically, even a small steak or individually cooked piece of chicken will rise at least three or four degrees during resting. A larger roast or turkey can rise as much as ten to fifteen degrees depending upon conditions. So you should remove your meat from the oven or grill prior to reaching your target temperature. Otherwise, it will be overcooked. Read the ultimate guide to resting meat here.
What precautions do I need to take when grilling with a thermometer?
Never leave a thermometer inside an oven, grill, smoker, or microwave while cooking unless it is specifically designed for this. Don't leave your thermometer on the grill hood or close to an open flame. Some probes are designed to be left inside an oven or grill, but the thermometer housing itself (where the electronic components are kept) typically needs to be kept cool and should only be brought near heat for short periods of time. When checking temperatures above a grill or fire, be careful that the thermometer body does not get too hot.
Why is my chicken still bloody when my thermometer says it's done?
Because the bone marrow in chicken bones can release blood while cooking. If the chicken has reached at least 71°C for five minutes or more, it is safely done.
What are the main food safety temperatures?
The UK Food Agency publishes temperature guidelines for food holding and cooking . You can use your ETI thermometer to check temperatures and minimise food-borne illness in your kitchen.
Bacteria thrive between the temperatures of 4.5°C and 60°C. Food should not be stored between these temperatures for extended periods of time. Some leftover foods must be reheated to minimum temperatures to assure sufficient "kill rates" of bacteria or parasites.
Holding hot foods 63°C or higher
Holding cold foods less than 8°C
Fridge temperature 4.5°C or colder
Freezer temperature 18°C to -23°C
See also our chart of chef-recommended food temperatures.
How do I take an accurate reading of liquids?
The best way to take an accurate reading of liquids is firstly to stir the liquid. Follow this by stirring the thermometer probe through the liquid, watching the temperature change as it moves through.
If cooking a liquid, such as oil, jam, or melted chocolate use a clip to position your probe on the edge of a pot, pan, or glass for continuous monitoring.
Where should I place the probe tip to see if meat is cooked?
When testing if your meat is cooked, the coldest part will be the very center of the thickest portion. With larger foods, you can take quick readings with your thermometer in several locations to verify that the entire portion is done. If you are chilling a food, the center of the thickest part will be the last to cool.
Why doesn't my thermometer settle on a final temperature in food?
The temperature of food keeps changing while it is cooking or exposed to ambient temperatures around it, unless it is in a controlled environment. Thermometers will only "lock in" on a given reading if they have a "hold" feature designed to do that.
Thermometer FAQ
My new thermometer reads different than my old one, why?
Your new thermometer will likely be more accurate, especially if it has a more recent calibration history as accuract can drift over time.
You can test this by making an ice bath or using a reference thermometer or sending your old thermometer in to or UKAS Lab after purchasing a calibration service.
How often should I clean my thermometers case?
Wipe the whole thermometer casing after each use.
Never put the housing of your digital thermometer near water unless it has an IP rating of IP66 or higher. Check the IP rating before splashing or submerging a thermometer.
IPA and other solvents may cause damage to the case and screen of this instrument.
Why does my thermometer read higher than 0°C (32°F) when put in ice water?
For an accurate 0°C (32°F) reading, the ice bath must be a tightly packed slush. If there is too much water and not enough ice, or if the ice is floating off the bottom, the water at the bottom of the glass will actually be warmer (around 4°C or 39°F)
The thermometer probe might be touching the bottom or sides of the container instead of suspended in the centre of the ice slush, causing it to pick up ambient room heat.
Over time, thermometers can drift. If your ice bath is prepared perfectly and you are still getting an inaccurate reading, your thermometer likely needs to be recalibrated.
What is an IP rating?
IP ratings show how dust proof, splashproof, water resistant or waterproof products are.
The International Protection Rating code (or IP code) consists of the letters "IP" followed by two numbers.
The first number following "IP" tells you how protected an instrument's electronics are from solids (like dust), rated from IP0 having no protection to IP6 being dust tight
The second number following IP tells you how they stand up against liquids. Such as:
IP64 - protected from splashing water.
IP65 - protected against water jets.
IP66 - protected from powerful water jets.
IP67 - protected from the effects of temporary water emersion.
IP68 - protected from the effects of continuous water emersion.
For more information see the International Electrotechnical Commission's table here
How frequently should I calibrate my thermometer?
For many critical temperature processes to comply with health and safety regulations, thermometers require a valid calibration certification to evidence accuracy to show when the thermometer was last calibrated and to what standard.
Check the stated recommendation for your type and model of thermometer or check with the appropriate health department or quality control agency with authority over your operation.
Over time and prolonged use, accuracy can start to drift. Depending on the process a small variation could be harmless, or harmful as most temperature controls are there for protection against harmful bacteria growth or to produce the highest quality outcomes.
If you'd like to speak to someone about your application for compliance or for your preference please contact our in-house team sales@etiltd.co.uk
Thermometer Probe FAQ
My new thermometer reads different than my old one, why?
Your new thermometer will likely be more accurate, especially if it has a more recent calibration history as accuract can drift over time.
You can test this by making an ice bath or using a reference thermometer or sending your old thermometer in to or UKAS Lab after purchasing a calibration service.
How often should I clean my thermometers probe?
You should wipe the probe clean with antibacterial cleaning wipes or soap any time it comes in contact with raw meat.
Does atmospheric pressure affect temperature reading of Boiling Water?
The boiling point of water is directly dependent on (atmospheric) pressure. It is a physical related property. Water boils at 100°C ONLY if it is pure (de-mineralized) and under atmospheric pressure of 1013.25 hPa.
At high altitudes or low pressure, you may think that the instrument reads the wrong temperature.
Low air pressure at 990 hPa water will boil at 99.3 °C and at higher air pressure 1040 hPa water boils at 100.7 °C.
What types of probes does ETI make?
ETI makes Thermocouple, Themistor, PT 100/RTD and bespoke probes. For any special requests take a look at ourBespoke Probes page.
How to avoid damaging a thermometer probe?
Temperature probes are precision measurement devices. At the probe tip there is an electronic sensor connected by wires.
• Do not 'stab' food, careful insertion will penetrate most food
• Avoid striking bones with the probe tip
• The probe shaft and tip should not be bent
• Do not lift heavy food items with the probe tip
• Do not use the probe as an ice pick
• For frozen foods place the probe tip between two frozen packs or use a drill to make a hole in the food before placing the probe tip in the hole. Do not create a hole with the probe tip
• Do not use the probe to pry or puncture non-food items
• Do not expose the probe tip to flames or temperatures beyond the probe temperature limit
• Do not expose the handle to high temperatures
• Do not coil the cable tightly around the handle
• Avoid excess heat that may melt the cable
• Avoid excess strain, crimping or stretching of the cable
• Do not lift the instrument by the probe or cable
• Keep the lead connector and instrument clean and dry
• When plugging the probe into the unit, avoid bending pins
• Do not immerse the probe handle in any liquid (except waterproof probes)
• Damage is not covered by the probe warranty
Infrared Thermometer FAQ
Why use an infrared thermometer?
Infrared thermometers are ideal for taking fast, non-contact surface temperature measurements from a distance, typically providing results in a fraction of a second.
They are invaluable across industries like food service, HVAC, manufacturing, and labs, especially when using a traditional probe is impractical or unsafe.
Best Used For Measuring Objects That Are:
- Moving or Out of Reach: Conveyor belts, living organisms, or high-up HVAC ducts.
- Dangerous or Fragile: Exposed gears, molten metal, or delicate computer circuitry.
- Impenetrable: Solid frozen foods.
- Sensitive to Contamination: Sterile lab solutions or raw food products.
Infrared thermometers only measure surface temperatures, making them perfect for quick safety scans without ever touching the object.
Are infrared thermometers safe to use?
All Infrared thermometers sold by ETI Ltd, that have Laser Pointers, comply with BS EN 60825-1: 2014: - Safety of laser products:
The built-in engineering controls ensure that the laser is safe for normal use. It is powerful enough to trigger a natural blink reflex, preventing damage to the skin or eyes during momentary, accidental exposure.
Avoid staring directly or deliberately into the laser beam for prolonged periods, as this can cause self-inflicted eye injury. Never point the laser at anyone else's eyes.
How do you clean an infrared thermometer?
For accuracy, an infrared thermometer should be kept free of dirt, dust, moisture, fog, smoke and debris. Always take the time to clean your infrared thermometer after exposure to a dirty, dusty, smokey or humid environment. You should also plan a regular cleaning every six months or so. Particular care should be taken to keep the infrared lens or opening clean and free of debris.
To clean your infrared thermometer:
1. Use a soft cloth or cotton swab with water or medical alcohol.
2. Carefully wipe first the lens and then the body of the thermometer.
3. Allow the lens to dry fully before using the thermometer.
4.Never submerge any part of the thermometer in water.
See the video of infrared basics here.
Can I calibrate my infrared thermometer?
Infrared thermometers can be calibrated for accuracy, preferred for temperature control processes are critical for health, safety or quality.
In calibration labs like the in-house UKAS certificated ETI Calibration Laboratory use industrial black bodies to calibrate infrared thermometers.
You can also do a quick calibration if using using a properly made ice bath.
What are infrared thermometers used for in food service?
Food borne bacteria usually land on the surface of foods first, so infrared thermometers can be useful for spot checking the holding temperatures of plated foods, serving areas, buffets and warming trays.
Can I check if food is properly cooked with an infrared thermometer?
Infrared thermometers only measure surface temperatures, so they will not give a reading on the internal temperature of meats such as a chicken, but they are great for Pizza.
If using an infrared thermometer with liquids like soups and sauces, ensure you stir before taking a measurement. Be aware that steam, even when a liquid is not boiling, can condense on your thermometer and affect the accuracy of your measurements.
What do spot size, spot ratio and distance to target ratio mean?
The "spot size" of any measurement is controlled by two variables:
1. The "distance to target ratio" or "spot ratio" of your infrared thermometer.
2. The distance between your infrared thermometer and the target.
Usually listed on the thermometer itself, the "distance to target ratio" (DTR) or "spot ratio" tells you the diameter of the "circle" of surface area an infrared thermometer will measure at a given distance.
For example, an infrared thermometer with a 12:1 ratio will measure the temperature of a 1" diameter circle of surface area from 12" away, a 2" diameter circle of surface area from 24" away, and so on.
What is emissivity?
"Emissivity" is a measure of a material's relative ability to emit radiated energy. It is measured on a scale from just above 0.00 to just below 1.00.
Emissivity depends on factors such as temperature, emission angle, and wavelength. Generally, the closer a material's emissivity rating is to 1.00, the more that material tends to absorb reflected or ambient infrared energy and emit only its own infrared radiation. Most organic materials, including the byproducts of plants and animals, have an emissivity rating of 0.95.
Check your infrared thermometer to see if it has adjustable emissivity settings as a feature. Then check your target material against this Emissivity Table.
What is fixed emissivity on an infrared thermometer?
Fixed emissivity is a setting on some infrared thermometers, usually of 0.95 or 0.97, that attempts to simplify their operation while leaving them suitable for most surfaces.
How do I measure the temperature of a shiny or low-emissivity surface?
Shiny surfaces (like polished metal) reflect infrared energy, which causes infrared (IR) thermometers to give inaccurate readings.
To get an accurate measurement, you need to create a temporary "high-emissivity" target area:
- Apply Black Tape or Paint: Put a piece of black electrical tape or a quick spray of flat black paint onto the metal. Both have an ideal emissivity rating of 0.95.
- Use Cooking Oil: For cookware like a polished skillet, coat the surface with a thin layer of cooking oil (which also has an emissivity of 0.95).
Always wait a few moments for the tape, paint, or oil to reach the exact same temperature as the underlying metal before taking a reading.
Make sure the black target spot is large enough to completely fill your thermometer's field of view. If the sensor picks up any of the bare, shiny metal around the edges of your spot, your reading will be incorrect.
Can infrared thermometers work through glass, plastic or through liquid?
An Infrared thermometer will not measure temperature accurately through glass, liquids or other transparent surfaces as it will measure the surface temperature translucent substance, and not the object you are aiming at.
Infrared measures surface temperatures, not core temperatures.
Data Logger FAQ
Where do I find the latest software for my data logger?
Each ETI data logger comes with its own software. You can download the software when you visit our dedicated Software & Apps page.
Thermapen FAQ
How to change the battery on my Thermapen ONE?
• Thermapen ONE - 1 x AAA
Please see the video which demonstrates clearly how you can change the battery on your Thermapen ONE.
A low battery symbol will appear when the battery needs replacing, in this condition the backlight is set to a low level to save battery life. The instrument continues to measure accurately but we recommend that the battery is changed as soon as possible.
To replace the battery, loosen the battery cover screw using a Pozi (PZ1) screwdriver to remove the battery cover. Replace with a single AAA battery noting the polarity. Tighten the battery cover screw until the battery cover is snug onto the seal. Do not over-tighten.
If you are having any issues replacing the batteries, just contact us via our online contact form and a member of our dedicated team will be in touch to assist.
How to change the battery on my Thermapen Classic?
• Thermapen Classic - 2 x 3 volt CR2032 lithium coin cell
Please see the video which demonstrates clearly how you can change the battery on your Thermapen Classic.
A battery symbol indicates that the batteries will need replacing. The instrument continues to measure accurately but we recommend that the batteries be changed as soon as possible.
To replace the batteries, remove the battery cover using a coin. Remove the batteries by pulling the battery retaining clip back whilst holding the unit upside down. Replace both batteries, positive side up, replace cover.
If you are having any issues replacing the batteries, just contact us via sales@etiltd.com and a member of our dedicated team will be in touch to assist.
Manometer FAQ
What is a manometer?
A manometer, otherwise known as a pressure meter or pressure gauge, is a portable device that measures the pressure of a gas or liquid in a system.
You can buy analogue or digital manometers, though digital options are often preferred due to their flexibility, reliability and wide range of units. Manometers often measure either absolute, gauge or differential pressure or a combination of the three.
What is a manometer used for?
Manometers are most commonly used by gas HVAC professionals to identify issues such as leaks in heating system pipes. Some specific applications include:
• flue draught measurement
• gas pressure in heating appliances
• air conditioning ducts
• monitoring of filter differential pressure
• velocity measurement with a pitot tube
How to use a manometer?
Digital manometers usually work by connecting the device to the system you’re measuring using a hose. Simply program the device to display readings in your desired unit, connect the hose and carry out the required test. The manometer screen will display the pressure in your chosen unit.
What is the Difference Between Absolute, Gauge, and Differential Pressure?
When selecting a pressure sensor, gauge, or transmitter, it is vital to understand the reference point being used. Pressure measurements are categorized into three main types: absolute, gauge, and differential pressure. Each serves a specific industrial or commercial application based on how it handles atmospheric pressure.
1. Absolute Pressure (psia)
- Definition: Absolute pressure is measured relative to a perfect vacuum (absolute zero pressure), where no air molecules or matter exist.
- Reference Point: A perfect vacuum ($0$ psi).
- Best Used For: Sealed systems unaffected by changes in barometric or atmospheric pressure. Common applications include altimeters, weather monitoring, and vacuum packaging equipment.
2. Gauge Pressure (psig)
- Definition: Gauge pressure is measured relative to the current ambient atmospheric pressure. It represents the absolute pressure minus the local atmospheric pressure.
- Reference Point: Ambient atmospheric pressure (approx. 14.7 psi at sea level).
- Best Used For: Systems directly influenced by local weather or altitude changes. Common applications include tire pressure gauges, hydraulic systems, and open storage tanks.
3. Differential Pressure (psid)
- Definition: Differential pressure is the difference in pressure between two distinct points within a system. It is calculated by subtracting the lower pressure value from the higher pressure value.
- Reference Point: A secondary variable pressure point within the system.
- Example: If a gas pipeline reads 50 psi at the inlet and 20 psi at the outlet, the differential pressure is 30 psi.
- Best Used For: Applications requiring a comparison between two spaces. Common applications include monitoring filter blockages, measuring fluid flow rates, and cleanroom airflow management.
PH Meter FAQ
How do pH meters work?
pH meters work by measuring minute particles, called ions, with two glass electrodes, one of which has a permeable junction. This permeable junction allows a small amount of gel solution to pass through to complete a liquid bridge. If this junction is allowed to dry out, the liquid bridge is prevented from being formed and the instrument will not perform accurately. Therefore, unlike most instruments, the glass electrodes need to be kept wet with a storage fluid for the junction not to get blocked.
The pH meter has a finite life due to the gradual aging of the sensor.
How to maintain a pH instrument?
As a minimum, you must always wash the pH electrode (the measuring part of the instrument) in clean water. Do not touch the pH electrode unless using a damp tissue or cloth for cleaning and then only using extreme care.
When not in use, ensure the pH meter electrode is kept moist in either storage solution or a pH 4 solution. If the sensor is allowed to dry out completely, the instrument’s performance will be effected and its warranty invalidated.
If an electrode has been allowed to dry out or becomes slow to respond, it may be rejuvenated by soaking the electrode overnight in storage solution. After overnight soaking, rinse the electrode and then soak in a 4 pH buffer solution before giving the electrode a final rinse. The electrode should then be ready for use.
Depending on the accuracy required, once a day if several measurements are required during the day; or at least once weekly if you use 2 or 3 times per week.
As a minimum, you must always wash the pH electrode (the measuring part of the instrument) in clean water. Do not touch the pH electrode unless using a damp tissue or cloth for cleaning and then only using extreme care.
When not in use, ensure the pH meter electrode is kept moist in either storage solution or a pH 4 solution. If the sensor is allowed to dry out completely, the instrument’s performance will be effected and its warranty invalidated.
If an electrode has been allowed to dry out or becomes slow to respond, it may be rejuvenated by soaking the electrode overnight in storage solution. After overnight soaking, rinse the electrode and then soak in a 4 pH buffer solution before giving the electrode a final rinse. The electrode should then be ready for use.
What do I need to calibrate my pH instrument?
To ensure accurate measurements, it is necessary to calibrate pH meters on a regular basis. For this you will require pH buffer solutions. These standard, inexpensive solutions are used to check that the pH reading is correct.
If it is not, it can be easily corrected following the procedure for the specific instrument. Generally pH electrodes have a limited working life, dependant on the frequency of use.
How long will a pH tester last?
All pH glass electrode will age with time and temperature. Most glass electrodes have a storage life of about 1 year. A life-span of about 3 to 6 months for frequent/continuous use.