1. Introduction
The BENETECH Non-Contact Infrared Thermometer is designed for quick and accurate temperature measurement of various surfaces without physical contact. It is ideal for measuring high-temperature, hazardous, or hard-to-reach objects. The device operates by detecting the infrared energy radiated from an object's surface, converting it into an electrical signal, and displaying the temperature reading on an LCD screen.
This unit consists of an optical system, photoelectric sensor, signal amplifier, signal processing circuit, and LCD display. The optical system converges infrared energy radiated from the object's surface onto the photoelectric sensor, which converts the energy into a corresponding electrical signal. This signal is then amplified and processed into a digital reading displayed on the LCD.
2. Safety Information
2.1. Warnings
- Do not point the laser directly at eyes or indirectly at eyes via reflective surfaces when using this unit.
- This instrument cannot measure through transparent surfaces. For example, glass, plastic, etc. Otherwise, the measured value will be the surface temperature of the transparent object.
- Moisture, dust, smoke, or other particles will obstruct the instrument's lens, affecting measurement accuracy.
2.2. Cautions
- Protect the thermometer from electromagnetic fields (EMF) generated by arc welders and induction heaters.
- If moving between environments with large or drastic changes in ambient temperature (thermal shock), wait 30 minutes for the thermometer to stabilize before use.
- Do not place the thermometer near or on high-temperature objects.
3. Product Overview
3.1. Components
The thermometer features a pistol-grip design for comfortable handling. Key components include:
- Infrared Sensor & Laser Aperture
- LCD Display
- Trigger
- Control Buttons (MODE, UP/Laser, C/F)
- Battery Compartment
Figure 1: Front view of the GM333 model, showing the display, buttons, and trigger.
Figure 2: Side view of the GM333 model, highlighting the trigger and battery compartment location.
Figure 3: Top view of the GM333 model, illustrating the Distance-to-Spot (D:S) ratio.
3.2. LCD Display Indicators (Refer to Figure 4 in the manual image)
Figure 4: Excerpt from the manual showing LCD display and button functions.
- HOLD Symbol: Indicates the last measurement is held on the display.
- Laser Aiming Symbol: Shows when the laser pointer is active.
- Backlight On Symbol: Indicates the display backlight is active.
- Emissivity Symbol: Displays the current emissivity setting.
- Low Battery Symbol: Alerts when battery power is low.
- Auto Power Off Symbol: Indicates the auto-off feature is active.
- Ambient Temperature Symbol: Shows the current ambient temperature.
- MAX/MIN Symbols: Indicate maximum or minimum temperature modes.
- °C/°F Unit Symbols: Shows the selected temperature unit (Celsius or Fahrenheit).
- Current Measurement Reading: The main temperature value.
4. Specifications
| Parameter | GM333 / GM333A | GM533A |
|---|---|---|
| Measurement Temperature Range | -50°C to 400°C (-58°F to 752°F) | -50°C to 530°C (-58°F to 986°F) |
| Measurement Accuracy | 0°C ~ 400°C (32°F ~ 752°F): ±1.5°C (±2.7°F) or ±1.5% -50°C ~ 0°C (-58°F ~ 32°F): ±3°C (±5°F) | |
| Resolution | 0.1°C or 0.1°F | |
| Repeatability | 1% of reading or 1°C | |
| Response Time | 500mSec, 95% response | |
| Spectral Response | 5um-14um | |
| Distance Spot Ratio (D:S) | 12:1 | |
| Emissivity | 0.95 (Fixed) | 0.10-1.00 (Adjustable) |
| Operating Temperature | 0°C to 40°C (32°F to 104°F) | |
| Operating Humidity | 10% RH - 90% RH non-condensing | |
| Storage Temperature | -20°C to 60°C (-4°F to 140°F) | |
| Power | 2 x 1.5V AAA Battery | |
| Battery Life | Approx. 12 hours | |
4.1. Emissivity Table (Common Materials)
Figure 5: Excerpt from the manual showing common material emissivity values.
| Material | Emissivity |
|---|---|
| Stone | 0.70 |
| Ice | 0.97 |
| Paint | 0.93 |
| Water | 0.93 |
| Wood | 0.94 |
| Rubber | 0.95 |
| Concrete | 0.94 |
| Asphalt | 0.94 |
| Brick | 0.93 |
| Paper | 0.90 |
| Ceramic | 0.92 |
| Glass | 0.85 |
| Iron | 0.70 |
| Copper | 0.78 |
| Aluminum | 0.90 |
| Oil | 0.94 |
| Food | 0.90 |
| Skin | 0.98 |
5. Setup
5.1. Battery Installation
- Locate the battery compartment on the handle (refer to Figure 2).
- Open the battery compartment cover.
- Insert two (2) 1.5V AAA batteries, ensuring correct polarity.
- Close the battery compartment cover securely.
6. Operating Instructions
6.1. Quick Measurement
- Pull the trigger to turn on the device. The LCD will display "SCAN" and the current temperature.
- Aim the laser pointer at the center of the object you wish to measure.
- Release the trigger. The temperature reading will be held on the display ("HOLD" symbol will appear).
- The device will automatically shut off after approximately 20 seconds of inactivity.
6.2. Locating Hot Spots
To find a hot spot, aim the thermometer at the area and slowly scan the region by moving the laser spot up and down. The highest temperature detected will be displayed.
Figure 6: Excerpt from the manual illustrating hot spot location technique.
6.3. Button Functions
- C/F Button (Red Button): Press to switch between Celsius (°C) and Fahrenheit (°F) temperature units.
- UP Arrow / Laser Button:
- Press to turn the laser pointer ON or OFF.
- In Emissivity (EMS) or Calibration (CAL) mode, use this button to increase values.
- DOWN Arrow / MODE Button:
- Press to cycle through measurement modes: MAX (Maximum), MIN (Minimum), AVG (Average), DIF (Difference), EMS (Emissivity), CAL (Calibration), and back to the standard measurement interface.
- In Emissivity (EMS) or Calibration (CAL) mode, use this button to decrease values.
Note on MAX/MIN modes: When in MAX or MIN mode, hold the trigger to continuously measure. The display will show the maximum or minimum temperature recorded during that continuous measurement session.
6.4. Advanced Functions (GM333A & GM533A only)
- Adjustable Emissivity: In EMS mode, use the UP/DOWN buttons to adjust the emissivity value between 0.10 and 1.00.
- Self-Calibration: In CAL mode, use the UP/DOWN buttons to adjust the calibration offset between -5.0°C and +5.0°C.
- High/Low Temperature Alarm: Set high and low temperature thresholds. An alarm will sound if the measured temperature exceeds or falls below these limits. (Specific setting instructions may vary, refer to on-screen prompts).
7. Maintenance
7.1. Cleaning the Lens
- Use clean compressed air to blow away any loose contaminants.
- Gently wipe away small residues with a damp cotton swab.
- Carefully wipe the surface with a damp cotton cloth.
- Do NOT use any solvents to clean the plastic lens.
7.2. Cleaning the Casing
Clean the thermometer casing with a damp sponge or soft cloth using mild soap and water.
Warning: Do NOT immerse the thermometer in water.
8. Troubleshooting
- No display or low battery indicator: Replace the batteries with new 1.5V AAA batteries.
- Inaccurate readings:
- Ensure the lens is clean and free from obstructions.
- Check the emissivity setting (if adjustable) and adjust it according to the material being measured.
- Allow the device to stabilize for 30 minutes if moved between environments with significant temperature changes.
- Ensure the D:S ratio is appropriate for your measurement distance.
- Laser not working: Check if the laser is enabled via the UP/Laser button.
- Device not turning on: Check battery installation and charge.
9. Warranty and Support
For warranty information or technical support, please contact your seller or the manufacturer directly. Keep your purchase receipt as proof of purchase.
