Benetech GM321/GM531 Infrared Thermometer Instruction Manual

A. Introduction

This infrared thermometer is used for measuring the temperature of an object's surface. It is applicable for various hot, hazardous, or hard-to-reach objects without direct contact, ensuring safety and speed.

The unit comprises Optics, a Temperature Sensor, Signal amplifier, Processing circuit, and an LCD Display. The optics collect infrared energy emitted by the object and focus it onto the sensor. The sensor then translates this energy into an electrical signal, which is digitized by the signal amplifier and processing circuit for display on the LCD.

B. Warning & Cautions

1. Warning:

• To avoid potential situations that may cause harm or damage to people, please pay attention to the following items:
• Do not point the laser directly at the eye or indirectly off reflective surfaces.
• The unit cannot measure through transparent surfaces such as glass or plastic. It will measure the surface temperature of these materials instead.
• Steam, dust, smoke, or other particles can prevent accurate measurement by obstructing the unit's optics.

2. Cautions:

Infrared thermometers should be protected from the following:

• EMF (electro-magnetic fields) from arc welders or induction heaters.
• Thermal shock: Allow 30 minutes for the unit to stabilize before use if subjected to large or abrupt ambient temperature changes.
• Do not leave the unit on or near objects of high temperature.

C. Distance to Spot Size

When taking measurements, pay attention to the Distance to Spot Size (D:S). As the distance (D) from the target surface increases, the spot size (S) of the measured area becomes larger. The Distance to Spot size ratio for this unit is 12:1 (Figure 1).

Figure 1: Distance to Spot Size Diagram
This diagram illustrates the relationship between the distance from the target and the size of the measurement spot. A 12:1 ratio means that at 12 units of distance, the spot size is 1 unit in diameter. For critical accuracy, ensure the target is at least twice as large as the spot size.

Field of view: Make sure the target is larger than the unit's spot size. The smaller the target, the closer the measurement distance. When accuracy is critical, make sure the target is at least twice as large as the spot size.

D. Emissivity

Emissivity: Most organic materials and painted or oxidized surfaces have an emissivity of 0.95 (preset in the unit). Inaccurate readings may result from measuring shiny or polished metal surfaces. To compensate for this, adjust the unit's emissivity reading or cover the surface to be measured with masking tape or flat black paint. Measure the tape or painted surface after it has reached the same temperature as the material underneath.

E. Operation

1. Operating the unit (Figure 2)

1. Open the battery door and insert the battery.
2. Pull the trigger to turn on the unit.
3. Aim at the target surface and pull the trigger; the temperature will be shown on the LCD.

Figure 2: Infrared Thermometer
Shows the device with a prominent trigger and finger indents for grip.

2. Locating a Hot Spot (Figure 3)

To find a hot spot, aim the thermometer slightly outside the area of interest, then scan across the surface with an up and down motion until you locate the hot spot.

Figure 3: Scanning Motion
Illustrates the technique of scanning a surface with the thermometer to identify areas of higher temperature.

F. LCD display & buttons

1. LCD display (Figure 4)

The LCD screen displays various icons and readings:

• A: Data Hold icon
• B: Scanning icon
• C: Laser on icon
• D: Backlight on icon
• E: Battery power icon
• F: Self-calibration icon
• G: Emissivity icon
• H: Environmental temperature icon
• I: Maximum icon
• J: Minimum icon
• K: Measuring unit (°C / °F)
• L: Measuring reading (numerical value)

Figure 4: LCD Display Layout
A diagram showing the typical layout of icons and the main reading on the thermometer's LCD screen.

2. Diagram description (Figure 5)

The unit has several control buttons:

• (1) Trigger: Press to display the temperature value with "SCAN" appearing on the screen. Release the trigger to enter HOLD mode, which automatically saves the data. The unit turns off automatically if there is no further operation.
• (2) Key: Switches between Celsius (°C) and Fahrenheit (°F). Also used for viewing emissivity and self-calibration settings.
• (3) Mode switch key: Press this key to cycle through modes: MAX (maximum temperature), MIN (minimum temperature), AT (current ambient temperature), EMS (emissivity adjustment), and CAL (self-calibration).
• MAX/MIN: When measuring, holding the Mode key switches the display between Max and Min readings.
• AT: Displays the current ambient temperature.
• EMS: Emissivity can be set between 0.10 and 1.00 using the °C/°F key and laser locating key. For example, if the measured temperature is 26.3°C but the actual temperature is 25°C, an adjustment of +1.3°C can be made. Press the Mode key again to return to the measuring mode after calibration.
• CAL: For self-calibration mode. Adjust the unit between -5.0°C and +5.0°C.
• (4) Laser location key and backlight switch key: Pressing these two keys simultaneously turns the backlight on or off. This key also functions as a value decrease key for self-calibration.

Figure 5: Device Button Diagram
Highlights the trigger and the various function buttons on the thermometer.

G. Maintenance

1. Lens Cleaning: Blow off loose particles using clean compressed air. Gently brush away remaining debris with a moist cotton swab. The swab may be moistened with water.
2. Case cleaning: Clean the case with a damp sponge/cloth and mild soap.

Note:

• Do not use solvents to clean the plastic lens.
• Do not submerge the unit in water.

H. Specification

Specific Declarations:

Benetech shall hold no responsibility resulting from using the output from this product as direct or indirect evidence. Benetech reserves the right to modify product design and specifications without notice.

CE