1. Introduction
The LR-Cal LRT 750 is a high-precision digital reference thermometer designed for checking and calibrating various types of thermometers. This system comprises a battery-powered digital handheld indicator and a pre-aged precision sensor, offering a wide temperature measurement range from -200°C to +450°C. It serves as a reliable comparison reference for temperature reading instruments, providing an accuracy of up to 0.03°C for precise comparison measurements.
2. Safety Information
Please read and understand all safety instructions before operating the LRT 750 thermometer. Failure to follow these instructions may result in injury or damage to the device.
- Do not expose the device to extreme temperatures outside its specified operating range.
- Avoid dropping or subjecting the device to severe impact.
- Do not attempt to disassemble or modify the thermometer. Refer all servicing to qualified personnel.
- Ensure the probe is securely connected before taking measurements.
- Handle the probe with care, especially when measuring high or low temperatures, to prevent burns or frostbite.
- Keep the device away from strong magnetic fields.
- Use only the specified battery type and ensure correct polarity during installation.
3. Package Contents
The standard package for the LR-Cal LRT 750 includes the following items:
- Adjusted, pre-aged precision probe
- Handheld digital indicator (adjusted to the connected probe)
- Batteries
- Operating manual (this document)
- Protective plastic case
- Certificate of Calibration (factory or DAkkS, depending on order configuration)
This image displays the LR-Cal LRT 750 Precision Reference Thermometer system. The main handheld indicator unit is visible in the center, surrounded by custom-cut foam within a durable blue plastic carrying case. The precision probe is positioned alongside the indicator, ready for use. The foam inserts ensure secure transport and protection of all components.
4. Setup
4.1 Battery Installation
The LRT 750 is powered by batteries. To install or replace batteries:
- Locate the battery compartment on the back of the handheld indicator.
- Open the battery compartment cover.
- Insert the batteries, ensuring correct polarity as indicated inside the compartment.
- Close the battery compartment cover securely.
4.2 Probe Connection
The precision probe connects to the handheld indicator via a dedicated port.
- Identify the probe input port on the bottom of the handheld indicator.
- Align the connector of the precision probe with the input port.
- Gently push the connector into the port until it is firmly seated. Do not force the connection.
- Ensure the connection is secure to prevent inaccurate readings.
This image shows the LR-Cal LRT 750 handheld digital thermometer with its precision probe securely connected. The probe extends from the bottom of the main unit, which features a clear digital display and control buttons. This setup illustrates the device in an operational configuration, ready to take temperature readings.
5. Operating Instructions
5.1 Powering On/Off
- To power on the device, press the POWER button. The display will illuminate.
- To power off the device, press and hold the POWER button until the display turns off.
5.2 Taking Measurements
- Ensure the probe is properly connected and the device is powered on.
- Insert the precision probe into the medium or environment whose temperature you wish to measure. Ensure the sensing tip of the probe is fully immersed or in good contact with the target.
- Allow sufficient time for the reading to stabilize on the display. The response time (t90) is typically 12 seconds.
- Read the temperature value displayed on the digital screen.
5.3 Display Interpretation and Functions
The digital display shows the current temperature reading. The LRT 750 also features several functions:
- Measurement Rate: Can be set to "Fast" (4 readings/sec) or "Normal" (1 reading/sec).
- MIN and MAX values: Allows viewing of the minimum and maximum temperatures recorded during a measurement session.
- HOLD: Freezes the current reading on the display.
- AVERAGE: Calculates the average of readings over a period.
- ZERO: Resets the current reading to zero, useful for relative measurements.
- Integrate: Real-time clock function.
5.4 Calibration
The LR-Cal LRT 750 is a reference thermometer used for comparison measurements. It comes with a Certificate of Calibration (factory or DAkkS accredited). For maintaining its accuracy, periodic recalibration by a qualified laboratory is recommended. Refer to your calibration certificate for recommended recalibration intervals.
6. Maintenance
Proper maintenance ensures the longevity and accuracy of your LRT 750 thermometer.
- Cleaning: The device and probe can be cleaned by wiping them with a soft, damp cloth. Do not use abrasive cleaners or solvents. Ensure the device is powered off and disconnected from the probe before cleaning.
- Storage: When not in use, store the LRT 750 and its probe in the provided plastic case to protect them from dust, moisture, and physical damage. Store in a dry environment within the permissible storage temperature range of -10°C to +50°C.
- Battery Replacement: Replace batteries promptly when the low battery indicator appears on the display to ensure continuous accurate operation.
7. Troubleshooting
This section addresses common issues you might encounter with your LRT 750 thermometer.
| Problem | Possible Cause | Solution |
|---|---|---|
| Device does not power on. | Dead or incorrectly installed batteries. | Replace batteries, ensuring correct polarity. |
| Inaccurate or fluctuating readings. | Loose probe connection; probe not fully immersed; device not stabilized; probe damage. | Check probe connection; ensure full immersion; allow time for stabilization; inspect probe for damage and replace if necessary. |
| Display shows "Error" or blank. | System malfunction; extreme environmental conditions. | Power off and restart the device. If error persists, contact customer support. Ensure operating within specified temperature range. |
| Slow response time. | Measurement rate set to "Normal"; large temperature difference. | Check measurement rate setting; allow more time for stabilization. |
8. Specifications
Detailed technical specifications for the LR-Cal LRT 750 Precision Reference Thermometer:
| Parameter | Value |
|---|---|
| Model | LRT 750 |
| Temperature Range | -200°C to +450°C |
| Accuracy | Up to 0.03°C |
| Display Type | Digital (4 1/2 digits, two lines, with back light) |
| Display Resolution | Up to 200°C: 0.01K; elsewhere: 0.1K |
| Response Time (t90) | 12 seconds |
| Power Source | Battery Powered (9 VDC block battery or optional rechargeable battery via USB adapter) |
| Permissible Operation Temperature | 0°C to +40°C |
| Permissible Storage Temperature | -10°C to +50°C |
| Housing Material | Rigid ABS plastic, transparent window |
| Weight | Approx. 350 g |
| Probe Dimension (Pt 100 sensor) | 300 mm insertion length x 3 mm diameter, with handle and connection cable |
| Manufacturer | LR-Cal |
This image presents the comprehensive specification sheet for the LR-Cal LRT 750. It details various functions such as measurement rate, MIN/MAX values, HOLD, AVERAGE, ZERO, and Integrate. Key performance metrics like measuring range (-200 to +450°C), accuracy (up to 0.03K), display resolution, and response time (12 seconds) are clearly listed. Environmental conditions, housing material, weight, and probe dimensions are also provided, along with order codes for different calibration options.
9. Warranty and Support
9.1 Warranty Information
The LR-Cal LRT 750 Precision Reference Thermometer comes with a one-year warranty from the manufacturer. This warranty covers defects in materials and workmanship under normal use. It does not cover damage resulting from misuse, accident, modification, or unauthorized repair.
9.2 Customer Support
For technical assistance, troubleshooting beyond this manual, or warranty claims, please contact LR-Cal customer support. Have your product model and serial number (if applicable) ready when contacting support.
For the most up-to-date contact information, please visit the official LR-Cal website or refer to the documentation provided with your purchase.