Extech Instruments 461920 - User Manual

USER MANUAL
Extech Mini Laser Photo Tachometer /
Counter — Model 461920

Summary

Introduction to the Extech Mini Laser Tachometer

Product Description and Components

Safety Precautions and Warnings

Meter Operation and Usage

RPM Mode Operation Guide

Instructions for setting the meter to measure RPM and performing non-contact RPM measurements using the laser.

Counter Mode Operation Guide

Instructions for setting the meter to measure counts (revolutions) using the laser pointer.

Measurement Notes and Tips

Tips and considerations for accurate measurements, including ambient light, reflective tape, and target properties.

Battery Replacement and Disposal

Technical Specifications

General Specifications Overview

Details general technical specifications such as display type, laser class, detection distance, operating conditions, power, weight, and dimensions.

Measurement Specifications Details

Outlines the specific measurement ranges, resolutions, and accuracies for Tachometer (RPM) and Counter (Revolutions) modes.

Warranty and Support Information

Calibration and Repair Services

Information on calibration services, repair availability, and the importance of annual calibration for meter accuracy.

Contact Customer Support

Provides contact details including telephone numbers and email addresses for customer support, calibration, repair, and returns.

Overview

1. Function Description
2. Usage Features
3. Maintenance Features

The Extech Mini Laser Photo Tachometer/Counter, Model 461920, is a versatile handheld instrument designed for non-contact measurement of rotational speed (RPM) and revolutions (Count). This device utilizes a laser pointer for precise targeting, ensuring accurate measurements in various applications. Its compact design and user-friendly interface make it suitable for both professional and casual use.

Function Description

The primary function of the 461920 is to measure the rotational speed of an object in Rotations Per Minute (RPM) and to count the total number of revolutions (REV). It achieves this through a non-contact method, using a laser beam and reflective tape.

In RPM Mode, the device measures how many times an object completes a full rotation in one minute. This is particularly useful for machinery, motors, fans, and other rotating equipment where monitoring speed is critical for performance, safety, or maintenance. To take an RPM measurement, a small piece of reflective tape is applied to the surface of the rotating object. The user then points the meter's laser at this reflective tape from a distance of 2 to 20 inches (50 to 500 mm). When the "Measure" button is pressed and held, the laser emits a beam that reflects off the tape. The meter detects these reflections, and an on-screen monitor indicator (()) confirms that the reflective tape is passing through the light beam. The device then calculates and displays the RPM. Once the "Measure" button is released, the last reading remains on the display for approximately 5 seconds before the meter automatically switches off to conserve battery. The meter also stores the maximum, minimum, and last RPM readings in its memory, which can be recalled using the "MEM" button when the meter is off.

In COUNTER Mode, the device counts the total number of revolutions an object completes. This mode is useful for applications where the total number of rotations, rather than the speed, is the desired measurement. Similar to RPM mode, the user applies reflective tape to the object and points the laser at it. When the "Measure" button is pressed and held, the meter counts each revolution as the reflective tape passes through the laser beam. The monitor indicator (()) on the LCD confirms detection. Upon releasing the "Measure" button, the final count value is displayed for about 5 seconds before the meter powers down. This final count value can also be recalled from memory using the "MEM" button when the meter is off.

Usage Features

The Extech 461920 is designed for ease of use and reliability.

• Non-Contact Measurement: The laser-based measurement system allows users to take readings from a safe distance, eliminating the need for physical contact with rotating machinery, which can be dangerous.
• Laser Pointer for Accurate Targeting: The integrated laser pointer ensures that the user can precisely aim the measurement beam at the reflective tape on the target object, even in challenging environments or at varying distances.
• Clear LCD Display: The device features a clear Liquid Crystal Display (LCD) that shows the measurement readings (RPM or REV) and other indicators, such as the monitor indicator (()) for beam detection.
• Intuitive Controls: The meter has a straightforward control layout, including a "Measure" button to initiate measurements and activate the laser, a "MODE" button to switch between RPM and COUNTER modes, and a "MEM" button to access stored memory readings (MAX, MIN, LAST for RPM, and final count for REV).
• Memory Function: The ability to store and recall maximum, minimum, and last readings for RPM, and the final count for revolutions, is a valuable feature for tracking performance over time or for later analysis without needing to manually record each reading.
• Automatic Shut-off: To extend battery life, the meter automatically powers off approximately 5 seconds after the "Measure" button is released, or if no activity is detected.
• Measurement Notes for Optimal Performance: The manual provides helpful tips for achieving accurate measurements. These include recommendations to avoid bright ambient light, which can interfere with accuracy, by holding the meter closer to the target or shading the area. It also advises ensuring that the non-reflective area on the object is larger than the reflective area. For inherently reflective shafts or objects, covering them with black tape or paint before applying reflective tape is suggested to improve contrast. For low RPM measurements, applying additional squares of reflective tape can enhance repeatability; in such cases, the displayed reading should be divided by the number of tape pieces to get the actual RPM.

Maintenance Features

Maintaining the Extech 461920 is simple and primarily involves battery replacement.

• Low Battery Indicator: The meter features a low battery indicator on the display, which alerts the user when the 9V battery needs to be replaced. This ensures continuous operation and prevents unexpected power loss during critical measurements.
• Easy Battery Replacement: To replace the battery, the user simply needs to open the rear battery compartment by removing two Phillips head screws. The 9V battery can then be replaced, ensuring correct polarity. After replacement, the battery compartment cover should be securely fastened.
• Environmental Responsibility: The manual includes a clear directive not to dispose of used batteries or rechargeable batteries in household waste, promoting environmentally responsible disposal practices.
• Durable Design: While not explicitly detailed in the provided text, the robust construction typical of Extech instruments suggests a design intended for long-term use in various industrial and field settings. Proper care and storage, as with any precision instrument, will contribute to its longevity.

Extech Instruments 461920 Specifications