Wahl DHSA24 1000°F Heat Spy Infrared Thermometer

The DHSA24 High Performance Heat Spy features superior accuracy and sensitivity between 0° to 1000°F (-20 to 550°C). Accuracy is ±0.3% of full scale. Repeatability of ±1°F. LED Display. Anti-reflective filter for accurate use in strong sunlight or other light sources. Applications include all normal materials, including glass surfaces. The DHSA24 is not affected by IR heaters, carbon dioxide or water vapor, and will not measure through glass. 8 to 14 Microns. Enclosed Optical Sight. 3 Year Warranty. Includes Carrying Case, Batteries, Owner's Manual, Trigger Lock, AC Adapter, 110V or 220V.

How Does the Heat Spy Work?
 
All solid objects emit infrared energy above absolute zero. The amount of energy emitted is proportional to the body or target temperature. Wahl’s Heat Spy directs this energy by means of fixed focus optics into a sensitive detector, which is amplified and processed by the micro processor to temperature readings in °F or °C. It is fast because it collects Infrared energy at the speed of light, and the detector has a very low mass. The time constant is 0.1 second, about 10 times faster than conventional contact methods. Measurements are displayed in less than one second. Some Heat Spy’s offer an analog output option of 1mV/deg for recording, while others feature RS232 computer interface.

Heat Spy Emissivity

Emissivity in Infrared measurement refers to the ability of the measured surface to emit radiation. Surfaces vary in emissivity and this must be taken into account before accurate readings can be obtained. The emissivity ratio represents the amount of radiated energy the measured surface allows to be returned to the instrument. A return of 100% of the energy is measured as 1.0 emissivity. If all the radiated energy is reflected and/or transmitted and none emitted, the emissivity ratio is 0.0.

A perfect radiator, such as a black body, has a 1.0 emissivity ratio and a very shiny or highly polished surface has a ratio of 0.2 or lower. Most textured or painted surfaces have an emissivity ratio of around 0.95. Many Heat Spy thermometers feature adjustable emissivity from 0.10 to 1.00. Other Heat Spy’s without adjustment are set at 0.95 and include instructions on how to adjust readings to take low emissivity into account.

Sighting with the Heat Spy

Understanding the relationship of target size to spot size is critical to obtaining accurate temperature readings with any infrared thermometer. Target size is the size of the object whose temperature you are measuring. Spot size is an indication of the diameter of the measurement area of the instrument. Picture a flashlight; as you shine it on a wall, the size of the bright spot on the wall gets larger as you move away from the wall. The same is true of the spot size for an infrared thermometer. For accurate temperature measurment, the spot size should always be smaller that the target size, since the instrument will “average” the temperatures of everything inside the spot. The spot size is expressed as a fraction of the distance to the target. For example a 10:1 instrument has a spot size of 1 foot at 10 feet from the target.

The distance to spot size ratio is specified for all Heat Spy models

Features for All Models

• Adjustable Emissivity
• Maxitemp® Peak Temperature Hold
• Self Test
• Auto Calibration
• Output to Recorder
• AC Adapter
• °F/°C Switchable
• NIST Traceable Accuracy
• Rugged Aluminum Housing
• Sighting and Display Options