AN Glass_201702_en
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Application Glass Basics and applications - pyrometric temperature measurements in the glass industry

Application note Glass Temperature measurements are a vital factor to monitor and to optimise the energy-intensive glass melting processes. Therefore, non-contact pyrometric measurements are of great significance for the determination of the glass temperature as the most important indicator in the glass forming process. A temperature variation of 1% in the processing area of the majority of glass types already causes a variation in viscosity of approximately 1%. Often contact measurements with thermocouples with ceramic sheaths are still used to monitor the crown temperature during the...

One can see that wavelengths between 0.5 and 7.8 µm exhibit a nearly constant emissivity between 0.95 and 0.96. For the spectral range 8 – 14 µm an average emissivity value ε = 0.91 should be selected. Unlike metal surfaces where the spectral emissivity decreases with increasing wavelengths or is fluctuating or varies in relation to temperature and time, clear glass surfaces with negligible transmissivity in the spectral range from 0.5 to 7.8 µm may be regarded as grey bodies. The clear glass surface is not subject to perceptible changes as it is, for example, the case with metal surfaces...

Application note Glass of the standardised glass depth D/X99 for green glass, sheet glass and borosilicate glass at homogeneous and inhomogeneous temperature gradients with the glass object. The pyrometer detects 50% of the energy from the glass surface and from layers below the surface down to a depth which is commensurate to one sixth of the measuring depth X99. When the temperature distribution is inhomogeneous (surface glass is hotter than layers below the surface), these 50% will be even shallower (indicated by the dot-dash line). Sheet glass Green glass Selecting a pyrometer according...

Fig. 5 demonstrates how considerable convection interference at the glass surface can occur due to the large size of the extraction opening. Glass extracted from lower depths will not be affected by convection. The control loop of an electric overhead heater, for example, is extremely sensitive to this external interference. The heater will shut off when the gathering ball, coated with molten glass, enters the gathering bay, and turn on again when the ball gatherer is withdrawn. This will produce misleading temperature data. This source of error can be eliminated by a pyrometer with Si...

Application note Glass Pyrometer types and typical applications in the glass industry The scope of KELLER pyrometers and accessories offers suitable solutions for all measuring spots. Stationary pyrometers Spectral pyrometers with Si or InGaAs sensors are especially suitable for measuring glass temperatures at the melting tank, in workcells and feeder, due to their large measuring depth for colourless glass and their temperature ranges from 250 °C to 3000 °C. The CellaTemp PA 20 / 30 with sighting aid or the CellaTemp PK 21 / 31 without sighting aid is preferable for measuring glass...

There is indeed a temperature difference between the mould’s inner surface and the temperature in the drilled cavity. This temperature difference will remain a constant value. The closer the bottom of the drilled cavity is to the inner surface down to a remaining thickness of approx. 4 mm, the smaller is the difference between these temperatures. The CellaTemp PA 21 or CellaTemp PKF 26 with optical fibre cable and optical sensor head is ideal to measure mould temperatures. The small sensor head can be mounted to a convenient location near the press or the press-and-blow machine. The spot...

Application note Glass RS 485 interface, allowing for an optimal adaptation to the measuring point from the control room. The instruments of the compact PK pyrometer series are merely 30 mm in diameter and are thus ideal when working in confined areas. Housed in an IP 65 stainless steel enclosure they can be employed in extremely harsh industrial conditions. The CellaPort PT 120 or CellaPort PT 130 with measuring ranges from 250 – 2000 °C or 500 – 2500 °C is ideal for temperature checks in the upper furnace section and for molten glass in melting tanks, workcells and feeders and to check...

Summary of stationary pyrometers and their technical specifications Series Stationary infrared temperature switches with fibre optics cable

Delivery program Mikro PV Intensity comparison pyrometer for ultra accurate measurement. CellaTemp® PZ Series Profibus pyrometers with focusable lens, through the lens sighting or laser spotlight. CellaPort PT Series Portable single-colour and two-colour pyrometers with through-the-lens sighting, laser spot light and USB interface. CellaTemp PA Series Versatile pyrometers with focusable lens, through-the-lens sighting/ laser spotlight or video camera. CellaTemp® PK(L) Series Compact infrared thermometer for cramped environments. Optional with LED spot light. CellaTemp PA-LWL Versatile fiber...

INFRARED THERMOMETER SOLUTIONS • Headquarters Sales and Service Center Sales abroad in terms of ACCURACY ~ RELIABILITY INNOVATION Keller HCW GmbH • Division MSR Carl-Keller-Stra^e 2 - 10 49479 Ibbenburen-Laggenbeck Germany