Hot Slug Detector:
Hot slugs form when a process upset causes molten glass to fall from the spinner and into the product during the manufacturing of fiberglass batting. Surrounded by insulating material, these hot slugs remain hot, and days later can cause the paper backing and organic binder material to ignite, creating an expensive and inconvenient fire in a warehouse, on a train or in a truck. The Williamson Model HSD identifies the presence of small slugs below the surface of the fiberglass batting during the manufacturing process. Sensitivity is greatest when mounted after the fluffing blower and before the curing oven.
The Williamson model HSD combines three innovative Williamson technologies to produce the most viable and reliable hot slug detector.
Short-Wavelength Technology
- Short Wavelengths view deep into the batting to sense even the smallest hot slug.
- Model HSD-00 views about 16 inches into the batting and is compatible with conventional lighting.
- Model HSD-01 views as deep as 30 inches into the batting and is compatible with LED lighting, fluorescent lighting, or an area in shadow. This model is more than 3 times more sensitive to hot slugs near the bottom of the batting compared to the model HSD-00.
Large Viewing Area
- Mounted at a 2.4 meter or 8-foot distance, the HSD views an area 923 mm or 37 inches across. This typical mounting distance requires 3 HSDs to be mounted across the width of the web.
- Mounted at a 1.8 meter or 6-foot distance, the HSD views an area 692 mm or 27 inches across. This more sensitive mounting configuration requires 4 HSDs to be mounted across the width of the web.
Unique Hot Spot Detection System
- The ROC Rate of Change alarm system senses the small but instantaneous change in temperature reading associated with the introduction of the hot slug into the field-of-view.
- To accomplish this, the pyrometer compares the current reading with the reading a fraction of a second earlier. Any rise in temperature is amplified and the result is used as the hot slug alarm parameter.
Performance:
Following are graphs showing the ROC output identification of small glass slugs manually inserted into the batting at various depths. The slugs were heated to 815°C / 1500°F. Naturally-produced slugs are expected to be hotter and more easily detected. Background noise levels in the 0-400 range are typical and are caused by the natural variation in the batting temperature and by light reflections. Any signal above 650 is caused by the presence of a hot slug.
Configuration:
The hot slug detector is available in two configurations. Both configurations include the Interface Module (IM) to provide the hot spot detection technology and alarm. standard configuration also includes laser aiming, water-cooling, air purge, and swivel mounting bracket.
HSD-00-IM-CF040: This model uses the original wavelength set which is able to sense a ¼-inch (6 mm) slug as deep as 16 inches below the surface of the batting material. This wavelength set is optimized for depth of penetration while also limiting the sensitivity to hot-light reflections.
HSD-01-IM-CF040: This model uses a shorter wavelength set which is able to view a ¼-inch (6 mm) slug as deep as 20 inches and a ½-inch slug as deep as 30 inches below the surface of the batting material. This wavelength set is optimized for depth of penetration and requires the area lighting to be LED or fluorescent or for the area of measurement to be shielded from traditional hot-lighting.
Mounting Location: For best results, the HSD pyrometer should be mounted after the fluffing blower and before the curing oven. As air from the fluffing blower passes over the hot slug it becomes heated and then it warms the batting above the slug. The hotter batting material above the slug becomes a more significant target for the HSD to detect and produces a stronger ROC response.
Alarm Action: The Williamson HSD system measures the average bulk temperature of the batting and also the ROC alarm parameter. Both of these signals are available using a 4-20 ma analog output signal and a form-C contact alarm. The typical customer ties the ROC alarm signal to a marking system which identifies the location of the hot slug along the length of the batting so that the identified area may be cut from the product before it leaves the production line. Williamson does not supply the marking apparatus
How the HSD works:
The HSD senses the small but rapid change in measured temperature as the hot slug enters the field of view. This small change in measured temperature is amplified by the ROC Multiplier setting (0 to 100), and the result becomes the alarm parameter. For example, with an ROC Multiplier setting of 100, a 7-degree rise in sensed temperature becomes amplified to produce an ROC output value of 700. This alarm technique allows the bulk temperature of the batting to gradually rise and fall with changes in ambient temperature and operating practices while still allowing the system to alarm on relatively small instantaneous measures of temperature change.
For more information on the Williamson Hot Slug Detector please click the link below to contact a Williamson expert
