SWT 316 cylinder temperature sensor

Description SWT 316 Cylinder temperature sensor

The surface temperature of drying cylinders in a paper machine is measured with SWT 316.

SWT 316 is a telescopic sensor with a Ni 100 sensor element. SWT 316 has a 4-wheel carriage that runs directly on the cylinder surface. The SWT 316 provides fast and accurate temperature measurement results in modern paper machines.

Developed for the application
SWT 316 has been developed and tested in cooperation with the Technical Institute of Lund, Sweden, specifically for the paper industry. It enables fast and accurate measurements of the surface temperature on drying cylinders in modern paper machines. The floating joint enables smooth running on the cylinder at different angles of the telescopic shaft.

High accuracy at high paper speed
Due to the fact that the sensor is practically in contact with the cylinder and the sensor is protected by a strong, flexible metal wafer, the SWT 316 offers excellent accuracy at high paper speeds. The contact of the sensor with the paper cylinder does not cause any negative effects, the small amount of frictional heat generated (1 °C) is simply transferred to the air.

Connects to various instruments.
SWT 316 is a temperature sensor for the handheld instruments SwemaTemp 21 or 20 and Swema 3000.

Why the SWT 316 is better than reflector-type sensors
The SWT 316 has a different handle than the SWT 315, which replaced the SWT 215. The SWT 215 is a non-contact reflector type temperature sensor. There is a gap of 1 mm between the sensor and the cylinder. In modern machines, the paper speed is up to 2000 m/min. The paper speed in paper machines in the 1950s was about 35–175 m/min. In the 1990s, Stenström at the Technical Institute of Lund, Sweden, tested the SWT 215.
The SWT 215 method was repeatable, a stable result was obtained after about 1 minute, but too low (8-29 °C) compared to the correct value. The higher paper speed created an air flow that cooled the sensor. In collaboration with Stenström and Lund Technical Institute, SWEMA started developing a new sensor. The result was SWT 315, now modified to SWT 316. Instead of a reflector (SWT 215), the SWT 316 has a durable metal wafer that has direct contact with the cylinder. This sensor has been tested at over 1800 m/min and by many specialists on the market. The result is convincing. The response time is about 7 seconds and the accuracy is within ±2 °C. For machines over 500 m/min, we recommend replacing SWT 215 with SWT 316.

Why SWT 316 is much better than IR for cylinder measurements.
Most cylinders are shiny and reflect radiation. With an infrared (IR) temperature measuring device, the temperature measurement result most likely comes from the environment and not from the cylinder. Humidity also absorbs infrared radiation of certain wavelengths.
IR measuring devices are very sensitive to the ambient air temperature and must be cooled.

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