Surface temperature on drying cylinders in a paper machine is measured with SWT 316.
SWT 316 is a telescopic sensor with a Ni 100 sensing element. SWT 316 includes a 4-wheel wagon that runs directly on the cylinder surface. SWT 316 gives fast and accurate temperature measuring results in modern paper machines.
Developed for the application
SWT 316 was specially developed and tested for the paper industry in liaison with the Technical Institute of Lund, Sweden. It gives fast and accurate measurements of the surface temperature on drying cylinders in modern paper machines. The floating joint allows for a smooth run on the cylinder at different angles of the telescopic shaft.
High accuracy at high paper velocity
Due to the fact that the sensor is virtually in contact with the cylinder, with the protection for the sensor being a strong flexible metal wafer, the SWT 316 offers outstanding accuracy at high paper velocity. The sensor contact with the paper cylinder produces no adverse effects, the small amount of generated friction heat (1°C) is simply transferred to the air.
Connects to different instruments
SWT 316 is a temperature sensor for the handheld instruments SwemaTemp 21 or 20 and Swema 3000.
Why SWT 316 is better than reflector type sensors
SWT 316 has another handle than SWT 315 that has replaced SWT 215. The SWT 215 is a non contact, reflector type, temperature sensor. There is an 1 mm gap inbetween sensor and cylinder. In modern machines paper speed is up to 2000m/min. Paper speed in Paper machines was in the 1950:s around 35-175 m/min. In the 1990:s Stenström at the Technical Institute of Lund, Sweden tested the SWT 215.
The SWT 215 method was repeatable, after approximately 1 min a stable result was achieved, but too low (8-29°C) compared with the correct value. The higher paper speed introduced an air stream that cooled the sensor. In liaison with Stenström and the Technical Institute of Lund SWEMA started to develop a new sensor. The result was SWT 315, now modified to SWT 316. Instead of a reflector (SWT 215) there is a long lasting metal wafer on the SWT 316 that has direct contact with the cylinder. This sensor has been tested at over 1800m/min and by many specialists in the market. The result is convincing. The response time is approximately 7 seconds and the accuracy is within ±2°C. At machines over 500m/min we recomend replacement of SWT 215 to SWT 316.
Why SWT 316 is much better than IR on cylinder measurements.
Most cylinders are shiny and reflects the radiation. Most likely, with with an infrared (IR) temperature meter, the temperature measurement result comes from the surroundings and not from the cylinder. Humidity in the air also absorbs infrared radiation of certain wave lengths.
IR-meters are very sensitive to the surrounding air temperature and require cooling.