Dryer Master AM3, Руководство по эксплуатации продукта

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Dryer Master  A M 3 Product Manual
© Dryer Master Inc. Page: 63
7 Moisture Sensor General Specifications
7.1 Moisture Sensor Installation
The moisture sensor, typically a Fin-style design, needs to be installed in a chute or pipe in which the
product flow is mechanically metered to a constant flow rate of less than 2.5 CM (1 inch) per second.
The sensor must be mounted vertical to ensure proper product flow. Typically the Fin sensor is
mounted in a 15
– 20 cm (6 – 8 inch) square or round pipe into which a portion of the product stream is
diverted. The exact dimension of the pipe is not critical provided a good flow cross section is achieved.
This pipe is completely full of compacted product during operation. The product is metered out of this
pipe with either a screw conveyor or a rotary valve. The speed of the conveyor or rotary valve is such
that the flow past the sensor is at less than 2.5 cm (1 inch) per second. In continuous operation with
highly abrasive products, or less than 2000 lbs per hour flow, it is recommended that the flow rate be
further reduced to 1 cm (0.4 inches) per second or less.
Product flow rates are approximate but must be no faster than 2.5 cm (1 inch) per second. Flow rates
must be constant; change in the speed of flow will affect moisture sensor accuracy and performance.
7.1.1 Moisture Range & Temperature range.
The sensors electronics typical operating temperature range is – 10 degrees Celsius (14 degrees
Fahrenheit) to 70 degrees Celsius (150 degrees Fahrenheit). Product temperature can range from – 25
to 95 degrees Celsius (-13 to 200 degrees Fahrenheit) although verification of the actual product
moisture at the temperature extremes becomes almost impossible. Moisture accuracy and
repeatability is absolute product moisture and moisture gradient depended. Typical accuracy is +/-
0.2% moisture or 2% of scale.
The Moisture Range is a function of the product and product temperature. Sensors are available to
cover moisture ranges from 0.5% to 45%, product densities from 0.15 g/cm
3 (10 lbs/foot 3 ) to 1.5 g/cm 3
(95 lbs/foot 3 ), and product temperatures from (negative) – 25 to (plus) + 95 degrees Celsius (-13 to 200
degrees Fahrenheit).
7.1.2 Sensor signal conversion
The dielectric conversion formula is a function of the sensor and the specific product. For most
products a linear conversion serves the narrow moisture range typically seen by the user. Dryer
Moisture Systems will provide a starting formula for the specific sensor on request. This formula will
provide a starting place for converting the dielectric voltage signal to an actual moisture value.
The temperature conversion formula:
For degrees Celsius (Volts * 40) – 60 = o C
For degrees Fahrenheit (Volts * 72) – 76 = o F