Extraction system with product accumulation sensor / s

Abstract

The invention relates to an extraction system with product accumulation sensor / s. The systemcomprises: one or more extraction inlets from which dust and air is extracted from a work place, a duct 2 or

Claims

1. An extraction system with product accumulation sensor / s comprising:a) one or more extraction inlets from which dust and air is extracted from a work place,b) a duct or ducts leading from each extraction duct inlet to an extraction duct outlet,c) an extraction fan to extract air and dust from the extraction duct outlet, andd) an air velocity sensor in the duct or ducts to detect build up of product in the duct / s, said air velocity sensor using a pair of pressure sensors, one measuring pressure upstream of a venturi or through the restriction of the venturi and the other measuring pressure through the restriction of the venturi or downstream of the venturi, ande) a pair of pressure sensors spaced either side of the air velocity sensor in the duct or ducts to detect build up of product in the duct / s,in use said air velocity and / or pressure sensor / s causing the fan to increase its extraction power upon build-up of product to cause said build up of product in ducts to be extracted until said sensor / s no longer sense build-up of product.

2. An extraction system according to claim 1, wherein said air velocity and / or pressure sensor / s cause the fan to increase its extraction power for a pre-determined period of time when the fan extraction power is then decreased, and then the sensor / s only increase the fan’s extraction if product continues to be sensed.

3. An extraction system according to claim 1 or 2, wherein the pressure sensors either side of the air velocity sensor compare a pressure increase or flow rate increase either side of the air velocity sensor with a pressure and flow rate value determined when a duct is known to be clear of product and at different flow rates.

4. An extraction system according to claim 1,2,or 3 wherein the sensor includes an infra-red transmitter and an infra-red receiver , and changes in infra-red waves received by the receiver due to product build up in the pipe compared to when the pipe is clear of product senses the build-up of product in the duct.10

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