Textile process control

Claim 1

In impregnation apparatus comprising: opposed means for squeezing material impregnated with liquid therebetween; means cooperating with the opposed means to define a liquid reservoir therewith; means capable of supplying liquid at a constant rate to the reservoir; and squeeze adjustment means for varying the pressure which the opposed means exerts on material passing therebetween; control apparatus for automatically controlling the level of liquid contained in the reservoir comprising: level sensing means including a tubular probe having one end open and adapted to be located below the level of liquid in the reservoir; means for passing air through the probe; and means responsive to the pressure existing in the probe to provide a signal indicative of the said pressure and means responsive to the signal from the level sensing means to actuate the squeeze adjustment means in accordance with fluctuation of liquid level in the reservoir and thereby to maintain the rate of liquid uptake in the material substantially equal to the rate of supply of liquid to the reservoir, the pressure responsive means comprising a closed chamber adapted to expand in response to the pressure therein; and a conduit maintaining said chamber in communication with said probe, whereby said pressure is transmitted to the said chamber, and a fluid pressure regulator valve operatively connected to a wall of said chamber, said valve being adapted to regulate the pressure of an actuating fluid in dependence upon the level of liquid in the reservoir, whereby said fluid can be supplied for actuating said squeeze adjustment means oN the impregnation apparatus, and a relief valve for said actuating fluid on the outlet side of said regulator valve, the relief valve being actuated by the pressure established in said probe to be opened to the atmosphere when the pressure in the probe falls below a predetermined value.