An Engine Filter with
Page 25
If you've noticed an error in this article please click here to report it so we can fix it.
Metal Element
A Fixed-ratio Filtering Medium Which Does Not Call for Replacement and Which Can Be Instantly Cleaned HE usual medium employed in the 1 average filter is of the absorbent type, there being many variations in the manner in which the material is disposed. • To be efficient, a metalelement filter demands careful attention to detail, as the element, being rigid and of fixed value as a filtering agent, must provide an unvarying surface to the filtrate. Such a type is found in the Purolator filter, which is handled by Automotive Products Co., Ltd., Tachbrook Road, Leamington Spa. " In this case, the filtering surface is formed by the use of a specially shaped wire which may be of brass, monel metal, stainless steel and certain other metals. This wire, which has a tapered cross-section, is coiled edge-wise on a perforated frame. The wire is so wmind that the wide edge of the taper faces the filtrate, the actual space through .,which the oil 'passes being formed by
providing what amounts to distance pieces in the shape of projections ,pf uniform height, on the wire. •
The height of these projections determines the degree of filtration which takes place, and they can be made as small as 0.0005 in., or even less, Some of the outstanding features of this method of building a filter are,that a rigid surface is Presented to the fluid, the degree of filtration remains constant over the whole surface of the element, and the element is practically everlaing.
The"' ventilatpd " nature of such an element ensures a minimum of pressure drop in the system, always assuming that reasonable precautions be taken in the way of cleaning. A relief valve is usually employed in the case of engine filters, to provide against oil starvation to the bearings should the operator fail to keep the filter clean. •
A variety of models is available,
including one which incorporates a simple and efficient form of externally operated cleaning device. This consists of a spring-bronze knife blade, supported by the operating rod which . passes ,out through the filter head. .This rod terminates in a hand wheel, and when this wheel is turned, the • blade, which is arianged to lie snugly' up to the filter element, passes around the element and frees it of any solid matter which may be adhering thereto.
Such deposits sink to the base of the filter and are subsequently removed by draining. A stuffing box, with an adjustable gland, is provided at the point where the shaft emerges from the filter top so that there is no possibility of leakage. Only one turn of the wheel is necessary completely to clean the element.
Fuller details, together with prices. may be obtained from the concern already mentioned.