GB639216A - Improvements in packing glands - Google Patents

Abstract

639,216. Stuffing-box substitutes. DOWTY EQUIPMENT, Ltd. June 25, 1947, No. 16814. [Class 122(v)] A packing gland for a seal between a high pressure cylinder 14 and a plunger 11 which reciprocates therein comprises a stepped bore through which the plunger operates, the smaller diameter portion of the bore being nearer the cylinder, a first packing gland 15 in the smaller diameter portion, a second packing gland 30 in the larger diameter portion and located against movement away from the cylinder, a differential piston 21 interposed between the two glands and in slidable sealing engagement with the stepped bore and slidably surrounding the plunger, a communication 35 between the spaces at opposite ends of the piston, both spaces and communication being filled with liquid, and means venting the space between the steps of the piston and bore. The pressure in the cylinder 14 acts on the top of the gland 15 and is transmitted therefrom by the differential piston 21 to the liquid in the space 23 beneath the piston at a reduced intensity which reduced pressure acts, via the bore 35 in the piston 21, on the underside of the gland 15 and on the gland 30 which is supported against movement away from the cylinder by a closure plate 33. The pressure differential between the pressure in the cylinder 14 and atmosphere is thus shared between the two glands 15 and 30. The liquid, preferably oil, is introduced into the space 23 through a non-return valve 31. The space 24 between the larger part of the piston 21 and the step of the bore is vented to atmosphere through a duct 25, and to ensure that direct leakage of liquid through the duct 25 does not occur due to the piston 21 moving sufficiently to allow its smaller diameter sealing ring 28 to enter the space 24, a dis-. tance piece 36 is inserted in the space 23. More than two packing glands may be used with a differential piston between each adjacent pair. Specification 539,966 is referred to.