Differential manometer pressure gage

Abstract

An improved closed-end manometer which overcomes the problems associated with prior U-tube manometer devices. The invention comprises a small bore tube which is transparent or translucent at least along the measuring portion and which may be of tapered or cylindrical bore, a permanent closure at one end of the tube, a relatively small indicating slug formed of a suitable liquid, a measuring scale to note the position of the liquid slug, and a measured quantity of a selected gas between the closure and the nearest end of the liquid slug. The open end of the tube is connected to the vessel or system whose pressure is to be measured or monitored. One feature of the present invention is its ability to provide quantitative pressure indications over a wide range of pressures, or the invention may be calibrated to provide increased sensitivity over a relatively short measuring range. Another feature of the invention is its ability to provide accurate pressure measurements regardless of the instrument's orientation. Furthermore, the invention may be readily formed in small sizes which renders it inexpensive to make and feasible for one-time, expendable use, for example with disposeable medical products.