Patent GB-390803-A (GB)
Title: Improvements relating to liquid pressure measuring apparatus and pressure gauge testing apparatus
IPC: G01L27/00
Filed: 1931-07-08
Abstract: 390,803. Pressure gauges. ANGLO-PERSIAN OIL CO., Ltd. and COMINS, D., Britannic House, Finsbury Circus, London. July 8, 1931, No. 19701. [Class 106 (ii).] Apparatus for measuring more especially oil well pressures comprises apparatus in which the pressure is balanced against weights applied to an element subjected to the fluid pressure by way of an interposed liquid medium the volume or pressure of which is under control. The parts are mounted on a base 1 and are arranged to be conveniently enclosed in a casing for transport. The pressure gauge comprises a pillar 2 on a base 2a provided with a transverse passage 3. A central vertical passage 4 communicates with the passage 3 and extends into a cavity 5 beneath a cylindrical block 6 in which works a piston 7 the movement of which is limited by a stop 7a. Mounted on the top of the piston is a cap 10 on which through the medium of a ball 11a is supported a carrier 9 for a series of weights 8 the lowermost of which rests on a flange 9a. A cylinder 12 forms with a flange 2b of the pillar 2 a receptacle for water by which the gauge is maintained at a uniform temperature of 100‹ F. Openings 9b allow insertion of thermometers into the water and into an oil pocket 6a. A three-way valve 3a is provided in the lower part of the pillar. A white line on the flange 9a co-operates with an index post 14 on the base 1 to indicate when the piston is floating and the pressures are balanced. The parts are filled with refined oil from a receptacle b by means of a hand pump c provided with suction and spring valves in a casing d. The plunger spindle is screwed and passes loosely through one head and is screwed into a second head which is screwed over the first when it is required to operate the pump as a screw pressure pump. The syphon or seal casing e contains refined oil and is provided with a hand-controlled valve 18, an inlet 19 affording connection to the oil well. The oil leaves the receptacle e through a passage 19a and passes upwardly through a narrow tube of the same height as the syphon casing. A differential mercury manometer f may be employed comprising vertical limbs 20, 20a provided at the top with bleeding valves 21, 21a. The steel limb 20 is connected to a mercury reservoir 22 while the limb 20a which is of non-metallic tubing is connected to the lower side of the reservoir 22. The tops of the limbs 20, 20a are connected by pipes to the casing e and pillar 2 respectively. The limb 20a is provided with a pointer exploring magnet 23a the frame 23 carrying which is moved over the limb until a steel ball floating on the mercury is located. When the magnet 23a is horizontal reading zero on its scale 23b and a mark on the tail of the magnet registers with a mark on an arm 23c, the reading of a pointer 23d on the scale 24 gives the pressure. The passage 3 is connected through a valve 27, a bleeding valve 28 and a three-way valve 29 to the upper end of the limb 20a. The limb 20 connects to a three-way valve 30, one branch of which leads to the casing e and the other to the three-way valve 31. One branch of the latter leads to the casing d and thence to oil reservoir b, and the other branch leads to the valve 29. The valve 29 is closed by a plug when the manometer is disconnected for transit. The apparatus is carefully levelled before use bv screws on the base which is provided with a level 26. The valves are first manipulated and the apparatus filled with refined oil, using the pump c. Certain valves are now closed and pressure exerted by the pump until the piston loaded say for 2,000 lbs. per square inch, floats. Oil from the well is now admitted at 19. Connection is made between the dead weight gauge and limb 20a of the manometer weight 8 being removed until the piston rises to the limit. Some oil is now released through the valve 21a until the piston falls to floating position and the magnetic indication is steady. The pressure of oil-from the well is now equal to the sum of the weights 8 and the head of mercury in the manometer. For testing pressure gauges, the gauge to be tested is connected at 3 and syphon e cut out of the circuit. Pressure is then applied by the pump c until the piston 7 floats when the reading of the gauge is compared with that represented by weights 8. In a modification, the gravity gauge is slightly modified and is connected directly with a liquid manometer.