Abstract: A method of calibrating mechanical pressure gauges utilizes the dial indicator pointer to amplify and measure the small angular displacement of a pivoting movement element drivingly engaging a pinion gear to turn the pointer shaft and determines with the aid of an analogue model, usually in one iteration, the gain setting necessary to span the gauge and the position of the pivoting movement to establish acceptable linearity without bending the mechanical linkage or changing the movement connecting link. The method includes a method of establishing the model and utilizes a programmed computer to accept the few measurements required, perform the method computations and instruct the operator. The method is applicable to gauges having a pressure measuring element which moves in response to pressure and a linkage connected to a movement, such as Bourdon tube gauges.

Abstract: An improved pressure gauge construction in which the pressure inlet to the Bourdon tube is supplied through a tubular socket having alternate connections for either a low-connected or back-connected gauge arrangement. An adaptor is provided for threaded mounting one end into a selected of said socket connections while the other end extends outward of the gauge housing with a thread of choice for connecting to a fluid pressure source. A threaded plug seals the unused socket connection while an interlock secures the installed adaptor against unthreading removal.

Abstract: A pressure gauge having a rotatably secured Bourdon tube, and a dial plate arcuately displaceable for effecting zero calibration of the gauge includes a rotationally presettable key for registered placement within a key-slotted receptacle in which the gauge is to be utilized. Keying is provided by a simulated Y-shaped washer mounted in an annular groove on the gauge stem and arcuately secured post-calibration at a predetermined angular setting from a reference point on the gauge dial.

Abstract: A leak-proof joint between a stainless steel gauge case and the brass socket of a pressure gauge includes a stainless steel sleeve brazed to the socket in the area of the case connection for enabling the gauge case to be welded thereto.

Abstract: An improved solid front casing for a pressure gauge that is readily field converted from a dust-tight to either a hermetically sealed air-tight or hermetically sealed liquid-tight construction. A flexible closure element is axially supported over a rear opening in the case by a threaded connection with threads formed in the case peripherally surrounding the opening. For either hermetically sealed air-tight or liquid-tight service a self-threaded closure element is replaced by a flexible diaphragm of controlled spring rate axially clamped by a threaded backup ring. Temperature induced volumetric changes imposed on the liquid fill or air fill are compensated for by the spring rate of the diaphragm. In the event of an overpressure occurring internally of the casing the diaphragm can escape from its clamping relation for affording pressure relief.

Abstract: Excess pressure being supplied to a pressure gauge is controllably relieved through the gauge cavity and an unsealed aperture in a spring-like crystal. A sleeve member extends transversely in a forced engagement between the inside face of the crystal and an annular gasket compressed in surrounding relation about the inlet of the Bourdon tube. The gasket normally seals the passage clearance about the tube inlet against supply pressure leakage therepast but in response to an overpressure is displaced inwardly toward the cavity until leakage can occur. Concomitant displacement of the sleeve member deflects the crystal outwardly a like amount afforded by its spring rate matched in correlation with the maximum anticipated overpressure to be provided for.

Abstract: Pointer zero adjustment in a pressure gauge is effected by means of a shaft (50) centrally extending laterally inward of the casing from a supportive centering flange (40) on the inside face of the crystal (10). A Bourdon tube (44) is radially coiled concealed from view through the crystal (10) about a pressure sealed rear portion of the shaft (50) to which it is rotationally secured. The pointer unit (42) is of a more or less U-shaped cross section with a tubular center (48) loosely supported on the shaft (50) juxtaposed to the crystal (10). The front pointer formation (42) simulates a conventional pointer appearance while its rear formation (52) is rotatably linked to the free end (56) of the Bourdon tube for incurring operational displacement therewith. On removing a detachable cover (37) from over an aperture (34) in the crystal coincidingly located opposite the shaft end thereat, access is provided for an external tool (78) to operationally engage a tool receiving hex socket (38) in the shaft end.