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Pressure Actuation is achieved by Bourdon tube movement . C tubes are typically used for lower pressures up to 600 psi, and coiled tubes are used for higher pressures.
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Pressure Ranges: Bourdon tube pressure gauges can measure pressures from full vacuum to 40,000 psi. Generally, a range of twice the working pressure is recommended, with maximum working pressure not exceeding 75% of the range. If pulsation occurs, working pressure should not exceed 65% of the range. Never use a gauge at pressure greater than the maximum range on the dial. PSI ranges are Standard, and several alternate single and dual ranges are available. See Range Chart
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Accuracy: Gauges are available with accuracies from ± 0.25% (ASME grade 3A) to ± 3/2/3% (ASME grade B). Percent accuracies are expressed as percent of full scale.
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Ambient Temperature: Normal ambient temperature limits are -30°F to 150°F (35°C to 65°C) for dry gauges and 23°F to 140°F for glycerine filled gauges. PTC gauges are calibrated at 70°F (20°C). Change in ambient temperatures causes ± 0.3% error per 18°F (10°C) rise/fall, respectively. Ambient error for Test Gauges is ± 0.05% per ± 18°F (10°C)
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Process Temperature: Gauges with stainless steel wetted parts have a welded tube and socket, and will withstand 750°F (400°C). Gauges with soldered copper alloy joints will withstand 150°F (65°C); with silver brazed joints 250°F (120°C). Maximum process temperatures should only be reached intermittently to avoid rupture, and may result in loss of calibration or damage to other parts of the gauge.
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Severe Conditions: In applications involving severe pulsation, the use of snubbers and/or restrictors is recommended. Also, for vibrating or pulsating applications, liquid filling will help prevent wear and extend the service life of the gauge. Glycerine is the standard fill material. Also available (with special gasketing) are silicone and Halocarbon. Halocarbon, though quite costly, is recommended for service with oxidizing agents such as oxygen, hydrogen peroxide,chlorine,nitric acid, ect.
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Pressurized Medium Considerations: All pressure gauge components should be selected to suit characteristics of the fluid being measured. For steam service, a siphon is required. For corrosive chemicals, stainless steel (or monel) wetted parts, or chemical seal should be considered (monel wetted parts are available on special order). For fluids that solidify or leave deposits, a diaphragm seal should be considered. For oxidizing fluids, no oil should be present.
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Mounting: NPT connections are located in the center back, lower back or bottom of the case. Rear flanges are available for surface mounting. For panel mounting front flanges or "U" or "O" clamps are available. Special threads (BSP, Metric, ISO) are also available.
