Category Archives for Pressure Instruments

Pressure Instruments – Specific Requirements

Pressure Gages Direct-mounted pressure gages may be installed with a ¾-inch root valve that meets the piping standards or with proprietary pressure gage block and bleed valves or approved equivalent. See Standard Drawings GB-J1143 and GB-J1144. Remote-mounted pressure gages should … Continue reading

20. April 2018 by Juan
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Diaphragm Seals

Diaphragm seals, also called chemical seals or gage protectors, use a thin flexible diaphragm to isolate the pressure element from the process fluid (see Figure 400-8). The space between the diaphragm and the sensing element is filled with a suitable … Continue reading

20. April 2018 by Juan
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Pneumatic Pressure Switches

Pneumatic pressure switches are on/off pneumatic controls used to operate equipment, alarms, and shutdown systems. Pneumatic pressure switches are also called pressure pilots and are of two basic types: stick pilots and Bourdon tube pilots. Stick pilots are spring piston … Continue reading

20. April 2018 by Juan
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Electrical Pressure Switches

Electrical pressure switches provide on/off contact closures for use with equipment or an alarm or shutdown system. They should have one of three standard case designs, depending on the electrical classification where they are installed: • Explosionproof (NEMA 7) • … Continue reading

20. April 2018 by Juan
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Receiver Pressure Gages

A receiver pressure gage operates on the 3 to 15 psig pneumatic signal from a pneumatic transmitter. It provides a local indication of the transmitter’s performance. The dial is specified to match the range of the transmitter. All blind pneumatic … Continue reading

20. April 2018 by Juan
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Pneumatic Pressure Transmitters

Pneumatic pressure transmitters transmit pressure signals to remote pneumatic receivers. Both blind and indicating transmitters are available. Blind transmitters are preferred because they use force-balance mechanisms (See Section 411). Accuracy should be within 0.5% of the calibrated span. Pneumatic pressure … Continue reading

20. April 2018 by Juan
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Electronic Pressure Transmitters

The electronic pressure transmitter is used to transmit a signal to a remote electronic receiver. The receiver may be a controller in a remote building, a remote marshalling cabinet for numerous signals, or a remote terminal unit (RTU). Transmitters should … Continue reading

20. April 2018 by Juan
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Field Pneumatic Pressure Controllers

The field pneumatic pressure controller (pressure controller) compares the measured process pressure to a setpoint and sends an output signal to a final control element (control valve) which acts to hold the process pressure at the setpoint. Field pressure controllers … Continue reading

20. April 2018 by Juan
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Field Pressure Recorders

Field pressure recorders should have weatherproof cases of fiberglass-reinforced plastic or aluminum. Colored epoxy or baked vinyl is used to provide a textured finish. If the case contains electrical components, it should meet the electrical classification requirements for the area. … Continue reading

19. April 2018 by Juan
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Pressure Test Points

Pressure test points consisting of a process connection with a plugged process quality root valve should be provided on process equipment and piping at the following locations: • Inlet and outlet of packed vessels and columns • Indicating pressure transmitters, … Continue reading

19. April 2018 by Juan
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