Pneumatic transmitters

In cases of pneumatic transmitters, check air supply to transmitter. 

If level controller has pneumatic transmitter, look for isolated or broken lines or leaks. 

In case of pneumatic transmitter, eheek air supply, loose or broken lines. 

Fig. 6.34. U-Tube specific gravity (density) meter and pneumatic transmitter...

Fig. 6.76. Temperature-sensing bulb and associated pneumatic transmitter...

It is important to maintain correct levels in the hoppers into which the elevators discharge. Too high a level causes spillage of catalyst, and too low a level results in insufficient pressure in the reactor seal leg. Hoppers in some units are equipped with a continuously rotating vertical shaft with paddles which ride on the surface of the catalyst the position of the upper end of the shaft is communicated to the control room by means of a pneumatic transmitter (185,191). 

Following development of pneumatic field control systems came the idea that a control house was needed to incorporate all controls for a process into a central room. Pneumatic transmitters, including the development of dP cells for flow measurements, provided the next step in instrumentation and moved the local process control room into a central control house for the entire plant. 

Pneumatic transmitter with switches (behind panel) Acceptable 1oo1/1oo2/ 2oo3 Acceptable 1 oo2/ 2oo3 Requires hazard and risk analysis team approval... 

The 10-50 mA transmitter is becoming very popuiar because it has a higher toierance to outside interference. Pneumatic transmitters require a 20-psig air suppiy in order to run the standard 3- to 15-psig output. (See Figure 8-7.)... 

For pneumatic transmission systems, the signal range used for the transmission is 3 to 15 psig. In each pneumatic transmission system, there can be only one transmitter, but there can be any number of receivers. When most measurement devices were pneumatic, pneumatic transmission was the logical choice. However, with the displacement of pneumatic measurement devices by electronic devices, pneumatic transmission is becoming less common but is unlikely to totally disappear. 

Pneumatic Controllers The pneumatic controller is an automatic controller that uses pneumatic pressure as a power source and generates a single pneumatic output pressure. The pneumatic controller is used in single-loop control applications and is often installed on the control valve or on an adjacent pipestand or wall in close proximity to the control valve and/or measurement transmitter. Pneumatic controllers are used in areas where it would be hazardous to use electronic equipment, in locations without power, in situations where maintenance personnel are more familiar with pneumatic controllers, or in applications where replacement with modern electronic controls has not been justified. 

Process-variable feedback for the controller is achieved by one of two methods. The process variable can (I) be measured and transmitted to the controller by using a separate measurement transmitter with a 0.2-I.0-bar (3-15-psi pneumatic output, or (2) be sensed directly by the controller, which contains the measurement sensor within its enclosure. Controllers with integral sensing elements are available that sense pressure, differential pressure, temperature, and level. Some controller designs have the set point adjustment knob in the controller, making set point adjustment a local and manual operation. Other types receive a set point from a remotely located pneumatic source, such as a manual air set regulator or another controller, to achieve set point adjustment. There are versions of the pneumatic controller that support the useful one-, two-, and three-mode combinations of proportional, integral, and derivative actions. Other options include auto/manual transfer stations, antireset windup circuitry, on/off control, and process-variable and set point indicators. 

Gas compressor anti-surge (GM-OFF) control circuit, comprising transmitters, computers and pneumatic control valve Reverse flow protection (on axnal compressors only) as supplementary protection device against surging, working independently of the control circuit Expander emergency stop valve with pneumatic actuator and solenoid valve... 

LThe compensated flow transmitter determines the process flow it converts this quantity to a signal that is proportional to the process flow and sends it to the flow controller. The transmitter could be a pneumatic device using a venturi primary element, with compensation for pressure by a pressure element and compensation for tern perature by a thermocouple. The output would be a pneumatic sic nal that is proportional to weight flow. 

TransmitterS Pneumatic-Flow Pneumatic 3.5.3.4 Valves-Operated-Solenoid... 

Transmitters-Pneumatic- Conrtections 4.2.3.2 Protection Systems-Fire-Fire... 

Taxonomy No. 2.1.3.2.1 Equipment Description TRANSMITTERS - PNEUMATIC-FLOW ... 

Taxonomy No. 2 13 2 2 Equipment Description TRANSMITTERS-PNEUMATIC" LEVEL ... 

COMMENTS Sources do not specify between pneumatic and electronic transmitters... 

Flow recorder with pressure recording pen, botli elements pneumatic transmission, Iransmiller local, and receiver board mounted. (Recei er should be written as FR-5 and PR-2, and each transmitter identified by its own element)... 

Flow recorder pneumatic transmission, transmitter local, receiver mounted on board... 

Luyben (1973) (see simulation example RELUY) also demonstrates a reactor simulation including the separate effects of the measuring element, measurement transmitter, pneumatic controller and valve characteristics which may in some circumstances be preferable to the use of an overall controller gain term. 

Signal transmission limitations of pneumatic control systems made it necessary to limit the distance between the control house and the transmitter or control valve. As a result, early control houses were located within or at the periphery of the process unit. 

The temperature control loop consists of a temperature transmitter, a temperature controller, and a temperature control valve. The diagonally crossed lines indicate that the control signals are air (pneumatic). 

The basic components of the solid state spectrometer are the same as the solution-phase instrument data system, pulse programmer, observe and decoupler transmitters, magnetic system, and probes. In addition, high-power amplifiers are required for the two transmitters and a pneumatic spinning unit to achieve the necessary spin rates for MAS. Normally, the observe transmitter for 13C work requires broadband amplification of approximately 400 W of power for a 5.87-T, 250-MHz instrument. The amplifier should have triggering capabilities so that only the radiofrequency (rf) pulse is amplified. This will minimize noise contributions to the measured spectrum. So that the Hartmann-Hahn condition may be achieved, the decoupler amplifier must produce an rf signal at one-fourth the power level of the observe channel for carbon work. 

Thermoelectric flame failure detection Analog burner control systems Safety temperature cut-out Mechanical pressure switch Mechanic/pneumatic gas-air-ration control Thermoelectric flame supervision Thermal combustion products, discharge safety devices Electronic safety pilot Electronic burner control systems Electronic cut-out with NTC Electronic pressure sensor/transmitter Electronic gas-air-ration control with ionisation signal or 02 sensor Ionisation flame supervision Electronic combustions product discharge safety device... 

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