Introduction to Pressure Transducers
Transducer Types
Input Control Signal
Output Pressure Range
Accuracy
Flow Rate
Maximum Supply Pressure
Supply Pressure Sensitivity
Supply Air
Exhaust Capacity
Air Consumption
Vibration
Zero & Span Recalibration
Field Selectable Reverse-Acting
Introduction to Pressure Transducers
Pressure transducers convert an electrical input signal, such as a 4-20mA signal, to a proportional pressure output. The pneumatic output is both linear and proportional to the analog input command signal. Pressure transducers are also referred to as I/P(current to pressure) transducers, E/P(voltage to pressure) transducers or electronic pressure regulators. The variable pneumatic output pressure is used to control valve actuators & positioners, HVAC systems, clutches & brakes, paper handling, textile processes, and many other industrial applications where precise pneumatic control may be required.
Transducer Types
Type 1000 Pressure Transducer combines performance, reliability, and value for many precision control applications. The accuracy ranges from 0.5 to 2% of span, depending on the selected pressure range. Output pressures up to 120 PSIG and flow capacity up to 24 SCFM are available from the T1000, Bellofram’s most popular I/P and E/P transducer.
Type 1500 Pressure Transducer offers a small compact size, built-in volume booster, and external zero and span adjustment. Accuracy of this unit is less than 1% of span. This unit is offered with a zero based output with pressures up to 120 PSIG. The standard T1500 model comes with a terminal block electrical connection. The T1500 can be mounted at any angle and is vibration resistant.
Type 2000 Pressure Transducer uses a new piezo-ceramic technology to provide typical accuracy of 0.1% of full scale. The T2000 transducers utilize closed-loop pressure feedback-control for precision output and minimized effects of temperature, supply pressure changes, supply voltage changes, vibration and mounting orientation. This unit has a large range of field selectable inputs.
Input Control Signal
We offer transducers that accept either a current or voltage input control signal. The industry standard 4-20mA signal is the most common, other standard input control signals include 0-5V, 1-5V, 1-9V, 1-10V, and 0-10V. The input control signal is field selectable on some transducers.
Output Pressure Range
Many standard output pressure ranges from 3-15 PSI up to 0-120 PSI are available to meet your specific application.
Accuracy
Accuracy is a measure of the overall performance of the transducer and includes the following:
Linearity is the error defined by the maximum deviation of a transducer output from a best fit straight line during any one calibration cycle.
Hysteresis is the error defined by the maximum measured separation between the upscale and the downscale indications of the measured pressure during a full range traverse from 0 to the maximum pressure.
Repeatability is the error defined by the ability of the transducer to reproduce an identical signal when the same pressure is applied to it consecutively, under the same conditions and in the same direction.
Flow Rate
The maximum air flow measured in standard cubic feet per minute (SCFM) that a transducer will output for a given pressure and input signal. Flow rate is a good indication of the speed and response time of a pneumatic actuator or system.
Maximum Supply Pressure
Typically indicates the maximum allowable inlet air pressure to the transducer for safe and reliable performance.
Supply Pressure Sensitivity
The amount of output pressure change for a given change in supply pressure. Usually given as a percent of full scale span per 1 PSI change in supply.
Supply Air
The inlet air supply should be oil free, clean, dry, and filtered. For the best performance and longest life, instrument quality air should be provided to most transducers.
Exhaust Capacity
The exhaust capacity of a transducer is the ability to relieve downstream pressure back through the outlet port and vent of the regulator body.
Air Consumption
The amount of air used even when the transducer has zero flow out is called air consumption. To keep the transducer in a dynamic state for faster response and accurate control, many transducers constantly bleed a very small amount of air, measured in cubic feet per hour (CFH).
Vibration
Whenever possible, the user should try to install the transducer in an area that minimizes vibration.
Zero & Span Recalibration
Many transducers have an onboard zero and span adjustment for recalibration. The span adjustment typically is not used for setting the maximum range of the transducer, but for recalibration (adjustment typically limited to +/- 10%).
Field Selectable Reverse-Acting
Some transducers are field selectable for direct acting (increasing pressure with increasing current or voltage signal) or reverse acting (increasing pressure with decreasing current or voltage signal). Standard units are factory calibrated for direct acting service.
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