PD Meter – Options

• Temperature Compensator—Temperature compensation (to provide standard volume) can be achieved by using a temperature sensor (e.g., RTD), a temperature transmitter, and a computer. This arrangement is the preferable method for large facilities. For remote, stand-alone LACT units, the traditional filled temperature bulb with an “automatic temperature compensator” (ATC) may be a better choice. The disadvantages of the bulb are that it is less accurate and it adds the weight of “stacking” on the meter.

• Transmitter Type—Use a high resolution pulse transmitter when high resolution of the output signal is required. Sometimes, a high resolution pulse transmitter and a low resolution pulse transmitter are used—one to pace an automatic in-line sampler.

• Transmitter Output—The format of the output signal must be compatible with the receiving unit that will scale it to volumetric units.

• Air Eliminator—An air eliminator (de-areator) is needed where the piping configuration or operation may allow gas or air to be trapped in the metering system.

• Strainer—A strainer upstream of the meter must be provided to protect the meter from abrasives and foreign objects. Determine the pressure drop across the strainer. A differential pressure gage (or two pressure gages) often can be very useful in determining the pressure drop across the strainer. (Sometimes, a d/p transmitter is used to remotely monitor the pressure drop across the strainer.) Consult the meter manufacturer for type, size, basket design, and mesh (typically 4, 10, 20, 40, or 80 mesh are standard sizes).

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