Chapter 3 About the Micro Motion® 7951

Page 3.1

3. About the Micro Motion® 7951

3.1 Background

The Micro Motion® 7951 is designed to meet the demand for a reliable, versatile, user-friendly and cost-effective
instrument for liquid and gas metering. It has a Motorola 68332 32-bit microprocessor and surface-mounted
circuit board components so that it is powerful, reliable and compact.
Features of the 7951 include:
• Simple access to information.
• Comprehensive interrogation facilities.
• Alarm and alarm history facilities.
• A menu-driven, user-friendly interface.
• NEMA12, IP52 panel mounted case.
• Dc powered.
• Three serial ports (using RS232 or RS485) for
Modbus communications and printing.
These facilities are described in more detail in the rest of this chapter.

3.2 What the 7951 Dual Channel Gas Signal Converter does

The 7951 Gas Signal Converter is primarily used to convert signals from one format to another. There is a need for
this conversion when a system is unable to accept a raw signal from a transducer or, perhaps, some intermediate
signal processing is required.
A common conversion is where a frequency input from a 7812 gas density transducer can be accepted by a 795x
and then transmitted (by the same 795x) through an analogue output as a 4-20mA signal.
In this application, the 7951 can calculate:
• Line density
√
(from Transducer, PTZ method or mA-type input)
• Specific gravity
√
(from Transducer, mA-type input or Base density)
• Base density
√
(from Specific gravity method, PTZ method or mA-type input)
• Energy (Cv/m) (from AGA-5 method or mA-type input)
Note: Dual-channel measurements are available for Items marked with a
√
It can also obtain:
• Line temperature.
• Densitometer temperature.
• Density pressure.
• Atmospheric pressure.
• Percentage of CO2(from a mA-type input)
• Percentage of N2(from a mA-type input)
• Compressibility (from S-GERG, NX19, NX19mod or NX19 3h)
• Special equations 1 and 2.