Discontinued: Model 755 Gaseous Oxygen Analyzer

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Replaced by: Model XGP or Model XF

Canadian Standards Association certified One sensing unit for all ranges Small, rugged, shock-resistant sensing unit Plug-in alarms/current output options Adjustable speed of response

Emerson's Rosemount Analytical Model 755 Gaseous Oxygen Analyzer provides a continuous measurement of gaseous oxygen with high accuracy and reliability. The heart of this instrument is a compact paramagnetic sensing unit, designed to monitor a wide variety of ranges for virtually every application. FEATURES The Model 755 Gaseous Oxygen Analyzer uses the physical paramagnetic measurement technique exclusively. This method offers distinct operating advantages over combination measurements such as thermal conductivity, thermal convection or electro-chemical. Two advantages of this technique are: (1) faster response and (2) linear detector output. The Model 755 offers range options varying from 0 to 1% to 0 to 100% fullscale, all accomplished with one versatile sensing unit. Housed in an aluminum case (with an optional explosion-proof version), the analyzer is available with options for dual alarms and 0 to 20 mA or 4 to 20 mA current output. All optional features can be added at the factory or in the field with the simple addition of plug-in circuit boards. The paramagnetic sensing assembly is mounted on a platinum suspension for shock resistance. This assembly is designed for ease of maintenance and installation. Standard response time is 20 seconds, but is adjustable from 5 to 25 seconds. PRINCIPLE OF OPERATION The Model 755 measures the paramagnetic susceptibility of oxygen. This susceptibility is much higher than other common gases. When oxygen is present in a magnetic field, the oxygen tends to concentrate in the area of the magnetic field. The Model 755 measures the total magnetic susceptibility of the sample. This total is almost entirely due to the oxygen present, so the measurement is an accurate indication of oxygen content. The test body is mounted on a platinum suspension in a non-uniform magnetic field (see Figure 1 below). The magnetic force exerted upon the test body is proportional to the difference in the volume magnetic susceptibilities of the test body and the surrounding gas. If the gas is more paramagnetic than the test body, the magnetic force tends to repel the test body; and if the gas is less paramagnetic, the magnetic force tends to attract the test body into the magnetic field. A diamond-shaped mirror is mounted on the platinum suspension and reflects light from the prefocused light source equally onto two photocells when the test body is in the neutral position. When the volume magnetic susceptibility of the gas increases, a magnetic force is applied to the test body, tending to rotate it out of the field. The suspension mirror on the test body also rotates, so that the photocells become unequally illuminated and through the amplifier, apply feedback current to the test body. The electromagnetic force generated by the feedback current is opposite and almost equal to the magnetic force. As a linear function of the oxygen concentration, this feedback current is easily converted to an analog output signal which is used for readout and recording purposes. Note: Intended Use – The Model 755 is intended for use as an industrial process measurement device only. It is not intended for use in medical, diagnostic or life support applications, and no independent agency certifications or approvals are to be implied as covering such applications.