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The ABB FAM3200 Armored Variable Area Purgemeter is a flowmeter designed for measuring small flows of gases and liquids. It operates on the float principle, where the position of a float within a conical meter tube is directly proportional to the flow rate. A magnet integrated into the float translates its height, which is a measure of the flow, to a magnet follower system. This system then drives a pointer on a rotating shaft, indicating the flow rate value on a scale.
The device is intended for vertical pipe mounting, with the measuring medium flowing from bottom to top. It can be used for conveying liquids, gases (including unstable liquids and gases), and vapors. Its primary function is flow measurement of the operating volume under constant operating conditions (pressure, temperature, density), with the option to output flow in standard or mass units. The FAM3200 can be used for local indication of the current flow rate and can integrate alarm signaling units for flow rate monitoring or differential pressure regulation. Optionally, it is available with an angular position transmitter that provides a 4 to 20 mA output signal.
For proper operation, the device should be kept as far as possible from pipe vibrations and powerful magnetic fields that could influence measurement results. Inlet and outlet sections are not required, allowing valves and pipe bends to be screwed on directly. To ensure accurate measurements, pulsating flows and sudden pressure surges should be avoided, and valves should be opened slowly. If the flowmeter is installed in a pipeline where decommissioning is not feasible, a bypass line should be provided. For gaseous measuring media, the flowmeter should be installed close to pipe constrictions, and the nominal diameter of the piping at the outlet should be as small as possible. Stop and throttle valves are preferably attached to the outlet. For liquid measuring media, the nominal diameter of the piping should be dimensioned as large as economically viable.
When piston pumps or compressors are used, pulsating flow of the measurement media can be expected. To reduce float pulsation, the installation of pressure chambers or collecting tanks in the piping before the flowmeter is recommended. If insulation is required, only the meter tube should be included in the pipe insulation, while the indicator housing must not be insulated to prevent excessive temperature rise within the device.
The FAM3200 is specified for a defined set of operating conditions of the measuring medium, including pressure and temperature-related properties (density and viscosity) for liquids and gases. For gases, this specifically means operating at a particular operating pressure and temperature. The specified accuracy of the device is always relative to these underlying operating conditions. The available operating pressure at the measuring point must exceed the pressure loss listed in the specifications for the flowmeter, and pressure loss downstream from the flowmeter due to piping and other fittings should also be considered.
During low flow amounts and low operating pressure when measuring gases, compression oscillations of the float can occur. If the maximum upstream pressure specified is not reached, the flowmeter can be equipped with a mechanical float damper. This damping is available for device types FAM3225 and FAM3255 with a process connection size greater than 1/4 inch. To prevent self-generated compression oscillations, it is recommended to select a flowmeter with the lowest possible pressure loss, minimize piping length between the flowmeter and the nearest throttling location, set the limit of the regular measuring range from 25 to 100%, and always start by assuming larger flow rate values. Increasing the operating pressure should be considered for its effect on flow rate changes due to gas density changes. Non-throttled, free volumes upstream and downstream of the device should be minimized. Pressure shocks, especially when measuring gases, can occur with fast-opening solenoid valves, unthrottled piping cross-sections, or gas bubbles in liquids. This can cause the float to be forcibly driven against the upper floatstop, potentially damaging the device. Mechanical float damping is not suitable for compensating pressure shocks.
Variable area flowmeters have limited suitability for measuring media containing solids. Increased mechanical abrasion can occur, especially at the critical measuring edge of the float, depending on the concentration, particle size, and type of solid. Solidified deposits on the float can alter its weight and shape, leading to erroneous measurement results. The use of appropriate filters is generally recommended for such applications. For measuring media containing magnetic particles, a magnetic separator upstream of the variable area flowmeter is advised.
Maintenance involves cleaning the meter tube and float, as soiling can impair measuring accuracy. The cleaning interval depends on operating conditions and must be set individually. The meter tube and float must be removed for cleaning. When cleaning the exterior, ensure the cleaning agent does not corrode the housing surface and seals. A damp cloth should be used to avoid static charge. Disassembly of the meter tube and float requires careful attention to prevent damage to the precision-made float, particularly the guide ring and measuring edge. The meter tube should not be exposed to impacts or mechanical loads during disassembly.
Repair and maintenance activities must only be performed by authorized customer service personnel using original spare parts. Replacing components with unauthorized parts will invalidate the CE conformity. For pressure equipment consisting of assemblies, CE conformity only applies to factory-supplied devices.
General| Brand | ABB |
|---|---|
| Model | FAM3200 |
| Category | Measuring Instruments |
| Language | English |
