Yokogawa ROTOMETER RAMC Metal Variable Area Flow Meter

Yokogawa ROTOMETER RAMC Metal Variable Area Flow Meter

Positioning and core use

The dedicated user manual for Yokogawa ROTOMETER RAMC series metal variable area flow meters is suitable for volumetric/mass flow measurement of liquids and gases, especially for turbulent, opaque or corrosive fluid scenarios. The core uses float magnetic transmission to achieve flow indication and supports extended functions such as electronic transmitters and limit switches.

Core principles and structure of the product

1. Measurement principle

RAMC is a variable area flowmeter that operates based on the principle of "float force balance"

The fluid flows through the conical measuring tube from bottom to top, generating upward lift on the float;

The float rises to the equilibrium position of "lift=gravity+buoyancy", and its height is proportional to the flow rate;

The float is equipped with a built-in magnet, which drives the indicator pointer through magnetic transmission or triggers the electronic transmitter to output a 4-20mA signal/limit switch action.

Key feature: Within the "viscosity independent range" (fluid viscosity below a specific value), flow rate is only related to float height; When exceeding this range, the influence of viscosity on measurement needs to be considered, and the calibration scale and EEPROM need to be recalculated by the manufacturer.

2. Product structure and core components

Component Name Function Description

The conical measuring tube provides a float rising channel, and the material is selected according to the corrosiveness of the fluid (such as stainless steel 1.4404/316L, PTFE)

Float core sensing element, built-in magnet, material adapted to fluid characteristics (such as corrosion-resistant alloy)

Indicator mechanical pointer indicates flow rate, optional LCD digital display (displaying flow rate, cumulative value, percentage, etc.)

The electronic transmitter (- E/- J type) converts the float position into a 4-20mA analog signal, while the - J type supports HART 7 communication

Limit switch (/K1-/K10 options) realizes flow upper and lower limit alarm, supporting standard type (/K1-/K3) and fail safe type (/K6-/K10)

Calibration EEPROM stores customized calibration data (such as fluid density, temperature, viscosity parameters), corresponding one-to-one with the measuring tube

Installation and wiring specifications

1. Preparation before installation and environmental requirements

Environmental restrictions:

Temperature: -40 ° C~+70 ° C (standard), -20 ° C~+60 ° C (explosion-proof type);

Avoid strong vibrations, corrosive environments (if necessary, choose high anti-corrosion coating shells), and strong magnetic field interference (keep a distance from solenoid valves, etc. Ferromagnetic objects should be kept away from ≥ 250mm);

The distance between adjacent RAMCs should be ≥ 300mm to prevent mutual interference of magnetic fields.

Pipeline requirements:

It must be installed vertically, with the fluid flow direction being "downward and upward", and the flanges should be aligned parallel to avoid pipeline stress;

For models with a nominal diameter greater than RAMC08, it is necessary to reserve a straight pipe section for the first 5 times the nominal diameter and a straight pipe section for the last 3 times the nominal diameter;

If the fluid may contaminate the measuring tube, it is recommended to install a bypass pipeline for easy disassembly and cleaning of the equipment.

2. Pipeline connection and wiring operation

Flange connection: Supports EN, ASME and other standard flanges, and bolt torque must strictly follow the specifications, such as DN15 PN40 flange (EN 1092-1) torque of 9.8 Nm, DN50 PN40 flange torque of 57 Nm; PTFE lined flanges require additional attention to sealing performance to avoid fluid leakage.

Wiring specifications:

Cable sealing sleeve: Suitable for cables with a diameter of 6-9mm. If not in use, M16 × 1.5 (shell 90 type) or M20 × 1.5 (shell 91 type) blind plug sealing is required for the entrance;

Signal and power separation: Analog signals (4-20mA), digital communication (HART), and power cables need to be wired separately to avoid interference;

Grounding requirements: The protective grounding (PE terminal) must be firmly connected, with a grounding resistance of ≤ 100 Ω, and an additional external grounding clamp is required for the 91 type shell.

Core functions and parameter configuration

1. Operation of electronic transmitter (- E/- J type)

(1) Basic functions and parameter settings

The electronic transmitter supports functions such as flow display, cumulative value statistics, 4-20mA output calibration, etc. It can be configured through two operation keys (up key "exit", down key "switch menu", combination key "confirm"). The core parameters are as follows:

Function Description of Key Setting Items for Parameter Categories

Display function (F11) default display of flow/cumulative value/percentage/temperature cumulative value, switchable units (such as m ³/h, L/min, kg/s)

Unit setting (F12/F13): Volume/mass unit+time unit. The European version supports m ³, Nm ³, kg, etc., while the American version (/A12 option) supports gal, scf, etc