Mechanical Shunt Rotor Steam Flow Meter

I. Overview

The LFX rotary-type steam flow meter is a specialized instrument for measuring the cumulative mass flow of steam, available in both mechanical and intelligent structural types. It provides on-site display via an indicator dial (mechanical) or LCD screen (intelligent), accurately reading the total mass of steam passing through the meter. It can also output pulse signals and features manual pressure compensation or automatic temperature compensation. Due to its simple structure, moderate price, and wide measurement range, it is widely used in petroleum, chemical, textile, heating, and other sectors requiring steam flow measurement, as well as in the cleaning industry.

II. Working Principle

    When the measured steam flows through the flow meter body, it is throttled by an orifice plate. Under the action of the pressure difference before and after, part of the steam enters the shunt pipe through the nozzle, forming a jet that drives the impeller at the upper end of the rotor shaft to rotate. The lower end of the rotor shaft has two damping blades that rotate in a damping chamber filled with damping fluid, allowing the impeller to fully absorb the kinetic energy of the jet. When the rotational torque of the impeller balances with the damping torque, the impeller's speed is proportional to the mass flow of the measured steam passing through the flow meter. After correction and calibration, the actual cumulative steam flow is reflected on the indicator dial.The steam flow meter mainly consists of three components: the throttling body, damper, and indicator. It operates on the differential pressure-shunt principle. When the measured steam medium enters the flow meter's throttling body, part of it passes through the orifice plate in the main pipeline, while another part flows through the shunt pipe to the nozzle, forming a jet that acts on the impeller, generating torque. This causes the impeller to drive the rotor shaft to rotate. Damping blades are installed at the lower end of the rotor shaft in a damping chamber filled with damping fluid, restricting the impeller's rotation. As a result, its speed is much slower than the steam's jet velocity, allowing the impeller to effectively absorb the kinetic energy of the steam jet. The impeller's rotational speed corresponds to the torque generated by the steam jet and the damping torque, establishing a definite quantitative relationship where the impeller speed is proportional to the flow rate.

1. Measurement Medium   Saturated steam, slightly superheated steam

(Degree of superheat ≤20℃)

2. Nominal Diameter       02;  05;  08;  10;

3. Operating Temperature   183℃(02)  

240℃(05; 08 10);

4. Ambient Temperature       Only for intelligent type: 0℃～55℃

(Special order required beyond this range)

5. Operating Pressure Range  0.03-1.0 MPa(02)  

0.05-1.6 MPa(05; 08 10);

6. Installation Method        Horizontal installation

7. Density Compensation Method    Mechanical type: manual pressure compensation; Intelligent type: automatic temperature compensation.

 Selection Guide

1. Estimate the steam flow based on site conditions;             
2. Based on the estimated steam flow and steam operating pressure, select the corresponding diameter and orifice plate number according to Table 1 (Table 2).