1. Overview

　　Metal tube float flowmeter, also known as the “metal tube rotameter”, is a measuring instrument commonly used in the industrial automation process management to measure the variable area flow. Being featured with characteristics of small size, wide application range, convenient usage, etc., it is designed for measuring the flows of liquids, gases and steam, especially applicable for measurement of low flow speed and small flow rate.

　　Over the years, with its excellent property and reliability as well as preferable cost performance, the metal tube float flowmeter has been applied widely in a variety of industries, such as the petrochemical engineering, iron and steel, electric power, metallurgy, light industry, food, pharmacy, water treatment, etc.

　　This manual, which is compiled to meet the needs of specialized technical personnel, is applicable for design selection of the metal tube float flowmeters and can be used as a reference for end users during operation as well.

　　In the manual, the operational principle, functional features, technical parameter, types and dimensions, flow rate calculation, electrical connection and installation, maintenance of TF Series Metal Tube Float Flowmeters have been respectively introduced.

　　This manual only focuses on the design selection and application of TF Series Metal Tube Float Flowmeters. In addition, the manufacturer reserves the right to conduct modification on some of the technical parameters.

2. Measuring Principle

　　TF Series Metal Tube Float Flowmeters are principally composed of two major parts: sensor and indicator. The sensor mainly consists of the joint flange, cone, float as well as upper and lower guiders; while, the indicator mainly consists of the casing, magnetic transmission system, dial scale and electric transmission system.

　　In the cone-shaped measuring tube, there is a measuring component which is flexible for upward and downward movements – float (Figure 1). As the fluid goes through the tube from bottom to top, the float moves upwards along the cone-shaped tube due to the acting force imposed by the fluid. The more the flow rate increases, the greater distance the float will travel; on the contrary, the distance the float travels decreases with the flow rate of the fluid. In other words, the flow rate of the fluid determines the location where the float stops in the measuring tube, which consequently determines the size of the annular area formed between the float and the cone-shaped tube. When the flow rate is maintained at a constant value “Q”, the float is in a dynamic equilibrium state, remaining at a fixed location “h” in the cone-shaped tube. At such moment, the annular area formed between the float and the cone-shaped tube is kept unchanged. There are three forces acting on the float: the gravity force “G” of the float, the buoyancy force “F” and the acting forces “P” the fluid imposes on the float, which are maintained in equilibrium. On the basis of Bernoulli Equation, force-balance principle and law of fluid continuity in the hydrokinetics, the instantaneous rate of flow currently passing through the annular area can be hereby figured out. Therefore, it is the principle of variable area that the metal tube float flowmeter adopts to measure the flow rate.

　　A permanent magnet with high performance is embedded into the interior of the float. When the float maintains an
equilibrium position, a homogeneous and stable magnetic field occurs around the float. In addition, a magnetic sensor will be installed outside the cone-shaped tube, which consequently makes it possible to transmit the straight-line displacement of the float inside the measuring tube to the indicator in a non-contact manner and finally display the results on the dial scale of the indicator or output corresponding standard current signals of 4～20mA after examination and treatment.

　　

cone-shaped measuring tube permanent magnet direction of flow

3. Functional Features

　　◆Designed for measurement of small caliber and low-speed medium

　　◆With reliable performance, few maintenance and long service life

　　◆Low requirement for the straight tube section

　　◆Widely measure ratio: 10:1

　　◆Dual-line display, instantaneous/ cumulative flow rates displayed at the field

　　◆With a keyboard on the indictor for convenient operation and setting

　　◆All in metal construction, designed for measuring corrosive medium of high temperature, high pressure and

　　strong

　　◆Non-contact magnetic coupling transmission

　　◆Applicable for inflammable and explosive occasion

　　◆Optional charging modes: DC power supply or battery power

　　◆With the functions of data recovery, data backup and power failure protection

　　◆Multiple parameters calibrating function

4. Technical parameter

　　▲Caliber of flow meter

　　DN15，DN25，DN50，DN80，DN100，DN150 (For other caliber dimensions, please negotiate with the
manufacturer.)

　　▲Range of flow

　　Liquid：1.0～150000l/h

　　Gas：0.05～3000m3/h(For the detailed flow range, refer to the Table of Flow on Page 11.)

　　▲Measure Ratio 10∶1，20∶1(special)

　　▲Precision Grade 0.5, Grade 1.0 (special)

　　▲Pressure rating

　　DN15、DN25、DN50：4.0MPa(Max: 20MPa)

　　DN80、DN100、DN150：1.6MPa (DN80：Max 10MPa;DN100：Max 6.4MPa;DN150：Max 4.0MPa)

　　▲Medium temperature Standard：-30℃～+120℃，high temperature：120℃～350℃

　　▲Power supply 24VDC(12～36VDC)

　　▲Output signal 4～20mADC (two-wire configuration); attached HART Protocol allowed

　　▲Output load 500Ω(24V power supply)

　　▲Environmental temperature Local type：-40℃～120℃ ;Remote-control type：-30℃～60℃

　　▲Storage requirement　　　 Temperature：-40℃～85℃ ;humidity：≤85%

　　▲Connection mode 　　　      Flange connecting. Flange standard ：GB/T9119-2000; User’s appointment

　　allowed(For other connection modes, please negotiate with manufacturer)

　　▲Cable interface 　　 　 M20×1.5

　　▲Housing protection grade IP65

　　▲Mark of explosion-proof 　Intrinsic safety type：ExiaIICT6，explosion-proof type：ExdIICT6

　　▲Pressure loss 　　　         See table of flow for detailed information

　　▲Viscosity of medium　　  DN15：η<5mPa.s ;DN25：η<250mPa.s;DN50～DN150：η<300mPa.s

　　▲Contact material 　　　 R1：304，1Cr18Ni9Ti; 　　　　　 Ro：316，0Cr18Ni12Mo2Ti;

　　                                                RL：316L，00Cr17Ni14Mo2Ti; 　　Ti：Titanium alloy;

　　                                                Rp：PTFE lining

5. Types of Flowmeters and Dimensions

　　TF Series Metal Tube Float Flowmeters consist of the measuring tube (sensor) and indicator (electronic converter), Choose different forms of measuring tubes and indicators to assemble different types of overall machines to meet needs at the field. Please refer to the following descriptions of all types of flowmeters for various configuration and dimension, joint flange standard and installation dimension of the magnetic filter.

　　5.1 Product Category

　　TF Series Metal Tube Float Flowmeters can be divided into 5 types according to the direction of liquid, and each type also be classified into the standard type, high-temperature type, jacket type and so on. All types will be respectively described below.

　　5.1.1 Vertical installation type



 

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