The delta and flow meter

Products overview:

ZW - DTB seriesThe delta and flow meterIs measured by differential pressure flow of the device, is in the pig developed on the basis of the velocity measurement principle.Can measure the liquid, gas and steam flow of the fluid.With no moving parts, almost no pressure loss, easy installation and maintenance, operation cost is extremely low, favored by users.

Sensor is through testing rod, pressure and guide bar, it across with internal pipe axis vertical pipe, on the incident flow of rod is equipped with multiple pressure hole measured average total pressure, have to measure static pressure in the back and side stream surface pressure hole, respectively by the total pressure guide pipe and hydrostatic pressure derivation, according to the total pressure and static pressure differential pressure value, calculate the traffic flowing through a pipe.Can also substitute flow tube wall static pressure sensor on the surface of the back flow static pressure.

Delta and consists of sensor, led accessories and differential pressure transmitter, pressure transmitter, pressure and other supporting flow totalizer.especially of flowmeter.

With my company production of differential pressure transmitter, pressure transmitter, temperature transmitter, and can be composed of various types of flow totalizer.especially velocity-equalizing tube flowmeter.Also can use any manufacturer production differential pressure transmitter, pressure transmitter, temperature transmitter and of various types of flow totalizer.especially differential pressure flow meter.

Second, the working principle:

ZW series - DTB delta the average flow velocity of flow meter is through the pipeline and pipe flow of product to determine the effective cross-sectional area.Average velocity distribution of pipe is not uniform.If it is a fully developed flow, the velocity distribution for the index law.Circular cross section in order to accurate measurement, the entire faceted and multiple unit area is equal to half more than half a ring.Sensor detection rod is composed of a hollow metal tube, flow surface of total pressure more holes, respectively in each unit area of the center of the reaction, respectively, the flow velocity of each unit area.Due to the total pressure hole is mutually, to each point in the detection lever average total pressure value, the total pressure out pipe leads to high pressure joint, the normal pressure chamber to the sensor.

When the delta and properly installed on the process piping of straight section of long enough, the traffic on the cross section should be no vortex, the whole cross section of the static pressure is constant, can be thought of in the back of the sensor or side is equipped with inspection hole, on behalf of the entire cross section of the static pressure.By the static pressure out pipe joint by low pressure leads to the negative pressure chamber of the transducer.The square of the positive and negative pressure chamber pressure differential is proportional to the flow of section average flow velocity, the cluster for differential pressure and flow rate is proportional to the relationship.On the relationship between the, can by the Bernoulli equation and continuity equation was derived velocity-equalizing tube flowmeter flow calculation formula

Qv = alpha, epsilon ﹒ ﹒ D2 (PI / 4), (2 p/rho (1) 0.5

Qm = alpha, epsilon ﹒ ﹒ D2 (PI / 4), (2 p ﹒ rho (1) 0.5

Qm: including: Qv: volume flow to mass flow

Alpha: sensor structure coefficient

P: the differential value of epsilon: fluid expansion coefficient

Rho: the density of fluid conditions epsilon: fluid expansion coefficient

For non-compressible fluid epsilon = 1, the compressibility of body epsilon ﹤ 1, if the type D, P, rho 1 use SI units, QV unit for the M3 / S, the basic unit of Qm is ㎏ / S.Sensors of flow coefficient alpha and lessens epsilon, sexual coefficient can be informed by calibration on the standard device, and indicated in the certificate book when leaving the factory.

Applications:

ZW series - DTB delta output for the differential pressure signal of the flowmeter, and measurement of differential pressure instruments and meters, can be accurately measured, pipe, rectangular pipe in a variety of liquids, gases and steam (superheated steam and saturated steam).The size of the pipeline under test range from 20 mm - 3000 mm.In the power industry (including nuclear industry) chemical industry, petroleum chemical and metal smelting industry departments such as the bank of China to the use of success, it is suitable for:

1, the gas and liquid transportation.

2, energy research, steam boiler heat rate, efficiency of pump, the gas compressor efficiency and fuel consumption.

3, process control, input and output, ratio and balance;Cooling water or air, steam heating.

4, material of chemical industry.

Four, the main features:

1, it is widely used in all kinds of dry or wet gas, liquid, steam or other medium measurement;

2, probe materials have special 1.4528 and the C4 alloy, specializing in all kinds of strong corrosive medium;

3, low pressure aperture is 8 mm, prevent performance good;

Four, probe section is symmetrical, can two-way measurement.

Five, the technical parameters:

1, the range than: in the case of differential pressure meet range than 1:10;

2, general diameter: 8 mm to 15000 mm;

Before 3, straight pipe required: normally after 7 d, 3 d to ensure measurement accuracy by 0.5% ~ 1.0%;

4, the accuracy of measurement: + 0.5% to + 1.0%;

5, the repeat precision: + / - 0.1%;

6, suitable pressure: 0 ~ 25 mpa, special applications can reach 40 mpa;

7, suitable temperature: 100 ℃ ~ 500 ℃, the special application of up to 800 ℃;

8, suitable medium: air, gas, gas, water, steam, boiler feed water, containing corrosion solution etc. Various kinds of gas and liquid medium;

9, reference standard, ISO 3966-197, JB/T5325-1991 and GB/T2624-2006

10, connection mode: insert flange connection, plug in threaded connections, pipeline flange, pipeline screw thread connection.

Main components:

1, according to pipe diameter customization of the delta, with flange is installed on the pipe, made of stainless steel refined but become, according to the various parameters of the users in high precision wind tunnel laboratory simulation, the characteristic curve and the database, used for calculation.

2 is to display the measured results, flow totalizer.especially secondary instrument.Through wires connected to each transmitter and thermometer, the motherboard is equipped with advanced CPU and the application software, can use the display window and switch button to setup, calibration and the parameters display.

3, differential pressure transmitters convert the delta of the differential pressure signal into 4-20 madc analog current signal.

4, pressure transmitter in the gas flow measurement with pressure compensation.

5 in gas flow measurement, temperature transmitter temperature compensation.

6, dc power supply for pressure transmitter, differential pressure transmitter power and thermal resistance thermometer.

Seven, form a complete set of scheme selection:

1, is according to the measured medium, and the user use the pipe inner diameter, working temperature, working pressure and flow design and production.

2, ZW - 3051/1151 dp series differential pressure transmitter or other types of differential pressure transmitter

3, ZW - 308 series pressure transmitter, or other type of pressure transmitter

4, temperature transmitter, or other type of temperature transmitter

5, ZW - XMJA series or other types of flow totalizer.especially flow integrating instrument

6, of this intelligent velocity-equalizing tube flowmeter, pressure compensation can take temperature, and can show the instantaneous flow and cumulative flow medium medium temperature, the pipe, the pipe pressure and differential pressure equivalent, equipped with communication interface and 4 ~ 20 ma output.

Eight, device:

1, velocity-equalizing tube flow sensor 1;

1 2, velocity-equalizing tube flow sensor operating instructions;

3, 1 certificate;

4, form a complete set of transmitter instrument and manual and certificate of approval (which can be ordered by the users themselves).

Nine, use requirements:

1, the current body shall be full of pipe flow and stability.

2, the fluid being measured should be single phase, the phase constant, the composition of complex fluid must be similar to a single component of fluid can be used.

3, the current body under actual conditions of ReD should be greater than 3 x 104.

4, should guarantee the sensor before and after the straight pipe length requirements.

5, pipe diameter greater than 100 ㎜ as well.

6, 2 d in front of the sensor on the surface of the pipe, should be clean and smooth.

Ten, sensor installation ways:

Eleven, installation requirements:

1, installation and test of measuring section should be straight, the upstream and downstream straight pipe length with reference to the length of the stipulated in the table below.

Note: pipe nominal diameter D, given the length of the data for the distance to the second elbow.

2, test rod inserted into the location of the point of allowable deviation range as shown in figure.

3, for vertical pipe, test bar can be installed in horizontal pipe along the pipeline circumferential 360 ° in any position, high pressure pipe joint should be in the same horizontal plane.For horizontal pipe, when measuring the liquid detection rod inserted into the position should be located in the pipe cross section under the horizontal centerline 45 ° range;When measuring gas detection rod inserted into the position should be located in the pipe cross section above the horizontal centerline 45 ° range;Steam when measuring rod should be inserted, as shown in figure:

(4), pipe Φ hole size 35.

5, compensating pressure transmitter on the straight pipe before, or platinum resistance temperature transmitter is installed in the straight pipe on the 2 d distance the throttle device.

Twelve, online installation disassembly type delta bar:

For some can't production installation of measuring point and medium containing impurities can choose online installation disassembly type delta bar.Online installation disassembly type delta barco without production of the installation or maintenance probes, especially suitable for not installed production point or medium are dirty need the measuring point of preventive maintenance.It equipped with single screw driven and used in high pressure double pole drive type.

Features: can be without shutdown for installation, disassembly, maintenance, cleaning.

Suitable conditions: normally used in low pressure air, water, gas, steam and other media.

Note: online should satisfy when install or remove t 120 ℃ or less P acuities were 2.5 MPa

13, the structure form:

Delta the flow sensor is detecting rod, taking pressure of the mouth, it across with internal pipe axis vertical pipe, is equipped with multiple total pressure on the surface of the test bar to meet flow detection hole, a multiple static pressure testing on the surface of the test bar back flow hole, respectively by the total pressure guide pipe and hydrostatic pressure derivation, according to the total pressure and differential pressure value of static pressure, flowing through a pipe flow calculation.

Theoretical basis

Delta is developed based on the pitot tube speed measuring principle, it is through the pipeline of average flow velocity and the effective cross-sectional area of the pipe product to determine the flow rate.

1, the probe of section shape: for child head form of power, the delta for class a diamond, type of diamond cut in can make the high and low area boundary is more obvious.

Taking the position of the hole, probe rod: power and total pressure of the hole in the front, static pressure hole on the two side wall bar;The delta of the flowmeter all pressure hole in the front, but the static pressure hole at the rear end of rod, measure the back pressure (pressure).

Therefore, under the condition of the same diameter and flow velocity, probe the differential pressure of the delta, the power and the probe are larger, about 20% - 40%.This is the obvious advantages of delta and flowmeter.Structure as shown in figure:

14, prevent blocking design:

1, the delta of the unique design of traffic probes thoroughly get rid of the past several average probe easily blocked, the characteristics of accuracy is not high, make a source of measurement accuracy, repeatability and reliability to a new height.

2, just boot, the fluid in the pipeline under the action of static pressure, into the pipe bending, quickly formed a pressure balance state.When pressure balance formation fluid in high pressure pipe inlet, detour, no longer into the bend.

3, the flow sensor of high, low pressure hole held in nature.

4, in general, dust, sａnd and particles under the action of the vortex street force, concentrated in the very back of the probe.This is why the autumn leaves are always in the leeward behind the house.Probe flowmeter probe held in unique design, coupled with the nature of gravity whereabouts, prevents the particles into, this design essentially prevent the congestion and can create a very stable low voltage signal.

5, continuous work of fundamentally put an end to the possibility of the wall, but in the following cases, still should pay attention to prevent:

A. when pressure pipe leaking, probe high pressure balance to destruction of impurities in the diameter of the smaller particles are likely to enter the hole.

B. when pipe production at, because of the brown movement of molecules, small particles of impurities may enter the hole.

C. system key, frequently at the instant of the high formation, small particles of impurities may enter the hole, accumulate over a long period, it is possible to probe the jam.

D. medium contains a large number of biological species, or containing fibrous material, may also cause the probe blockage.

15, product maintenance:

Delta the flow sensor should be performed in the process piping overhaul regular cleaning, cleaning the way many, such as air blow test tube accumulated filth;Scrub with kerosene and soft silk net, make each hole to maintain patency.May produce the cause of the failure and remove methods: serial number of failure causes clear way.

1, differential pressure signal output: high and low pressure valve is not open, open the high and low pressure valve.

2, high and low pressure balance valves did not tighten, tighten balance valve.

3, differential pressure signal output is too small, pressure system has a leak phenomenon;Seriously looking for, eliminate the leakage.

4, improper secondary table range selection: uninteresting facts limit pressure transmitter.

5, differential pressure signal output is too large, secondary table range matching is undeserved, augmenting the upper limit, differential pressure transmitter back-pressure aperture jams, cleaning velocity-equalizing tube, eliminate congestion.

16, commissioning work:

The preparing work before put into operation:

1, sensors installed correctly:

Complete sensors installed in the line, must carefully check before put into operation, require welding is firm, in the right direction, not leak, strictly proper insertion depth, etc.

2, instrument calibration:

Sensor matching instrument differential pressure transmitter and intelligent flow integrating instrument (there could be pressure transmitter and temperature transmitter), etc.Must be after inspection and calibration, can be put into use.The instrument measuring range to conform to the requirements of the sensors and the measured medium.Such as air flow to be tested Qmax = 5000 m3 / h, the calculation to calculate differential zui big value of sensor

Delta Pmax = 0.6 Kpa, the measuring range of differential pressure transmitter should be set-up of 0 ~ 0.6 Kpa, the corresponding output 4 ~ 20 madc current signal.For universal, flow totalizer.especially should according to the real-time flow range, differential pressure range, medium density, temperature, pressure, flow operation requirements, etc., prior programming configuration, input totalizer.especially can correct operation and make sure totalizer.especially display traffic.

3, instrument wiring correct:

Sensor and differential pressure transmitter, flow integrating instrument of measuring system, such as supporting the power cord, signal output to the input line between instrument, control and alarm, etc., in various instrument wiring board (also known as terminal board) are clearly marked, is must confirm and don't choose to use, before the operation of the instrument connection to check again and again.In order to do the preparing work before put into operation, in addition to read the instruction for use, you should also read the differential pressure transmitter operation instruction handbook ", "operation instruction handbook" intelligent flow totalizer.especially etc, comply with the instruction manual for the guidance of work.

The flow operation of work:

1, the measurement system is closed:

Operation of preparatory work has been completed, the medium to be measured with flow process piping, sensor measuring system is temporarily closed, then should make three balancing valve is fully open valve group, high pressure valve Pl P2 and low pressure valve closed.Meter is in a state of power supply, preheating about 15 minutes.

2, open measurement systems:

Instrument after preheating, open measurement system.Open the Pl on three valve group and P2 valves, balance valve is still in the open.At this time, the differential pressure transmitter has filling the measured medium (gas or liquid), open the drain valve on the transmitter, quickly closed after discharge dirty liquid or gas.Then close three the balance valve on the valve group, transmitter that is entered into a state of differential pressure measurement.Output and the corresponding signal current differential delta P I delta P from the signal current value (m A) to calculate the pressure delta P values (KP) A.Also flow totalizer.especially into work state, show the measured medium flow.

If the above work all goes well, the flow meter works well, commissioning work is complete, delivery production use.

The 17th and matters needing attention:

1, the delta of the mechanical size is according to the size of the installation of pipeline tailored, its measuring range is provided according to the craft flow calculation and calibration data.Selection, must give manufacturers to provide the correct flow data and pipe size, pipe size including outside diameter and wall thickness.Flow meter must be installed according to the standard, to ensure that the error of the measuring system in the permitted range.

2 lever measurement sensor, front line must ensure that there are 7 ~ 9 d d straight pipe length (the various manufacturers have different information, data from all 3 d and 30 d), to make the big pipe the flow velocity of liquid, gas (vapor) axis symmetrical distributed in as far as possible.Only in this way, the flow rate of the measured points can be calculated through the whole cross section of flow, otherwise the big pipe of liquid, gas (vapor) velocity distribution will be very complicated, fluctuations in discharge coefficient K will be very big, can guarantee the accuracy of the measurement.But in the actual process design can't guarantee a long straight pipe.The author thinks that if determined to choose some kind of, can consult with suppliers under the precondition of guarantee system of repeatability, try to shorten the straight pipe, the relevant information, as long as the ratio of the diameter and process pipe diameter measurement is less than 1/10, the front line of straight pipe length to be 3 d to 4 d.

3, lever measurement sensor, total pressure hole must be positive to flow, deviation is not more than 7 °.Detection rod should be inserted to the bottom along the pipe diameter, and the vertical pipeline detection bar can be installed in horizontal pipe along the pipeline circumferential 360 ° in any position.High and low lead pressure tube should be in the same plane;For horizontal pipe, measuring lateral tilt down when installation.Flow meter can be measured accurately and the length of its service life has direct relationship with whether or not installed correctly, once the flow meter installed, has affected the accuracy of flowmeter system error will always accompany, it is difficult to remove from the software.You may refer to the correct installation of differential pressure type flowmeter installation specification, go here.

4, test rod through joint fixed on the pipeline, tighten the joint, after testing stem not loosening and leakage.Pipeline vibration and fluid impact can make detection rod fixed head mobility, detecting rod fracture damage, affect the accurate measurement and cause economic losses.

Eighteen, selection of coding:

Example: ZW - DTB - M1 - S1-4 - SL - Y133 / CS - H - A

Description: 1, threaded connection type;10 # sensor;Circular tube (diameter 133 mm, wall thickness 4 mm);The probe material of 316 l stainless steel;Horizontal piping installation;Pipe material is carbon steel;Meter connector for threaded joints, side.

Choose and order notes on the 19th, design:

1, the name of the measured medium;

2, the biggest, commonly used, flow range (m3 / h);

3, work pressure (Mpa), temperature (℃), the maximum pressure (Mpa), upper and lower temperature (℃);

4, medium density, viscosity,

5, pipe material, inner diameter, outside diameter;

6, the pipe laying and local resistance.

7, you need to display instrument of the measurement and control of form a complete set, please refer to the corresponding specifications, choose the right model or the information provided by our company technical personnel according to your designs for you selection.

8, if you have special want to, please contact our sales department.

After-sales service commitment:

1, from the date of signing of the contract, I in the way provided for products of the company offers free maintenance and maintenance service, commitment to lifelong maintenance service;

2, jiangsu wei measurement and control instrument co., LTD. Sales manager will be in regular contact with customers, understａnd the usage of products, and solve the problems of the customers to use in the process of produce, free of charge to provide technical support;

3 the man-made damage is found, the warranty period, our company is responsible for the maintenance, and the resulting maintenance fee;

4, product quality problems or are not satisfied with product, the user can choose unconditional return, wei tt&c don't charge any fees, appear quality problem, bear the freight back and forth.