The orifice flowmeter is a high-range differential pressure flow device,that combines a standard orifice plate with a multi-parameter differential pressure transmitter (or differential pressure transmission, temperature transmitter and pressure transmitter) to measure gas and steam , liquid and natural gas flow. The orifice flow meter throttling device includes a ring chamber orifice plate, a nozzle, and the like. The throttling device (orifice flowmeter) integrates flow, temperature and pressure detection functions, has strong functions, compact structure, simple operation and convenient use. Different configurations, there will be a variety of orifice plate types.
The orifice flowmeter throttling device produced by Huaheng Instrument is used with the differential pressure transmitter to measure the flow of liquid, steam and gas. The orifice flowmeter is widely used in petroleum, chemical, “gold, electricity, light”. Industry and other industries.
For the instrument, if the instrument is not installed properly, it will cause problems such as inaccurate measurement, high failure rate and increased maintenance. However, it may cause unplanned parking or even cause a safety accident. Below, Huaheng Instrument(orifice plate manufacturer) has arranged various problems and precautions that will occur when installing the orifice flowmeter, and hopes to be helpful to everyone.You can use it as your orifice plate installation guidelines.
1. Straight pipe sections before and after the orifice plate do not meet the requirements
The function of the straight pipe section before and after the orifice plate is to ensure the stability of the fluid flow in the pipe. However, due to the frequent occurrence of bending, bifurcation, confluence and other resistance parts on the process pipe, the fluid becomes stable and disturbs, resulting in measurement error. The elimination method is to properly design the installation position of the throttle device according to the requirements of the front and rear pipelines.
2. The downstream surface of the orifice is damaged or the orifice flange gasket protrudes into the pipe.
During the process of installing the orifice plate by the transport orifice plate or the construction personnel, it is easy to cause damage to the upstream and downstream surfaces or the flange gasket protrudes into the pipeline, resulting in measurement error. The elimination method is to improve the technical quality and responsibility of the construction personnel. The construction personnel should carefully inspect the orifice plate before installing the orifice plate. If the downstream surface of the orifice plate is damaged, it should be replaced in time; during the process of installing the orifice plate, the orifice plate should be avoided; when installing the flange gasket, the method should be used. The center line of the blue gasket is the same as the center line of the pipeline.
3. Reverse the reverse side of the hole
Before installation, the flow direction of the medium in the pipeline and the direction of the orifice plate should be correctly identified, otherwise the measured value will be low. This is due to the carelessness of the construction personnel. The elimination method is to make the surface marked with "+" on the orifice plate on the upstream side of the flow direction when installing the orifice plate.
4, The wrong position of different orifice plates
This situation is generally particularly prone to occur during the commissioning phase. In the commissioning phase, each process pipe needs to be purged multiple times, and the orifice plate is frequently disassembled. If the size of the orifice plate is the same, an error will occur if you pay attention to it, and the orifice plate will be returned to normal.
It can be seen that in order to maximize the function and function of the instrument, correct selection is the primary condition, and correct installation is the decisive factor.
Integrated orifice flowmeter diagram
1. Before the instrument is installed, the process pipeline should be purged to prevent the ferromagnetic substances retained in the pipeline from adhering to the instrument, affecting the performance of the instrument and even damaging the instrument. If it is unavoidable, a magnetic filter should be installed at the entrance of the meter. The meter itself does not participate in the air sweep before the production, so as not to damage the meter.
2. The instrument should be inspected for damage before it is installed in the process piping.
3. The installation form of the instrument is divided into vertical installation and horizontal installation. If it is vertical installation, the angle between the center vertical line and the vertical line of the instrument should be less than 2°; if it is horizontal installation, the horizontal center line of the instrument should be The horizontal line angle is less than 2°.
4. The upstream and downstream pipelines of the instrument shall be the same as the diameter of the instrument. The connecting flange or thread shall be matched with the flange and thread of the instrument. The length of the straight pipe upstream of the instrument shall be at least 5 times the nominal diameter of the instrument, and the length of the downstream straight pipe segment shall be greater than Equal to 250mm.
5. Since the instrument transmits signals through magnetic coupling, in order to ensure the performance of the instrument, at least 250px around the installation, no ferromagnetic substances are allowed.
6. The instrument for measuring gas is calibrated at a specific pressure. If the gas is directly discharged to the atmosphere at the outlet of the meter, it will cause a pressure drop at the float and cause data distortion. If this is the case, install a valve at the outlet of the meter.
7. The instrument installed in the pipeline should not be subjected to stress. The inlet and outlet of the instrument should have appropriate pipe support to keep the instrument under minimum stress.
8. Be especially careful when installing PTFE (polytetrafluoroethylene)-lined instruments. Since the PTFE will deform under the action of pressure, the flange nut should not be over tightened at will.
9. The instrument with liquid crystal display should avoid direct sunlight when installing, and reduce the service life of the liquid crystal.
10. When measuring low temperature media, you need to select the jacket type.
Integrated orifice flowmeter
1. The opening of the meter should avoid opening holes in the forming pipe.
2. Pay attention to the length of the straight pipe before and after the flowmeter.
3. If there are grounding electromagnetic, mass and other flowmeters, grounding should be carried out according to the instructions.
4. When the process pipeline is welded, the grounding wire should avoid the instrument body to prevent the grounding current from flowing into the ground through the instrument body and damaging the instrument.
5. When welding the process, avoid the grounding current flowing through the capillary pressure guiding tube of the single and double flanged instrument.
6. For medium and high pressure impulse pipes, argon arc welding or socket welding can be used, and argon arc welding or socket welding should be adopted. Wind speed > 2m / s, there should be wind protection measures, otherwise the coating wire should be used, wind speed > 8m / s, must have wind protection measures, otherwise the welding should be stopped.
7. Pay attention to the installation direction of the flow port of the flowmeter throttling device.
8. Stainless steel pressure pipe is strictly prohibited; it is strictly prohibited to flatten the pressure pipe.
9. The installation position of the instrument's impulse piping, air duct and threading pipe should avoid the process production operation in the future, should avoid the high temperature corrosion place, and should be fixed firmly; the lowest lead end of the threading pipe drawn from above should be lower than The wiring inlet end of the connected instrument; the lowest end of the threading pipe should be added with a drip tee; near the instrument side, a Y-shaped or tapered explosion-proof sealing joint should be added; the lowest point of the main wind line of the instrument should be added with a condensing (stain) valve.
10. The copper gasket used in the instrument, if not annealed, should be annealed before use, and pay attention to the allowable temperature, medium and pressure conditions of various material gaskets.
11. In the field instrument junction box, the grounding of different grounding systems should not be mixed. The shielding wires of all instruments should be connected separately to the upper and lower shielding layers.
12. When the instrument is in a position where it is difficult to observe and repair, change the position or install the platform.
13. The joint is forbidden in the middle of the instrument line, and the hidden record is made. The compensation wire joint should be welded or crimped.
Integrated orifice flowmeter
14. Stainless steel welds should be pickled, passivated, and neutralized.
15. Instruments and fittings that need to be degreased should be degreased in strict accordance with the specifications, and the sealing and storage work of the instrument and fittings after degreasing should be carried out to prevent secondary pollution during storage and installation.
16. Stainless steel pipelines are strictly prohibited from direct contact with carbon steel.
17. Galvanized and aluminum alloy cable trays are strictly prohibited from being cut and opened by electricity, gas welding, and similar mechanical cutting and opening should be used without tooth saw and special hole opener.
18. Stainless steel pipes are strictly prohibited from being cut and opened by electricity or gas welding. Plasma or mechanical cutting or opening should be used.
19. Instrument threading pipes, cabinets, discs, etc. larger than 36V should be grounded, grounding instrument threading pipe thread with conductive paste; instrument threading pipe thread of 36V or less should have at least anti-rust treatment; exposed thread should not be larger than one wire buckle.
20. Instrument Threading Pipes in Explosive Hazardous Areas shall maintain electrical continuity.
Insulated instrumentation lines below 21.100 volts are measured using a 250V shaker to measure the line insulation resistance and ≥ 5 megohms.
22. The aluminum alloy bridge should be short-circuited across the short-circuit. The galvanized bridge should be tightened with not less than two anti-loose screws. The length should be reliably grounded within 30 meters. If it exceeds 30 meters, a grounding point should be added every 30 meters.
23. When the instrument line or instrument line of different grounding systems shares a slot with the power line, they are separated by a metal partition.
24. It is strictly forbidden to use the gas welding method in the installation and processing of the instrument panel, cabinet, box and table. The welding method should not be used for the installation and fixing. The mechanical opening method should be adopted for the opening.
25. The blind end of the instrument for heating and returning water should not exceed 100mm.
26. The lower part of the transmitter drain valve should be equipped with a cap that prevents leakage of the valve (especially in the explosion-proof area).
27. The orifice flow meter and its threading pipe and pressure pipe are fixed at one end in a thermal expansion zone (such as a tower, an accessory that moves with the thermal expansion of the tower), and one end is fixed in a non-thermal expansion zone (such as a labor protection room), and the instrument should be connected according to On the actual situation of the site, the flexible pipe, the threading pipe and the pressure pipe must have a certain thermal expansion margin.
28. The tower bridge and the threading pipe shall be provided with thermal expansion joints or flexible joints according to the actual conditions on site.
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