The instrument is one of the common equipments in the chemical plant. Today we are talking about the related issues that need to be noted during the installation of the instrument. The instrument installation of the project involves the detection of temperature, pressure, flow, level, process analysis and data display, automatic adjustment and control. To ensure the normal display and play of the above functions, installation is the key. Let's talk about it in detail below.
01
Pre-installation considerations
1. Before the instrument is installed, the process pipeline should be purged to prevent the ferromagnetic material trapped in the pipeline from adhering to the instrument, affecting the performance of the instrument, or even damage the instrument. If unavoidable, magnetic filters should be installed at the entrance of the instrument. The instrument itself does not participate in the air sweep before it is put into operation to avoid damage to the instrument.
2. Before installing the instrument into the process pipeline, check whether it is damaged, and open the shell to remove the filler of the fixed pointer.
3. The installation form of the instrument is divided into vertical installation and horizontal installation. If it is a vertical installation form, the angle between the vertical center line of the instrument and the vertical line should be less than 2°; if it is a horizontal installation, the horizontal centerline of the instrument should be guaranteed. The angle between horizontal lines is less than 2°.
4. The upstream and downstream pipes of the instrument should be the same as the diameter of the meter. The connecting flange or thread should match the flange and thread of the meter. The length of the straight pipe upstream of the meter should be guaranteed to be 5 times the nominal diameter of the meter, and the length of the downstream straight pipe should be greater than or equal to 250mm.
5, because the instrument is transmitted through the magnetic coupling signal, so in order to ensure the performance of the instrument, installed at least 10cm around, do not allow the existence of ferromagnetic material.
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 instrument, it will generate a pressure drop at the float and cause data distortion. If this is the working condition, a valve should be installed at the outlet of the instrument.
7. The instrument installed in the pipeline should not be subjected to stress. The inlet and outlet of the instrument should have proper pipeline support, which can make the instrument in the minimum stress state.
8. Be especially careful when installing PTFE (Teflon)-lined instruments. Because the PTFE deforms under pressure, do not over-tighten the flange nuts.
9, with a liquid crystal display instrument, the installation should try to avoid direct sunlight, reduce the LCD life.
10, low-temperature medium measurement, the need to choose jacket type.
02
Precautions during installation
1, the instrument opening 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 is grounding requirements of electromagnetic, quality and other flow meters, should be grounded 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 through the instrument body into the ground and damage the instrument.
5. During the process welding, avoid the grounding current flowing through the capillary pressure tube of single and double flange instruments.
6ã€The medium and high pressure impulse pipes can be used for argon arc welding or socket welding, and argon arc welding or socket welding should be adopted. Wind speed>2m/s, windproof measures should be adopted, otherwise the welding wire should be coated, wind speed>8m/s, windproof measures must be taken, otherwise welding should be stopped.
7. Pay attention to the installation direction of the pressure metering device of the flowmeter throttling device.
8, stainless steel pressure tube is prohibited enthusiasm; it is strictly forbidden to flatten the pressure tube.
9. The installation positions of the instrument pressure tube, air tube and threading tube should be avoided in the future to hinder the process production operation, should avoid high temperature corrosion places and should be fixed firmly; from the upper thread guide tube, the lowest lead end should be lower than Connect the instrument to the wiring of the import end; threading pipe should be added to the lowest end of the drop three links; close to the instrument side should increase the Y-shaped or conical explosion-proof sealing joints; instrument main wind line should be added at the lowest condensate (pollution) valve.
10, copper gasket used in the instrument, if no annealing treatment, should be annealed before use, and pay attention to a variety of material gasket allowable temperature, medium and pressure conditions.
11. In the field instrument connection box, the grounding of different grounding systems cannot be mixed. The shielded wires of all the instruments should be separately connected to the upper and lower shielding layers. It is forbidden to screw them together to connect the upper and lower shields.
12. When the instrument is not easy to observe and check the position, it is reported to Party A that it agrees to change its position or install a platform.
13. No connector is allowed in the middle of the instrument line. If there is any special situation, please report to Party A's consent and make a hidden record. The compensation wire connector should be welded or crimped.
14, stainless steel welding should be pickling, passivation, and neutralization treatment.
15. The instruments and fittings that need to be degreased should be degreased in strict accordance with the specifications, and be well sealed and stored after the degreasing of the instruments and fittings, and must be prevented from secondary pollution during storage and installation.
16, stainless steel pipeline is strictly prohibited and direct contact with carbon steel.
17. Galvanized and aluminum alloy cable bridges are strictly prohibited from using electricity and gas welding to cut and open holes. Machine-like saws and special hole cutters and other similar mechanical cutting and opening holes should be used.
18, stainless steel tube is strictly prohibited power, gas welding cutting and opening, should use plasma or mechanical cutting, open hole.
19, greater than 36V instrument threading pipe, cabinets, plates, etc. should be grounded, grounding instrument threaded pipe thread with conductive paste processing; less than equal to 36V instrument threaded pipe thread buckle at least anti-rust treatment; exposed thread buckle should not be greater than a wire buckle.
20. The instrument threading tube in explosion hazardous areas should maintain electrical continuity.
21,100 volt insulated instrumentation line 250V megger to measure the line insulation resistance, and ≥ 5 megohms.
22, aluminum alloy bridge should be connected short wiring, galvanized bridge should be less than two locking screws tightened, the length of 30 meters should be reliably grounded at both ends, more than 30 meters should be added every 30 meters a grounding point.
23, when the instrument line or instrument line of a different grounding system shares a slot with the power line, separate them with metal partitions.
24. It is forbidden to use the gas welding method for the installation and processing of instrument panels, cabinets, boxes, and tables. The installation and fixation should not use welding methods. Openings should be mechanically opened.
25. The blind end of the instrument heating and return water should not exceed 100mm.
26, Transmitter drain valve lower mouth should increase the valve leakage cap (especially in the explosion-proof zone).
27. One end of the instrument and its threaded pipe and pressure pipe are fixed in the thermal expansion zone (such as the tower and the accessories that move with the thermal expansion of the tower), and one end is fixed in the non-thermal expansion zone (such as the labor protection room). When connecting the meter, it should be based on the actual situation on the site. Its flexible pipe, threading pipe, pressure pipe must leave a certain thermal expansion margin.
28, attached tower bridge, threaded pipe should be based on the actual situation of the site to leave thermal expansion joints or flexible connections.
03
other
1. Brass connection should be socket welding, casing welding or snapping, aluminum tube should be welded, and oxide layer should be removed before welding.
2. Special attention should be paid when measuring lines are connected to measuring instruments. Lines for gas and low-boiling liquid fluids should be laid upward; pipelines for general liquids should also be laid upwards.
3, measuring the liquid pressure tube, in order to reduce the measurement error to improve the measurement accuracy, the pressure tube out of the container should be placed along the horizontal direction of the minimum measurement of the long enough distance (more than 500mm). Make sure that the level of the bottom of the liquid surface changes.
4. The pressure guiding tube at the bottom of the liquid surface shall protrude into the liquid container with the nozzle facing downwards to avoid impurities blocking the measurement.
5. The location of the gas phase outlet above the liquid container. Should choose to avoid the impact of liquid flow and fluid impact in the container. After leading from the container, the pressure guiding tube shall be laid vertically upwards (usually larger than 150mm) and then laid horizontally.
6. The installation of pressure guiding pipe should implement the technical standards for the installation of large-scale air separation equipment instrument pressure pipe, the bending radius of the pressure guiding pipe is R=5D, and the pressure guiding pipe inside the cold box should be in accordance with “HTA1107-93, Technical Requirements for Large Air Separation Installationâ€. , R=10D.
7. The source material of the instrument and the material of the pressure guiding tube should be consistent with the material requirements of the process piping or equipment, especially the source parts and the pressure guiding tube for the measurement of the corrosive toxic medium must be checked before installation.
8. The welding technical requirements for the source components of the instrument and the pressure guiding tube of the instrument must be consistent with the welding technical requirements of the process piping or equipment.
9. The instrument installation in the tank area and installation area with explosion-proof requirements shall strictly observe the requirements of explosion protection and grounding. The connection between the protection tube and the field instrument, meter box, junction box, and junction box shall be sealed and strictly follow the design requirements. .
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Digital Visual Interface Cable Connectors
DVI ConnectorWith the advent of technologies such as DVD players, high-definition televisions, and even digital cable, the need for more advanced cables and connectors has increased. Digital Visual Interface (DVI) is one response to the growing need for interconnected systems, enabling digital systems to be connected to an array of displays. Yet DVI cables and connectors can also be complicated, and may lead to confusion between High Definition Multimedia Interface (HDMI) and DVI. Although the two systems have much in common, they service different niches of digital technology.
Digital Visual Interface
Older systems aren`t necessarily outdated systems. Although DVI preceded HDMI, it`s still widely used in both business and domestic settings. DVI connectors are designed to handle digital data transmission, incorporating three transmission channels in every connector link. The maximum bandwidth for data transfer is 165 megahertz, which is enough to relay up to 165 million pixels per second. Data is encoded for effective transfer, but a single link can handle around 4.95 gigabits per second of information. Double links can handle twice that amount.
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A standard DVI Connector is 37 mm wide and has 24 pins, 12 of which are used for a single link connection. When analog is involved, four additional pins are needed to support the additional lines of an analog signal. It is not possible to cross from a digital source to an analog display or vice versa. In those instances, an integrated connector is probably the best option. There are five common types of DVI connectors.
DVI-I Single Link
This kind of connector has three rows, each with six pins. There are two contacts. Because the connector is integrated, it can be used with both analog and digital applications.
DVI-I Dual Link
A DVI-I dual link connector can also be used with both digital and analog applications, but is configured with more pins to accommodate a dual connection. There are three rows with eight pins each, as well as two contacts.
DVI-D Single Link
Specifically designed for digital applications, a DVI-D single link connector has three rows of six pins, and looks much like a DVI-I single link connector. However, a DVI-D connector has no contacts.
DVI-D Dual Link
Also made specifically for digital applications, a DVI-D dual link features more pins (three rows of eight) for dual connections. Like a DVI-D single link, a DVI-D dual link connector has no contacts.
DVI-A
This particular type of connector can only be used for analog applications, and has three rows of pins. One row has five pins, one has four pins, and the last row has three pins. Like single link connectors, a DVI-A link connector has two contacts.
Female DVI Connector
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