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1. Commonly used standard throttling devices (orifice plate), (nozzle), (Venturi tube). 2. Commonly used non-standard throttling devices include (double orifice plate), (round orifice plate), (1/4 round nozzle) and (Venturi nozzle). 3. Commonly used pressure measurement methods for orifice plates include (corner connection pressure measurement) and (flange pressure measurement). Other methods include (theoretical pressure measurement), (diameter pressure measurement) and (pipe connection pressure measurement). 4. For the standard orifice plate flange pressure sensing method, the distance between the center of the upstream and downstream pressure sensing holes and the front and rear end faces of the orifice plate is (25.4±0.8) mm, which is also called 1-inch flange pressure sensing. The operating power supply range of 5.1151 transmitter is (12) VDC to (45) VDC, and the load is from (0) ohm to (1650) ohm. 6. The measurement range of the 1151DP4E transmitter is (0~6.2) to (0~37.4) Kpa. 7.1151 The maximum positive migration of the differential pressure transmitter is (500%), and the maximum negative migration is (600%). 8. The fluid velocity in the pipeline, under normal circumstances, the flow velocity at the (pipe center line) is the largest, and the flow velocity at (the pipe wall) is equal to zero. 9. If (Reynolds number) is the same, the motion of the fluid is similar. 10. When the fluid filling the pipe flows through the throttling device, the flow jet will occur (local contraction) at the (constriction), thereby increasing the (flow rate) and reducing (the static pressure). 11.1151 differential pressure transmitter uses variable capacitance as the sensitive element. When the differential pressure increases, the measuring diaphragm is displaced, so the capacitance on the low-voltage side (increases) and the capacitance on the high-voltage side (decreases) 12. When the minimum adjustment range of the 1151 differential pressure transmitter is used, the maximum load migration is (600%) of the range and the maximum positive migration is (500%). If the maximum calibration range of the 1151 is used, the maximum negative migration is (100%) and the positive migration is (0%). The accuracy of 13.1151 differential pressure transmitter is (±0.2%) and (±0.25%). Note: Large differential pressure transmitter is ±0.25% 14. Commonly used flow units, volume flow rate are (m3/h), (t/h), mass flow rate is (kg/h), (t/h), and gas volume flow rate under standard conditions is (Nm3/h). 15. Use an orifice flowmeter to measure steam flow. When designed, the density of steam is 4.0kg/m3, but the density during actual operation is 3kg/m3. The actual indicated flow rate is (0.866) times the design flow rate. 16. Use an orifice plate flowmeter to measure the gas ammonia flow rate. The design pressure is 0.2MPa (gauge pressure) and the temperature is 20°C. However, the actual pressure is 0.15MPa (gauge pressure) and the temperature is 30°C. The actual indicated flow rate is (0.897) times the design flow rate. 17. The straight pipe section in front of the throttling orifice plate generally requires (10) D, and the straight pipe section after the orifice plate generally requires (5) D. For correct measurement, the straight pipe section in front of the orifice plate is preferably (30-50) D, especially when there is a pump or regulating valve in front of the orifice plate. 18. In order to make the flow coefficient α of the orifice flowmeter tend to a constant value, the Reynolds number of the fluid should be greater than (limit Reynolds number). 19. Among the technical requirements for orifice plate processing, the upstream plane should be (perpendicular to) the center line of the orifice plate, there should be no (visible scars), the upstream and downstream surfaces should be (parallel), and the upstream entrance edge should be (sharp). * * thorns and scars). 20. The pressure measurement position in the picture is correct for which fluid? (A) A. Gas B. Liquid C. Steam D. High viscosity fluid E. Principle of settling fluid: When measuring gas, in order to allow a small amount of condensate in the gas to flow smoothly back to the process pipeline without flowing into the measuring pipeline and instrument, the pressure tapping port should be in the upper half of the pipeline, i.e. at position 1 in the figure. When measuring liquid, in order to allow the small amount of gas precipitated in the liquid to return to the process pipeline smoothly without entering the measuring pipeline and instrument, the pressure port should preferably be at an angle of 0 to 45 degrees below the horizontal centerline of the pipeline, as shown at 2 in the figure. For steam media, stable condensate should be maintained in the measuring pipeline, and at the same time, solid media at the bottom of the process pipeline should be prevented from entering the measuring pipeline and instrument. The pressure port should preferably be at an angle of 0 to 45 degrees above the horizontal centerline of the pipeline, as shown at 3 in the figure. 21. What should you pay attention to when opening and closing the balance valve of a differential pressure flowmeter filled with isolation fluid? What's the point? Answer: Before the differential pressure flowmeter for isolation liquid is used, that is, before opening the orifice plate pressure valve, the balance valve must be cut off to prevent the isolation liquid from being washed away. When it is deactivated, the pressure valve must be cut off first, and then the balance valve can be opened to keep the meter in a balanced state. When there is fluid flowing in the process pipeline, there will be a differential pressure on both sides of the throttling device. For instruments filled with isolation liquid, if both pressure valves are open, the situation is similar to the fact that the liquid in the "U"-shaped pipe cannot be connected. The positive pressure end cannot enter and the negative pressure end cannot draw out. This ensures that the liquid in the "U"-shaped pipe will not escape. Therefore, the flow differential pressure meter filled with isolation fluid emphasizes paying attention to the relative position of the balance valve, and the reason is here. 22.What is the static pressure error of a differential pressure transmitter? Answer: When the same pressure is input to the positive and negative pressure chambers of the differential pressure transmitter at the same time, the output zero position of the transmitter will be offset, and the offset value will change with the increase of static pressure. This error due to static pressure is called static pressure error. 23. What are the pressure-taking methods of the throttling device? Answer: 1. Corner joint pressure taking 2. Flange pressure taking 3. Theoretical pressure taking 4. Diameter pressure taking 5. Pipe connection pressure taking. 24. When using a differential pressure transmitter to measure flow, under what conditions is it necessary to install a packet? How to install? Answer: When the measured medium is a corrosive gas or liquid, an additional package is required to protect the membrane box and measuring conduit of the differential pressure transmitter from corrosion. ； When the measured medium is a viscous medium, in order to ensure accurate measurement, a packet must also be installed. The connection port between the packet and the throttling member is the "inlet", and the interface with the measuring tube is the "outlet". When the density of the measured medium is less than the density of the sealing liquid, the packet must be "up in and out". When the density of the measured medium is greater than the density of the sealing liquid, the packet must be "bottom in and out".