How to use the measurement accuracy that can be achieved with a turbine flow meter?
Author: Instrument Co., Ltd. Guangzhou Dichuan
How to use the measurement accuracy that can be achieved with a turbine flow meter ? Turbine flowmeters can be installed and maintained in accordance with scientific installation methods, and the turbine flowmeter can achieve measurement accuracy to the accuracy level of the calibration. How to install a turbine flow meter scientifically? The small series of Qinlu flow measurement and control instrument on the scientific installation of the turbine flowmeter is as follows:
Turbine flowmeter operation and maintenance
1 When the pipe of the turbine flowmeter needs to be cleaned, the bypass must be opened and the cleaning liquid cannot pass through the flowmeter.
2 When the pipeline system starts, it must first open the bypass to prevent the sudden increase of the flow rate, causing the turbine to rotate too much and damage.
3 Turbine flowmeter bearings should be replaced regularly, generally the bearing wear can be observed according to the change of small flow characteristics.
Turbine flowmeter installation requirements
The installation of the flowmeter has a great influence on the measurement accuracy of the flowmeter.
1. The transmitter should be installed horizontally to avoid vertical installation. It should be installed coaxially with the straight pipe sections before and after, and the gasket should not be inserted into the pipe. 2. The uneven distribution and the existence of secondary flow in the pipe are important factors affecting the measurement accuracy of the turbine flowmeter. Therefore, the turbine flowmeter has certain requirements for the upper and lower straight pipe sections. For industrial measurements, the upstream 20D , downstream 5D straight tube length is generally required . To eliminate secondary flow, ** install a rectifier on the upstream side. If the upstream end can guarantee a straight pipe section of about 20D and a rectifier is installed, the measurement accuracy of the flowmeter can reach the accuracy level of the calibration.
3. In order to ensure that the liquid passing through the flowmeter is single-phase, that is, air or steam cannot enter the flowmeter, a gas trap should be installed upstream of the flowmeter if necessary. For liquids that are easily vaporized, a certain back pressure must be guaranteed downstream of the flow meter. The back pressure can be doubling the pressure drop of the flow sensor at ** flow rate plus one or two times the vapor pressure of the liquid being tested at ** temperature .
4, a meter constant turbine flowmeter is factory calibrated with clean water, but the medium is not water, the test site, a viscosity greater than 5 centistokes and a density greater than 10% of the liquid turbine flowmeter needs to be corrected viscosity and density. Density compensation must be performed when measuring gas with a turbine flow meter.
5. The general working point of the turbine flowmeter ** is more than 50% of the upper limit value of the measuring range of the instrument . When the flow rate is slightly fluctuated, the working point does not move to the area outside the lower limit of the characteristic curve.
6. The power cable of the transmitter is made of metal shielded wire. The grounding should be good and reliable, and the length of the signal wire should be limited. The power supply is DC 24V , 650 Ω impedance.
7. The flow direction of the fluid is the same as the direction of the arrow on the instrument casing, and must not be reversed. 8. The measured medium should not corrode the turbine, especially at the bearing, otherwise measures should be taken. 9. When disassembling the flowmeter, the magnetic induction part cannot collide.
10. Before installing the turbine flow meter, the pipeline should be cleaned. When the measured medium is unclean, add a filter. Otherwise, the turbine and the bearing are easily stuck, and no flow can be measured.
11. Set the meter factor before shipping. Check carefully to make sure that the meter wiring is correct and the grounding is good before power can be sent.
Only the correct scientific use according to the installation requirements of the turbine flowmeter, the measurement accuracy of the turbine flowmeter is greatly improved!
"Gravity Die Casting. A permanent mould casting process, where the molten metal is poured from a vessle of ladle into the mould, and cavity fills with no force other than gravity, in a similar manner to the production of sand castings, although filling cn be controlled by tilting the die."
Gravity Die Casting
Sometimes referred to as Permanent Mould, GDC is a repeatable casting process used for non-ferrous alloy parts, typically aluminium, Zinc and Copper Base alloys.
The process differs from HPDC in that Gravity- rather than high pressure- is used to fill the mould with the liquid alloy.
GDC is suited to medium to high volumes products and typically parts are of a heavier sections than HPDC, but thinner sections than sand casting.
There are three key stages in the process.
- The heated mould [Die or Tool] is coated with a die release agent. The release agent spray also has a secondary function in that it aids cooling of the mould face after the previous part has been removed from the die.
- Molten metal is poured into channels in the tool to allow the material to fill all the extremities of the mould cavity. The metal is either hand poured using steel ladles or dosed using mechanical methods. Typically, there is a mould [down sprue" that allows the alloy to enter the mould cavity from the lower part of the die, reducing the formation of turbulence and subsequent porosity and inclusions in the finished part.
- Once the part has cooled sufficiently, the die is opened, either manually or utilising mechanical methods.
Advantages
- Good dimensional accuracy
- Smoother cast surface finish than sand casting
- Improved mechanical properties compared to sand casting
- Thinner walls can be cast compared to sand casting
- Reverse draft internal pockets and forms can be cast in using preformed sand core inserts
- Steel pins and inserts can be cast in to the part
- Faster production times compared to other processes.
- Once the tolling is proven, the product quality is very repeatable.
- Outsourced Tooling setup costs can be lower than sand casting.
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