The following points should be noted during the installation of the flow meter

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　　Many problems can arise during the installation of flow meters. Below, the technical staff from the manufacturer will share some personal insights in the hope that they will be helpful to everyone: 1. The filter screen cannot be removed after the flow meter is installed: Since the design of the metering system generally does not specify the spacing between various devices, and commercial customers often provide very limited space for installing flow meters, the installers arrange everything in a very compact manner. As a result, some filter screens become inaccessible due to obstruction by other devices, which hinders future maintenance of these filters. Other problems of this kind include: the ball valve handle being blocked and thus unable to be closed; the IC card controller cover being blocked and thus unable to be opened; and it being impossible to read the meter when its surface faces the wall. 　　Regarding the above issues, the quality inspector has made corrections many times; yet this tendency to deliberately or inadvertently ignore the convenience of subsequent equipment maintenance remains very serious during the installation of flow meters. Quality inspectors should exercise strict oversight during project acceptance, working together with the construction units to change this mindset of merely ensuring that the flow meters are installed in place without considering their future use. 　　2. The lengths of the straight sections before and after the turbine flowmeter are not appropriate: The turbine flowmeter is a type of velocity-type flowmeter; it calculates the gas flow rate by measuring the speed of the gas flow in the pipeline. To ensure measurement accuracy, the gas flowing into the turbine flow meter must have a typical laminar or turbulent flow pattern; this requires sufficient straight pipe sections at both the front and rear of the meter to stabilize the gas flow. Generally, we require the length of the straight pipe section at the front end to be 10d, and that at the back end to be 5d; there should be no fittings such as elbows, tees, or globe valves within this range. 　　Due to limited space for installing the flow meter or insufficient construction experience, contractors often fail to follow the above requirements, and such turbine flow meters cannot be put into use. Before installing the equipment, we should carefully read the installation instructions to understand the specific installation requirements for each type of equipment, draw on past experience, and avoid unnecessary mistakes. 　　3. Equipment not installed according to the flow direction indicators: Some equipment may appear to have identical interfaces at both ends, but its internal structure requires it to be installed in accordance with the flow direction. Such equipment usually has markings on the outside indicating the direction of flow; if workers fail to notice these markings during installation, they may install the equipment in the wrong direction. 　　Components in the instrumentation system that have flow direction requirements include various flow meters, IC card controllers, emergency shut-off valves, bellows compensators, filters, and so on. Strictly speaking, there are also flow direction requirements for the installation of ball valves; the standard method for installing flow meters is to place the seamless end in the direction of the airflow. 　　4. Equipment not installed in the direction of gravity: Some equipment is sensitive to the direction of gravity and requires to be aligned parallel or perpendicular to it. 　　The cutting action of the IC card controller and the emergency shut-off valve is achieved by the weight of the valve element causing it to drop and press against the valve port; therefore, the equipment must be installed on a horizontal pipeline. 　　The Y-type filters used for artificial gas also need to be installed in horizontal pipes; otherwise, the condensate water in the pipes will not settle at the bottom of the filter due to gravity, which will affect the filtering efficiency. Installing a Roots flow meter in the vertical section of the pipeline can enable self-cleaning. 　　Installing devices in the direction of gravity is necessary for some devices, such as IC card controllers and emergency shut-off valves, while for others it is advisable to do so but it is not mandatory. 　　5. Instrument system with undetected leaks during airtightness testing: Quality inspectors often detect leaks in the instrument components when conducting airtightness inspections on commercial customer installations. Upon asking the workers carefully about how they conducted self-inspections, it was found that when checking the flow meters, they often forgot to open the ball valves at both the front and back of the metering system, as a result of which only the pipeline behind the meter was inspected, while the metering system itself was not checked. The instrument part has many interfaces, and leaks often occur in this area. Neglecting the airtightness test is unforgivable, as its consequences can be extremely serious.