On-site installation of explosion-proof zone detectors
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In the petrochemical industry, field instruments are connected to the instruments through galvanized pipes; currently, explosion-proof flexible pipes are commonly used for this purpose. However, issues such as poor installation quality and exposure to weather conditions can lead to water leaking from these explosion-proof flexible pipes into the instruments. With the emergence of explosion-proof flanges, can they serve as a replacement? It would be best to have a legend.
It can be used as a substitute; currently in the petroleum and petrochemical industry in the south, explosion-proof gland seals are used in most cases, and the key is to choose seals of reliable quality with good sealing performance
Granhead and explosion-proof flexible hoses each have their advantages and disadvantages. Make a choice after comprehensive consideration
We use explosion-proof flanges everywhere
Use explosion-proof sealed joints with flexible connection pipes; those equipped with sealed joints
What this friend meant, as I understand it, is that water stored in the flexible tube caused water to enter the instrument. I have some installation suggestions for you: the flexible tube connecting the instruments should be installed at a lower level than the instruments themselves, and a tee fitting should be placed at the lower end of the flexible tube to allow drainage.
Take a screenshot from the chemical engineering installation atlas HG/T 21581-2012, \"Automation Control Installation Atlas\". 1. The use of flexible pipes is referred to in the installation manual as continuous cable protection connection (flexible pipe connection) ； 2. The connection between the cable protection tube and the flexible tube is made using a dust-proof tee. Note the following points here: a) A tee is used, not an elbow ； b) The tee is located below the instrument inlet ； c) There is no plug under the tee ； d) Flexible pipes come in waterproof and explosion-proof versions, but tees are all dust-proof.
Does it mean that there is no plug below the tee, so it’s hollow underneath? Otherwise, will the combustible gas get in?
Conduit trays can be left unsealed, so why can’t wire ducts have openings? Logically, it’s fine for the area below the three connections to be open, but some managers who don’t fully understand the situation might use this as an issue, so it’s best to install plastic dust plugs, pipe caps, and similar items to cover them.
Originally, chemical engineering design institutes all used this connection method: a single cable was pulled, along with a 3/4\" galvanized steel pipe and a wire gland leading to the meter. However, many of our previous clients reported that even with a drain tee installed in the flexible pipe, water still seeped into the meter over time. Mainly, the water cannot flow out and thus accumulates in the flexible tube, and the actual installation process does not take place at the ideal position shown in the diagram. Therefore, in most of the oil and petrochemical design drawings I have worked on, the installation method involves main cables, junction boxes, branch cables leading to the meters, along with explosion-proof gland fittings. In these setups, the junction boxes are usually mounted on tray systems, from which the cables then go back into the ductwork to reach the various branch trays connected to the meters. Since tray systems of 100*100 and 50*50 sizes are commonly used, the cables going to the meters, equipped with explosion-proof armored gland fittings, can provide sealing. However, to prevent mechanical damage to the cables, it is necessary to use armored cables (it is recommended to specify steel-wired armored cables in the design drawings); this approach not only ensures sealing but also protects the cables from mechanical damage. I can’t find the old photos anymore; the text here is just a rough approximation – it’s not clear. Ask me if you need more details
In this type of diagram, what is the role of the trough frame? Prevent mechanical damage?