Indicator next to the tank
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May I ask whether the installation location of the servo/radar gauge beside the tank is inside or outside the tank area dike? Are there any regulations regarding this? For these gauges beside the tank, is communication via digital signals preferred over analog signals in most cases? Please provide some guidance
It should be fine inside the cofferdam; there’s no need to set one outside as well: lol:L
The E+H indicator is connected in series in the circuit – what’s the use of it, so that field inspectors can check it? Just check the magnetic flip plate during on-site inspections – why would anyone bother looking at this thing?
Indicator next to the tank – it’s placed right next to the tank. As for the measurement scale, it seems that communication is required… The radar system is more complex when placed next to the tank, while the servo system is simpler in that regard
There are regulations (I didn’t check; it’s from memory). Hazardous liquid tanks must have two sets of level gauges, one on-site and one with remote transmission. Remote level gauges must provide indications outside the cofferdam, and some also require alarms and interlocks. In fact, a set available on-site can be visual level gauges such as panel-mounted level gauges (in some cases, regulations require the use of visual level gauges) ； In addition, there are indication alarms outside the cofferdam, which ensures compliance. As for the rest, it’s just something extra to enhance things; you can decide for yourself. .
I checked some standards, and none mention a display next to the tank. However, the display next to the tank is called a Local indicator, that is, an on-site display of the liquid level. There are strict requirements for local level indicators. SH/T 3007-2014 \"Code for Design of Tank Areas in Petrochemical Storage and Transportation Systems\", 6.3.2 For pressure storage tanks, a set of remote sensing instruments and a set of local indication instruments shall be provided for level measurement; glass plate level gauges shall not be used as local indication instruments. SH 3136-2003 \"Code for Safety Design of Spherical Storage Tanks for Liquefied Hydrocarbons\", 5.3.1 Spherical storage tanks for liquefied hydrocarbons shall be equipped with local and remote level gauges; however, glass plate level gauges should not be used. \"Regulations on Safety Technical Management of Liquefied Hydrocarbon Spherical Tank Areas in Sinopec,\" 4.4.3 Liquefied hydrocarbon spherical tanks shall be equipped with local and remote level gauges. The installation locations are generally chosen outside the cofferdams, so as to facilitate observation without the need to enter each cofferdam. Enraf’s tank-side display is communicative; after an upgrade, it was originally four-wire based but was changed back to two-wire. E+H’s proprietary version also uses the 4–20mA plus Hart protocol as a second output.