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Can anyone advise if it is considered essential to fit a locknut to the inside of a compression gland for a steel-wire armoured cable entering a threaded cable entry in an ex'e' enclosure in a Zone 2 hazardous area? I can understand that the locknut would be essential to maintain earth...

You can run Modbus over Ethernet, which allows redundancy and avoids having to have hardwired controls. (Should still have a hardwired ESD signal though). When getting into decisions about adopting software communication to MCCs, make sure you scrutinise the vendor's communications architecture...

It's not clear from your description of the rail car unloading, precisely what safety functions you are assessing the SIL values for. Most engineers in the process industry work with SIFs and their SIL values for low demand functions that rarely if ever require to activate. In those cases the...

In answer to your questions: 1. Yes 2. Your question doesn't make sense in English. I think that what the sketch is trying to convey is that the ESD system includes a software latch whenever the trip condition is activated. This latch prevents the solenoid from automatically re-energising when...

I'm not sure which jurisdiction the OP is in, but in Australia the area classification standard AS2430.3 for flammable liquids (Section 3.3) requires you to regard a combustible liquid as a flammable one if it is being handled or stored within 6 degrees C of its flashpoint. In such a case the...

This all comes back to the operating company and their acceptance of risk (or not) by insisting on industry standards. The usual standards for design of safety systems are IEC61508 (for equipment) and 61511 (for process systems). If your plant is being built to those standards, then there are...

I'm working for an engineering firm (we do some consultancy) and one of our clients has asked us to do a CHAZOP on a plant that another company is building for him. I've attended and even facilitated numerous HAZOPs and SIL assessments, but I've never been to a CHAZOP. I've got a very vague...

Anybody have any idea how much the SG in an atmospheric tank (and therefore the level as detected by a DP measurement device) would be affected by air sparging in the tank? The application is a sanitary waste water equalisation tank on the inlet of a waste water treatment plant. Air blowers are...

Thanks very much for all the suggestions. Any others?

I guess that the ability to measure flow after a fashion using the pump could be an advantage. Maybe you could avoid the need for a separate flowmeter if high accuracy was not required or money was not changing hands. I'm not convinced this would be the main reason. With regards to "working...

I'd like to understand why vendors offering diesel fuel storage / handling / dispensing systems seem to prefer to offer positive displacement vane pumps, rather than centrifugal pumps. I can understand the requirement for a self-priming pump when intermittently taking suction from a top entry...

Thanks for the comments; I probably haven't been clear enough in my explanation. Absolutely right, but that's the verification part of the SIL process. The shutdown function (typically a detector triggering off some sort of valve closure) has to first be given a target SIL value (effectively...

Hope this is the right forum for this question... I have a client who operates a not-normally-manned ten-year-old compressor station on a natural gas pipeline. He wants me to do a SIL evaluation of the ESD shutdown system (hardwired relay-based) for the station in accordance with IEC61511, as...