Thanks for the response. I work in the gas processing / pipeline industry and other than the occasional boiler or fired heater we rarely see the need for using a PLC or other electronic device for our SIS applications. Ie we typically do it all with hardwired safety relays. Your situation is...
Just curious- what are you working with that requires SIL2 or SIL3? I have just ordered the add-on packages for Step 7 Professional that are required to work with the 414-FH. The 414-FH is NOT a friendly package to use.
I haven't figured out how to edit posts so I guess I'll write one more reply.
If Set/Reset isn't possible email me directly and I'll help you with the problem.
mikell@cvtv.net
Here's a simple version using set/reset coils. It would be a little more cumbersome to write latch/delatch rungs but that would work too.
Here's a bigger version of the photo I posted below:
http://images5.fotki.com/v67/free/d6152/4/42560/212863/Merged-or.jpg
Sounds like a fun test. Can you use Set/Reset coils in this logic solver?
If you can you could use them to do what you want to do.
(1) Push the button (call it PB1), set a coil (S1), set another coil (S2). S2 controls the light. Between the button and the set you put a set of NC contacts that...
I understand your frustration but if someone here tells you HOW to do it then you will have missed a great learning experience.
Try to think of an application where you could use this function in the real world. My first thought was of a traffic light that is controlled by a (very bored) human...
I've only seen once instance where leaking fluid ignited but it's definitely something to pay attention to in the design. From my limited experience, it's hard to find a good heat transfer fluid whose autoignition temperature is above operating temperature. Our systems are typically hot oil...
The velocity of the gas stream is not unimportant either. It and the viscosity of the return stream are very important things to consider. You don't want all of your injected glycol stacking up in the equipment and then "returning all at once". If the velocity is too low there will be...
Glycol injection is a "contact sport" :D
And here's a few rules of thumb...
(1) Try to put about 80% of the glycol that you inject at the front end of the exchanger train. If there is a front end split, divide the amount injected evenly between each exchanger.
(2) When you select a...
Thanks for the reply. I've read API RP521 but I did not find anything specific concerning the SAR. I am having a problem backing into the design criteria for one of our air assisted flares. I calculated the amount of air that I need for stoichiometric combustion, assumed 50% excess air, and came...
From what I've seen, 11echo's lamentations are on the mark. I learned how to generate a P&ID from "old school" draftsmen back in the late 70's. One of them is still in the business and he has transitioned to CAD (and loves it by the way). The problem, as I see it, with a lot of today's...
Can anyone give me an idea of how much excess air is typically used for an air assisted flare? I am trying to reverse engineer a smokeless flare design. I calculated the stoichiometric air requirments for our design and by using the design capacity of the blower I came up with over 300% excess...
Hmm... I see the acronym SIL used so often these days.
The aformentioned ISA book Safety Shutdown Systems: Design, Analysis and Justification s an excellent resource as is the 3.5 day class. Personally I think that the ISA should require class attendance before they sell the book to anyone. I...
