Thanks SAK9, I should've mentioned that the cell fans are configured for both dual fan operation and duty/standby. I was just wondering if it's industry practice to have a seamless changeover on duty/standby vent systems.
Hi,
I'm reviewing a specification for a vent control system upgrade and I'd be grateful for some advice.
The system has three fan sets operating duty/standby. The first is for a cell extract. The second for building extract. The third is the air handling unit to supply conditioned air. The...
Here's one for you to consider.
I attended my Chartered Engineer interview with 2 colleagues, who were getting interviewed as well. We had all joined the company at pretty much the same time. Myself and another colleague each wore a suit and tie whereas the other wore a shirt and tie with...
I'm not sure what PLC you're using, but can you assign the tank level to a PLC memory address (variable)? Usually there are Data Files or Variable configuration set-ups where you can configure the PLC memory locations as variables.
You only need one PLC variable and you should set up an...
Set-up a timer, say every couple of hours, to record the tank level to a PLC variable, then compare the current tank level with the PLC variable on every PLC cycle. If current tank level < (PLC variable + a tolerance) then enable alarm. You need the tolerance to prevent spurious alarms. You...
In the Electronic Books in iFix Workspace under the Help & Information in the system tree, select the 'Writing Scripts' for basic details on scripting.
The VB Editor also has help on basic functions etc.
For ifix objects, methods, functions etc goto the ifix Automation Reference. If you...
Hi,
Sounds like you have the system responding far too quickly because your proportional gain is far too high for the characteristics of the valve.
Have you tried ziegler-nichols loop tuning? It gives a good starting point from which you can then fine tune the loop.
We have valves that...
I agree with itsmoked, if you're paid to design a system then you can't have your cake and eat it. However, the one aspect that you have in your favour is that they asked you to design and develop the panels. To me this would indicate one of two things, either they don't have the in-house...
Check polarity, from item powering the loop is + to +, - to -, remainder of loop is + to -, - to + (if more than 2 items in the loop).
If the instrument is loop powered (2 wire) make sure only 1 PLC input card is configured to be active.
If instrument is powering the 4-20mA (4 wire) make sure...
If you're only checking the loop on the transmitters but you're using a dry block on the RTD's on the direct IO inputs then the tests are a bit inconsistent as you're only actually testing the sensing element with the dry blocks. All the transmitter test is doing is checking the 4-20mA from the...
We have a diaphragm metering pump designed to pump around 80L/hr. We are pumping nitric acid. The nitric acid is in a 5000L tank standing about 3m. The pump sits about 1m from the base of the bund. The pump has 1/2" inlet and outlet, but it is connected by 10mm pipe to the process inlet line...
The IDC manual is correct because it specifies that it's dealing with a "dangerous hidden fault" which in standard terminology is dangerous unrevealed failure.
A dangerous unrevealed failure will not be detectable by the diagnostics but the safety function is still valid as the trip function...
