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If there isn't a typo in the previous posts, we are all getting SERIOUSLY underpaid. LOL

Another way to do it: Use an e-stop switch with two sets of contacts. Use the "NC/closed on mushroom up" contacts to interrupt control power to the starter. Use the "NO/open on mushroom up" contacts to signal the PLC that an e-stop switch has been pushed.

I think everyone who has done PLC programming has felt this confusion at one time or another. You are actually programming a PLC input (if high then... if low then...). You must consider the input device separately, (voltage presented to input when pressed, voltage presented to input when not...

A P&ID may not give all the information you need to safely lock something out. Electrical energy, energy in springs and weights are a few things that come to mind.

Great information from both of you! Thanks!

Anyone have experience with VFD's on motors that drive reciprocating pumps or compressors? My gut tells me the pulsating currents would not be good for electronic components.

Whew! I brain-f**ted. Instead of discharge valve I should have said vent valve. The discharge path actually presents a good amount of resistance. The vent valve has the low resistance path. It gets opened to help chill the pump rapidly (cryogen) and then gets closed 10 seconds after pump start...

We have a centrifugal pump that is started with the discharge valve wide open. Valve is closed after 10 seconds. Of course, the pumping-of-gravel sound is present while valve is open. The pump is started once, and sometimes 2 or 3 times a day. The pump runs far back on its curve (about 15 GPM...

When it comes to reciprocating pumps for cryogenic fluids, the industry apparently likes to use NPSPR as a figure for comparison. The problem I see is that this particular figure is specific to a fluid. Is it safe to use the feet/psi conversion formula to get an "NPSHR" for a reciprocating...

State laws pertaining to engineering state that one cannot present himself/herself to the public as an engineer unless he/she is licensed.

Could you convert to a batch process where you load the capsules into a reservoir and then pressurize the surface, driving the beads down the line? Could you use a pig to drive the batch? Maybe you could have two reservoirs-load one while the other is being emptied into the line. That could...

Thanks for the feedback. I failed to mention that the water circulating through the compressors will be in a closed loop. The fluid cooler looks like a cooling tower, but has separate water systems. More like a heat exchanger, I suppose.

We are in the review stage of a project to install a fluid cooler that will service four compressors. I think the compressors will require 50 GPM each for cooling. Height will be ~13 feet (3 feet from buried pipe to pump and 10 feet from pump to top pipe on the fluid cooler. We plan to install...

This is wild speculation: The distance (and volume) from station A to the crimp is much less than that from the crimp to station B. The charging bottle volume is not large compared to the B side volume. As volume (behind the traveling pig)expands pressure drops to the point where it will not...

I have used explosion-proof cable glands that have a two-part epoxy compound for sealing. As rbalex says, you have to get the sealing compound along with the sealing fitting. The fitting and compound are listed together as a system.

Does each unit/section have its own flow switch? Could you base usage on the amount of time a switch is in a tripped state?

You might try googling "Autoclave Engineering". I agree with the caveat about galvanic corrosion. Are there aluminum connections on the other side of the bulkhead union? Any chance of changing the bulkhead fitting to a more compatible metal?

Space is a problem, but it is interesting to hear about 1 cooler/compressor. Compressors are recips. Gas is helium.

We are planning to add compressor capacity. Compressors will operate intermittently. There are lots of ideas related to cooling. One proposal says get two coolers-each cooler sized to handle the total compressor load (1 cooler for 4 compressors). Another proposal says turn off cooling water to a...

Iainuts, thanks for the response. I have the impression that the swept volume is not that large since one does not want to flex the diaphragm too much. You say that the speed is low, so I gather that a flow rate based on 15 psia suction is quite low compared to a rate based on 200 psia suction...