The stuffing box pressure is highly dependant on the flush plan and the clearance of the box bushings as well. We have some pumps that use Vespel bushings with a high stage flush stream to maintain vapor pressure margin for the seals.
You can calculate an order of magnitude estimate by having...
We had some reciprocating pumps in isobutane service and they were plagued with VOC emission issues.
Eventually they were fixed by replacing them with API BB3 centrifugal pumps.
The unfortunate part about recip pumps is that they are so good at a wide range of flows in a fixed head...
In that case, there's only so much hydraulic resistance in the circuit so you'll be running an extremely high flow rate. The pump will heat due to the loss of efficiency because of that high rate of flow.
BigInch's post details the fun unbounded heat rise until failure results!
We have a...
Well, I'd probably start with the hydraulic calculation to determine where the energy comes from. Then, you take the energy and determine the forces on the impellers. Then the forces become torque.
There's also friction (static and kinematic) to account for.
You'll be lucky to find out what...
321GO:
I switched to the midstream part of the pet-chem/energy biz.
The manufacturer I worked for was real big into outsourcing the bulk of the engineering to India. Of course the justification was, "The engineering they do is the basic stuff! We do all the exciting parts!"
My boss was a...
MCSF is Minimum Continuous Stable Flow, parlance for the lowest flow allowed by the pump OEM for reliable operation.
It's a highly controversial topic (between myself and my operators) that is scattered with junk science and hearsay.
To my operators, MCSF is whatever you need it to be!
What happens below the MCSF point is large amounts of recirculation which results in cavitation and overheating of the pump. This in turn results in shaft deflection, vibration, and a whole host of other issues.
You will not be able to have a reliable pump if you run below the MCSF for...
Greg,
You'll definitely be the guy to shed some reality on the sexy world of automotive engineering!
My experience in the automotive world is limited to the "get hired as a doe-eyed college grad with dreams of working on race cars and suddenly realizing that there's much more to designing...
Quote: However, I will not be doing what I see myself doing or doing what I sought out to do when I began my college career in ME.
I'm not doing what I saw myself doing even when I graduated with my ME. However, I've found my work to be fulfilling in a way that even driving cars could never...
*Puts operator hat on*
"There's a difference? It's just water!"
*Takes off operator hat*
In all seriousness, I don't think there will be a major problem with teflon if you don't tighten it more than necessary.
Unfortunately, our firewater pumps rarely last much longer than the packing; our...
I work in areas where FRCs are required at all times, which makes finding good cold weather gear difficult.
If you're going to find yourself in a job site where Nomex or other flame retardant clothing is required, find out if you can get insulated coveralls. I've got a set that are nice and...
From a car guy engineer to another car guy engineer:
Don't work in the auto industry. I got plenty of job opportunities when I graduated (FSAE, amateur racing experience) that were "dream jobs." I found out after the pay sucked and the corporate cultures were ridiculous.
Now, I work in the...
It may be that his VFD is looking for <40% speed as the "idle" speed. The program is also looking for a certain pressure setting. The VFD/Pump combo is probably running at some higher speed to maintain deadhead pressure.
We had a new VFD driven compressor that was programmed to "idle" at a...
Centrifugal pumps are fun like that.
Is your pressure sensor downstream of the check valve? Does the check valve leak? Might be that the pump is running at 50-60% speed to keep the pressure up and never goes into the idle mode.
Check the pump curve and calculate what the "deadhead"...
Obviously the debris is a major problem.
The VFD can cause problems if the motors are not capable of running with one. I'm not a VFD expert at all, but I do know there are plenty of electrical and mechanical problems (line harmonics, torsional excitation, localized heating, etc.) that can...
