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You did not mention the length of the suction line. You might want to google "acceleration head".

Check the surface finish of the pump internals. Low flow/high head pumps such as Sunflo/Sundyne and other pumps with straight vane impellers will definitely draw high current even at lower than design flow if there are issues with the surface finish.

That is an excellent, thorough reply. Star for you.

If you go with some bellows device such as the one shown in your picture, I would specify it to be lined to minimize pressure drop.

Issues with threaded connections include the reduction of pipe wall thickness caused by the cut threads. To mitigate this issue, our specs call for the threaded piece of pipe to be xxs or Sch. 160. Look at some of your other pumps and I expect you'll see tubing connections to seal glands made...

As stated, it is unlikely that pipe strain would show up at the crank coupling. If it did, I believe the pipe misalignment would certainly be easily visible before being made up. Take the advice and focus on piping alignment. For small vent and drain connections a visual check will do. For...

It makes the effective area of the opening larger. This regains some of the area of the opening lost caused by the bars.

I agree that threaded connections can be problematic and should be avoided if possible except for utility piping. Having said that, allowing zero threaded connections doesn't seem feasible. How do you make a tubing to pipe connection or pipe to pump seal gland connection? Part of the problem...

A little off topic here...As I look at the data sheet, I would be concerned with a 150# suction flange. He may have RV protection on the suction side but I'm used to seeing the discharge flange rating carried back to and including the suction block valve.

Excessive high speed shaft bearing clearance can cause low lube oil pressure. This is usually a sleeve bearing where the input and intermediate shaft bearings are ball bearings. The difference between cold oil pressure and operating temp pressure would explain the drop in pressures due to lower...

Some thoughts on pump casing drains for pumps handling hydrocarbons or other chemicals. Process operators both love and hate casing drains. While insuring complete pump drainage and increased prepping flexibility, they are also potential leak points and could be additional fugitive emissions...

In my opinion, the spec relates to having all of the equipment mounting surfaces parallel and less to do with absolute levelness. Having said that, I would accept a baseplate the was .005/foot (or more on smaller utility pumps) out of absolute level as long as the equipment mounting surfaces...

I have seen problems pumping butene with a low efficiency pump. Wonder what the heat rise is across the pump?

I would consider grinding out,welding with minimum heat input, and machining back to proper dimensions. Thrust loads should be relatively small...that's why it has a simple radial ball bearing as a thrust bearing.

Regarding metering accuracy... While I have no experience with the specific pump mentioned, my experience with other metering pumps is that a consistent minimum back-pressure is required for metering accuracy. At least one manufacturer recommends a minimum of 25psig. This can be supplied by a...

While I have used all of the mentioned methods, radial setscrews are my preference. A small weld bead at three places around the face of the ring is fast and easy but many times the ring metallurgy and ring material hardening can lead to poor quality or cracked welds. I've also seen rings plug...

Any possibility that these are reducing flanges?

Be aware of where the system curve intersects the 2 pump operation curve. If this intersection is in a "flat" section of the composite curve, the parallel pump operation could be very sensitive and/or unpredictable.

My "rule of thumb" is no cast iron in any hydrocarbon service regardless of temperature. At -30C, I would not use ductile iron. Go with steel.

Don't forget about the potential for overspeeding the turbine(pump). Seen this happen a couple of times when the clutch failed.