Potential of extreme surge pressures.
Trapped Vapor Surge (2)
Potential for Extreme Surge Pressures – Scenario:
A long section of uphill piping is partially filled with vapor (bubble) and an upstream pump is started.
Pressure will start to compress the bubble of vapor and the upstream edge of the bubble will accelerate into the bubble until the pressure is equalized.
The momentum of the upstream fluid will cause the upstream bubble edge to continue to move and will decelerate until the momentum is expended.
Pressure continues to rise during deceleration, which can cause the pressure to magnify considerably.
The results could include extreme pipe movement on aboveground piping, Maximum Operating Pressure violation and possible line rupture.
Slack Line (2)
Determining slack line operation:
Convert your downstream suction or inlet pressure to feet of head
Determine desired flow rate and commodity
Calculate the head loss per distance (slope of operating grade line)
Draw a line from the downstream pressure / head back to the mile post of the upstream station maintaining the calculated slope.
If the line passes through the elevation line, move to the first upstream high point and continue drawing the line with the same slope back to the next elevation intercept or the station.
Slack line exists between any high point and the elevation intercept point.
A few added comments:
The *fluid is at its vapor pressure* in the slack region
The fluid in the slack region is flowing down the hill like a creek flowing down a hill (Open Channel Flow)
Hydraulic Gradient – Slack Line Conditions
Slackline
Liquid is in free-fall and is at approximately 0 psi (Open Channel Flow)
Pipe in slack line can be >70% empty of liquids

и хотелось бы обратиться к вменяемым доброхотам
отвечать на форуме --- это не вид спорта, где важно всех опередить
здесь всегда есть время подумать
в частности, о том, как аскер объяснит свой перевод, если дословно спишет, что ему тут насоветовали
например, аскер, мало знакомый с матчастью --- как этот