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Questions tagged [pressure]

Questions pertaining to pressurized systems and their applications, from containment to system losses to using as a benchmark for measurement.

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What's a good way to equalize pressure between 2 spaces without allowing gas exchange under normal circumstances?

I have a reaction chamber where gasses are injected to maintain a certain mixture. The container is sort of like a bell, where the bottom is submerged in water to make a seal. The issue I have is ...
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21 views

How to determine ideal flow path length for specified pressure drop

I have designed a flow resistance element and I would like to be able to keep the total pressure drop across the element to < 5.0 inches of water (from 5cc/min to 5,000 cc/min). I have run some ...
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Parts needed for controlling vacuum line pressure with pressurized nitrogen

I'm trying to assemble a simple setup where a line which is typically under vacuum can be pressurized by an external nitrogen supply, with this pressure regulated to less than 1 bar absolute (let's ...
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99 views

Is Scrooge's giant glass dome feasible in real life?

In an Uncle Scrooge (or Scrooge McDuck, not sure of the translation here) comic named "Treasure Under Glass", Scrooge orders a giant glass dome to be manufactured in order to aid his endeavours ...
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Unusual idea for fish tank design. Unsure if plausible or not

I looked through the stack exchange list of sites, hoping to find one more suitable for my question, but decided that this was the most likely place to get the answer I'm looking for. I'm not an ...
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Cylinder Pressure vs Crank Angle - How to read chart

Can anyone explain to me how to read a Cylinder Pressure vs Crank Angle chart? HE- blue line, CE - orange line, Ps Line - grey line, Pd Line - yellow line HESV -Head End Suction Valve HEDV - Head End ...
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22 views

Use of Absolute vs. Differential Pressure Transducers to Calculate Flow Through Annular Restriction

If using a laminar flow element, in conjunction with Poiseuille's equation, to calculate mass and volumetric flow rate, what would the benefit be to using two absolute pressure transducers to measure ...
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What pressure value to use for Poiseuille's equation?

If using a mass flow meter with a annular gap to produce laminar flow and the reading across the restriction is 871 Pa, is this the correct value to use for dP in the Poiseuille equation? Or must that ...
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45 views

Fluid Mechanic Buoyancy problem. How to determine the height?

I tried to solve it but I don't know how to bring the Area A in this equation. I used the area of the small vessel, but this one shouldn't be in the equation. Thanks a lot
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How to obtain the radial strength of a stent model in ABAQUS

I am simulating the crimping of a stent in ABAQUS/Standard using a 3D deformable cylinder on which I impose a displacement in order to crimp the stent from an initial diameter of 2.5 mm to a final 1 ...
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Create low velocity pressure drop?

I need to create a variable 3-7 psi / 0.2-0.5 bar in a low density gas running through some piping. I can calculate the required Cv factor to do this with a valve would be in the 30-200 range. Looking ...
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Pressure delivered to an object under a pneumatic press

I'm hoping some kind person can tell me if I have this right or not. I swear this isn't a homework problem. I'll be using a heated pneumatic press to heat seal lidding to plastic containers (...
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34 views

How to adjust power requirements for a propeller working against a pressure head

I'm in the process of building a hovercraft. In order to lift it, I'll need a motor directing the flow of air into a skirt. The specs for the motor I'm looking at say that it can turn a 15x5 dual-...
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1answer
27 views

Will the pressure inside a pressing mold will be constant if I'm working with a fluid inside?

I'm pressing glass and I want to know if the pressure that the walls of my mold feel is the same through all the internal surfaces. I'm willing to assume that glass will behave purely as a fluid (very ...
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78 views

A latch that’s easy to open under lateral pressure

My middle schooler is building a catapult that’s supposed to hurl a ping-pong ball 5 meters: The problem is that the pressure on the latch is so high that the kid just cannot trigger it: The door ...
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Hydraulic motor sizing

16 Examples of Tensile Strength has a list of items and their tensile strength. bamboo has these tensile strength ratings Bamboo MPA 350 PSI 50,763 If I needed to have a hydraulic motor to shred ...
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56 views

Manually Attempting Empirical Measurement of Flour Dough Compressive Strength

I want to make a DIY dough press, so need to know how much pressure I would need to apply. I don't have mechanical engg background, so based on some googling, I think this is what I need to do, but ...
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33 views

Issues creating a high pressure chamber for corrosive solution

I'm trying to do an experiment on high pressure's effect on the electrical impedance of a really corrosive solution. I'm aiming for at least 2,000 psi with a pressure chamber but the only material I ...
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1answer
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What is the difference in CFM, at a given static pressure, between a CPU fan and a Squirrel Cage Blower fan when moving air through ductwork?

I have a Delta ASB0912L DC Brushless fan. PDF here. In the datasheet it says, RPM 3800 CFM 67.80 IN H2O 0.302 On the blower, squirrel cage fan, Dayton from ...
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16 views

Head loss curves for PEX tubing?

Is there a reliable online reference for head losses of PEX tubing at various nominal sizes and flow rates?
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57 views

Strength of Plastic Underwater Domes with various thicknesses

I'm currently researching the strength of domes underwater and I went down the rabithole of material science. The basics of this research (or though experiment) is to bring a dome filled with air to ...
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33 views

Choosing a blower for a Pneumatic Conveyor

Basically we are designing a pneumatic conveyor system for transferring 11 tons of beans per hour. We need to decide on the specifications of the blower. What are the calculations necessary to decide ...
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52 views

Pneumatic cylinder: Pressure rating

I want to create a Pneumatic cylinder, The purpose is, Inside it will will contain a Nylon piston, and one end will be filled with clay. Cylinder will be closed from either side using end caps, which ...
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Breath Sensor: A low range pressure sensor that won't be affected by humidity

I am designing a device that will measure the force of a breath through a tube. A small differential pressure sensor like this https://www.digikey.ca/product-detail/en/MPX10DP/MPX10DP-ND/464046 would ...
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103 views

Why using average pressure in calculations gives the most accurate results?

In the saga of trying to answer the question that came into my mind while studying the basic concepts of Fluid Mechanics, "Why textbooks use geometric center to calculate hydrostatic pressure when ...
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What is this part called, and where could I get one?

I'm fairly illiterate when it comes to Engineering, so please understand I have pretty much 0 idea what I'm talking about. I'm having to build a seawater distillation device for school, and we ...
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132 views

Why textbooks use geometric center/centerline of the pipe when calculating/measuring pressure?

Studying Fluid Mechanics, I started to notice that almost every textbook/website uses a specific point to make calculations about the pressure in a liquid at a given depth (hydrostatic pressure): the ...
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1answer
71 views

Check valve with precise cracking pressure

I have two containers of air, one at 100 kPa and rising, the other at 30 kPa and decreasing. I need a valve that lets air through when the pressure difference is >70 kPa. Where would I find a valve ...
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64 views

pressure loss in a T fitting

For weeks I have been searching internet , but still unable to find answer , so here it goes: I have to calculate pressure losses in heating circuit , and am stuck at calculating losses in T fittings. ...
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1answer
36 views

Pressure rise in horizontal pipe

What causes the pressure change in a horizontal pipe with no energy input. Is it the head loss? If so, how?
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51 views

What pressure to take in surface tension question?

Pressure inside a water droplet is $0.32 N/cm^2$ if surface tension of liquid is $0.095 N/m$. We have to find the radius of the bubble since it's a water droplet the formula used is $$P_i-P_o=\frac{...
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141 views

Programming a gas mass flow controller rig

I'm trying to upgrade a multiple gas flow controller, which must be capable of controlling the mass flowrates of three gases independently through one outlet line to our system, and am in need of a ...
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How much pressure would I need to push water out of tank?

How much pressure would I need or, better yet, how do I compute for the pressure required to push water out of a submerged tank? Do I use 1 meter as head or 7 meters? (Please just bear with the ...
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Is it standard practice to use a pressure relief valve as a pressure regulator?

I'm attempting to understand the difference between a pressure relief valve and a pressure regulating valve. From my research far, I've come to the following conclusion: Pressure relief valves are ...
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46 views

Reduce and compute flow in self designed pen

I am currently designing a simple pen for drawing with different types of liquid varnishes. My current design has a tip at the bottom side of the pen (blue) and a tank at the top side where the ...
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How does placement of a pressure gauge in a tank of fluid affect the pressure readings?

This is not a real system but rather something I made up to understand how the placement of pressure gauge in a tank takes its readings. Here’s a diagram of it- The pressure gauge placed in the ...
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Why does the water pressure initially drop then stabilize when pressure testing a valve?

Sometimes the dropping goes on so long(10-15 minutes) that the test is thrown out and the valve is opened and filled with water for a longer period of time. Pressure testers claim that it is because ...
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Area ratio using Bernoulli's equation

I am using Bernoulli's equation in order to calculate a relative area between two points in a pipe. Problem is, based on the solution I have obtained, I end up with imaginary numbers and not sure what ...
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111 views

How an airlock works?

From wikipedia: Before opening either door, the air pressure of the airlock—the space between the doors—is equalized with that of the environment beyond the next door to open Anyone knows how this ...
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How to calculate change in pressure from LN2 state change (constant volume)

I am trying to calculate the increase in pressure caused by liquid nitrogen at the moment it changes from liquid to vapor within a closed, constant volume at atmospheric pressure. Do I need to include ...
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2 mm accuracy in an affordable water level sensor (pressure transducer) - Does one exist? [closed]

I'm looking to conduct water level monitoring in streams and rivers for water resource engineering purposes. My plan is to use Arduinos and Raspberry Pis in conjunction with a pressure transducer, as ...
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How to analytically estimate the pressure loss through an liquid injector?

The simple orifice and a pipe have well-documented pressure loss calculation. But when an injector has complicated flow patterns, is it possible to break it down into simpler sections by which the ...
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2answers
64 views

What happens when pumps are blocked off?

What will be the result if the pipe losses is greater than head produced by the pump? What will be the result if outlet is closed?
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250 views

Do flexible water hose cause pressure drop with constant flow?

My dad has a tub by a lake. He has a water pump in the lake to pump up water into a tub. He claims that if he use a flexible hose, the pressure in the hose at the top will be lower than if he use a ...
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What kind of pressure switch can I use for pressures up to 5-10 tons/cm^2?

I need a pressure switch for an electric circuit that has to be closed once a piston is compressing at a pressure of (approximately as we haven't specified how much force we have to use, and maybe it ...
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24 views

Overcoming gravity with fluid pressure

How would I determine if an upward flow of liquid at 100 bar forces a bed of porous solid upwards or flows through without affecting the same bed of material? Is it related to bulk density and pores?
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How does a Vibratory Pump (“Schwingankerpumpe”) work?

in my aquarium Ive got a little pump for bubbling air through the water so it is substained with enough oxygen. Internaly the pump works fairly similar to old door bells, where the mains is flowing ...
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Difficult Toy Ball Analysis

Note, as I have my degree in chemistry, I denote "=>" as the next step in the equation. Also, sorry for any obvious mistakes that I made - as I mentioned, my degree is not in engineering. Thanks! I ...
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multiple wall, pressurized gas pressure vessel

I was thinking about interesting powder metallurgy method, hot isostatic pressing. Often thick steel walled vessel is required increasing costs and decreasing the prevalence of this technology. This ...
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38 views

Calculate or approximate force required to expand a thin-walled elastic cylinder held rigidly at both ends?

How might one calculate or approximate the negative pressure applied to the outer surface of a cylinder required to expand it a certain distance, when held open rigidly at each end? The cylinder ID = ...