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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65 views

Why was the challenger deep so small?

According to James Cameron, the submarine barely had any space for him to move around etc., and as he approached the bottom of the Mariana Trench, the submarine shrieked down by a few inches (due to ...
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717 views

Why did the Plexiglass on the Bathyscaphe Trieste crack?

After passing 9,000 metres (30,000 ft), one of the outer Plexiglas window panes cracked, shaking the entire vessel. (Wikipedia) Why did the first layer of plexiglass Window panes crack on the ...
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2k views

Pipe diameter, Flow Rate, Pressure & Velocity for water

I am hoping for some help with calculating the size of pipe for a given length. The system design is a 10000L supply fills a 5 tonne water tank that then feeds a variable speed pump. The pump sends ...
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6k views

Retaining Wall: Saturated Soil & Hydrostatic Pressure

I understand that Hydrostatic pressure and Soil pressure exist concurrently. I'm curious how these separate loads interact with each other. Full disclaimer: I am not an engineer nor do I pretend to ...
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1answer
4k views

Can PWM be used to control the flow of a solenoid valve?

Most cheap pump can achieve, according to the Amazon page, around 5 PSI and I would need something a way higher that can still be controlled. I have this solenoid valve. Can I use pulse-width ...
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29 views

Compression and check valves

Pressure pumps are used to apply pressure to a system. What would happen if someone attempted to fill, for example, a bicycle tire (with a check valve) to 2 ATM of pressure using a pressure pump that ...
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43 views

How to convert ton force to pound force, manual pellet press

I'm looking into manual pellet presses and the one in mind lists a 12T clamping force and then goes on to detail that the analogue gauge goes from 0- 24,000 lbs. Are these two numbers related? When I ...
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1answer
89 views

How do you get a closed vessel to >90,000 psi internal pressure

Im trying to build a cold isostatic press with a internal vessel area of 300mm3. A cold isostatic press forms green metal components using pressures greater than 90,000 psi. Using an oil or water/...
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1answer
129 views

Equivalent Force: Hydraulic rams in H frame machine press

A 100ton H frame machine press can use 1x100 ton ram to exert this amount of force. Can 3x33 ton rams do the same job if they are applied to same area as the 100ton ram? Also in relation to a H ...
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4answers
194 views

How to quickly equalize pressure in a low pressure container?

Background: This is for a science project I'm creating where I use an airpump connected to a sealed 5gal pail bucket to create a vacuum. That vacuum is then connected to water source to "suck" liquid ...
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37 views

Triple point storage in space travel

Watching Apollo 13 and rereading Lost Moon, Jim Lovell's exciting recollection of the events on the crippled spaceship, I began to wonder. Why does NASA maintain the gasses at the triple point? A ...
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Is a metal Prince Rupert's drop possible?

Can a Prince Rupert's drop be made of metal instead of glass?
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385 views

Tubing for explosive gas or hydrogen transfer

Recently, I heard that there is a law/ OSHA/ ASME piece of regulation dictating that hydrogen should be transferred (suppose from a tank of hydrogen to another location) by using specially approved ...
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2k views

Liquid vs. gas check valves

Suppose that I want to transport gases in a tube in only one direction. Can a liquid check valve be used in place of a gas check valve or is there a specific reason to use only a gas check valve?
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Toy ball check valve functionality and details

In the making of an inflatable toy ball (think of a basketball), a check valve is used to assist the user in the inflation of the ball by preventing backflow of inserted air. Is this check valve made ...
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1answer
241 views

Burst pressure of a sphere

Is there a formula for the burst working pressure of a spherical pressure vessel that takes into account its material peoperties? It should be noted that this is not a concentric sphere design (it has ...
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1answer
328 views

Measurement of static pressure

What is the logic behind using a wall tap/piezometer to measure the static pressure. Is it that near the walls, the fluid velocity is zero, because of the no slip condition and hence the pressure ...
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2answers
385 views

How to measure the air pressure of a pipe without having water resistant sensor

I'm having a question regarding the sensors and the techniques in fluid mechanics. Since my skills are amazing in this field, here I'm asking you questions xD I want to measure the air pressure of ...
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1answer
127 views

How to find properties of supercritical CO2 as a working fluid in a system

I'm working on a process flow currently and am using carbon dioxide as the working fluid because of its heat properties and because it's an inert gas. In the reactor that I am designing I'm looking to ...
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240 views

Pressure distribution on an inclined plate

I'm attempting a fluid mechanics questions that requires me to sketch a pressure distribution along the surface of the plate and explain why it shaped the way it is. I'm struggling to comprehend how ...
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39 views

Measuring vessel pressure scenario

I need someone to confirm or deny my understanding in the following situation. I have an empty vessel that is in equilibrium with the atmosphere and I have a pressure gauge on the vessel that ...
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1answer
42 views

I need clarification on how pressure is measured

I have a vessel that has a pressure measuring device. The value it shows as the pressure inside the vessel is 6 inches of water column. Is inches of water column meant to always be used as gauge ...
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1answer
39 views

Pressure sensors - gauge vs unidirectional differential

A gauge pressure sensor measures a pressure at a port against ambient pressure. A unidirectional differential pressure sensor measures a pressure at a "high" port against a "low" port. Is a gauge ...
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0answers
26 views

Hugoniot Equations and Impact Pressure

I have a wave propagation question that regards two materials impacting each other. The question asks to find the impact pressure of the impact with a tungsten carbide flyer and a steel target. I ...
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2answers
158 views

How can I build and maintain an accurate pressure on a fuel line without using a fuel pump?

Background I am building an engine from scratch for the sole purpose of becoming a better mechanical engineer--I'm currently a second year undergrad. The engine I'm designing is a single piston 4-...
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Calculating discharge on the pipe diameter and the pressure?

Is it possible to сalculate discharge / flow rate on the pipe diameter and the pressure (for constant pressure)? For example: Pressure_internal = 5 bar, ...
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1answer
109 views

Boiling Point, Pressure and Distillation

I have a line in my text that states the following: "For systems with low boiling points (e.g. Ethane-Ethylene, propane-propylene etc.), high pressures are used so the vapour leaving the column at ...
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1answer
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Why was Freon used in spray cans before it was declared a threat to ozone?

I've heard that in the past, spray cans (aerosol cans) contained Freon. I found that the Montreal Protocol made the usage of Freon illegal due to its effect on the ozone layer, but I can't find the ...
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41 views

Stable liquid pressure [closed]

How to obtain a constant pressure by a mini water pump to 9 bar? Ex given a common engine for the aquarium, how to obtain at the output a pressure that is stable to 9 or 10 bar?
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102 views

Where is the contact point between screw spindle teeth and nut teeth?

So this is a screw press used to hmm disconnect the clamp connection (sorry if these are not the correct terms I really don't know how to translate it properly). Anyway, I think it's obvious what this ...
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584 views

Why is high stagnation pressure important for propulsion?

In my propulsion notes I always see mention of the importance of minimizing stagnation pressure loss across the inlet shock of a ramjet/turbojet/turbofan. Could anyone explain further why this is the ...
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47 views

Long-term storage of a gas?

Can this formula be used to evaluate the minimum thickness of a spherical pressure vessel that holds hydrogen gas at 10 ATM for a long time? $$\sigma = \dfrac{p r}{2 t}$$ I was told, "As long as you ...
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91 views

Units to use in this formula?

Should standard SI units be used in this formula or are other units supposed to be used for the formula for stress in a thin-walled spherical pressure vessel? $$\sigma_{yield}=\frac{P_g r_i}{2t}$$ ...
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64 views

Safety factor for pressurized container at 10 ATM

There is no secondary containment to hold any potential shrapnel. How would this change the safety factor that is standard at 2.5? The consequences of this container exploding would be quite extreme ...
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2answers
346 views

Measure stress of gas acting on a spherical container

How can I measure stress in a thin- walled sphere containing a gas? Is there a way to predict what the stress will be without actually needing to fill a sphere with gas? I am talking about hoop stress/...
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1answer
2k views

Why can soda bottles withstand so much pressure?

Is it due to the PET material that it is made of or is it more the shape and structure of the bottle? If it is due to the shape/structure of the container, is it possible to achieve such pressure ...
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381 views

Automatic siphon above max height

The soil in my area has a very thick clay content (apparently left behind by glaciers, damn ice age). Because of this drainage in my yard is horrible. I've put in some underground drainage (french ...
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1answer
40 views

Are “Imperial Eastman” compression connections sized the same as regular imperial connections?

I have some high pressure and vacuum lines off of a tool from the 1980s and they are labeled as, for example, "3/8 imperial - eastman," which seems to be different from how normal compression ...
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206 views

Can mercury escape undectectably from a CFL bulb? or does it have to shatter for the mercury to be liberated?

I read that the mercury vapour inside a fluorescent lamp is pressurized at 0.2% of atmospheric pressure. Can mercury escape undectably through a small crack in the glass yet still light up? Or will ...
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1answer
103 views

Helium is leaking through manometer

I have connected a 200 bar helium tank and a manometer to a pressure regulator. The end of the manometer's tube connected to the regulator is leaking. It's attached with anaerobic thread sealant, so I ...
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1answer
32 views

Can I inject plastic in a RTV mould?

Can I inject plastic in a RTV mould? Will the interior of the mould get deformed by pressure?
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54 views

Piezoelectric Pressure Gauge [closed]

I would like to know how the pressure of a blast is measured when using a piezoelectric gauge as well as if this is the best way to measure the reflective wave from an explosion. In better terms I ...
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1answer
41 views

Force and Headloss Calculations for Three Stage Condenser

I am looking for some guidance on calculations for a natural condenser project. I am a Computer Engineering student, so this stuff is out of my range. The fundamental question I am trying to answer ...
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2answers
449 views

How to get remove water from a submarine that is submerged

How can water be removed from a submarine that is submerged? If a submarine is opened, while it is submerged, water would get in because of the difference between the pressures. For example, I have ...
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1answer
3k views

Relationship between output mechanical power and max pressure for a pump?

If an air pump needs to able to generate a particular pressure at a particular flow rate. How do we size the electrical motor for this particular scenario? The electric motor would be coupled to the ...
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357 views

Why is there negative static pressure in contour?

I studied a paper about turbine and i seen that there is negative static pressure in contour. Why does this happen? Wave Energy Harvesting Turbine: Performance Enhancement
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Alternatives to shimming valve springs

Generally, in a pressure drop control valve that uses a piston and a spring (for example, in jet engines to control fuel flow), there is always potential for error in terms of the height of the spring....
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206 views

How do I find the impact pressure of cavitation due to implosion of a super critical fluid bubble?

I have solved the Rayleigh-Plesset equation for a time varying bubble of a super critical fluid. I am trying to find if the impact pressure caused by SCF bubbles is lesser as compared to that caused ...
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326 views

Some questions about liquid nitrogen cooling [closed]

I am currently tinkering with a railgun experiment, and I was thinking of using a liquid nitrogen loop to cool the rails down to very low resistance, and inject some nitrogen into the barrel between ...
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When beverage can stay-on tabs are lifted do they depressurise the can by lifting the rivet?

I understand that the inside of a carbonated aluminium beverage can is pressurised. When the tab is pulled up,a rivet is lifted. Does this cause the can to depressurise? So then the can can be pierced ...