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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8
votes
4answers
6k views

Would engineering bricks explode if used to build an oven?

I'm building a pizza oven and, to do so, I bought a whole load of engineering bricks (not these but similar). They've got five holes vertically through them, each hole is 2x6x6.5 cm (80 ml) and the ...
3
votes
2answers
211 views

Water pressure divider

Let's suppose I have a water jet as source, and this jet goes through a tube and is equally divided into 4 tubes. Is there a way to control the flow/pressure at each of those tubes separately by ...
7
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1answer
2k views

What is this pressure gauge on the London Underground measuring?

I noticed this pressure gauge on the Piccadilly Line of London Underground yesterday. It was located on the side of a row of seats. Close-up of the gauge at hand: click for larger version of image ...
4
votes
2answers
3k views

Solenoid valve pressure drop

I'm designing a solenoid valve for an automated irrigation project that I'm working on. After having looked at some designs, I have a question. For most of the designs I've seen, the orifice is ...
5
votes
1answer
189 views

Minimising permeation rate of hydraulic fluid through hydraulic hose

I am designing an experiment where the hydraulic hose is going to be subjected to relatively high internal pressure for prolonged period of time and it is absolutely imperative that the rate of ...
5
votes
1answer
9k views

Why is my Venturi pump much weaker than expected?

I'm trying to make a simple Venturi tee which will have air flow through it while sucking some water from down below (like paint sprayers do). I want the device to pull the water to a height of 1 ...
3
votes
1answer
146 views

Hydrocyclone effectiveness vs. absolute pressure

Some sources say that higher pressure in hydrocyclones implies better performance it leads to a finer filtration. But why? Is it because water is almost incompressible and the particles can be ...
5
votes
1answer
413 views

Are there any precedent designs for a mechanically-delayed pressure release valve?

I need to release pressure of around 50psi, after 3-4 seconds of initiating, from a vessel using a mechanical switch. I had considered a pneumatic solenoid, but I want to forgo the inconvenience of ...
5
votes
2answers
126 views

Recoil of hydraulic lift/elevator

I noticed that when a group of people enter in an hydraulic lift/elevator often when the last person steps in the lift/elevator has a small but noticeable recoil: the lift goes down a few mm then it ...
4
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2answers
1k views

How do I calculate the weight needed on a press board to deliver a certain amount of pressure?

I'm building a press for cider. I'm going to be using a 24" x 24" press board. I'm looking to deliver 40 psi to the cider. How can I determine the amount of weight required, in tons? What sort of ...
5
votes
2answers
679 views

Gigapascal pressures in a small package

How small/compact can a pump or other mechanism be, that would allow compressing gas (or liquid) to pressures of excess of 10GPa, continuously? Throughput may be minuscule, of order of milligrams per ...
3
votes
2answers
306 views

How to design a hemispheric flexible pressure vessel?

Consider a balloon, it is a flexible, expanding pressure vessel made of synthetic rubber. I am trying to design a system that will use hemispheric pockets of neoprene to grip an object, much like the ...
6
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4answers
3k views

Is a circle the strongest 2D shape for containing internal pressure?

I understand how a circle (or sphere if you want 3D) is the best shape for holding a vacuum inside a container, but what if you wanted to have a large positive pressure inside of the container instead ...
14
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7answers
10k views

Why is air pressure in all directions?

Here is a typical definition of air pressure: Air pressure is caused by the weight of the air molecules above. Even tiny air molecules have some weight, and the huge numbers of air molecules that ...
3
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3answers
7k views

CFM in relation to Static Pressure

My background is more Chemistry and Biology, not Physics, or specifically engineering with fluid dynamics, so bear with me! Also, this is a little long, so I will do my best to make it easy to follow. ...
5
votes
1answer
191 views

Determine elevation from the difference in air pressure

Given: A problem in my thermodynamics text reads as follows... The barometer of a mountain hiker reads $13.8$ $psia$ at the beginning of a hiking trip and $12.6$ $psia$ at the end. Neglecting the ...
1
vote
1answer
149 views

Determine abs pressure in a tank where the atm and vac pressures are given

Given: A problem in my thermodynamics text reads as follows... A vacuum gauge connected to a tank reads $5.4\cdot psi$ at a location where the barometric reading $P_{Hg}= 28.5\cdot in$. Determine ...
2
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1answer
3k views

Mass and weight of air in a room

Given: A problem in my thermodynamics text is stated as follows... Determine the mass and the weight of the air contained in a room whose dimensions are $V=$ $15ft$ x $20ft$ x $20ft$. Assume the ...
0
votes
1answer
187 views

Px26-015 pressure sensors output

I had a PC Mountable Wet/Wet Differential Pressure Sensor I used it to measure a pressure difference , I don't know how to convert its output to pressure !
6
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4answers
972 views

Is it possible to fire a ball of water that holds its shape?

Background I participate every year in a huge water balloon battle. The clash happens between two universities so you can imagine that the commitment, at least for some people, is quite high. To give ...
2
votes
1answer
377 views

Dead weight pressure tester for very low positive pressures

Does the dead weight tester technology provide capability for an accurate, low pressure calibration standard in the range of zero to 150 cm H2O, and if so is there a manufacturer that provides such an ...
9
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3answers
3k views

How to seal a pressure vessel

I'm trying to construct a stainless steel high pressure containment vessel (pressure reactor) (2000 psi or so). Yes I realize that this is a don't try this at home type of thing, and I plan to put ...
4
votes
1answer
1k views

Tankless air compressor for electronics desoldering station

I purchased a Weller WSD161V soldering station (similar to this one, at least with regards to the pneumatic system I'm about to describe -- sorry, I was unable to find a manual for my specific model ...
4
votes
2answers
256 views

Ensuring even flow in liquid pumping in distribution circuit under suction

I have a liquid circuit which looks a bit like that: The system is under suction, and the flow rate through each unit should be about 10ml/min. However, we noticed that unit ...
5
votes
2answers
180 views

For a small valve in a fluid system, what is the relationship between pressure and flow rate?

The specific example I have in mind is a car tire with a small leak in it. As the pressure increases, does the outflow of air increase linearly, i.e. $v\propto P$, or does it have some more ...
6
votes
2answers
1k views

How to equalise the water distribution in a leaky pipe irrigation system?

I have a 200 litre water butt and plenty of 22 mm plumbing pipe and fittings and I want to build an irrigation system for my vegetable patch so that I can open the tap after a few dry days and ensure ...
12
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5answers
5k views

What is the difference between pressure and stress?

Since the units are the same ($\frac{N}{m^2}$), what's the difference between pressure and stress?
20
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1answer
444 views

Sizing a pressure safety valve for two-phase flow

I understand that valves in two-phase vapour / liquid were sometimes sized by considering the required vapour and liquid flow rates separately, and then adding the results together. But this is now ...
9
votes
2answers
7k views

How to calculate the pressure a pipe can withstand?

I was looking at high pressure pipes and their pressure ratings. I'd like to know how these pressure ratings are determined. I assume that pipes are tested until failure, and the failure pressure is ...
7
votes
1answer
116 views

Multi-gas barometric height formula in isotope separation devices?

What is the barometric height formula for a mixture of gases? The main problem I can see, the curves describing the minimal energy (kinetic + gravitational/centrifugal) won't be any more a simple ...

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