# 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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### Pressure gauge on flow test pipe reading zero, why?

I'm trying to determine the cv values for water of a collection of 90-degree 4-inch elbow valves, and one of the things I need to determine this for a particular flow rate is the input and output ...
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### How Can I Seal a Sensor into a Cylindrical Tank?

I am trying to seal a dissolved CO2 sensor (From Oxyguard) and a dissolved O2 sensor into a cylindrical tank with a PVC cap. I have a few constraints. The tank will need to be pressurized so I need to ...
1 vote
20 views

### Static pressure calculations for laser fume extration

I'm trying to estimate the static pressure (SP) of a exhaust system for a laser cutter in order to select an appropriate exhaust fan. From what I've read so far (https://www.centralblower.com/Pdf/...
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### How does this water canon function?

While idly watching shorts, I came across this one. And after watching it a hundred times, I still don't understand how the water canon functions. I mean, where is the pressure coming from? The design ...
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### Palm tree misting system to kill beetle pest "rhino beetle"

In Hawaii we are having a huge issue with this pest called a "rhino beetle" These beetles eat the heart of palms, eventually killing the palm completely. Soon Hawaii will have little or no ...
1 vote
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### Conductive Materials

When one measures the resistance of a highly conductive material, like graphite (I am not sure how conductive it is actually - in comparison to other conductive materials); would it matter what is the ...
1 vote
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### Wind Pressure on Chimney

I have this question that I am trying to solve. I will explain problem as best as I can. A brick chimney has parallel sides and a height of 18m. It has a square sectional plan with dimensions of 2....
88 views

### Twisting of thick ring due to internal pressure

I have an axisymmetrical part that is subject to an internal (non-constant along the inner border, but constant in time) pressure (among other loads, but this is the one I am interested about) and I ...
75 views

### Pressure drop in air flowing through an array of tubes

I have a pipe with ID=75 mm interrupted with an array of N=121 tubes (as shown in the drawing), forcing the air to flow inside the tubes (ID of each tube is 2mm) spaced apart by 5mm. Length of tubes ...
26 views

### Restrictor Nozzle Back Pressure

Using a flow restriction to create backpressure. The back pressure is very important as it is used to drive a piston. What nozzle/flow restrictor shape will create the highest pressure drop/back ...
81 views

### Does it matter where a reduction happens in a fluid system to the amount of back pressure at the source?

I currently have an exhaust hood that produces a lot of back draft due to limitations of the ducting and a 4" diameter exhaust. The hood has a 7" circular output. It uses a reducer ...
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### Fuel cell power output

I've spent innumerable time over the years looking for commercially available hydrogen / oxygen fuel cells that might actually be usable in one project concept or another. The best I've ever managed ...
14 views

### How to handle air pressure circuit with very different setpoint values

I'm a hw/sw guy, with a very limited knowledge about pressure/pneumatic circuits. For my new job I have to design a closed-loop controller to inflate and maintain two chambers with a given pressure. ...
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### Are there pressure vessels with hand inserts?

I'd like to work with some bike-tire parts while at moderate pressure (60 psi), so I'm hoping to use a pressure vessel, but it has to be transparent and have inserts so I can use my hands to ...
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### Can the volume of fluid flow affect a strain gauge's measurement accuracy?

I have two machines for testing solenoids, one new and one old. When a bypass is connected to both hoses (the input hose is connected to the output hose), I get ~1:1 for the input output pressure; the ...
70 views

### Will a lid hovering above bursting air bubbles catch smog particles

The bubble bursting phenomenon goes like the above describes: At 1, the air bubble is under water. At 2, the bubble emerges above the surface, with a thin film of water rising to keep it from bursting....
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518 views

### How can I calculate the pressure in a pipe?

I am an engineering student designing a pipe system for a fluid flow and I calculated everything including the pressure loss. Now I have to choose a pipe material and pipe thickness for the piping ...
36 views

### Air flow rate through thin pipe from a tank

I would like to study the air pressure in a rigid box. One side of the box can be moved like a piston, so I can change its volume, which results in pressure change inside the box. Morover I installed ...
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### Pump Head Requirement in dividing flow

I'll preface this by saying that I'm looking for kind of a simple answer, and will be providing almost all the initial conditions that I'm aware of. I have a single pump, which is to provide 80 m³/h. ...
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### What pressure sensor and how should it be installed on to the medical ventilator to get the pressure flow graph?

I'm currently building a project named camshaft mechanism medical ventilator. One of the objective of my project is to get the pressure flow graph from my user. I succesfully build my camshaft. ...
1 vote
41 views

### Why carbon water filter can build air pressure inside (before installation)?

Today I got a new refrigerator carbon water filter (this). Before installing, out of curiosity, I dripped a bit tap water into the filter’s outlet to see if water could flow in and out. Obviously it ...
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### How can I make sure that my outflow is the same as my inflow?

I have a basin that is 110 mm wide, 200 mm long, and 15 mm deep. The walls are 2 mm thick. It has water being pumped into it at a rate of 0.1078 gpm from one side. In order to ensure that this pan ...
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51 views

### Calculate heart valve flow rates over time. What formulas are involed?

I'm trying to program a simulation of a human heart which I want to produce results close to the following: (Source: https://en.wikipedia.org/wiki/Cardiac_cycle#/media/File:Wiggers_Diagram_2.svg) For ...
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257 views

### Measuring Pressure of a Press Machine

I am designing a heat press and need pressure feedback of the force or pressure being applied to the product. I need to measure the pressure between to press plates on a hydraulic press. I would like ...
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1 vote
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### Darcy-Weisbach: Static or Total Pressure?

Does the Darcy-Weisbach equation give the change in static pressure or does it give the change in total pressure (static plus dynamic)? I’m assuming here that the static pressure includes the ...
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### How to design a pressure regulator test?

We're designing a pressure regulator test. It is taking an input from an N2 tank at 300 bars, output pressure should be around 70 bars. We are thinking of using 2 pressure transducers, a solenoid to ...
700 views

### Calculating Pressure Loss (K Value) of Pipe Bends at varying Angles

I am analyzing the total pressure loss of a run of pipe that has several pipe bends at varying angles (30, 60, 45, 90, etc. degrees). Reading through CRANE: Flow of Fluids Through Valves, Fittings, ...
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1 vote
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### Hertz contact pressure formula for cone on a plane

Can anyone please point me to some literature that contains formula for Hertz contact pressure for conical body on a plane? I know that there are general solutions that probably cover also this, but I'...
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### Backpressure vs Pressure Drop

We were asked by a customer to calculate the backpressure of an exhaust system we were supplying a muffler for. The system includes piping from the engine to our muffler, then from the muffler to the ...
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1 vote
2k views

### Do I need a pressure relief/safety valve if my pump can't exceed the rated system pressure?

I am designing a resin dosing & mixing room for a production plant. This will use pneumatic diaphragm pumps to pump the resin & additives, flow meters to measure the dose, and pneumatic ball ...
22 views

### Cuboid pressured container - will the pressure reach the shear pressure of the material?

I'm having a go at designing a water electrolyser for producing hydrogen. I would like to store the hydrogen with minimal compression effort. Up until the past week I have been thinking about using a ...
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1 vote
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### How can I determine the size of holes along a pipe so that the flow rate is equal out of each hole?

Suppose I have a pipe with holes on its top (kind of like a flute, but with different sized holes). One end of the pipe is open and the other is closed. The pipe is submerged in water horizontally, ...
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### Piston Compressed Pneumatic Cannon

During an discussion with friends regarding pneumatic cannons, I came up with this gem :). Piston power pneumatic cannon. My friends however, didn't share my excitement regarding this revolution in ...
87 views

### How to get a wire from the inside to the outside of a pressure vessel?

Imagine you have a pressure vessel, e.g., the hull of a deep sea submersible. A good one would be a sphere of inches thick metal. But how could I wire the inside to a component on the outside? If I ...
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### Fluid Mechanics about Hydrostatic Pressure

The rectangular gate will open authomatically, when the depth of water becomes very large. What is the minimum value of d that will cause the gate to just open? The width of the gate is 2 m.
1 vote
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### What happens when running a piston pump below minimum air drive?

My question is what happens when you give an air driven liquid piston pump less air drive pressure then the minimum recommended. I have a pump that says its minimum drive pressure is 25psi. What would ...
367 views

### Can a fluid have more or less static pressure than atmospheric pressure in atmosphere?

We assume static pressure of a fluid coming out of a pipe or nozzle of gas turbine with high temperature and velocity is equal to atmospheric pressure, which confuses me for some point. Does it mean ...
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### Value of the manometric pressure

I need to know the pressure acting on the left side of the surface in this picture. And the answer is that $p_{M0} = \rho*g*h$ and the $\rho$ in that equation is equal to the $\rho$ of the fluid on ...
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### Why are the water tank walls made of stretch film warping a lot whereas theoretically they shouldn't that much?

I am building a water tank of custom dimensions (1.5 m x 0.72 m x 0.86 m) out of stretch film. The stretch film is wrapped around a steel frame (see here for more info on this open source project). I ...
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### Pressure drop across orifice plate

I have been trying to estimate pressure loss caused by an orifice plate. The fluid flowing through it would be water. I found equations for discharge efficient and pressure loss coefficient K from ISO ...
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### Why did pressure decrease above the piston?

I can understand the pressure increase below,but why did pressure decrease above as more bricks were added? Image source: https://www.youtube.com/watch?v=4REdJIW6-Kg
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### What pressure do objects at exhaust of pipes feel from flowing fluid? Dynamic or Total?

Let's imagine that we have one fluid source separated somewhere in two pipes of R1 and R2, and we put one object at exhaust of R1 pipe and one more object at exhaust of R2 pipe (R1 > R2). Let's ...
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### Does a disk placed in a pipe perpendicular to flow direction of fluid feel dynamic pressure or total pressure?

There are two discs in the pipe but not at the same time. You can consider conditions with X but without Y, then with Y and without X. I am pretty sure that disc X will feel less force from fluid than ...
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### Steel expanding in a tight space

Hypothetical question: What would happen if I were to cool down a steel cylinder to make it contract, and then slide it all the way into a cylindrical hole in a room-temperature solid steel box? The ...
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### What is the most appropriate set-up to pressurize air in a closed, confined space?

Assume that we have hot air in a confined closed space of 36 m^3. This hot air will be distributed trough a piping network of 500 m to be blown on trees. What is the most appropriate set-up to ...
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### Pumping machine (Centrifugal ) fails to pump

I have a centrifugal pumping machine that fails to pump up consistently. When powdered on, it spills up water, then stops and continues intermittently like that without a consistent flow of water out. ...
167 views

### How to calculate the required power to pump out (to vacuum) a container?

Consider I have a cubic container with its volume is 1m cubic as in the simple picture above. It is sealed nicely, it is air proof, no air leaking. I would like to pump out (to vacuum) the container ...
35 views

### Why would the compressor provide more pressure than necessary? Isn't the pressure determined by the resistance?

I clearly misunderstood something