Check That Water and Oil

Feb 26
2017

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing the pressure in water and oil.

Check That Water and Oil

And don’t forget to check the tire pressure, too. A little over 50 years ago these were commonly used in the predecessors to today’s gas stations – service stations. In addition to pumping gas, the service station attendant would perform routine but often mandatory measurements. In those days, the reliability of vehicles would frequently require adding water, oil and air. Vehicle reliability has improved significantly since then. With today’s rugged and affordable sensors for pressure and other parameters, these and other measurements are performed continuously – the vehicle provides the service of monitoring itself for the driver and mechanics.

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Source: https://www.pinterest.com/pin/147774431494414724/

Common pressure sensor measurements in modern vehicles include engine oil pressure, tire pressure, side airbag pressure in crash detection systems, manifold absolute pressure, barometric pressure, seat occupancy pressure and more.

 What do you think/Comments?
Do you have a pressure sensing question? Let me know and we’ll address it in an upcoming blog.
– info@allsensors.com

Atomization Pressure

Jan 31
2017

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing the pressure in washing machines.

Atomization Pressure

Pressure applied to a liquid flowing through an orifice produces atomization. Factors affecting the atomized droplets or particles’ size include surface tension, viscosity and density of the fluid. With increased fluid pressure, the particle size will increase. Two common applications of atomization are atomizing spray guns and spray drying.

The pressure feed system for Air Atomizing Spray Guns consists of a pressure feed spray gun, a pressure feed tank (cup or pump), an air filter/regulator, air and fluid hoses and an air compressor. Three pressure reading are made in the process. Critical steps in the set-up include setting the fluid pressure on the fluid regulator between 5 to 10 psi and setting the air atomization pressure on the air regulator between 30-35 psi. The atomization pressure is increased in 3 to 5 psi increments until particle size and finish texture are acceptable.

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Pressure readings in an atomizing spray gun. (Source: Parex USA.)

In a spray drying process, a spray is created by forcing the fluid through an orifice.  A spray dryer feed pump provides the energy required to overcome the pressure drop. In contrast to spray painting, while the spray drying pressure depends on feed characteristics and desired particle size, it can range from 300 to 3,000 psig.

 What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
- Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)

Sensing Pressure in Washing Machines

Oct 13
2016

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing the pressure in washing machines.

Sensing Pressure in Washing Machines

Initially, timing was used to estimate the amount of water for various washing machine cleaning cycles. Today, many manufacturers sense the pressure developed in an air dome that is referenced to the water level and provides a much more accurate measurement. The air pressure level is measured either by a pressure switch or a pressure sensor with air providing isolation from the long term effects of operating a diaphragm in direct contact with water and other contamination.

The pressure switch can close and/or open contacts to provide an input to other circuitry. In contrast, the pressure sensor can provide either an analog or digital output to the washing machine control unit. Since the pressure sensor’s output directly results in a power control function such activating a pump or motor, in some manufacturers products, the pressure sensor is mounted in a Power Control and Pressure Sensing Module. The water level in most washing machines is well below 2 feet (0.87 psi), so a pressure sensor that can measure 1 psi would work in this application.

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Air pressure is sensed to measure water level in washing machines. Source: http://removeandreplace.com/wp-content/uploads/2013/12/washer-overfill.jpg

 What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
- Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)

The Pressure in Bubbles

Sep 27
2016

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll be discussing the pressure in bubbles.

The Pressure in Bubbles

The surface tension of the interface between liquid and gas creates a pressure difference. For a soap bubble, the pressurized bubble of air is contained within a thin, elastic surface of liquid. When the bubble bursts, the difference in pressure causes an audible pop.

The pressure difference can be calculated by using a simplified version of the Laplace pressure equation since the inner radius is essential the same as the outer radius. In this case,

Pi-Po = ΔP = 2*(2γ/R)

Where:

ΔP is the pressure difference in N/m2 or Pascals (Pa)

γ is the surface tension in N/m

R is the radius of the bubble in meters, and

2γ/R is the Laplace pressure.

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The ΔP is 2 times the Laplace pressure since there is a complete sphere instead of a semi sphere on a layer of water.

Based on the diameter, the pressure inside an air bubble in pure water, where γ = 72 mN/m at 25°C (298 K), can vary greatly.

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What do you think/Comments?
Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Han Mai, Senior Marketing Specialist, All Sensors Corporation (hmai@allsensors.com)