Tag Archives: All Sensors

The Pressure in an Iron Lung

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.

The Pressure in an Iron Lung

Before today’s respirators, patients with several breathing problems relied on a machine called an iron lung. Unlike the modern respirators that use positive pressure (greater than 1 atmosphere) that force air into the lungs, the iron lung was a negative pressure ventilator. The machine surrounded the person and the sealed cavity’s pressure was reduced to induce inhalation by the patient and then the pressure was increased to 1 atmosphere (15 psi or 750 mmHg). While all but obsolete today, these types of machines were extensively used when patients with polio were treated because of loss of muscle control that extended to their ability to breath. Thankfully, Dr. Jonas Salk discovered a vaccine to prevent polio (in 1953) and subsequent vaccines have eliminated polio as a health problem and today positive respirators using microelectromechanical systems (MEMS) pressure sensors can be so small that they are portable.

Iron Lung

The pressure gauge in this iron lung has been replace in modern respirators by MEMS pressure sensors. Source: Pittsburgh Post-Gazette website.

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Pressure – Can You Dig It?

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.

Pressure – Can You Dig It?

You certainly can dig a trench with pressure. Even a rather small pedestrian (walk behind) trencher with a 48” or smaller boom uses 2,900 psi of hydraulic pressure. With a 48” boom, a compact trencher has track ground pressure of around 4.6 psi. While the high pressure is developed in a hydraulic drive using a pump and motor to transmit power, the much smaller ground pressure indicates how well the weight of the machine is distributed.

Ground pressure is very important in areas that require a light footprint from equipment, such as public parks, ball fields, cemeteries, public beaches and, in fact, any finished landscape. The choice of tires or a track system makes significant difference in ground pressure. A track model can exert from 2 to 4 psi of ground pressure and a model with tires will exert about 7 to 12 psi of ground pressure. While the tires value may seem like it is way too high, for comparison, an adult standing on the lawn would exert about 6 to 8 psi of ground pressure. So, in most instances, a person digging the trench by hand actually generates more ground pressure. This is just another example of how knowing the actual pressure value is important to make the right decision.

Ground Pressure by the Numbers

A heavy-duty construction rubber track crawler carrier has a lower ground pressure than the average human being. Source: Teremac News, 12/6/2013.

Comments/Questions?
Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
Email us at info@allsensors.com

Water Pistol Pressure

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.

Water Pistol Pressure

Q. How do you elevate the basic water pistol experience?

A. By giving it more pressure.

Operating similar to the opposite of a hydraulic jack, a common water pistol employs Pascal’s Principle for a fluid at rest in a closed container: a pressure change in one part is transmitted without loss to every portion of the fluid and to the walls of the container. In equation form, it’s:

P1=F1/A1=P2=F2/A2

For the pressure to remain constant, if A1=n*A2, then F1=n*F2.

SuperSoaker water pressure

To take the water pistol to the next level, NASA engineer Lonnie Johnson conceived of the idea of a pressurized water gun with a pressure reservoir that became the Super Soaker. The ultimate Super Soaker used a constant pressure system (CPS) with a separate compression chamber that contained a thick-walled rubber balloon.

While the difference in the length and amount of the output (flow) of a standard water pistol vs. the Super Soaker vs. the CPS 2000 Mark1 Super Soaker is discussed in several blogs, the pressure in each is not. Those interested in pressure will just have to make their own measurements. All Sensors’ SPM 401 Series or CPM 602 Series pressure sensors with media isolation could provide those measurements.

Comments/Questions?
Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
Email us at info@allsensors.com

Widget Pressure

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.

Widget Pressure

Inside a can of Guinness and a few other beers, a plastic widget releases pressure when the can is opened and exposed to atmospheric pressure. While the process is explained briefly and to the extent that a typical beer drinker cares to know on the can, there are a few other compelling technical aspects that someone involved with or interested in pressure sensing might want to know.

For one, the widget is a patented approach to solving a problem that a canned stout beer, like Guinness, has compared to typical lager or lighter beer or ale. For the later types, carbonating the beer with carbon dioxide (CO2) is sufficient to give the beer its expected head when the beer is poured. In contrast, Guinness and some other beers are expected to have a smoother head. With a widget in the can, these beers have the desired, much creamier, longer lasting head that the draft version has.

The 3-cm diameter widget looks like a ping pong ball but it has a laser-drilled, 0.61-mm pinhole in it. In the canning process, in addition to filling the with CO2 and nitrogen (N2) supersaturated stout, liquid N is added to the stout at the end. The liquid N boils off during pasteurization, the top of the can pressurizes and forces the stout into the pod until equilibrium is reached at about 25 psi.

Mug of Beer with widget

When the can is opened, the pressure is released and the small amount of beer in the cavity rapidly escapes through the pinhole providing sufficient agitation to reproduce the tap handle character for the beer. Enough of the technical stuff. It’s time to verify the results.

Comments/Questions?
Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
Email us at info@allsensors.com