The Pressures That Were Rome

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 Pressures That Were Rome

Engineering was among the skills that allowed the Romans to expand and maintain their vast empire: the roads that led to Rome, Hadrian’s Wall that divided Britannia, the Coliseum, the Pantheon and aqueducts, the plumbing that brought water to the Seven Hills.

The Aqua Claudia, one of 11 aqueducts of Rome, channeled fresh water 46 miles into Rome (Unearthed: S7 E12, Seven Wonders of Rome) based on gravity alone without any additional pressure. To maintain a consistent gradient with minimal deterioration of the channel, the water flowed due to a drop of only 9 inches (0.3 psi) in 30 feet.

Roman Aqueducts - Aqua ClaudiaA mountain channel and portion of Aqua Claudia
Source: http://www.romanaqueducts.info/aquasite/romaclaudia/

According to legend, one of the more amazing water pressure feats in Rome was the flooding of the Coliseum to hold simulated sea battles. Archeologists believe a three-foot-wide tunnel running between the walls of the Coliseum may lead to a labyrinth of circular channels that flooded the floor in the center of the arena. The hydraulic system would have required significant pressure and produced a rapid flow of water to flood the arena to a depth of around 1 ½ meters with 3 ½ million gallons of water within a few hours. Water flowing directly from the aqueducts could not have produced these results.

Discovering the ruins of a monumental fountain uphill from the Coliseum, archeologists speculate that water from an aqueduct fed the fountain and was stored 6 meters (almost 20 feet) above the Coliseum. With a sufficiently steep grade, the hydraulic pressure from this height (8.7 psi) may have been enough to accomplish the flooding. After the sea spectacle, four huge drainage channels opened to flush the water away so the more well-known gladiator competitions could be held.

Pressure to Resuscitate

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 to Resuscitate

Unless you have had specific training, what you know about cardiopulmonary resuscitation (CPR) may be based on what you have seen on television or in a movie. You push on the unresponsive patient’s chest when they are not breathing. The compressions (pressure on the chest) take the place of a non-beating heart to keep blood flowing.

According to “Technique for chest compressions in adult CPR,” “Chest compressions have saved the lives of countless patients in cardiac arrest as they generate a small but critical amount of blood flow to the heart and brain.”

And, unlike other medical actions, chest compressions can be initiated by any healthcare provider without a physician’s order.

First aid response for CPR

First aid response for CPR
Image source: Science Photo Library.

For those not trained in CPR, the American Heart Association recommends hands-only CPR: uninterrupted chest compressions of 100 to 120 a minute until paramedics arrive. This means pushing straight down to compress the chest using your upper body weight (not just your arms) at least 2 inches (or about 5 centimeters) but not greater than 2.4 inches (about 6 centimeters). With the compression, the heart is squeezed and increases both the aortic and the right atrial pressures. Normal aortic pressures during systole (from the time the aortic valve opens until the peak aortic pressure), range from 80 mmHg to 120 mmHg. So how much pressure is required for the heart and for the brain in CPR? In a laboratory environment, researchers continue to explore the implications to improve the outcomes of CPR.

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Pressure in Food Processing

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 in Food Processing

High pressure processing (HPP) is a method of preserving and sterilizing food. Also called high hydrostatic pressure (HHP) processing, pascalization and even bridgmanization, pressures above 400 MPa (58,000 psi) at cold (+ 4°C to 10°C) or ambient temperatures inactivate bacteria, virus, yeasts, molds and parasites present in food. Unlike other food processes that use heat to remove bacteria, the high-pressure, cold pasteurization approach preserves the taste, freshness and texture of food.

Hiperbaric USA - pressure in food processing

In HPP, a food product sealed in its final package inside a vessel is subjected to a high level of isostatic (uniformly applied) pressure from 300–600 MPa (43,500-87,000 psi) transmitted by water.
Source: Hiperbaric USA.

The process is used for a wide range of foods from juices and beverages to fruits and vegetables and meat and seafood products to baby and infant foods, dairy products and more.

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Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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Pop goes the Chip Bag

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.

Pop goes the Chip Bag

Transitioning from lower altitude to a higher altitude decreases the pressure on a sealed container. Normally this would be recognized by the bloated appearance of the product in a sealed bag and a rapid release of the pressurized air inside when the bag is opened.  However, if the bag’s seal is weak, the bag can explode with a surprisingly load pop, en route.

This occurred recently on a trip where the altitude changed from 1248 feet to 7500 feet. Taking the temperature difference into account, the external air pressure changed from 14.08 psi (97.8 kPa) to 11.25 psi (77.6 kPa). This resulted in the decrease in external pressure of 2.83 psi (20.2 kPa or 78.3 inches of water) – sufficient to explode the weak seal.

Surprisingly, this wasn’t the only time that a bag of the same brand of chips lost its seal during the same trip but previously the bag did not explode. Since several other brand of pretzels and other munchies did not experience a bag failure during many trips, it appears that a little product line pressure testing during packaging is in order to minimize a weak seal.

Air Pressure in a Chip Bag

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